efficient home heating - the Sustainable Energy Authority of Ireland

efficient home heating - the Sustainable Energy Authority of Ireland
efficient home heating
your options
If each of us becomes aware of our own power when it comes to energy efficiency,
and use it properly, we can collectively make a big difference to ourselves, to our
pockets, and to the environment. By taking individual responsibility and changing our
behaviour in small ways every day, we’ll help save energy while we save money too.
All we have to do is recognise our power, and use it.
That’s what the Power of One is all about.
For more information check out www.seai.ie/powerofone
The change campaign is a vital part of Ireland’s plan of action on climate change.
The campaign’s overriding goal is to engage the nation on the issue and to drive
the significant behavioural changes that will be required to lower greenhouse
gas emissions. At the core of the campaign is the change.ie website and carbon
calculator which helps people identify real savings you can make because when you
cut carbon, you cut costs.
For more information visit www.change.ie
efficient home heating
your options
1
Content
About the Sustainable Energy Authority of Ireland ....................................................... 3
How this booklet can help you . ........................................................................................... 4
Your home and your heating requirements ........................................................................ 4
Practical ideas for heating systems in new homes .............................................................. 6
Practical ideas for heating systems in existing homes ........................................................ 7
Renewable heat generation options – the sustainable alternative .................................... 8
Choosing your conventional space heating system ........................................................... 11
Choosing your water heating system ................................................................................. 12
Heat distribution systems – the options ............................................................................. 13
Heat emitters – the options ................................................................................................. 14
Control systems – take charge of your heating .................................................................. 16
Problem solving .................................................................................................................. 20
The BER scheme .................................................................................................................. 21
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About the Sustainable Energy Authority of Ireland
The Sustainable Energy Authority of Ireland (SEAI), established by Government under
the Sustainable Energy Act 2002, has a mission to play a leading role in transforming
Ireland into a society based on sustainable energy structures, technologies and
practices.
Its key objectives are implementing strong energy efficiency actions, accelerating
the development and adoption of technologies to exploit renewable energy sources,
supporting innovation and enterprise for our low-carbon future and supporting
evidence-based responses that engage all actors.
SEAI’s activities can be divided into two main areas:
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Energy Use – SEAI can help to reduce the amount of energy we use in Ireland by
assisting our homes, businesses and industries to be more energy efficient.
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Renewable Energy – By promoting the development and wider use of renewable
energy in Ireland, SEAI can help to further reduce the threat of climate change and
benefit the environment.
SEAI is here to help every energy user in Ireland – homeowners and businesses,
farmers and food outlets, schools and hospitals. We do this by raising awareness and
providing information, advice and publicity on best practice; stimulating research and
development; advising on energy policy and publishing energy statistics.
You’ll find up to date information about our activities, as well as advice and tips, on our
website at www.seai.ie
Contact us, engage with us, ask for advice, put forward your ideas. We’re here to listen
and to help. By working together, we’ll create a greener, cleaner, sustainable future for
Ireland.
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How this booklet can help you
This booklet is designed to give you clear, impartial advice about how best to maximize
the efficiency of your home heating system, whether a new build or a retrofit. It will
show you how to do this in ways that are cost effective, sustainable and environmentally
friendly.
It examines the practical ideas and the various heating technologies you should consider
for your home and offers clear, concise advice.
Your home and your heating requirements
Home is where the hearth is
We live in a world of ever growing energy-awareness. Increasing home heating costs
driven by fluctuating fuel prices mean we must try to use energy as efficiently and
sustainably as possible, without compromising the comfort of our homes, workplaces
and public buildings.
The aim of this leaflet is to give householders an informative guide to the various home
heating systems available, and their relative merits. Perhaps you want to improve the
efficiency of your existing heating system? Or maybe you wish to learn about the most
up to date home heating technologies? If so, this booklet will give you clear, concise
guidance on how to create warmth and comfort in your home, in ways that will help the
environment and your pocket.
