GPG316 - undertaking an industrial energy survey

GPG316 - undertaking an industrial energy survey
Good Practice Guide 316
Undertaking an industrial
Advice for end users on finding energy cost savings
this guide
Why and how to use this guide
finding savings
Topic guides on common industrial processes, related topics and site services
survey pro formas and reporting
Data sheets for recording survey data and results
Supporting data, and sources of further advice
Appendix A Reporting
Appendix B Selecting and briefing a consultant
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why and how to use this guide
why and how to use this guide
Purpose of this guide
Energy surveys in perspective
Surveys and audits
Doing your own energy survey
The UK industrial sector uses the equivalent of about 36 million tonnes of oil each year,
and the service sector 21 million. Between them, they spend over £10 billion a year and
account for over a third of total inland energy consumption. Transport uses a similar
amount. There is now little doubt that the resultant carbon dioxide emissions
contribute to global warming, and the Government is committed to reducing our
output of CO2 to 20% below 1990 levels by 2010. So what? How does this big picture
relate to your everyday business needs, when you are focused on costs, and energy
probably doesn’t account for even 2% of your overall business purchases? Four reasons:
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Energy bills are often regarded as an overhead charge to be paid ‘on the nod’ without rigorous
scrutiny. This view can be challenged. Energy costs may be a small proportion of total costs, but they
are a significant proportion of controllable costs, and furthermore carry a high risk of being partly
unnecessary. The cost of eliminating avoidable excess energy expenditure can be much lower than
the cost of ignoring it, and cost savings of 5%-25% are generally achievable. Moreover, for a
company operating on slender margins, this small saving on energy can give a disproportionate
boost to profit. An equivalent boost to profit might be achieved by increasing sales; but that would
obviously entail far higher costs (otherwise the company would already be doing it) and might
require investment in extra production facilities.
Most scientists believe that global warming is a real threat. In a busy industrial site, such global
considerations may seem remote. But your workforce may be sympathetic to the environmental
message, and may even include enthusiasts who would welcome their employer adopting a socially
responsible, proactive stance. Green credentials may also influence customers, and relations with
local communities may benefit. If you have environmental certification, you will need a continuous
flow of quantifiable improvements if you are to retain your status; an energy-saving campaign is
one of the few ways of guaranteeing demonstrable year-on-year improvement. It will also help if
your company is applying for ISO14001 or a similar environmental management certification.
Active energy management often results in reduced plant running hours, bringing reduced
maintenance costs, less frequent breakdowns, and less noise and unwanted heat. Sometimes,
working conditions are improved as well. For example, modern high-frequency fluorescent lamps are
flicker free as well as cheaper to run, and heating systems recommissioned to operate economically
sometimes work more effectively too. These factors improve staff morale and productivity. Even a
small reduction in electricity demand can be valuable because of the reduced peak demands; this
has enabled some factories to avoid paying for costly upgrades to supply transformers when extra
capacity is needed. And advanced techniques of energy management can even inform and enhance
other cost-reduction activities.
If your company is covered by Part A of the Pollution Prevention and Control (PPC) Regulations you
will find that you are under a legal obligation to save energy. And if you are a party to a Climate
Change Agreement (CCA), you could lose a valuable Climate Change Levy (CCL) discount by failing
to make progress against your agreed energy saving targets. Loss of CCL discount would typically
be the equivalent of a fine equal to more than 10% of your non-oil energy bills. Finally, the new
Building Regulations compel businesses to incorporate energy-efficiency measures when even
relatively minor work is carried out on existing buildings.
this guide
The role of senior management
A successful energy saving campaign demands the
active support of senior management. There is no
suggestion that energy saving should enjoy ‘special
pleading’ unless the company’s policy says otherwise.
You will need to create the right corporate conditions
for progress:
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The company should appoint an ‘energy manager’ somebody (possibly acting part time) whose task it will
be to originate and coordinate energy-saving projects
and procedures.
The appointed energy manager must be allowed
reasonable specialist training to make them fully
effective, and their knowledge and experience must
be respected.
The company must back the appointed energy manager
when they cannot get the required help and information
from department heads.
If levels of service provided by energy systems are
inadequate, the company must be willing to
resolvethese issues. Otherwise there will be no support
for energy-saving initiatives.
The company must be prepared to adopt an energy
policy, in the interests of curtailing argument about
whether and how certain things should be done.
When faced with proposals for spending on energy
saving projects, the company must assess the financial
case fairly. Just because a cost-reduction project
increases profit without increasing sales should not
count against it.
this guide are a general manager, please focus on:
Section 1 and the management topic guides
2.a to 2.d
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responsibility please start on
Sections 1 and 2 and then move on to
the other sections
Section 1
Section 2
Section 3
Section 4
Contains a series of
survey topic
guides, each
focussed on a
particular factory
service or generic
process. There are
also four
management topic
Provides guidance
on reporting
including examples
of usefull tables
Contains reference
The purpose of this guide is to help you find
practical opportunities to save energy in
your business. It is based on the assumption
that while you may know little about
energy, you nevertheless have eyes and ears,
and common sense. The guide provides a
structured framework for a simple ‘walkthrough’ energy survey, supported by ‘topic
guides’ which deal with the more common
industrial processes and factory services.
The survey which you will carry out with the help of
this guide is only a first step on the journey to lower
energy costs, improved environmental performance,
and all the other incidental benefits of active energy
management. It will be a snapshot – with all the
limitations that implies. But it will be a start, and in
the course of your survey you will probably make
immediate economies by detecting and rectifying
some obvious things which are wasting money.
You will also establish how much energy you are using
through the year, and how much it is costing. You may
be able to attribute some of the consumption to
specific processes or activities and if consumption is
driven by production and/or other factors, you will
have calculated a headline performance ratio which
you will be able to use for tracking future progress.
Saving energy requires action. A survey will provide a
list of opportunities with associated costs and savings
from which priorities can be determined. Some
measures will involve no expenditure (eg resetting
heating controls). Some will require investment.
This guide does not set out to provide tuition in the
principles of energy management, nor to act as a
substitute for the wealth of useful information published
by the Energy Efficiency Best Practice Programme.
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Once you have listed a number of opportunities for
further investigation, you will know where to turn for
more information and advice on a particular topic. In
some cases, using the ‘tips and tricks’ mentioned in
some of the topic guides, you will have been able to
estimate current energy losses and associated costs.
This will put you in a stronger position when assessing
the viability of solutions proposed to you by suppliers
of energy-saving equipment and services.
1.1-1.2 this guide
Energy surveys are important because they identify
how savings can be achieved. But there is more to
energy management than surveys alone. This diagram
structures the task of saving money through energy
management, and thereby sets surveys in perspective:
Save money
Reduce quantity purchased
and environmental impact
Reduce cost per unit
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Reduce avoidable waste
This is the activity for
which an energy
survey is most
relevant, especially
where money is
available to carry out
remedial works or
modifications. The
survey explicitly
reveals the
opportunities for such
physical changes,
which also have the
benefit of reducing the
environmental impact
of an organisation.
During an energy
survey, examples of
bad practice may be
revealed. These will
often have ‘no-cost’ or
‘low-cost’ solutions.
The question also
needs to be asked: are
there procedures in
place which would
prevent these things
happening again?
diagnose and
A one-off energy
survey is of limited use
in support of this
activity because it is
only a snapshot. The
detection of
waste is best dealt
with by regular longterm routine
monitoring and
targeting. However,
periodical snap
inspections based on
energy survey
principles could
provide some measure
of defence.
and monitor for
billing errors
Because energy
surveys focus
exclusively on the
physical aspects of
energy consumption,
they have little
relevance to this
activity – with one
major exception.
Where costs are
dependent to any
extent on peak
demand, the energy
survey may reveal
opportunities to
improve load factor
and thereby cut the
peak-demand element
of energy charges.
Fig 1.1 Energy management- an overview
At the beginning of an energy management initiative
it is important to determine the current position.
Once this has been established it is then possible to
set goals and priorities for future improvement.
To determine the current position it is important to be
able to answer questions such as:
What types of energy are used?
How much is being used?
How much does it cost?
Where is the energy being used?
How efficiently is energy being converted,
distributed and used?
What are the potential savings?
How can they be achieved?
How much will it cost to achieve the savings?
What are the priority areas?
All the questions posed are important and can be
answered by conducting an energy survey.
Energy audit: a study to determine the quantity and
cost of each form of energy to a:
Process/manufacturing unit…
Piece of equipment…
…over a given period, usually a year.
This example is from a food manufacturing site with data from a 12-month period:
Average cost
Energy type
Natural gas
Energy survey: a technical investigation of the control
and flow of energy in a:
Process/manufacturing unit…
Piece of equipment…
…with the aim of identifying cost-effective
energy saving measures.
Energy surveys can be conducted on entire sites,
individual manufacturing units, utility systems or
specific items of equipment.
Usually surveys include an examination of:
Energy conversion: where energy is converted from
one form to another, eg heaters, boilers, furnaces,
refrigeration units, compressors, turbines, etc.
Energy distribution: where energy is distributed,
eg electricity, gas, steam, air, water, hot oil systems.
Energy end use: where energy is used in plant,
equipment and buildings.
Management systems: how information is
obtained, analysed, and used. Management
and people issues.
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Gas oil
1.3 this guide
An energy survey will usually give a management
summary and divide recommendations into three
main categories:
No-cost measures (good housekeeping).
Low-cost measures.
High-cost measures.
Examples of these three categories are
given below:
Estimated annual saving
Reset cooling plant time switch controls
Reset AHU time switch controls
Reset conditioned areas temperature set
point during summer
Isolate skirting heating during cooling season
Reinstate AHU heating coils
Switch off air conditioning plant
Estimated costs
Estimated annual saving
Estimated costs
Install dehumidifier in building 10
Insulate boiler headers
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Estimated annual saving
Overhaul flue gas dampers, flow isolation
controls and sequence control on main boilers
Estimated costs
Presence-detector control of lighting
Insulate valves on heating pipework
When an outside consultant does an initial energy
survey to identify likely avenues for further
investigation, they will usually cover the following
gather base data on monthly consumption
and expenditure over the last year;
become familiar with the site and the work
done there;
become familiar with how energy is
currently managed;
study the main services facilities
(boilers, compressed air, lighting, etc) searching
for energy saving opportunities;
review opportunities for saving energy at the
point of use;
estimate likely implementation costs, savings,
and paybacks, usually from insufficient data;
write a report in a prescribed format and have
it checked for accuracy.
The consultant’s advantages are primarily depth of
technical expertise, breadth of experience, and
freedom from urgent interruptions. The consultant can
look at your site and its problems and opportunities
with a fresh pair of eyes. An appropriately-chosen
consultant will have surveyed many sites and will
know the likely sources of possible energy savings in
your sector. But he or she usually has limited time:
perhaps only one day on site and two days for analysis
and reporting. Your ability to take your time, spreading
the work over a longer period if you wish, is only one
advantage which you enjoy. Here are the others:
You will already be familiar with the site and
its activities.
You will be freer to come and go, and won’t
need an escort.
You know who has the information you need,
and if you overlook something, you can go back
at any time.
You can ask others to help you, parcel out some
parts of the survey to more appropriate colleagues
if you want, or mobilise a workplace study group
in the style of a quality improvement team.
If there are other surveys going on
(on safety, quality, or environmental themes),
you may be able to join forces.
If the base data which you need is not
forthcoming, you can ‘pull strings’ or even get
into the ledgers yourself – or simply busy yourself
with other aspects while the data works its way
through the system.
You are not obliged to write a formal report
(although it would be unwise not to record your
findings, calculations and recommendations for
others to read later; you may also need a
summary to obtain funds for investment in
energy saving measures).
You can legitimately build on the work of others
before you.
You can elect to ignore whole aspects.
You can improvise measurement techniques, even
turning things on and off (within reason) to gauge
their effect on consumption.
You may be able to experiment with variations
to processes.
This guide has been designed so that you can work
within the limits of your own expertise. Once you
need to go beyond those limits, or cannot devote the
necessary time, using the guide will not only equip
you better to brief an outside expert; it will have
helped you establish that his or her fee is justified.
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This provides a backdrop to your eventual findings and helps to
set the subject in a meaningful context for general
management. Copies of energy invoices should be available in
your accounts department, but suppliers will sometimes
provide historical summaries.
Establish current patterns of overall
consumption and expenditure at
site level.
Does a meaningful yardstick energy
ratio exist for your industrial sector?
Calculate the figure
for your site.
Tabulate where in the works you
have examples of particular
processes and services
(eg compressed air, treatment vats).
You can use the topic matrix at the beginning of Section 2
as a guide.
Visit each area or department in
turn. Using the appropriate topic
guides as a prompt, look for things
which are obviously wrong and need
to be corrected.
Common generic processes and services are each covered by a
survey topic guide sheet in Section 2.
If you are not sure what to look at first, start with the principal
central services and the largest process users.
Report your findings, and put into
effect whatever low-cost and no-cost
measures you have identified.
There is a selection of pro forma recording sheets in Section 3.
Identify opportunities which may
apply to your site in particular.
Might funding be available for
energy-saving projects?
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Continue to monitor performance
systematically in order to track and
verify subsequent savings.
Systematic monitoring against targets can
save money in itself, by revealing the onset
of unexpected hidden waste. Further
advice on this topic is in management
topic guide sheet C.