Wrap up well
Before examining your heating system, it is important to review how well your house is
insulated. For example, fitting draught excluders around windows and doors, where no
draught protection is in place, can cut heat loss by as much as 20% in winter.
Investing in high-grade insulation does more than cut down on heat loss. It also means
that once your home is heated to the required temperature, it is easier for your heating
system to maintain this temperature, so it uses less energy. Insulating your home can give
long term benefits through reduced running costs. Capital investment in your heating
system will also be reduced, as a smaller, more efficient heating unit will be required.
For further information on how to effectively seal your home consult SEAI’s Guide to
Insulating Your Home.
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Fuel – choose the sustainable option
There are a number of factors to consider when selecting the type of fuel for your home.
For example, availability, storage and cost all have to be taken into account.
But just as important are the environmental impacts your choice of fuel will have.
Most of the energy we use in Ireland comes from fossil fuels - oil, coal, peat and gas.
These are not renewable – once they are gone, they cannot be replenished. Burning
fossil fuels releases carbon dioxide (CO2) into the atmosphere. This is a major contributor
to climate change.
The sustainable alternative to fossil fuels is renewable energy and this will never be
exhausted. Renewable energy is available to us in many forms. The main ones are:
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Solar energy (the sun) – for space and water heating;
Geothermal (heat from below the surface of the earth) – heat pumps for space and
water heating;
Biomass (woodchip and pellets) – boilers and stoves for space and water heating;
Wind powered turbines (the wind) – for electricity generation;
Hydro-electric power (moving water in streams) – for electricity generation.
Heat – meet your annual heat demand
The total amount of heat required for a dwelling is called its Annual Heat Demand. This is
a factor of:
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heat lost from inside to outside through the roof, windows, doors and walls;
heat required to offset the loss of warm air escaping through windows, doors,
chimneys and other openings and heat to warm up the cold fresh air that replaces
the lost air and provides ventilation;
heat required to provide adequate hot water; and
free heat from the sun, from occupants and household appliances.
The Annual Heat Demand for a house will determine the required power output of the
heat generator to be installed. It can be met from two main types of heating systems:
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Central heating systems: oil, gas, solid fuel (coal or biomass) or biomass boilers, or
heat pumps are used to heat water or air and distribute it throughout the house in
pipes or ducts;
Localised heaters: open fires, electric heaters, closed gas fires or stoves are used to
provide heating and, where equipped with a back boiler, hot water.
The types of central heating generators available to deliver the Annual Heat Demand
for your home are detailed in the following sections. Information about localised heat
generators that produce heat separately in each room can be found in the Heat Emitters
section on page 14.
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Practical advice for heating systems in new homes
There are a number of areas where you can optimise the heating system when you are
building your new home. These will help to minimise the load on the heating system,
and ensure it operates as efficiently as possible over the building lifecycle:
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Site and design the most sustainable building possible
Locate the living areas to the southern aspect, so that most use can be made
of available light and solar energy. Also, shelter the building from the external
elements in a suitable manner.
Ensure the building is insulated and sealed efficiently
Ensure the building is insulated to as high a specification as possible. The minimum
requirement set out in Part L of the Building Regulations is air permeability of 10m3/
m2/h. Best Practice is considered to be 5m3/m2/h. Air tightness should also be
discussed with your building contractor to ensure that good construction practices
are used during the build. You can also refer to Good Practice Guides 224 and 268
on ventilation, visit www.seai.ie
Size and select the most efficient heat generation system possible
Part L of the Building Regulations requires all new dwellings to have 10kWh per
m2 per year thermal or 4kWh/m2/yr electrical energy supplied by renewable
technologies. So choose a heating system that will meet this requirement, using
sound engineering and best practice principles. Take energy efficient designs into
consideration in sizing the most efficient heat generation system for the dwelling.
Also balance long-term running costs against short-term savings.
Select the most efficient and practical heat emission system
Make sure the heat emission system (radiators, etc.) is as efficient as possible, taking
into consideration the type and location of units specified.
Ensure efficient control of both space heating and Domestic Hot Water (DHW)
Make sure that once the most efficient heating system has been chosen, good
control systems are also employed.
Practical advice for heating systems in existing homes
There are a number of areas where you can optimise the performance of your heating
system when renovating your home, or replacing an existing heating system:
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Ensure the building is insulated, sealed and draught-proofed
There is little point in incorporating the most energy efficient generation and
distribution system, if the building is leaky and un-insulated - allowing the
unrestricted flow of energy from the dwelling. A poorly insulated house could
be losing up to 30% of its heat through its roof alone – costing you money and
contributing to global warming.
Ensure the heating system is in good working order
Ensure the good performance of your heating system through regular
maintenance via a qualified boiler service engineer.
Replace defective equipment with an energy efficient and/or renewable
technology alternative
Only once the building fabric and ventilation heat loss have been minimised,
and you are sure the current heating system is operating inefficiently, should
investment in a new technology be considered.
Ensure system control is as efficient as possible
Make sure your present control system operates efficiently, and if possible,
enhance it in line with the suggestions in this booklet.
Whatever your decision check www.seai.ie/grants as grants may be available.
Finding out an appliance’s efficiency – HARP
SEAI’s Home-Heating Appliance Register of Performance (HARP) is a performance
database of the majority of home heating appliances used in Ireland. This very
helpful tool will help you identify the most efficient appliances available, including
renewable appliances, for heating your home.
It can be found online at www.seai.ie/harp
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Renewable heat generation options – the sustainable alternative
We are rapidly depleting our supplies of non-renewable energy (oil, gas, coal and peat).
We also need to reduce our emissions of greenhouse gases. This means it makes sense
to adopt sustainable energy solutions wherever possible. Indeed, current building
legislation means we must address these issues – Part L of the Building Regulations
states that all new dwellings receiving planning permission after 1st July 2008 must use
renewable technologies.
The good news is that there now are a range of efficient renewable energy
technologies we can use to heat our homes. These energy systems include:
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Solar energy
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Biomass systems
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Heat pump systems
We shall examine each of these technologies in more detail:
Solar energy
Even in Ireland’s temperate climate, solar energy can still contribute significantly to
our domestic heating requirements. Current technology allows heat to be gained in a
passive or active way.
Passive solar energy
Passive solar energy involves capturing heat from the sun via windows and other glazed
surfaces. Modest levels of passive solar heating can reduce building auxiliary heating
requirements from 5% to 25%. Planning the use of passive solar heating can reduce
heating energy use from between 25% to 75% compared to a typical structure.
In Ireland, glazing should be concentrated on the south façade to make best use of solar
energy (windows on the north façade should be minimised to limit heat loss). Passive
solar energy can also take advantage of the thermal mass of building materials, such as
masonry walls or concrete floors. These can absorb and store energy during the day and
release it gradually during the evening.
However, south-facing glazed areas should not be increased too dramatically. Otherwise
additional measures will be required to avoid overheating in summer and excessive heat
loss at night and on overcast days in winter.
Active solar energy
Active solar energy systems use solar collectors positioned on south-facing roofs to
harvest heat from the sun and distribute it using an air or water network. Solar systems
can provide on average 60% of a family’s annual hot water requirement.
Solar heating is best contemplated when building a new house. However, while
retrofitting of an existing house can be difficult and expensive, convenient solar heating
‘packages’ are now available which can produce a sizeable volume of a typical house’s
annual hot water demand.
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However, whether new or retrofit, a cost analysis of solar heating systems should be
completed prior to installation, in order to determine the possible payback period on
investment based on operational cost saving.
Biomass systems
Biomass boilers burn wood from managed forests to produce hot water for heating and
domestic use. The wood matter is chipped or compacted into small pellets of uniform
size and moisture content. Some models offer up to 90% efficiency. Chips are slightly less
energy efficient but are cheaper to buy.