By measurement, experiment, or
inference, estimate present energy
consumptions of affected plant, and
likely savings in each case.
Obtain quotations for possible
energy-saving solutions.
Calculate the financial viability of the
projects you are proposing, and present
recommendations for those most likely
to receive approval.
Implement approved projects.
1.4 this guide
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topic guides on common industrial processes and site services
topic guides on common industrial processes and site services
Management topic guide a:
2.10 Fans and pumps
Organising energy management
2.11 Burners
Management topic guide b: People
2.12 Steam systems
aspects of energy management
2.13 Crushing and grinding
Management topic guide c:
2.14 Mixing and blending
Targeting and monitoring
2.15 Drying
Management topic guide d:
2.16 Baking and curing
Making the case
2.17 Machining, forming, and fabrication
2.18 Tanks and vats
2.19 Treatment booths and cabinets
2.20 High temperature processes
Space heating
2.21 Cooling systems
Air conditioning
2.22 Heat recovery
Hot water services
2.23 Mechanical handling
Compressed air services
2.24 Motor transport
Central vacuum services
2.25 On-site catering
Electric motors and drives
2.26 Building fabric
2. finding savings
The topic guides in this section provide a framework
for your survey. They are structured as follows.
Each deals with a generic industrial process (boilers,
for example) or a site service such as lighting or
compressed air.
Each starts with a list of things to look for. These are
things which are often amiss, where common sense
and local knowledge will normally be sufficient to
dictate an appropriate remedy, and where it should be
quick and cheap – or even free – to put the problem
right. This may be as far as you need to go.
For those who want to go further, each topic guide
has a selection of tips and tricks.
Next comes a list of potential opportunities. These
only apply if you are prepared to contemplate
moderate to high cost remedial works.
Finally, each topic guide includes references to further
information. Much of this is free information from
the Energy Efficiency Best Practice Programme.
Note: other common sources of information
are listed in Section 4, ‘Sources of
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The site can be zoned however you wish. Illustration
(A) shows just two zones – production and nonproduction. (B) has six buildings split into eight
distinct zones, while (C) is a geographical split.
Not all of your site will feature every kind of process
and service covered by the topic guides. You can use
the matrix to record which topics are relevant where.
First divide the establishment into appropriate zones
and label each column of the matrix accordingly.
A ‘zone’ might be a boiler house or plant room, an
entire production floor, a store, a canteen block, or
however you decide to define it. Take the matrix with
you on your initial walk-round and tick off which topic
guides you will need for each zone. The completed
matrix will help ensure that you later investigate (and
report) every aspect.
Before carrying out any experiments or modifications,
prepare a method statement and assess the risk of
unintended consequences.
Success factors to look for
An enthusiastic champion.
A motivated and energy-aware workforce.
A culture of engagement and co-operation.
Support from senior management.
True accountability for energy costs.
Corporate willingness to rectify problems with
existing energy-related services.
Training for those whose day-to-day work
impinges on energy efficiency.
A team approach on the part of the
relevant players.
Continuous feedback of results and achievements.
Opportunities created by external factors
(eg supply capacity constraining growth).
Assessment and goal-setting
The energy management matrix (fig 2.1) is divided
into six key organisational aspects of energy
Performance measurement
To obtain an indication of the current state of the
organisational aspects on your site complete the
matrix by putting one cross in each column. The box
you mark under each column should represent the
current status on your site. Then join your crosses
across the columns to produce your organisational
profile. This will show your strengths and weaknesses.
Weaknesses can undermine strengths so the ideal
profile is one which is relatively flat. From that
position it is important to advance on all aspects
up the matrix.
Some companies find it useful to copy the matrix and
get a group of managers to individually complete the
matrix in a meeting and then compare findings.
It provides useful management overview in a pictorial
form and highlights points for further action.
In the rest of this section each of the organisational
aspects are covered briefly with pointers to further
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Communicating Investment
Energy Policy,
action plan and
regular review have
active commitment
of top management
Fully integrated into
structure with clear
accountability for
Appropriate and
comprehensive staff
training tailored to
identified needs,
with evaluation
against targets with
communication of
energy issues within
and outside
Resources routinely
committed to
energy efficiency in
support of business
Formal policy but
no active
commitment from
Clear line
accountability for
consumption and
responsibility for
Energy training
targeted at major
users following
training needs
measurement for
each process, unit,
or building
Regular staff
reporting and
energy promotion
Same appraisal
criteria used as for
other cost
reduction projects
Unadopted policy
Monthly monitoring
Some delegation of Ad-hoc internal
responsibility but
training for selected by fuel type
line management
people as required
and authority
Some use of
mechanisms to
promote energy
Low or medium
cost measures
considered if short
payback period
Unwritten set of
Informal mainly
focused on energy
Technical staff
Invoice checking
occasionally attend only
specialist courses
Ad-hoc informal
contacts used to
promote energy
Only low or no cost
measures taken
No explicit energy No delegation of
responsibility for
managing energy
No energy related
staff training
No communication No investment in
or promotion of
improving energy
energy issues
Further information on energy policy
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Developing an effective energy policy
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A strategic approach to energy and
environmental management
Further information on organising
energy management
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Organising energy management - a
corporate approach
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Organisational aspects of energy
management: a self-assessment
manual for managers
Standards for managing energy
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Further information on energy training
GPG 85
Energy efficiency training and
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Managing people, managing energy
No measurement
of energy costs or
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M&T in small and medium
sized companies
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Introducing information systems
for energy management
Further information on communication
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Managing and motivating staff to
save energy
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Marketing energy efficiency raising staff awareness
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Managing people, managing energy
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Maintaining the momentum
Running an awareness campaign
action pack
Further information on energy-saving investment
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Investment appraisal for industrial
energy efficiency
Further information on measuring energy
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Financial aspects of energy
management in buildings
FEB 13
Waste avoidance measures
GPCS 251
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M&T in large companies
An energy management and
investment campaign in a
2.a finding savings
Fig 2.1 Energy management matrix
Every employee can make a contribution to saving
energy. Often, contractors should also be included.
Two key aspects are required: awareness and
Raising awareness covers the knowledge and skills so
that people see the potential for saving energy as an
integral part of their daily work. Awareness is knowing
what to do.
Motivation is more complex. It varies from person to
person. Key factors include ‘external’ motivators, e.g.
incentives, targets, competition to perform and
‘internal’ motivators related to personal outlook and
values (e.g. concerns for the environment).
Good housekeeping campaigns need to be integrated
into other energy management initiatives if
momentum is to be maintained.
On every site there are key people who can have a
large influence on energy consumption because of
their job function. These people need to be identified
along with their training needs so that they receive
appropriate training to be energy efficient. Individuals
are usually saving energy or wasting it and there is
rarely any neutral ground. In many industrial sites the
Pareto principle rules: 20% of the workforce control
80% of the energy.
If energy efficiency investment measures are not
supported by appropriate training then potential
savings will not be fully realised because of poor
operation, control and maintenance practices.
Investment in vocational training for key staff (e.g.
boiler or plant operators) not only saves energy but
also improves environmental performance and
standards of health and safety. The specialised needs
of the individual energy manager must not be
overlooked. Note that since 1997 when the National
Vocational Standards for Managing Energy were
introduced, it has been possible for individual energy
managers to gain a National Vocational Qualification
(or a Scottish NVQ) by compiling an evidence
portfolio based on their work.
In addition, the Standards may help you review or
specify the energy management function within
your organisation.
A framework for training needs
In a large operation, an integrated programme of
training may be worth developing. This will need to
address three categories of training need, and the
matrix below shows what topics might typically be
covered and at what level:
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Overview of energy efficiency and energy
management; Climate Change Levy, grant schemes
Operatives and
Engineers and
line managers
management and
technical services
Energy billing and procurement
Performance monitoring and targeting
Meter reading
Energy considerations specific to the process used
at the target site
Boiler operation
Steam distribution, utilisation, and condensate recovery
Pumps and fans
Electric motors and drives
Compressed air services
Heat recovery
V Vocational. Material directed at improving skills,
enabling trainees to do their jobs better. Likely to
include some practical element.
T Theoretical. Material aimed at improving
knowledge and understanding, enabling better
analysis and decision making.
A Awareness. Brief coverage to help trainees
understand other people’s objectives and
activities, to put their own contribution in context,
and to defuse potential conflicts.
Case studies
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At a small injection-moulding plant, about £2,000 was spent on meters
to make staff more aware of where and how energy was being used.
They saved £21,000 in the first year.
A manufacturer of decorative tiles persuaded its suppliers to donate
prizes for an energy awareness campaign.
2.b finding savings
Common shortcomings
If any of the following apply in your organisation, your
ability to manage the consumption of energy will be
Unable to provide routine weekly assessment of
performance and losses.
Prime drivers of consumption
(eg production flows) not catalogued.
Quantitative relationship between each
consumption stream and its drivers not known.
Timeswitches and other self-acting controls failing
in the ‘on’ position.
‘Best achievable’ relationships between
consumptions and drivers not used as targets.
Maintenance errors, such as fitting an oversized
replacement motor.
Regular records of driver values not kept in
synchronism with consumption data.
Inadequate submetering of significant processes.
Operating errors, such as running an air
compressor against a closed isolation valve.
No regular in-house meter readings or other
consumption figures.
Lax discipline, for example leaving auxiliaries to
run when not required.
No stocktake of bulk-delivered commodities in
synchronism with meter readings.
Analysis and reporting starts afresh each year
(instead of being continuous).
A management technique called monitoring and
targeting (M&T) is the most effective defence against
these kinds of loss, which a one-off survey would miss.
The next-best option - a regular programme of routine
energy inspections – would be a more costly exercise,
and would anyway miss many kinds of energy-wasting
fault because they are frequently of an unforeseen nature.
Reliance on crude ‘specific energy ratios’ as targets
for management control.
Reliance on same-period-last-year as a basis
for comparison.
Focus on percentage deviations
(instead of their absolute cost).
M&T works by combining regular consumption data
(usually weekly or monthly) with corresponding data
on production throughput, weather, or other driving
factors (called ‘variables’ in the older literature). An
M&T scheme is primed with targets for each stream
of consumption, these targets being related to the
relevant driving factor, so that given the level of
activity in the facility, a ‘correct’ ration of energy can
be estimated at each point of use. The deviation
between actual and expected consumptions indicates
the extent of any unexpected loss, which can then be
converted to its implied cost in order to establish
its significance.
No system for initiating and pursuing
investigations into unexplained deviations.
When a fault detected in this way proves persistent,
the pattern of deviation can be analysed as an aid
to diagnosis.
At another paper mill, losses of £13,000 a year were detected when it
was found that an oversized replacement motor had been fitted to a
vacuum pump following a breakdown.
An effective M&T scheme provides, in effect, a
continuous review of the site’s performance, and as
well as revealing random unexpected losses, it can be
used to monitor and verify the effectiveness of other
energy conservation measures. Verification is doubly
significant if your company is engaged in
emissions trading.
Specialist advice should be sought to rectify any
such shortcomings, and thereby maximise the value
to be obtained from regular meter readings and
other returns.
Case studies
Steam losses worth £9,000 a year were detected at a paper mill.
Someone had left a bypass valve open on a steam trap.
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An energy survey can only ever be a snapshot. It is
therefore best at detecting opportunities for
permanent modifications to plant, equipment,
buildings, and operating procedures. However, your
organisation may be incurring considerable hidden
costs through avoidable waste occurring at random
and remaining undetected. Examples could include
be done as a ‘before-and-after’ calculation
(based on, say, a change in running hours) or a
percentage reduction can be assumed.
Equipment and service providers will often help
with such estimates, but check their assumptions
and arguments critically – remember they have
an optimistic bias.
Most organisations can achieve significant energy
savings through low and no cost measures, such as
good housekeeping.At some point investment
will be needed.
Energy is one of the few cost elements present in the
manufacture of every industrial product. It is also one of
the key measurable and controllable contributors to
cost in at least 80% of all industrial production.
Commercially available equipment exists to reduce UK
energy consumption by 25%.
Barriers to energy-saving investment
There are three main barriers to overcome:
the low priority given to energy efficiency in
most organisations;
application of inappropriate standards of
investment appraisal;
decision taken at wrong level in the organisation.
Investment appraisal is merely a rational method of
making choices.Any healthy commercial enterprise
ought to be able to identify more viable opportunities
than it can afford to fund. It therefore has to choose
which projects are priorities for investment.
Very often energy managers use simple payback as the
criterion, even when promoting large projects. More
sophisticated methods are needed if the people judging
the case, who will usually have an accountancy or
business management training, are to take it seriously.
Suitable methods are explained fully in GPG 69
(see details below).
Multiply the reduction in units by the unit cost
of energy saved. Remember that the cost per unit
saved will often be less than the overall average
unit price.
Add any quantifiable incidental savings, such as in
manpower, maintenance, or capacity charges.
Note any additional costs which will offset the
expected savings.
Assembling the information
Before making a proposal the energy manager needs to
know the following:
The cost of the proposed work.
Any subsequent recurring costs.
The expected savings.
Risks and incidental benefits.
The criteria against which other capital expenditure
projects are assessed.
Presenting the case
An effective proposal will have the following attributes:
There should be a single unequivocal
recommendation (not a selection of choices).
The full costs must be stated.
Known risks must be disclosed and accounted for.