Biomass boilers can be fully automatic once installed. In order to keep them topped up
with fuel, some boilers have special ‘hoppers’ (storage tanks) which provide enough fuel
for months of operation. Capacities of up to three tonnes are typical and this may last
the average dwelling for a year. Storage conditions of the chips/pellets are important, as
their moisture content affects the efficiency of the boiler.
Chips and pellets produce ash after burning. This can be easily removed and spread in
the garden as it contains nutrients.
Pellets and wood chips are bulky products and do require a lot of storage area. This
should be a consideration in your decision. Typically an average year’s supply of pellets (3
tonnes) will need at least 6m3 of storage volume, while wood chips (approximately 4.5 – 5
tonnes) will require between 8 and 10m3.
Heat pump systems
Heat pumps release heat that is stored in air, ground or water and make it usable for
domestic heating applications. Although they have higher installation costs than
conventional fossil fuel heating systems, heat pump systems offer a very energy-efficient
way of providing heat.
As heat pumps typically exploit low grade temperature sources, they will be more
efficient when supplying heat to low temperature emitters (e.g. under floor heating, low
temperature / large area radiators). It is also very important that the house is very well
insulated and draught-proofed. You will need to ensure that this is the case if you are
considering using these systems in an existing house.
Heat pumps exploit their heat sources in one of two ways:
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Open systems
Water from vertical boreholes, rivers, streams, lakes, etc. is pumped up into the
heat pump where useful energy is transferred to the heating system water, and the
extracted water is then pumped back into the ground. A similar principal applies to
air source heat pumps – see next section.
Closed systems
These use a loop of buried plastic pipe as a heat exchanger. They are particularly
appropriate for underfloor heating in a house, as the typical distribution
temperature is 30ºC to 40ºC.
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Air source heat pumps
Air source heat pumps heat the interior of a building using air from the outside. There are
two types of air-source heating systems.
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Air-to-air systems
Provide warm air, which is circulated to heat the building.
Air-to-water
heat water to heat a building through radiators or an underfloor system.
Ground source heat pumps
Energy from the sun is stored in the soil. As the heat pump system extracts this energy,
the sun constantly tops it up to maintain a constant temperature all year round.
Heat is extracted from pipes buried horizontally or vertically in the soil, a metre or more
deep to ensure that frost cannot damage them. The ground above the pipes cannot be
planted with large trees or shrubs and care must be taken to ensure it is used in a manner
which does not adversely affect the piping system.
A geo-thermal heating system may be used if the dwelling has a large enough area with
a suitable soil type around it.
Water source heat pumps
Where there is a sufficiently large body of ground water available close to a house, it may
be used as a heat source, using either an open or closed system.
For detailed Buyers’ Guides for renewable technologies visit:
www.seai.ie/renewables
Grants
Whatever your decision check www.seai.ie/grants as grants may be available.
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Choosing your conventional space heating system
Conventional boiler
Gas, oil or solid fuel boilers, located inside or outside the house, heat water which is then
distributed by pump or gravity circulation to heat emitters (radiators) in each room.
New boilers can achieve good efficiencies (minimum seasonal efficiency of 86%) when
installed, commissioned and serviced effectively. Distribution pipes for all boilers should
be well insulated and waterproofed to minimise heat loss.
Condensing boiler
Condensing boilers burn gas or oil and condense their flue gases to achieve efficiencies
of 91% or higher. Although more expensive than conventional boilers, their lower
running costs mean the price difference will be recovered over the boiler’s lifetime. They
emit a harmless plume of water vapour to the atmosphere during operation.
Please note that as of March 31st, 2008, installation of condensing boilers is mandatory in
all new dwellings and, where practical, as a replacement boiler in existing dwellings.
Cooker and boiler
Suitable for large kitchens, these appliances burn solid fuel, oil or gas to provide cooking
ovens and to supply hot water for heating. When using solid fuel, the flue/chimney
should be cleaned twice annually and the appliance itself should be cleaned as often as
twice weekly, particularly if bituminous (i.e non-smokeless) coal is used. This type of coal
produces a lot of slag deposits when burnt. These can stick to the boiler surfaces and
reduce efficiency.