Against the risks, incidental benefits must be
presented as bonuses.
The method of analysing the financial return must
be as used for all other projects.
The proposed investment must satisfy the
company’s current criteria.
Assessing costs and savings
GPG 316 This version published 02/02
A short energy survey carried out by a consultant can
often provide nothing more than indicative payback
periods for each recommended energy-saving measure.
As the end user (and therefore the potential customer)
you are in a better position to get more definite figures,
and indeed it is in your interests to do so if your
proposal for capital expenditure is to be acceptable.The
sources of cost information are, in descending order of
Estimates or quotations from suppliers.
Knowledge gained from other people who have
done similar projects.
Generic estimates from engineers’ yearbooks.
A proposal will always stand a better chance of
acceptance if it can be aligned with the goals of any
current corporate campaign. Energy projects for
example often have beneficial environmental impacts
and can improve reliability.
Further Information
GPG 69
Investment appraisal for industrial
energy efficiency
GPG 75
Financial aspects of energy
management in buildings
GPCS 251
An energy management and
investment campaign in a glass plant.
The procedure for calculating savings is
Estimate the reduction in unit consumption
achieved by each proposed measure.This can either
2.c-2.d finding savings
A. Identify appropriate zones
B. Check which topic guides are needed for each zone
1. Lighting
2. Ventilation
3. Boilers
4. Space heating
5. Air conditioning
6. Hot water services
7. Compressed air
8. Central vacuum
9. Electric motors and drives
Processes and devices
10. Fans and pumps
11. Burners
12. Steam systems
13. Crushing and grinding
14. Mixing and blending
15. Drying
16. Baking and curing
17. Machining and fabrication
18. Tanks and vats
19. Treatment booths/cabinets
20. High temperature processes
21. Cooling systems
22. Heat recovery
23. Mechanical handling
24. Motor transport
25. On-site catering
Copy the matrix if you need to define more zones.
GPG 316 This version published 02/02
26. Building fabric
Potential opportunities
Things to look for
Note: the new Building Regulations compel you to
treat replacement lighting systems as if the building
were a new one.
People not even knowing where the light
switches are.
Brief security staff and cleaners to turn off lights
when leaving unoccupied areas.
Tungsten filament lamps running more than four
hours per day.
Improve labelling of switches, combined with a
staff awareness and motivation campaign.
Excessive light levels for the type of work
being done.
Replace lamps with more efficient equivalents
(e.g.T12 tubes with T8 tubes if fittings are suitable).
Large banks of lights controlled by a single switch.
Convert fluorescent lights to high frequency fittings.
Lack of labels on switches controlling
shared workspace.
Fit more switches per bank of lights, if
wiring permits.
Outside lights on fixed timeswitch or manual
Dirty or discoloured diffusers and shades.
Fit automatic lighting controls (carefully chosen to
suit the circumstances) especially in infrequently
occupied rooms. Photocells can be used for
external lighting.
Empty areas lit unnecessarily.
Dirty rooflights or other opportunities to use
more daylight.
Fit more effective reflectors and remove a
proportion of lamps.
In areas where colour rendering is unimportant,
use high-pressure sodium discharge lighting.
Artificial lighting in areas with sufficient daylight.
Further information
Survey tricks and tips
GPG 316 This version published 02/02
FEB 21
CIBSE Guide F Energy Efficiency in Buildings,
Section 19.6
GPCS 169
Energy efficient lighting in factories
GPCS 309
Subject to safety considerations, turn off some
lights and see if anyone notices.
Energy efficient lighting in
industrial buildings
GPG 158
Walk the site at night or during shutdowns to see
what lights get left on.
Energy efficiency in lighting for
industrial buildings
GPG 159
Converting to compact fluorescent
lighting - a refurbishment guide
GPG 199
Energy efficient lighting - a guide
for installers
GPG 272
Lighting for people, energy
efficiency and architecture - an
overview of lighting requirements
and design
CIBSE AM5:1991-Energy Audits and Surveys - grants for lighting
efficiency improvements for
small and medium enterprises
Estimate the lighting load by means of a
controlled test with the building unoccupied: read
the electricity meter at (say) ten-minute intervals
first with lights off, then with lights on.
Make a point of examining areas which have had
a change of use.
An inexpensive light meter will give enough
accuracy to establish if lighting is in line with the
following ‘adequate’ levels:
Type of use
Close detailed work
Stairs and corridors
Rest rooms
Street lighting
Security lighting
Simple measurements for energy
and water efficiency in buildings
Case histories
Use time-lapse video recording to study
intermittently-occupied spaces.
A cosmetics manufacturer invested £17,000 on automatic lighting
controls. Even with today’s lower electricity prices the project would
have yielded about 20% internal rate of return.
A plastics moulding factory refurbished its very inefficient lighting at a
cost of £9,640 and saved £47,750 a year.
2.1 finding savings
What to look for
Potential opportunities
Interlock local extract ventilation to occupancy
and/or activity.
Where dampers are used to control air flow rates,
consider variable speed control of the fans
(or even just two-speed motors) instead.
Local extract ventilation likely or able to run when
not required.
Eroded or fouled fan blades.
Fit high-efficiency motors to fans.
Clogged or obstructed grilles or filters.
Stuck or overridden dampers.
If excessive ventilation rates are confirmed, reduce
fan speed by changing pulley ratios.
Failure to exploit any existing air-recirculation
Further information
Inappropriate timeswitch settings.
CIBSE Guide F Energy Efficiency in Buildings,
Section 19.3
GPG 257
Energy-efficient mechanical
ventilation systems
GPG 139
Draught-stripping of existing
doors and windows
Survey tips and tricks
If fans are not visible or audible, air movement can
be detected by various means, including
improvising with a child’s bubble maker. Thin strips
of tissue paper can be suspended near extract
grilles to provide a more permanent ‘tell-tale’.
Pay special attention to areas which have had a
change of use where the original ventilation
requirements were more demanding.
To make a rough estimate of air flow into a
building through an air handling unit (AHU)
measure the cross-section of its inlet duct and
assume an average air velocity of 1.5 m/s. The AHU
may also carry a rating plate stating its design
capacity. Commissioning test reports may exist.
In the absence of other evidence, assume air
handling plant was designed to prevailing design
codes for the type of use.
Case study
A pigment manufacturer was discharging extract air containing water
vapour and traces of fine powder. A spray condenser, fitted at a cost of
£284,000, recovered the heat and scrubbed the powder from the
extract air. At today’s fuel prices the investment would have realised an
internal rate of return close to 50%.
GPG 316 This version published 02/02
Note: this section deals with water-circulation boilers
only, as commonly found on space heating systems. For
issues specific to steam boilers, see survey topic sheet
12, steam systems.
What to look for
Isolate boiler capacity in excess of peak requirements,
fitting isolation valves if necessary.
Fit flue dampers if heat loss from idle boilers cannot be
prevented by other means.
Rectify faults in boiler sequence control if low heating
loads are being shared by more than one boiler.
Improve control so that boilers are only enabled
when there is demand from one or more of the circuits
On boilers serving space heating on optimum
start control, ensure that there is a separate timing
signal for domestic hot water, which will require a fixed
start time.
Damaged or insufficient insulation on boilers and
associated pipework, valves or flanges.
Check for water losses by assessing the water
make up rate (which should be zero: see Survey
tips and tricks).
Check whether multiple boilers are sharing low
loads, when one unit ought to suffice.
Could boilers be running when there is no demand
other than their own standing losses?
Optimise high/low firing sequences to minimise the
number of ignition purge cycles.
Check if idle boilers are dumping heat up the chimney.
Apply weather-compensated boiler temperature
control if feasible.
Is heating-boiler time control dictated by hot-water
service preheat time (see Opportunities)?
Fit one condensing boiler to operate as the lead unit or;
See also the section on burners.
Evaluate a small combined-heat-and-power (CHP)
unit to substitute for the lead boiler.
Survey tips and tricks
A significant system-water leak will be evident from
the continual filling of the feed and expansion tanks.
Low leakage volumes can be detected by suspending
a small weighted container (such as a seaside
bucket) under the ball-valve spigot. If subsequently
found full, it signifies that the feed-and-expansion
tank must have been emptying.
GPG 316 This version published 02/02
Potential opportunities
To assess the degree to which boilers are oversized
and therefore likely to be incurring avoidable
standing losses, observe their firing cycles with a
stop-watch for about an hour, noting the ignition
and shutdown times for each boiler.
On space heating boilers, noting the outside air
temperature and the observed load factor, it will be
possible to extrapolate to peak demand
conditions (say -3°C outside).The alternative is to note
how monthly fuel consumption varies with degree days
and use this to estimate total demand on the peak day.
To assess whether idle boilers are dumping heat up
the chimney, check for air flow through the boiler, and
if confirmed, measure the stack temperature to see if
it is elevated (this technique is not always practical).
Check water temperature in off-line boilers to
confirm that they are isolated. If feeding a common
flow header, relate common flow temperature to
individual boiler flow temperatures to estimate the
proportion of flow through idle boilers.
Further information
CIBSE Guide F Energy Efficiency in Buildings,
Section 19.6
GPG 30
Energy efficient operation of
industrial boilers
FEB 17
Economic use of coal-fired boiler plant
FEB 15
Economic use of gas-fired boiler plant
FEB 14
Economic use of oil-fired boiler plant
GPG 43
Introduction to large-scale combined
heat and power (revised)
GPG 115
An environmental guide to small scale
combined heat and power
GPG 227
How to appraise CHP - a simple
investment appraisal methodology
GPG 226
The operation and maintenance of
small scale CHP
Applications Manual Condensing Boilers
Case history
A water company had numerous old cast-iron heating boilers. It conducted
a campaign to improve combustion efficiency through a standard retrofit
modification.The same project at today’s fuel prices would yield
70% internal rate of return.
2.2-2.3 finding savings
Note: Survey Guide Sheets 2.2 (Ventilation) and 2.10 (Fans
and Pumps) will also be relevant.
What to look for
See also the sections on hot-water boilers or steam-raising
plant, regarding inefficiency and losses in the boiler room.
The rate of heat loss from a building can be estimated
from the rate of temperature decay when the heating,
lights and equipment are turned off at the end of the day.
Potential opportunities
Fit improved heating system controls including possibly
zone isolation.Additional features could include optimum
start and weather compensation.
Fit de-stratification fans to prevent warm air pooling
at high level.
Fit fast-acting roller shutter doors, or secondary doors
to create an air lock.
Ventilation fans controlled on indoor air quality
(eg CO2 sensing).
Heating outside working hours
(whether deliberate or accidental).
Excessive space temperatures
(even if only in localised areas).
Uncontrolled heat output from distribution pipework.
Unauthorised supplementary electric heating.
Interlock loading-bay doors with heating.
Circulation pumps running when no heat is required.
Mechanical ventilation runs (or able to run) when
building is unoccupied.
Use docking seals around vehicles during
Irregular or irrational relationship between heating fuel
demand and prevailing weather.
In high-bay buildings, replace convective ‘blown air’
heaters with radiant tube or plaque heaters.
High ceilinged buildings in which warm air remains
at high level.
Have the heating system rebalanced to prevent some
areas having to be overheated in order to satisfy others.
Uncontrolled heat release from uninsulated distribution
pipework, or from fan assisted convectors in the ‘idle’ mode.
Replace electromechanical thermostats with electronic
equivalents, which give more precise control. Use the
opportunity to locate the thermostats in more
appropriate positions.
Temperature sensors and thermostats situated in
inappropriate locations.
Fit thermostatic radiator valves in rooms which suffer
from overheating.
Wrong thermostat type.
Frost thermostats set too high.
Fit black-bulb sensors to thermostats in areas served by
radiant heaters.
Anything which restricts heat output.This includes
blocked grilles, obstructed radiators, clogged air filters,
and missing air filters which have allowed convector
tubes to become fouled.
Where there is occasional out-of-hours working, provide
an extension timer to avoid having to reset the main
time control.
Risk of cooling and heating being used simultaneously.
Doors and windows which require draught proofing
or repair.
Fit a seven-day programmable controller if circumstances
warrant it.These can be applied not only to heating
systems but also to mechanical ventilation.
Automatic door closers not working.
In mechanically-ventilated buildings, investigate the
possibility of increased recirculation.
Holes in the building, for example under the eaves,
through which warm air can escape.
Possibly recover heat from air compressors (for example).
Walls and ceilings which have inadequate insulation.
Implement two-stage frost protection (eg when below
zero outside, start circulation pumps only; boilers not to
fire until internal temperature falls below say 5ºC)
Vehicle access doors which may be left open for
long periods.
Survey tips and tricks
Check that monthly fuel demand varies in a rational way
with changing weather (as recorded in published
degree day figures).
To measure temperature at high levels, use a digital
thermometer with a thermocouple on the end of
a long pole.
A 1ºC drop in average space temperature can cut fuel
consumption by about 8%.
Temporary datalogging can provide valuable evidence.As
a minimum record the inside and outside air temperatures
at ten-minute intervals. In ‘wet’ systems record the boiler
casing or flue temperature to detect when the system
starts and stops, and the circulation temperature to
check that heat distribution is appropriately controlled.