Back boiler
Open fires are very inefficient, perhaps as low as 20%, with most heat being lost up
the chimney stack. By trapping more of the fire’s heat energy and using it to provide
domestic hot water and space heating, a high output back boiler increases the efficiency
to approximately 40–50%. Solid fuel back boilers must be cleaned frequently (as often as
twice weekly).
Open fires
Solid fuel and gas open fires, while a visually attractive form of heating for Irish homes,
are extremely inefficient. Typically they offer only 15% to 20% efficiency, meaning that up
to 80% of the heat literally goes up the chimney. Open fires require air for combustion,
and cause an increased ventilation rate in rooms. Draughts can be avoided if the air
supply is located close to the fire, (e.g. ducted in directly from outside). A damper that
closes the chimney when not in use will help to avoid unnecessary heat loss. Fully sealed
gas fuelled fires with back boilers offer an alternative to open fires - most models comply
with current building regulations.
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Choosing your water heating system
Systems for meeting Domestic Hot Water demand (DHW) fall into three main types:
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Centrally stored systems – these store hot water in a cylinder, tank or thermal store
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Locally stored systems – these store hot water for a specific appliance
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Instantaneous water heating – these heat water when it is required
Centrally stored systems
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Boiler systems
The central boiler heats water in a hot water storage vessel such as a cylinder or
thermal store. The hot water is then distributed to the taps on demand as required.
There will be heat losses from the cylinder / storage vessel from the hot water
stored there, and it is recommend to lag or insulate this as much as possible to
minimise this loss.There is also some heat loss through the primary pipework from
the boiler to the hot water storage vessel.
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Room heater systems
Heat exchanger in the room heating unit, such as a back boiler in an open fire, heats
water for domestic use. This system incurs both storage and distribution losses.
These should both be minimised to enhance system performance.
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Immersion heater systems
These systems use the electric heating elements installed in hot water storage
cylinders. These typically have two electric elements: (i) a low rated element to
supply small quantities of hot water for sinks or showers, and (ii) a higher rating
element to heat sufficient water for larger demands, such as baths.
Locally stored systems
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Larger storage type
A range of gas fired or electric wall or floor mounted domestic water storage
heaters are available for baths and multi-outlet applications.
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Over-sink type
Gas fired or electric hot water storage heaters of this type are available for single
outlet sinks or basins.
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Under-sink type
Electric under-sink hot water storage heaters are available for single outlet
applications and work in much the same way as over-sink types.
Instantaneous systems
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Gas fired instantaneous water heater
A suitable natural or liquid petroleum gas supply and a minimum water supply
pressure of 1 bar or 10 metre head is required to operate this type of water heater.
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Electric instantaneous water heater
An electricity supply of 30 amps and a minimum water supply pressure are required
to operate this type of water heater.
Heat distribution systems – the options
Once generated, heat is distributed throughout the house by means of water or air, using
a network of pipes or ducts.
Water distribution
Hot water from a boiler is pumped around a circuit to the heat emitters/radiators at a
required flow rate to meet the heating demands. The water circuit may be open or closed
to the atmosphere:
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Open systems
Open systems (e.g. solid fuel systems) use a small feed and expansion tank located
in the attic to fill the system and to allow for the expansion of water during the
heating process. A vent pipe from the heat generator provides a safety outlet in the
event of water boiling.
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Closed systems
These systems are closed to the atmosphere (pressurised systems), which means
they can operate at slightly higher temperatures than open systems. Closed systems
must incorporate a small expansion tank and air safety release valve. The system is
filled by an automatic valve instead of a feed tank.
Air distribution
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Warm air generators
Use ducting to distribute heat throughout a dwelling. Ducting is usually made of
metal and is hidden in the ceiling void. Warm air systems are particularly suitable for
thermally lightweight buildings, i.e. buildings in which the walls floors and ceilings
of the rooms are constructed of plasterboard or timber.