Further information
Energy Efficiency in Buildings,
Section 19.6
Degree days
Economic use of fired space heaters for
industry and commerce
FEB 16
Economic thickness of insulation for
existing industrial buildings
FEB 10
Controls and energy savings
GPG 132
Heating controls in small commercial
and multi residential buildings
GPG 197
Case study
Energy efficient heat distribution
A local authority halved the cost of heating its surveyor’s depot when someone
discovered that a maintenance contractor had left the heating running 24
hours a day.
GPG 316 This version published 02/02
Note: Survey Guide Sheets 2.2 (Ventilation) and 2.10
(Fans and Pumps) will also be relevant.
Things to look for
Excessively-low cooling set point (say below 22ºC).
Lack of time control, excessive hours of operation,
or risk of time-schedule being overridden.
Discontinue control of relative humidity if possible.
Consider alternatives to electric evaporative
Increase air re-circulation.
Make maximum use of fresh air for cooling,
including pre-cooling at night.
Implement enthalpy control.
Selectively inhibit out-of-hours ventilation to
optimise energy requirement.
Provide ‘spot cooling’ systems for zones with year
round cooling requirement, so that the main
central system need only be operated seasonally.
Excessively tight control of relative humidity.
Blocked filters.
Uninsulated supply ductwork.
Portable electric heaters.
Frost on pipework and fittings.
Further information
Air-recirculation potential not exploited.
Ventilation outside working hours
(other than for free cooling benefit).
CIBSE Guide F Energy Efficiency in Buildings,
Section 19.3
GPG 118
Risk of simultaneous heating and cooling.
Managing energy use - minimising
running costs of office equipment
and related air-conditioning
Risk of doors and windows being left open, holes
in building structure, or other infiltration routes.
GPG 290
Ventilation and cooling option
appraisal - a client's guide
Risk of air exchange with non-conditioned spaces.
GPG 291
Fouled evaporator or condenser coils.
A designer's guide to the options
for ventilation and cooling
Electrical appliances (e.g. computer monitors)
and lighting running unnecessarily.
Survey tricks and tips
GPG 316 This version published 02/02
Potential opportunities
Log chiller run hours regularly to detect running
during cool weather.
Observe operating patterns of air conditioning
chillers, cooling towers, etc., relative to outside
conditions; look for excessive running or frequent
on/off cycling.
Compare refrigerant suction/discharge
temperatures and condenser water temperatures
on similar plant items. Significant differences may
point to physical problems or incorrect settings.
2.4-2.5 finding savings
Survey tips and tricks
If a hot water cylinder is fed from its own break
tank you may be able to estimate the draw-off
rate by shutting off the rising cold feed and timing
the fall in water level.
Clamp-on ultrasonic flow meters can be hired but
are very prone to error and should be calibrated in
situ, at least approximately.
When measuring hot water flow, remember to
account for secondary recirculation if necessary.
Run a hot tap which has not been used for a while
and time how long it takes to deliver hot water.
Establish the number of full-time-equivalent
occupants and how they use hot water, in order
to estimate their requirements.
What to look for
Summer immersion heaters running
simultaneously with boilers, or at risk of doing so.
Long runs of uninsulated hot water pipework.
Hot taps being allowed to run to overflow.
Hot water being used where cold water
would suffice.
Poor insulation on hot water storage vessels.
Excessive temperatures at hot taps
(unless essential for control of legionella).
Unreasonable quantities of hot water being used
(see Survey tips and tricks).
Potential opportunities
Fit point-of-use water heaters in order to dispense
with central storage and long distribution runs.
These may be wall-mounted electric types in
washrooms, or direct gas fired for catering and
other larger users.
Fit flow restrictors to wash hand basins.
Fit time control to point-of-use heaters,
immersion-heater elements, and secondary
circulation pumps.
If HW is generated from main heating boilers,
consider alternative heat source for use outside
heating season.
If central HW generation is to be retained look for
alternative heat sources such as hot process drains
(beware contamination risk), flash steam or
hot condensate.
Rationalise multiple storage cylinders if demand is
low relative to stored volumes.
Recover heat from water-cooled equipment
and processes.
Further information
GPG 188
Maintaining the efficient operation
of heating and hot water systems a
guide for managers
GPG 316 This version published 02/02
Things to look for
Air leaks; particularly on connectors, flanges, and
flexible hoses.
Are compressors running when there is no demand
for air?
Air intakes drawing in warmer air than necessary.
Use the coldest possible air source to maximise
compressor efficiency.
Inappropriate uses. Low-grade duties (like swarf
blowing, or agitating liquids in tanks) do not warrant
clean, dry, air from the central system. See ‘Potential
Excessive distribution pressure. Higher pressure
means greater losses through leaks and higher power
requirement for the same delivered air volume.
Dead legs on distribution pipework. These present a
leakage risk.
Safety valves operating frequently, or leaking
Manual drains left cracked open.
Control pressure at the point of critical demand, not
necessarily at the compressor.
Divert compressor cooling air to where heat is
required. Look for a nearby application which could
benefit from air preheat. Even preheating boiler
combustion air is beneficial.
Heat rejected from oil coolers can assist hot
water generation.
Fit improved control of central compressors.
Computerised sequence controls could reduce
compressor run hours and prevent air loss and
wasted power through pressure overshoot.
Fit zone-isolation valves. These can be under time
control, or interlocked to the packing/production line
served, to enable parts of the site to operate out of
hours without air going to the whole works. If
combined with a pressure gauge, local leakage tests
would be possible.
To permit zone isolation it may be necessary to
rationalise air supply lines to eliminate cross-feeds
between different production units.
Install local air blowers for low-grade duties, for
example, liquid agitation, where low pressure and
high volumes of air are required without drying or
filtering. A separate blower reduces demand on the
central system and may permit a pressure reduction
or reduced operating hours.
Substitute alternatives for air tools. Would the
operators prefer electric tools (especially cordless
ones) capable of doing the same job? This is most
beneficial where a whole zone of air supply can
be cut out. But note: cordless tools are attractive
targets for theft.
Survey tricks and tips
Look and listen. Are air-pressure safety valves
operating? If so, control is inadequate. Can you hear
air escaping during meal breaks and after hours?
Are compressors starting and stopping frequently?
If the compressors have hours-run meters, read them
all at intervals through the day to see whether you
have more units running than necessary.
Compare on-load hours against total run hours to
check for idle running.
When production is shut down, isolate constant
bleed pneumatic controls.
If the air supply is metered, read regularly through
the day to establish patterns of use relative to
production activity. Look for unexplained idle losses.
Use actuators to time blowers instead of constant
air flow.
Use specially-designed nozzles for blowing applications.
Air meters can be unreliable. If a meter provides a
chart recording, look for symptoms such as the trace
being unexpectedly smooth, clipped off at maximum,
or never returning to zero.
Replace timed receiver drains with water-sensing
or float traps.
Switch to high-performance lubricants.
Consider high-efficiency motors and variable-speed
drives. See the Survey Guide Sheet 2.9 on Motors
and Drives.
GPG 316 This version published 02/02
After hours, shut off the compressors and either (a)
record the rate at which pressure subsequently falls
or (b) time the load/unload periods.
A ten-percent air loss might be considered acceptable.
Power delivered to air tools is ten times the cost of
electricity to do the same job.
Compressed air and energy use
GPG 126
Compressing air costs
Reducing air inlet temperature by 6ºC increases
output by 2%
GPG 216
Energy saving in the filtration and
drying of compressed air
Ask how often the filters are replaced. Blocked filters
cause pressure drop.
GPG 241
Energy savings in the selection;
control and maintenance of
air compressors
Potential opportunities
Further information
Use low-pressure blowers for applications such as air
knives, air lances, air agitation, blow guns, product
ejection, powder transfer, etc.
Case history
In 1991 a vehicle manufacturer spent £32,000 on an automatic
sequence control of its air compressors. Although electricity was then
more expensive in real terms, the same project today would still yield an
internal rate of return of 70%.
2.6-2.7 finding savings
What to look for
Potential opportunities
Install variable-speed drive controls on vacuum
manifold pressure.
Consider refrigeration circuits for liquid-ring
water cooling.
Replace vacuum-pump motors with high
efficiency equivalents.
Air getting in through leaks.
Ineffective closure flaps on vacuum hoses.
Oversized nozzles on hoses.
Redundant legs of vacuum pipework.
Manual on/off control, with risk of out-of-hours
Upgrade complete vacuum pump sets with more
efficient units during replacement.
Seal water running to drain from liquid-ring
vacuum pumps.
Where vacuum is provided for local cleaning of
components and assemblies at workbenches,
alternative methods (e.g. dedicated local systems
or even brushes and pans) may be feasible (but
consult the user).
Increase system working pressure.
Survey tips and tricks
Run vacuum pumps against shut-off conditions, and
measure air flow in the outlet duct. This equates to
upstream air in-leakage. Measure vacuum at inlet
manifold under these conditions and compare with
manufacturer’s load curve. Low vacuum at the
measured flowrate indicates loss of pump efficiency.
If necessary a manometer for low pressure
differentials can be improvised from a length of
transparent tubing bent into a ‘U’ with water in the
bottom, but beware any risk of water getting into the
measured system
Further information
GPG 83
Energy efficient liquid ring
vacuum pump installations in
the paper industry
GPCS 127
Cooling and recirculating liquid
ring sealing water
GPG 316 This version published 02/02
Repeat these measurements at appropriate intervals
(quarterly or annually) depending upon the degree
of risk.
Things to look for
Driven equipment not doing a useful job.
Oversized motors.
Risk of unnecessary running.
Voltage imbalance, low or high voltages, harmonic
distortion or poor power factor.
Unusually hot or noisy gearboxes.
Worn or slack V-belts.
Individual belt broken on multi-belt drive.
Misaligned pulleys or couplings.
Worn bearings in motors, driven equipment,
or intermediate drive train.
Start with the largest motors and longest running
hours first.
Pay particular attention to the noisiest machines.
3-phase motor power is derived from the
ammeter reading (I) by the following formula,
where V is the supply voltage and PF is the power
factor (typically 0.8 - 0.9)
√3 x V x I x PF
Compare the result with the motor’s nameplate
rating to see if it is only part-loaded.
Thermal imaging equipment can help pinpoint
frictional transmission losses.
Potential opportunities
GPG 316 This version published 02/02
On a part-loaded multi-belt drive, remove one or
more belts to leave only the minimum required for
the power actually being transmitted.
Consider variable speed drive or multi-speed
motor depending on the circumstances.
Where the duty toggles between high and low
load, consider replacement with a multi-speed
motor (up to four load steps may be
accommodated by MSM).
When V-belt pulleys need replacing opt for wedge
belts (2% improvement) or synchronous, flat, or
ribbed belts (5-6% improvement).
Where possible replace gearboxes with variable
speed direct drives.
Adopt high-performance lubricants.
Further information
Survey tips and tricks
Power =
Introduce time switching.
Fit automatic stop/start control
(this might include motor load sensing).
Substitute a high-efficiency motor when
replacement is necessary.
Consider soft-start controllers for intermittent
running motors.
Reduce losses in the driven equipment.
Change pulley ratios to run driven equipment
at optimum speed.
If permanently lightly-loaded, switch to
permanent star connection or fit a smaller motor.
Energy savings with motors
and drives
GPCS 215
Automatic switch-off of
power presses
GPCS 219
Two-speed motors on
ventilation fans
GPCS 337
Low cost speed reduction by
changing pulley size
GPCS 170
Variable speed drives in a
chemical plant
GPCS 222
Purchasing policy for higher
efficiency motors
GIL 56
Energy savings from motor
management policies
Case history
Changes at a food manufacturer had left them with excessive capacity
on a pneumatic conveying system. They spent £58 on a new pulley for
the blower (to reduce its speed from 2,420 to 1,700 rpm) and claimed
annual savings of £4,960.
2.8-2.9 finding savings
Further information
Energy savings with motors and drives
What to look for
GPG 14
Retrofitting AC variable speed drives
Unintended recirculation paths.
Variable speed drives on water pumps
Oversized motors.
GPCS 124
Excessive fan/pump speed.
Variable speed drives on secondary
refrigeration pumps
Excessive system resistance (for example because
of dirty filters, stuck valves or dampers).
GPCS 170
Variable speed drives in a
chemical plant
Unbalanced distribution networks with excessive
flow in some branches at the expense of others
being starved of flow.
GPCS 215
Automatic switch-off of
power presses
GPCS 219
Two-speed motors on
ventilation fans
GPCS 222
Purchasing policy for higher
efficiency motors
GPCS 232
Variable speed drives for wood dust
extract fans
Survey tips and tricks
Measure the flow and inlet/outlet pressures.
Compare them not only with manufacturer’s data
but with system design intent.
Air movement can be detected with tissue paper,
a smoke generator, or even a child’s bubble maker.
GPCS 300
Energy savings by reducing the size
of a pump impeller
Compare the performance of identical duty and
standby units.
GPCS 337
Low cost speed reduction by
changing pulley size
Potential opportunities
Case history
Where fans and pumps have variable duties
(controlled by dampers or valves), variable speed
drives should be considered as an option.
Inlet dampers are preferable to discharge dampers.
An airport operator fitted variable-speed drives to chilled-water
circulating pumps in 1990, achieving payback of a £50,000 investment
in just under two years. Even at today’s lower real electricity prices,
payback would still be less than three years, with an internal rate of
return approaching 30%.
Where fans or pumps are operating continually
at part load, consider reducing the impeller size or
changing the speed by using a different drive ratio.