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Warm air recovery systems
These systems incorporate a ventilation system and an air-to-air heat exchanger in
the attic space. They are designed to work in conjunction with passive solar design
and heat recovery ventilation in newer, more sustainably designed homes.
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Heat emitters – the options
Heat gets into your room via a heat emitter. They fall into three distinct types:
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Centrally generated heat emitters
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Underfloor heating
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Localised heat emitters
All types offer advantages and disadvantages, which are examined in turn.
Radiators (centrally generated)
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Radiators are flat, sealed metal containers through which hot water flows from the heat
generator e.g. boiler or heat pump. They normally operate at temperatures of between
60º and 65ºC (depending on the boiler thermostat setting). However, low temperature
radiators are available for use in conjunction with heatpump or condensing boiler
systems.
Advantages of radiators:
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Fast response (heating up) time
Can be situated near cold surfaces, e.g. single glazed windows, thus reducing
down-draughts
Individual room control possible using TRVs
Relatively low installation costs
Retrofit possible in older homes
Disadvantages of radiators:
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Subject to leaks and require maintenance
Some systems (condensing boiler/geothermal heat pump) require larger radiators
to operate efficiently
Can create uneven heating, particularly in larger rooms
Unsightly and interfere with positioning of furniture
Underfloor heating
This is a means of distributing heat throughout a home via a network of hot water pipes
built into the floor, through which flows heated water.
Advantages of underfloor heating:
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No radiators, so easier decoration and improved room appearance
Lower temperature, radiant heat provides a stable comfortable environment
Provides a background level of heating
Ideal for use with heat pumps or condensing boilers
More uniform heat distribution throughout the room
Intelligent/self-learning controls can improve response times
Disadvantages of underfloor heating:
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Up to 20–25% more expensive to install
Slow response time is less suited to the Irish climate
Controls and design must be of high standard to ensure satisfactory operation
Limited flexibility – considerable building work is required to change the system
Room furniture may impede the emission of heat from floors
Low temperature surface of floor may be inadequate to heat poorly insulated
spaces
Generally only appropriate for new homes/new buildings
Need higher levels of insulation in the floor than for conventional building.
Building regulations require a U-value better than 0.15 W/m2/K
Localised heat emitters (room heaters)
These are heat emitters which generate and emit heat into the space they occupy,
independent of a central heating system. The main types are:
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Wood pellet/solid wood stoves
A wood burning stove can easily power many radiators as well as providing hot
water.
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Gas or oil fired room heaters
operate at 100% efficiency by burning LPG or kerosene, but release CO2 and water
vapour, so require adequate ventilation.
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Electric heaters
radiant, blow heaters, convectors, oil filled radiators and storage heaters. Costly,
but nearly 100% efficient
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Open Fires
visually attractive but highly inefficient form of heating (only 15-20% in terms of
heat output).
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Enclosed gas fires
Aesthetically pleasing and highly efficient, with no draught effect.
Advantages of localised heat emitters
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Provide instant and convenient heat
No distribution network required
Can be very efficient, depending on type used
Can provide a quick, reliable and cost-effective heating solution
Disadvantages of localised heat emitters
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Some use non-sustainable fuels. Greenhouse gas emissions much higher
compared to alternative energy sources.
No storage capacity
May pose a safety risk
Controls limited
Usually have little or no water heating facility
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Control systems – take charge of your heating
Under current Irish legislation, it is a necessary requirement to manage the output
of space and water heating via control systems. Whether it is for a new build, or the
upgrade of an existing system, as many as possible of the relevant energy saving control
measures shown in this guide should be included. By implementing these measures, you
will not only reduce your heating bill, but also reduce the carbon footprint of your home.