Avoid sharp bends in ducts or pipework and
consider low-friction pipework when refitting.
On a pumped distribution network, reduce general
supply pressure and use a small booster pump for
the index circuit.
Rebalance any distribution system in which
throttling valves or dampers are being used to
regulate flow, so as to achieve design flow in all
branches with the minimum total flow.
On primary heating and chilling systems, replace
three-port diverting valves with two-port valves
and use variable-speed control of pumps to
regulate pressure.
GPG 316 This version published 02/02
Potential opportunities
Poor burner tuning resulting in flue losses through
excess air or unburned fuel (evidence by yellow
flame, soot in flue-ways, etc.).
Locate a source of preheated combustion air, such
as the exhaust from a dryer or other waste heat,
or even just ducting from the roof space. But note:
if preheat is not consistent, this can cause the
air:fuel ratio to vary.
Consider direct recuperation.
Unusual-shaped or unstable flame.
Flame impingement.
No probe-hole in exhaust flue, making combustion
tests impossible.
Reduce burner ratings to reduce stack exit
temperature and minimise on-off cycling;
or consider high/low or modulating burners.
Results from earlier combustion tests chalked
up nearby.
Use a larger number of smaller, self-proportioning
Combustion results identical from one test
to another.
Improve combustion control; consider
oxygen-trim control.
Combustion test reports where the reported
efficiency is inconsistent with measured parameters.
Pressure-regulation of combustion chambers
enables tighter adjustment of air:fuel ratio.
In some high-temperature furnace applications,
using pure oxygen instead of air can be
economical and may for example give a hotter
flame or better product quality.
Things to look for
Survey tips and tricks
GPG 316 This version published 02/02
If testing for combustion efficiency by means of
CO2 percentage, remember to test for smoke
(in the case of oil and solid fuel) and carbon
monoxide (in the case of gas). Without these
measures it is impossible to say whether a given
percentage of CO2 represents lean or rich
combustion; a rich mixture will cause losses
in unburned fuel.
Compare similar units. Is one appreciably better
than the others?
Where several items of combustion plant discharge
into a common flue, beware the effects of variable
suction. Record draught-gauge measurements.
With pressure-jet oil burners, ask when the nozzles
were last cleaned or replaced. It is often
economical to replace them at every service;
whereas ‘cleaning’ usually damages them.
Look for hot spots on casings
(may indicate impingement or refractory damage).
Time on/off/purge cycles.
Further information
GPCS 356
Conflict control of a combustion air
fan on a large continuous furnace
GPG 252
Burners and their controls
Variable speed drives on a boiler fan
GPCS 125
Variable speed drive on a batch
furnace combustion air fan
Case history
In 1993 an engineering works installed recuperative burners,
improved burner control, and fitted low-thermal-mass insulation to
a heat treatment furnace. £21,000 investment was recovered in
1.5 years and the indicative internal rate of return at current fuel prices
is just under 50%.
2.10-2.11 finding savings
Things to look for
Steam leaks.
Missing, wet or damaged insulation.
Flooding in pipe ducts.
Steam traps passing steam.
Steam traps not passing condensate.
Condensate running to waste.
Flash steam being lost from receivers and hotwell.
Dead lengths of pipework, or long runs of pipework
with very small users at the end.
Potential water pockets caused by concentric
reducers, large globe valves or wronglyfitted strainers.
Group trapping (several heat exchangers sharing
one trap).
Bypass valves on traps (not strictly necessary
and may be left cracked open).
Manual temperature control of process items.
Condensate overflowing to waste at
collecting points.
Pipework which does not have a fall towards
drain pockets.
Low feed tank temperature.
Manual control of dissolved solids.
Unnecessarily-low total dissolved solids.
Insufficient reserve volume in feed tank
to accommodate peak condensate return
during start-up.
Ask the boilerman about the frequency and
quality of maintenance.
Steam traps may be fitted with sight glasses or
‘Spiratec’ devices to verify operation.
Thermodynamic traps may be heard opening and
closing frequently.
GPG 316 This version published 02/02
Survey tricks and tips
It may be possible to divert condensate
temporarily downstream of the trap, into a bucket
or barrel. Note the volume or weight at intervals,as
a means of estimating steam demand.
The weighing vessel must contain cold water
because of the potential hazard of flash steam
from the condensate.
If condensate is pumped from a receiver of known
volume, intermittently, timing the pumping cycles
will provide a load estimate.
Check the temperature of condensate pipework
after each trap. If significantly below 100°C, the
trap is not working.
Put a temperature logger on blowdown pipework
to record timing and duration of blowdown.
Estimate the percentage of condensate returned
to the boiler.
Ineffective insulation in underground ducts can
manifest itself through the ground drying unusually
quickly after rain, frost clearing sooner, etc.
GPG 316 This version published 02/02
Potential opportunities
Reduce boiler pressure.
Put a lid on the feed tank.
Increase feed temperature to aid oxygen removal,
reduce dosing requirements and
resultant blowdown.
Where steam is exclusively used at high pressure
and there is no use for flash steam, consider using
CBA pumps in a pressurised condensate return
loop directly injected into the boiler feedwater
(see GPCS 153 under ‘Further information’).
If condensate is all dumped because of potential
contamination risk, fit automatic quality
measurement to control a diverting valve and
recover what is safe to reuse.
Further information
ECG 66
Steam generation costs
ECG 67
Steam distribution costs
Differential drainage and boiler
return system
Consider dispensing with steam and adopting
alternative heating techniques.
GPG 18
Reducing consumption costs by
steam metering
Rationalise pipework to reduce distances travelled
(and reduce diameters where feasible).
GPG 30
Energy efficient operation of
industrial boilers
Make alternative provision for small loads at the
ends of long dedicated pipe runs (or relocate them).
GPG 197
Energy efficient heat distribution
Insulate fittings.
Case histories
Find a use for flash steam (e.g. sparging it into
the feedwater tank or cascading to lower-pressure
users) or use condensate coolers on calorifiers
and heater batteries where feasible.
Fit thermostatic air vents to reduce warming
through times.
Measure warming-up time to establish
the minimun necessary
Eliminate bypass valves on steam traps and if
necessary fit better-matched traps.
Fit automatic temperature controls in place
of manual valves.
Use an engine or turbine for pressure reduction.
Reduce steam pressure if possible, to give
improved performance and less flash-steam loss.
Recover heat from boiler blowdown.
Implement automatic TDS control on boilers.
A tyre manufacturer installed flash steam recovery and improved
condensate collection, cutting boiler make-up from 70% to 10%. The
project cost £20,000 and (including the incidental savings on boiler
make-up water and chemicals) would yield an internal rate of return
exceeding 100% at today’s fuel prices.
A chemical company spent £21,000 insulating pipe fittings in 1994,
achieving a nine-month payback period (equivalent to an internal rate
of return of 170% at today’s values).
A food ingredients manufacturer noticed that a fluidised-bed spray
dryer was the only unit needing steam overnight. They fitted a standby
electric air heater for overnight use, and proceeded to recover the
£1,350 installation cost eight times a year.
2.12 finding savings
Things to look for
Mill speeds higher than necessary; continuous
running at lower speed and throughput is more
efficient than intermittent operation at high
Crushing techniques used on too small particles,
or grinding used on oversized particles
(30 mm is the approximate energy-efficient
particle size to change from crushing to grinding).
Continuous stop/start operation because of
downstream operations.
Survey tips and tricks
Examine how size sampling is carried out.
Question the method of control.
Potential opportunities
See also Survey Topic Guide 2.23, mechanical handling.
Convert open to closed-circuit milling with
efficient size separation.
Fit higher-efficiency separators
(on ball or roller mills).
Replace ball mills with roller-based systems if
feed conditions permit; or use roller mill for
Optimise mill internals, feed/discharge system,
and milling parameters such as speed and air flow.
Use buffer store if downstream operations impose
stop/start regime.
Fit variable speed drives, especially on fans.
Use soft start on main motors.
Improve instrumentation and control
(for example using laser fineness sensors).
Use grinding aids if product conditions permit,
especially if increased throughput is required.
GPG 181
Energy efficient crushing and
grinding systems
GPG 212
Reducing energy costs in
flour milling
GPG 316 This version published 02/02
Further information
What to look for
Manual control of batch blending operation with
inadequate end-point detection.
Unnecessarily long mixing times.
Lax ingredient control.
Blade wear (increases mixing time).
Inadequate insulation on mixing vessels.
Use of compressed air to agitate mixtures.
Survey tips and tricks
Record mixing times and look for suspicious
Question the nature and frequency of
end-point tests.
Try to identify physical properties which could be
used to determine completeness.
Potential opportunities
Convert to low-loss stirrers.
Fit high efficiency motors.
Optimise stirring speed.
Improve end-point detection and control.
Use soft start motor control.
Consider intermittent rather than
continuous mixing.
Convert batch mixing processes to continuous.
Further information
ECG 20
Rubber compounding in the
rubber processing industry
GIL 53
Optimising energy use in pulpers
and refiners
GPG 316 This version published 02/02
Case history
A manufacturer of rubber seals put a soft-start motor controller on a
100 kW mixing mill motor which was operating four minutes on, six
minutes off. The £1,600 investment (1990 prices) was paid back twice
in the first year.
2.13-2.14 finding savings
What to look for
Product over-dried.
Manual control of end-point at operators’ discretion.
Raw material moisture higher than necessary, for
example because of damp storage conditions.
Excess airflow into dryers.
Hot external surfaces on dryers (missing insulation).
Dryers actually running empty, or able to do so.
Air filters clogged or ripped.
Air leaks into or out of the dryer.
Airflow imbalance on multiple tunnel dryers
(evidenced by wet or overdried product from
different driers).
Survey tips and tricks
In direct-fired dryers, variations in exhaust oxygen
content will indicate the degree of dilution by
air ingress.
Measure the moisture content of the dried product
as it enters the next process stage, especially if it
goes through a buffer store. Drying below this
‘natural regain’ moisture level is pointless.
Measure the energy input per kg of water evaporated.
Compare this against dryer manufacturer’s data sheets,
or one dryer against another.
Repeat the measurement from time to time to guard
against future deterioration in performance.
In theory a perfectly efficient dryer would require only
0.63 kWh of input energy per kg of water removed.
Potential opportunities
Two-stage drying may be more economical when the
product contains both large and small particles.
Investigate whether the output dryness specification
can be relaxed.
Are you drying product to stabilise for storage pending
subsequent processes which add water? If so, can
storage be eliminated?
Mechanical de-watering of powders (and subsequent
drying) can both be accelerated by reducing the
proportion of fines.
Where product is conveyed on perforated belts
or trays, reduce the blank supporting area under
the product.
Increase air velocity over the product.
Subdivide or granulate the product.
In direct-fired dryers, if dilution air is introduced before
the combustion zone, mix it after the combustion zone
instead to avoid flame chilling.
Cascade chamber dryers from dry through
intermediate to wet, reheating as required to
avoid condensation.
Reduce supply air temperatures over weekend closures
if full of partially-dry product.
On major processes use mechanical vapour
recompression to recover exhaust heat.
Consider matching CHP to a continuous
drying system.
Further information
GPG 66
Rotary drying in the chemical industry
GPG 149
Rotary drying in the food and drink
industry (page 18 shows a method for
calculating rough gas balances)
GPG 185
Spray drying
GPG 243
Drying of particulate solids - survey
finding and auditing guide
Prevent accidental moisture gains to feedstock.
Mechanical de-watering (pressing, centrifuging, etc.)
can reduce the need for thermal drying.
GPG 248
Energy efficient operation of dryers in
the ceramics industries
Preheating the feedstock may aid drying.
GPG 343
Avoid high air supply temperatures and use more air
if necessary.
Model-based predictive
control systems
Insulate dryer casings to reduce heat loss.
Case histories
Fit recirculation fans to improve internal velocities,
reduce dead spots, and maximise relative humidity
in exhaust.
A chinaware manufacturer dispensed with ‘open-shop’ drying in favour of a
microwave/vacuum dryer costing £562,500.The investment would have
yielded an estimated 45% internal rate of return at today’s prices.
Recover heat from exhaust air. If contaminated by
dust, etc., consider use as preheated combustion air.
A major sugar factory implemented model-based predictive control of
dryers in 1996.The project gave energy savings, increased yield, and quality
improvements which at today’s fuel prices equate to an internal rate of
return of 120%.
Control dryer end-point automatically, for example
on exhaust relative humidity.
An animal-feed producer eliminated some dryers completely by rebranding
the product and selling it undried.
GPG 316 This version published 02/02
Things to look for
Part-loaded ovens or autoclaves.
Excessive equipment preheat times.
Oven doors left open longer than necessary.
Air ingress especially at seals, sightholes,
access panels.
Potential useful heat gains to surrounding space.
Plant in unnecessarily cold or exposed location.
Incorrect damper settings.
Excessive exhaust volumes.
Survey tricks and tips
Use a datalogger to record local air temperature
above oven doors.
Potential opportunities
Optimise loading schedules to operate equipment
for shorter periods at full capacity.
Use combined heat and power.
Review supply options, eg, substitute gas for steam
or radiant tube; electric radiant; microwave;
gas radiant, etc.
Fit curtains to tunnel-oven entrances.
Further information
GPG 271
Selecting and specifying new paint
curing and stoving ovens
GPCS 387
Energy savings from optimised
operation of painting and
curing lines
GPG 309
Energy savings in industrial
GPG 316 This version published 02/02
Case study
An aerospace components manufacturer operated a large autoclave for
curing resin-bonded components in relatively small batches. By
rescheduling operations to run it fully loaded, they not only reduced
energy costs, but cut 70% off their nitrogen demand.
2.15-2.16 finding savings
What to look for
Auxiliaries such as hydraulic packs, coolant pumps,
waste removal, etc., running on idle machines.
Fit quick-acting doors for vehicle access.
Redecorate in lighter shades for improved
Fit destratification fans in high-bay buildings.
Insulate barrels of plastics extrusion presses.
Change to near-final-size castings.
Hydraulics, compressors, chillers and other
services or auxiliaries able to run when main
machine is idle.
Variable-speed AC drives to replace failed
DC drives (for example on filament or film
uptake drives).
Uninsulated cooling systems.
Dirty skylights.
Variable-speed drives on hydraulic packs to limit
pressure or spill-back when off load.
Blunt tooling.
Optimise source of compressed air for blowing
(eg poly bottles).
Open or slow-acting vehicle access doors.
Soft-start motor controllers.
Incorrect temperature settings on product
cooling or baking.
Additives to assist flow of polymers.
Worn extruder screw surfaces.
Improved lubrication.
See also Survey Guide Sheets 2.1 (Lighting),
2.7 (Compressed air), 2.8 (Central vacuum),
2.18 (Treatment booths/cabinets)
GPG 48
Reducing electricity use in
injection moulding
GPG 92
Fit run-hours meters (if not already present)
and reconcile running hours of auxiliaries
against work schedules.
Reducing electricity use in
extrusion-blow moulding of
GPG 239
Compare similar machines and use the fastest
or most efficient as the benchmark.
Energy efficient thermoplastics
GPG 292
Energy in plastics processing –
a practical guide
GPCS 215
Automatic switch-off of
power presses
Survey tips and tricks
Further information
Canvass the views of machine operators.
Observe operations during meal breaks and
other quiet periods.
Potential opportunities
Interlock auxiliaries to the main machines
which they serve.
Use machines with lowest specific energy
Fit high-efficiency motors when replacing
failed ones.
Replace centralised heat supply with locally
controlled gas radiant heaters.
Fit power-factor correction capacitors if necessary.
Implement zoning and variable speed pumps
on central cutting-fluid systems.
Recover waste lubricating oil for use as
heating fuel.
Case histories
A company making metal pressings spent £630 on controls which
automatically turned off motors on presses which had been idle for a
preset period. At today’s prices the project would have yielded close
to 100% internal rate of return.
An injection moulding company put heat shields around heated press
platens at a cost of £2,000. At today’s prices this project’s internal rate
of return would have been about 200%.
Another injection moulding company spent £500 in the early 1990’s
on timers to turn off the heaters on idle presses. They recouped their
investment once a month thereafter.
GPG 316 This version published 02/02
Potential opportunities
Reduce temperature if only being maintained
to assist drainage from treated parts; consider
alternative methods of accelerating drainage
if necessary.
Use lids or ball blankets to reduce heat loss
and evaporation.
Local fresh air supply duct to conserve heated
air in surrounding space.
Things to look for
Tanks preheated for excessive periods.
Tanks heated while not in use.
Lack of insulation (including associated pipelines).
Lack of lids on tanks.
Oversized tanks or levels higher than needed.
Excessive extract air velocities over exposed liquid
Use contra-flow arrangement for sequential
rinsing tanks.
Continuous uncontrolled top-up and overflow
or run to waste.
Where there are steam coils and condensate
is dumped because of contamination risk,
consider direct steam injection via sparge pipe.
Excessive or unwarranted agitation.
Agitation by compressed air from a high-quality
central source.
Consider switching to direct gas firing
where appropriate.
Maintain lowest possible tank level.
Tank contents boiling when 95°C would
be effective.
Insulate sides and bottoms of tanks.
Recover heat from effluent fluid.
Steam blowing through directly-heated
tank contents.
Local ventilation extract drawing air from
general heated space.
Survey tricks and tips
On vessels open to atmosphere, look for
temperature controls set at 100°C
(impossible to achieve without risk of boiling).
Assess tank leakage by observing how the fluid
level falls when not topping up.
Further information
FEB 19
Process plant insulation and
fuel efficiency
GPCS 133
External spray insulation on
furnace regenerators
Heat recovery from
contaminated effluent
NPCS 122
Reducing tank evaporative
losses using hexagonal floats
Case histories
A supplier of colours, glazes and clays to the pottery industry added
microprocessor control to reduce unnecessary stirring of agitator tanks.
Although the project cost £56,000 in 1985, it achieved a 1.3 year
payback and even at today’s lower real electricity prices it would give
an internal rate of return of 45%.
GPG 316 This version published 02/02
A manufacturer of decorative tiles went further and switched off
agitation of glaze tanks completely outside working hours, saving
£16,000 a year without prejudicing quality, and achieving 100% IRR.
A maker of metal tubing used floating hexagonal polypropylene shapes
to insulate the fluid surfaces of treatment tanks. For an investment of
£2,500 he saved an estimated £4,000 a year, giving an internal rate of
return of the order of 1,000%.
2.17-2.18 finding savings
Things to look for
Lighting or air extract running, or able to run, when
not required (Note: containment booths need to
run continuously).
General ventilation relied on where local extract
could be applied.
Local extract systems drawing heated air from
surrounding space.
Inadequate insulation if heated or cooled.
Defective seals where airtightness is needed.
Common air extract from multiple cabinets.
Unnecessarily high air extraction rates.
Survey tips and tricks
Use smoke generator or strips of tissue to track
air movement.
Use the site’s list of local extract ventilation (LEV)
equipment as a checklist.
Observe pattern of use, especially during breaks.
Potential opportunities
Arrange air extract and cabinet lighting to run on
demand, with automatic switch-off.
Recover exhaust heat.
Arrange dedicated extract for lightly-used
Install dedicated fresh air supply ducts to avoid
drawing in heated air.
Implement reduced or variable fan speed.
Fit more-efficient fans.
Further information
GPG 303
The designer’s guide to energy
efficient industrial buildings
GPG 316 This version published 02/02
Things to look for
Use direct gas firing if possible on furnaces with
radiant tubes, or electric induction for metal
heating or melting.
Reduce air ingress into tunnel kilns using
end doors.
Note: see also Survey Guide Sheet 2.11 (Burners)
Evidence of unnecessarily long preheat periods.
Ensure sand traps create an effective seal.
Unnecessarily high processing temperatures.
Extended holding periods at high temperature
(for example while awaiting results of chemical
analysis on product).
Subject to product requirements, aim for lowest
oxygen content at exhaust.
Use hot-gas recirculation to reduce temperature
stratification and promote heat transfer
to product.
Transfer clay goods direct to kiln from dryer to
avoid moisture pickup.
Batch process plant maintained at temperature
between charges.
Batch oven/furnace doors left open for longer
than necessary.
Evidence on external casing of hot gas leakage.
Product allowed to pick up moisture between
dryer and kiln.
Further information
GPG 50
Efficient operation of coreless
induction furnaces
GPG 77
Continuous steel reheating
furnaces: operation and
GPG 164
Energy efficient operation of kilns
in the ceramic industries
GPG 244
The use of low thermal mass
materials and systems in the
ceramic industries
GPG 252
Burners and their controls
GPG 253
A manager’s guide to optimising
furnace performance
GPG 255
Electroheating in industry:
making the right choice
GPCS 135
Furnace scheduling advisory
GPCS 160
Expert system improves
performance of PLC controlled plant
Survey tricks and tips
A thermocouple on the end of a pole can be used
to check surface temperatures on large plant.
Use infra-red thermography to detect hot spots.
Compare actual energy ratio per tonne with
theoretical requirement based on specific heats
and temperature rise.
GPG 316 This version published 02/02
Potential opportunities
Maximise hearth loading.
Automatic pressure control of furnaces permits
tighter control of combustion efficiency.
Reduce furnace temperatures if excessive.
If heavy refractory lining is used in an intermittent
furnace, replace inner face with a ceramic-fibre
insulation blanket or tiles.
Move stock into heated space if stored outside;
preheat further if suitable waste heat sources
are available.
Case histories
Where parts need to be reheated for successive
operations, use insulated transit containers.
Fit permeable radiation walls in furnaces.
Recover heat from exhaust.
Reduce the mass of refractory furniture in
tunnel kilns.
Optimise speed of kilning.
A forge installed a fluid-bed furnace for heating bar ends, replacing
a less efficient conventional furnace. Their investment of £45,000 in
1984 offered a payback every 8 months, which translates into an
internal rate of return of 70% (in today’s terms).
A glass container manufacturer installed recuperative heat recovery
at a cost of £16,000, giving a present-day internal rate of
return exceeding 80%.
2.19-2.20 finding savings
What to look for
Further information
GPG 38
Commercial refrigeration plant:
energy efficient installation
GPG 42
Industrial refrigeration plant:
energy efficient operation
and maintenance
Fouling of cooling tower.
Uninsulated pipework and fittings.
Excessively low chilling medium temperatures.
GPG 44
For an air-cooled condenser, check for short-circuit
air path to evaporator inlet.
Industrial refrigeration plant:
energy efficient design
GPG 59
Air bypass or recirculation in cooling towers.
Energy efficient selection
and operation of refrigeration
Fouled coils, air filters, air inlet screens or cooling
tower spray nozzles.
GPG 225
Industrial cooling water systems
Excessive cooling water flow rate and hence
pumping power.
GPG 256
An introduction to absorption
Abnormal temperatures or pressures in
refrigeration circuit; avoid low evaporating
GPG 278
Purchasing efficient refrigeration –
the value for money option
GPG 279
Running refrigeration plant
efficiently – a cost saving guide
for owners
GPG 280
Energy efficient refrigeration
technology – the fundamentals
GPG 283
Designing energy efficient
refrigeration plant
CG 7
Energy efficient cooling water
systems in chemicals manufacture
FEB 11
The economic use of refrigeration
GIL 52
The engine of the refrigeration
system: selecting and running
compressors for maximum
GPCS 301
Use of larger condensers to
Improve refrigeration efficiency
GPCS 302
Improving refrigeration
performance using electronic
expansion valves
Multiple cooling towers with more units running
than necessary.
Survey tips and tricks
The temperature efficiency of a water cooled
condenser can be checked against the
manufacturer’s specification.
Measure refrigerant liquid temperature upstream
and downstream of the strainer. A high differential
implies clogging.
Excessive cooling water flow rate can be inferred
from lower-than-expected temperature rise.
Potential opportunities
Inhibit chillers below a certain ambient
temperature, or exploit other free cooling potential.
Satisfy localised winter cooling demand
with dedicated package chillers instead of
a central system.
Fit a chiller load management system.
Raise the chilled water temperature to its
feasible limit.
Where duty is shared by diverse chillers,
optimise by letting the best take the lead.
Use thermal storage to smooth the load
profile, reduce start/stop cycling, maximise
use of most efficient chiller, and possibly stand
down excess capacity.
Buy in liquid nitrogen rather than generating on site.
Case history
An acid manufacturer installed heat recovery on an exothermic
process at a cost of £51,000. The equivalent internal rate of return
in today’s terms would be 10%.
GPG 316 This version published 02/02
GPG 13
Guidance notes for the
implementation of heat recovery
from high temperature waste
GPG 242
Process integration
Things to look for
GPG 89
Guide to compact heat exchangers
Fouled heat exchangers.
GPCS 355
Fans fouled, worn, or even stopped.
The use of pinch technology in a
food processing factory
In air re-circulation systems verify operation
of control dampers.
GPG 141
Waste heat recovery in the
process industries
Incorrect configuration or control of batch
heat reclaim.
Low temperature heat recovery
Lost fluid or failed pumps in run-around
coil system.
Dumping of heat because of mismatched
sources and loads.
Note: heat recovery is itself sometimes an
opportunity. These points concern opportunities to
improve existing heat-recovery installations.
Survey tips and tricks
Check temperature differentials against
manufacturer’s specification or original
design intent.
Compare temperature efficiencies of similar units.
Note the temperature and heat content of
the high-temperature stream at outlet, in case
there is potential for further heat recovery.
Potential opportunities
GPG 316 This version published 02/02
Further information
On HVAC, inhibit heat recovery between 16-24°C
to prevent heat gain to chiller plant.
Consider variable-speed drives on fans and pumps.
Fit thermal storage to improve utilisation where
heat is being dumped because of mismatched
supply and demand profiles.
Case histories
An animal-feed producer had bypassed a heat recovery unit because it
was fouled and thought to be beyond repair. An enterprising employee
devised a method of unblocking it, which was done at a cost of £1,000
including equipment hire. Once recommissioned, it resumed saving
£30,000 a year.
A dairy ran into a constraint on increasing output because it appeared
to be short of chiller capacity for cooling the milk output from its
pasteurisers. However, on investigation, it was found that the
pasteuriser’s regenerator was performing well below industry norms.
The regenerator partly cools the milk output by exchanging heat with
the cold input stream. By improving the regenerator heat exchanger, at
a cost of £25,000, the company obviated the need to spend £150,000
on a new chiller and incidentally saved £10,000 a year on electricity.
2.21-2.22 finding savings
Potential opportunities
Reduce the thermal capacity of conveying
equipment and transit containers which go
through heating or chilling equipment.
Optimise carrying capacity; use buffer stores to
isolate from downstream stoppages.
Things to look for
Conveyors running empty.
Motors running lightly loaded.
Compressed air used for positioning or sorting
without proper nozzles.
Reduce distances and minimise or eliminate
vertical lifts.
Compressed air bleeding during inactive periods.
Electric trucks charged during daytime
tariff period.
Use control with sensors to enable conveyors to run
only on demand (ideally combined with short runs).
Manually control to run intermittently at full load
rather than continuously at part load or empty.
Replace pneumatic conveyors with bucket
conveyors or other mechanical alternatives.
In pneumatic handling systems:
Dust on fan blades or filters.
Air leaks.
Apply low-friction coatings to conveyors.
Transport velocities higher than necessary.
Use infra-red thermography to detect hot spots
caused by friction.
Where conveyors pass through heated process
equipment, insulate the return leg, route it
through the heated equipment, or cool it to
preheat air.
Listen for air being discharged when handling
system is idle.
Where product passes from heating to cooling
zone, use separate conveyors.
Stand and watch during production, at breaks,
and during shift changes.
Fit purpose-designed nozzles and isolating valves
to air jets.
If possible, charge truck batteries overnight; if this
is not possible, at least avoid charging on winter
weekday afternoons.
Survey tricks and tips
Further information
GPCS 222
Purchasing policy for higher
efficiency motors
GPG 63
Metal distribution and handling
in iron foundries
GPG 316 This version published 02/02
Things to look for
Unexplained discrepancies in fuel consumption.
Vehicles left with engines idling.
Survey tips and tricks
Check vehicle mileage and fuel
consumption records.
Analyse performance by driver if vehicles are
pooled or shared.
Check tyre pressures.
Compare similar vehicles doing similar duties.
Ask how routes and loads are planned.
Potential opportunities
Provide driver training.
Improve load and route planning.
Improve vehicle aerodynamics.
Use alternative-fuel vehicles, at least for
intra-site duties.
Outsource transportation.
Further information
ECG 59
Fuel consumption in freight
haulage fleets
ECG 64
Fuel consumption in UK car
and van fleets
FEB 20
Energy efficiency in road transport
GPCS 311
Energy saving through improved
driver training
GPCS 342
Fuel management for transport
GPG 218
Fuel-efficient fleet management
GPG 307
Fuel management guide
GPG 316 This version published 02/02
Case history
A parcel delivery company provided driver training and achieved a 14%
reduction in fuel use.
2.23-2.24 finding savings
Survey tricks and tips
If kitchen supplies are sub-metered, take frequent
readings throughout the day to establish patterns
of demand.
Visit directly after meal time to see if cooking
equipment is still running.
Things to look for
Kitchen ranges turned on before they are needed.
Kitchen ranges used as source of space heating.
Vending machines running 24 hours per day.
Badly-fitting door seals on refrigerators
and freezers.
Observe activity during preparation period at start
of working day.
Hot water left running into kitchen sinks.
Gas consumption during summer months may
indicate catering demand.
Kitchen ventilation fans drawing heated air
from dining area.
No ‘night blinds’ on chilled display cabinets.
Ovens and sterilisers preheated for
excessive periods.
Dishwasher running part-loaded or empty.
Fridges and freezers next to heat sources.
Potential opportunities
Provide energy training for catering staff.
Fit soft-start motor controllers on freezers,
refrigerators, and chilled display cabinets.
Fit night blinds on open chilled display cabinets.
Control vending machines, bains maries, heated
cabinets, and counter lighting by timeswitches.
Inadequate ventilation for condenser units of
cold rooms.
Heat recovery from kitchen extract.
Heated cabinets or counter display lighting
left running.
Motor controllers on refrigerators and freezers.
Vigorous boiling of unlidded pans.
Provide efficient fixed water boilers to obviate
the need for kettles.
Replace conventional ovens with microwave
cookers in mess rooms.
Further information
GPG 222
Reducing catering costs through
energy efficiency
GPCS 223
Night blinds on refrigerated
GPCS 350
Strip curtains on chilled
display cabinets
Catering establishments
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Further information
Things to look for
CIBSE Guide F Energy Efficiency in
Buildings, Section 19.1
1991 -
Poorly-utilised space.
Doors and windows propped open.
Broken windows and rooflights.
Dirty windows and rooflights.
GPG 139
Holes in walls or roof.
Draught stripping of existing
doors & windows
Substandard or damaged insulation.
GPG 303
Damp which may have compromised
existing insulation.
The designer’s guide to energy
efficient buildings for industry
GPG 304
Substandard or damaged draughtproofing.
The purchaser’s guide to energy
efficient buildings for industry
Survey tricks and tips
An infra-red camera can be used on cold nights
to detect hot spots (from outside) or cold spots
(from inside).
A bubble-maker or smoke generator can be used
to sense unwanted air movement.
A building’s heat loss characteristics can be
estimated from the rate of temperature decay at
the end of the working day, taking outside
temperature into account.
Potential opportunities
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Building Regulations, Part L
Repair holes and broken windows.
Apply draughtproofing.
Apply insulation.
Clad and insulate over roof lights.
Fit air-locks or high-speed doors.
Energy Audits and Surveys
Case study
In 1989 a steel company applied sprayed insulation to a corrugated
roof. Their investment of £235,000 would have yielded a 10% internal
rate of return at current fuel prices.
2.25-2.26 finding savings
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data sheets for recording survey data and results
data sheets for recording survey data and results
Site energy consumption and
Register of sources of data and
their ‘drivers’
Meter reading pro-forma
Schedule of identified opportunities
Tables like these can be used to record information
about annual energy consumption and expenditure.
Table 3.1.A is applicable in all cases, and is typical of
the background information which would normally
be recorded in a consultant’s report.
Table 3.1.A: Site total statistics (actual)
A table in this form could be used to record statistics
for at least the most recent year, and preferably two
years. The ‘quantity purchased’ and ‘cost’ columns
can be completed by aggregating data from invoices
for the year(s) in question. The CO2 figure must be
derived by applying the conversion factors shown
below, if necessary first converting quantities into
kWh units.
Table 3.1.B Major energy-using equipment
Where possible, you should estimate the annual
energy used in major plant items (or in services such
as heating or lighting). This will later help you to
estimate likely savings. Where dedicated submeters
are not fitted, it may be possible to infer consumption
from the equipment nameplate rating, by making
assumptions about annual running hours. Note that
some equipment may be fitted with hours-run
counters to facilitate this.
The cost column can be calculated by multiplying
the units consumed by the prevailing price. To avoid
overstating any likely savings, it is better to use the
marginal unit price rather than the average cost per
unit of energy. The marginal price is the amount saved
by consuming one unit less than expected.
Table 3.1.A
Year: Jan-Dec 2001
Energy source
Units of delivery
(in original
46,789,012 46,789,012 £1,871,560 20,119,000
Oil (35 second)
to kWh)
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Table 3.1.B
Plant item description
Annual units consumed
Annual cost
Air compressor
120,000 kWh
Curing Oven 1
230,000 kWh
2,400 kWh
3.1 survey pro formas and reporting
Note: The tables refer to EACs (energy accountable
centres). Some managers notionally split their
businesses into EACs to improve energy
accountability. An EAC usually has these attributes:
These tables provide a site-specific record detailing
the sources of data which might be needed for
analysis or for future regular monitoring. Although not
essential for the purposes of the survey, completing
tables like these is good practice and will at least help
to ensure that all the requisite information could be
obtained if needed later.
The ability to measure energy flows into it.
The ability to measure production output from it
(or some other determinant of demand).
A person accountable for the energy used.
Failure to account for ‘drivers’ (the things which
determine demand), when analysing patterns of
energy consumption, is a prevalent management fault.
These tables are provided as templates, and may not
give you enough room for your entries. You should
prepare your own versions with more appropriate
layouts, and with provision for more than the four
entries illustrated here.
Table 3.2.A: Consumption drivers
Energy consumption depends upon the amount of work
being done - be it production activity, or space heating
to provide comfort in cold weather. Consumption
patterns cannot be analysed without reference to these
driving factors, and therefore if setting up an energy
monitoring scheme, it will be necessary to record them
as frequently as the meter readings.
Consumption drivers
(eg production,
weather, etc)
Unit of measurement
(eg tonnes, degree
days, etc)
Where is the data
available for routine
weekly updates?
Which EAC(s) does
this relate to?
A1 Popcorn throughput Cartons
Packing dept
A2 Biscuit production
Bakery production planning Bakery
A3 Toffee production
Work study dept
A4 Heating demand
Degree days
Offices and stores
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Table 3.2.A
This table catalogues the available energy
consumption meters. The information collected
about individual meters could subsequently help,
for example, to resolve discrepancies in meterreading records.
Table 3.2.B
Energy source
Zone or
(eg electricity, gas)
item served location
Digits on
(eg kWh
EAC served
x 10)
B1 Electricity
Whole site Intake near
6 All
B2 Gas
Whole siteCanal gate DEF456
B3 Gas
Main boilers
Hu cu ft 4
9876543 M 3
Rear of boiler
Table 3.2.C: Consumption streams – unmetered
Some energy sources, notably oil, solid fuel and
liquefied petroleum gas, are delivered in bulk and
stored on site without any provision to meter the
quantities used. Failure to measure the consumption,
as opposed to deliveries, is a common management
fault. Completing this table will help to ensure that
consumptions can be calculated from successive
stock-level records after taking account of
intervening deliveries.
Table 3.2.C
Energy source Location of storage
(eg LPG, oil)
C1 Oil
on tank
C2 etc
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Rear of staff car park
Units (eg litre)
Method of
measuring stocks
EAC served
Sight gauge
3.2 survey pro formas and reporting
Table 3.2.B: Consumption streams – metered
Regular recording of energy consumption (and of the
factors which determine how much energy is used)
is fundamental to the good management of energy
resources. The following pro forma weekly return
sheet should first be customised, by completing the
shaded boxes only, to suit the specific site where it
will be used. The customised sheet can then be used
as a master copy for routine weekly return forms. If
the design below does not suit your needs, use it as
a template for your own design.
Weekly energy return
The body of the form is in three parts:
Determinants of demand (consumption drivers).
Metered supplies.
Unmetered supplies.
These correspond to the three tables in Section 3.2
above, where the correspond static information
is recorded.
Note that the columns headed ‘Previous reading’ and
‘Previous stock level’ in parts B and C may not be
necessary if you are entering data into a database or
spreadsheet where the previous data are
already stored.
Site name
Date of return
Time of readings
Part A: Consumption drivers
Current reading
Stock in hand
Part B: Metered supplies
Meter or submeter
Previous reading
Part C: Unmetered supplies
Commodity/delivery point
Previous stock level Deliveries received
Name of person making the return
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A table of this form can be used to register the
potential energy-saving projects for which funding
might be sought. For example, one measure identified
might be a recirculation fan on a dryer. If this had an
implementation cost of £4,000, recurring annual costs
of £200 (for extra electricity) and expected annual
cash savings of £1,200 (through reduced gas
consumption), it would offer a simple payback period
of 4,000/(1,200-200) = 4 years.
Measure identified
costs thereafter
cash savings
Simple payback*
Destratification fans in
packing hall
Draughtproofing offices
Agitators in intermittent mode
at night
Note: this table is used merely to identify the possible
opportunities. As projects are accepted it will be
necessary to identify an individual to accept
responsibility for progressing each one. A suitable table
for project tracking is available in CIBSE Guide F, Table
18.4 (see Section 4.1, Sources of Assistance)
GPG 316 This version published 02/02
*For simplicity’s sake, simple payback is used here but
it is recommended that more sophisticated financial
assessments are used, eg internal rate of return.
See GPG 169: Investment Appraisal for Industry
3.3-3.4 survey pro formas and reporting
GPG 316 This version published 02/02
supporting data, and sources of further advice
supporting data, and sources of further advice
Sources of assistance
Recommended instruments and tools
Energy data and conversion factors
Appendix A
Appendix B
Selecting and briefing
a consultant
The Environment and Energy Helpline
(0800 585794)
MACC2 is a way of helping organisations improve
their resource efficiency and environmental
performance in a managed, targeted and transparent
way. It is designed to work equally well in industrial,
commercial and public sector organisations.
This service can provide quick answers to simple
questions related to energy efficiency and is
particularly useful as a starting point for those new to
energy saving. Contact the Helpline for free advice
and publications from the EEBPP.
Energy Efficiency Best Practice Programme
Nearly all the documents cited in the ‘further
information’ sections of this Guide are available free
of charge from this Government programme, and can
be ordered via the Environment and Energy Helpline
or this web site. Many are even available online for
immediate downloading. See Institute of Energy for
how to obtain the Standards for Managing Energy.
Envirowise (
This programme can help with wider aspects of waste
minimisation. It features a Fast Track visit, which is a
confidential on-site waste review, available to
companies with fewer than 250 staff. Within the space
of one day, a consultant will identify waste
minimisation opportunities, and help you plan to
make these savings a reality.
Action Energy (
This is a grant scheme to support the provision of
energy-saving advice from consultants. It operates at
two levels. Site Energy Assessment (SEA) provides for
a short general assessment of energy-saving
opportunities, free of charge to the applicant. Specific
Measures Assessment (SMA) can subsidise more
focussed in-depth help where the need has been
identified in an SEA report or its equivalent.
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Design Advice
Design Advice offers professional, independent and
objective advice on the energy-efficient and
environmentally conscious design of buildings as part
of the Energy Efficiency Best Practice Programme.
Clients are offered a one-day general consultancy on
their chosen building project, paid for by a cashback
scheme. The consultancy recommendations, covering
energy efficiency, environmental improvements and
the potential commercial benefits, are contained in
a client report. More detailed specialist consultations
will also be supported under the service.
MACC2 is a challenge to individual organisations to
bring their use of resources and management of waste
into line with targets which the Government has set
for reducing greenhouse gases and other emissions
and reducing, recycling and recovering waste.
BREEAM is a tool that allows the owners, users and
designers of buildings to review and improve
environmental performance throughout the life of a
building. It is a widely accepted and respected scheme
that sets a benchmark for environmental performance
and provides a wide range of benefits. It is
independent and authoritative, being based on many
years of construction and environmental research
carried out at BRE together with the input and
experience of the construction and property
industries, government and building regulators
Energy Efficiency Accreditation Scheme
This voluntary scheme enables an organisation to
prove that it has met testing standards in its approach
to energy efficiency. Reviews are carried out by
independent assessors using strict criteria, and periodic
reaccreditation helps to ensure that momentum is
maintained. Being accredited provides qualitative
evidence in support environmental systems
certification and may help in relation to Climate
Change Agreements.
The Chartered Institution of Building Services
Engineers (CIBSE)
CIBSE is an international body that represents and
provides services to the building services profession.
These services include publications and events.
Croner’s Energy Management
(Croner.CCH Group, 020 8247 1175)
This loose-leaf manual provides a wide range of
information and reference material on energy
management topics. It is supplemented by a monthly
update newsletter, including monthly and weekly
degree-day figures, and its content is subject to
regular amendments.
4.1 reference
Gee’s Energy Saver
(Gee Publishing, 020 7393 7666)
This loose-leaf reference manual provides a wide
range of information on energy management topics.
Its content is subject to regular amendments,
including updates to monthly degree-day data.
Energy Systems Trade Association
As the trade association for suppliers of energyefficiency equipment and services, ESTA provides a
useful first point of call in the search for equipment,
materials, and expert advice.
Institute of Energy (
The Institute is the UK's professional association
for those active in the energy scene (whether as
suppliers, users, or academics). As such it can provide
energy managers with useful individual contacts.
Contact the Institute to get a copy of the Standards
for Managing Energy.
CHP Club (
The CHP Club is a new initiative under the
Government's Energy Efficiency Best Practice
Programme, aimed at helping users and potential
users in getting the maximum benefits from CHP.
It provides members with a free one-stop-shop, a
unique combination of information, exchange of
experience and advice facilities on CHP and related
topics that will give everybody what they need and
when they need it.
Combined Heat and Power Association
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In some circumstances, combined heat and power
(CHP) can be an important contributor to energy
efficiency. The CHPA exists to promote this
technology and can provide a great deal of technical
and market information, as well as news on grants
and subsidies.
For the purposes of energy surveys, it is not usually
necessary to have traceable calibrated instruments
because approximate measures usually suffice.
Exceptions to this rule are noted below.
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Digital thermometers with type K thermocouple
probes. You will need one instrument operating in
the range –50 to 200ºC, ideally with 0.1ºC
resolution, and another for 0-500ºC with 1ºC
precision. For high-temperature applications a
robust probe is needed. For lower-temperature
work, a ‘band’ probe designed for surface
measurements makes a good general-purpose
instrument capable also of measuring air
temperatures. Even a bare thermocouple junction
can be used. Thermocouples can be left in place
and read manually by connecting the instrument
when required. Compensating extension cable is
necessary if the probe will need to be used at a
distance (on the end of a pole), for instance.
A sling hygrometer enables a spot check to be
made on wet and dry bulb air temperatures.
Alternatively, use a digital relative humidity probe,
especially if moisture contents of product need to
be measured.
Non-contact thermometers can be useful to give
approximate temperatures of inaccessible surfaces,
or to scan for hot spots. An infra-red camera can
be hired if large areas need to be assessed in detail.
Results of infra-red thermography must be
interpreted with caution.
Miniature data loggers which record temperature,
relative humidity, voltage, or pulses, may be
useful for extended tests. Pulses may be logged
from a variety of sources including PIR sensors
(logging occupancy levels) or even improvised
temporary contacts on valve linkages and other
moving equipment.
A light meter. An inexpensive unit will suffice,
capable of working over the 100-2000 lux range.
Photographic light meters are not suitable.
A clip-on power meter is useful for checking on
lighting circuits, motor consumption and small
power loads.
A compact camera. An inexpensive 35mm
compact model is adequate, but a powerful flash
is recommended.
A video camera can be very useful. An inexpensive
PC-connectible camera can be used in
many instances.
Pressure/vacuum gauges.
Combustion analysis kit. This is one instrument
which ought to be calibrated against a traceable
standard. Although relatively expensive, this is a
good long-term investment because it enables
poor combustion to be detected through regular
checks. Always choose one with carbon monoxide
measurement. If using oil or solid fuel, you will also
need a smoke pump.
Anemometer to measure air velocities especially in
supply and extract ducts.
Smoke generator to detect air leaks. Alternatively,
improvise with tissue-paper tell-tales or a child’s
bubble maker.
Pocket tape measure.
Crowbar (for access to water meter).
Meter compartment keys.
Walkie-talkie radio or mobile telephones to
coordinate ‘drop tests’ when one party is reading
meters while another starts and stops equipment.
Permanent metering should not be overlooked as a
source of data. Manually read at frequent intervals,
it can provide useful profile information. Do not
forget that on equipment with fixed power
demands, an elapsed-hours counter will provide a
rough estimate of demand.
Instruments which are too expensive to buy can
be hired.
4.1-4.2 reference
CO2 equivalents of electricity and fuels
Energy source
Grid electricity (from 1998)
Coal , typically
Jet kerosene
Natural gas
Gas/diesel oil
Heavy fuel oil
Energy contents of fuels (gross colorific value basis)
Measured units
To get kWh multiply by
Natural gas (typically)
hundred cu ft
Class D oil (35s)
Class E oil (290s) (typical figures)
Class F oil (950s)
Class G oil (3500s)
(typical industrial)
Note that where figures quoted are ‘typical’, actual values will be available from your fuel suppliers.
CO2 ratio
kg CO2
Natural gas
Gas oil
Litre =
GPG 316 This version published 02/02
appendix-A reporting
Although not essential, it is a good idea to record your
survey findings in a formal report. It does not need to
be lengthy; just sufficient to inform others of what
you found and how you arrived at your conclusions. It
could also help you to remind yourself of these things
should you need to return to the subject at a
later date.
If you are seeking authority to spend money on
projects, it is absolutely vital to present clear,
unambiguous recommendations. Do not give the
reader multiple options to choose between. Always
support your recommendations with appropriate
calculations and estimates.
Your report should contain the following sections:
Background to the site and its operations.
Measures to be taken.
Energy consumption and expenditure statistics
(see tables in section 3.3 above).
Expected costs.
Estimated savings.
If appropriate and available, the trend in specific
energy ratio (and comparison with
published norms).
Incidental benefits.
Payback periods or internal rates of return.
Any special considerations supporting
subsequent recommendations.
A table similar to that shown in section 3.4 above.
Brief narrative introducing the findings
and recommendations.
Survey findings
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Detailed discussion of survey findings, presented
either by production area, or by technology theme
(eg lighting), or both.
Energy prices.
Charts and diagrams.
Data gathered during the survey.
Calculations of savings.
Any other information.
There are various circumstances in which you might
require the services of an energy consultant.
In the course of your energy survey, you may find
energy-saving opportunities for which expert help
is required.
After attempting a survey unaided, you may
conclude that it would be better to engage an
outside specialist to do the job for you.
You may have surveyed only certain aspects of
your site, or you may have other sites which you
cannot survey in person.
The terms of a grant scheme may require that a
formal energy survey is first carried out by an
accredited person.
There are several ways of finding a consultant if you
do not already know of one:
Recommendations from contacts in your industry
or from your trade association.
Approaching expert authors writing in the
specialist press.
Registers are maintained by independent bodies
such as the Institute of Energy and the Energy
Systems Trade Association (details in Section 4.1).
In making your shortlist selection, look for
these attributes:
Relevant experience (not necessarily in your own
industrial sector: many energy projects are generic).
Relevant qualifications: Are they properly
qualified? Do they hold membership of a
recognised professional body which has a code of
conduct? Is it important that they should be
chartered engineers?
True independence. The consultancy should not be
tied to any particular product or to any given
energy supply company. Ask who owns them.
Professional indemnity insurance. Ask for a copy of
their current certificate.
Quality system: Does the consultancy perform
work to a recognised quality standard?
Affordable rates. Most reputable consultants will
quote a fixed fee, although some may quote on a
‘shared-savings’ basis. Be circumspect about
shared-savings offers. Apart from the high risk of
costly disputes, there is a risk that the consultant
will ‘walk away’ from a job where he finds nothing
he is interested in doing. The other risk is of
savings being much higher than promised, inflating
the fee well above what was expected.
Having found one or more suitable candidates,
describe your project and ask them about similar work
they have done for other clients. If they are able to
provide satisfactory answers, ask for references and
follow them up.
When you are ready to commission the work,
brief the consultant properly. The project must have
clear objectives and deliverables. Avoid ambiguities
about what is or is not included in the fee offer.
A model brief for a consultant’s report is provided in
Section B.4.
When the project has started, expect to spend time
with the consultant: perhaps half a day for every day
that he works on the project. Do not expect to see the
consultant on site for the whole of the project. Most
projects would require the consultant’s attendance on
site for at most one day in three.
Choosing an energy consultant
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If you are briefing a consultant to do a general energy
survey of the kind dealt with by this Guide, The
following model brief can be adapted to suit your
particular site’s circumstances. It is adapted from
CIBSE’s Energy Audits and Surveys AM5: 1991.
1. Objectives
4. Energy use
The objectives of a concise energy audit and
survey are:
Boiler plant
to identify opportunities for reducing energy costs;
to estimate the potential savings, and where
applicable, implementation costs;
to provide an audit for the site on the basis of the
previous 12 months’ invoiced accounts.
Combustion efficiency, based on waste gas analyses,
shall be assessed for the main boiler plant under
operating conditions as found. The general condition
of the boiler plant and associated pipework insulation
shall be checked. Recommendations for improved
energy efficiencies within the boiler house shall be
based on the above analysis and observations.
Methods of achieving these objectives are:
Process/manufacturing equipment
Observations on:
by observations and, where applicable, analysis of
how efficiently energy-consuming equipment is
being used;
by considering possible improvements to energy
management control.
factors affecting consumption;
product quantity/quality;
2. Report format
GPG 316 This version published 02/02
A short report shall be written to outline the findings
and recommendations arising from the survey. The
report shall be preceded by a summary outlining the
potential energy savings available at the site. These
will primarily be of the good housekeeping and lowcost type but will also indicate where further
opportunities may exist. The body of the report shall
contain the following sections:
Compressed air
Observations on:
end use;
Site information.
Energy audit.
Energy use.
Electrical power and lighting
Energy management.
Observations of power and lighting systems shall be
carried out to determine the following:
3. Scope of survey and report
the condition of lighting equipment;
The following shall be covered:
any unnecessary use of lighting;
Site information.
The site, its functions and services, shall
be described.
the type of existing luminaires and possible
replacement by higher-efficiency lighting;
use of electric heating and its control;
Energy audit.
the operation and loading of refrigerators and
air compressors;
efficient use of large electric motors.
Based on data obtained from the previous
12 months’ fuel invoices, a table showing annual fuel
consumptions and costs shall be compiled of the site.
Performance indicators against published benchmarks
shall be determined and commented on.
Recommendations to reduce energy costs shall be
made on the basis of the above observations.
appendix-B selecting and briefing a consultant
Ventilation/air conditioning
5. Energy management
The settings of existing time and capacity controls
shall be obtained and included in the report, together
with comments on control, operation and potential
energy savings.
Existing energy management procedures shall be
assessed, and outline recommendations shall be
made in any improvement which can be made to
the existing system.
Space heating and domestic hot water
The heating and hot water systems shall be assessed
and recommendations made on:
the heating period compared with
occupancy periods;
the condition, settings and siting of existing
controllers and sensors;
instantaneous temperature measurement taken
during occupancy periods;
the condition of insulation on pipework, valves
and flanges;
the condition and siting of heat emitters and
any obstruction;
HWS temperature.
Consideration should be given to:
Energy purchasing/procurement.
Energy policy.
Management structure/responsibilities.
Training of key staff.
Management information systems (M&T).
Awareness/motivation of employees.
Investment strategy.
Building fabric
Observations shall be made of:
insulation standards;
excessive air leakage into buildings due to badly
fitting doors and windows.
GPG 316 This version published 02/02
Recommendations shall be based on the above
Written by NIFES Consulting Group
Designed and produced by: Creative Climate Ltd
© Crown Copyright. This version published 02/02
GPG 316 This version published 02/02
On behalf of the Energy Efficiency Best Practice Programme
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