It is worthwhile noting that the Home Energy Saving (HES) scheme, administered by
SEAI, provides grants to homeowners seeking to improve the energy efficiency of their
home in order to reduce (i) energy use, (ii) costs and (iii) greenhouse gas emissions. This
national scheme is open to all owners of houses built before 2006. The types of measures
currently eligible under HES include the installation of high efficiency (> 90%) gas or oil
fired boilers and heating control upgrades, as well as roof and wall insulation. For further
information visit www.seai.ie/hes
This section will examine the four key areas where control measures can be implemented
to improve the efficacy of your home heating system:
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Control of the heat generator
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Control of the heat distribution system
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Control of the heat emitters
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Control of the hot water system
Control of the heat generator
Where economically viable, as many as possible of the following control options should
be included for the efficient and safe operation of a fuel burning heat generator.
Time switch
A time switch enables the boiler to provide heat to either the space heating and/or
the domestic hot water supply circuits when required. This means, for example, that
domestic hot water can be provided in the summer when heating is not required.
The provision of separate space heating and domestic hot water supply circuits is a
requirement for new buildings.
Delayed start thermostat
This control device uses a time switch to monitor internal and external temperatures
and delays the boiler start. In this way, it reduces the number of hours per day that the
heating system runs, without creating any discomfort.
Programmer
This device controls both the space and water heating systems, allowing you to choose
when you want the system to operate (usually on a daily/weekly schedule). There are
three types of programmers, offering varying degrees of control.
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A mini-programmer which allows (i) space heating and hot water to be provided
simultaneously, or (ii) hot water alone, but not space heating alone.
A standard programmer which uses the same time settings for space heating and
hot water.
A full programmer which allows the time settings for space heating and hot water
to be fully independent.
Programmable room thermostat
This device combines a time-switch and room thermostat and allows you to set different
time periods with different target temperatures for space heating.
Boiler interlock
This is an arrangement of the system controls which your electrician can undertake to
ensure that the boiler does not fire when there is no heat demand.
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Control of the heat distribution system
Distributing heat efficiently around your home is just as important as generating it
efficiently. This section discusses the options available for controlling the distribution of
heat.
Zone control
Individually Controlled
Zone Controlled Valves
Dividing the heating system into separate zones allows it to operate independently in
different parts of your house. Typical zones might be (i) the living room, (ii) the rest of the
ground floor, (iii) the first floor, and (iv) the domestic hot water storage cylinder. Each
zone will be switched on only at the times when there is a demand for heat in
that area.
All heating systems should have a separate hot water circuit to allow for the heating of
hot water without needlessly heating the home. This is a legal requirement of all new
buildings. Additionally, current regulations suggest that for homes over 100m2 the
heating system should be split into at least two zones – namely the bedrooms (cooler)
and living areas (warmer).
Load compensator
This device regulates the water temperature in the DHW circuit in direct relation to the
temperature measured inside the dwelling.
Weather compensator
Designed for larger installations, a weather compensator control helps reduce energy use
and associated utility costs by linking the temperature inside a dwelling to that outside.
This means, for example, that when outside temperatures rise, the demand for space
heating in the house is reduced, thus saving on heating costs. Weather compensation is
particularly beneficial in conjunction with condensing boiler systems as it can help the
boiler run more efficiently for longer.
Boiler energy manager
This device improves boiler control by using a selection of features previously detailed,
such as load and weather compensation, boiler interlock, zone control, etc. It is an
extremely efficient way to operate the heating system in your home.
Flow switch
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A flow switch detects when there is no water flow through the Domestic Hot Water (DHW)
system, for example, when all TRVs are in the fully closed position and there is no heating
requirement.
Control of heat emitters
Water is the most common distribution medium in heating systems and heat is generally
emitted to rooms via radiators or convectors (fan assisted radiators). When heating is not
required in a particular part of your home, you can isolate heat emitters in this area either
manually or automatically.
Manual control
Most radiators and convectors are fitted with a hand wheel valve. This is essentially an
on-off switch which allows the heat emitter to be isolated from the heating circuit.
Thermostatic Radiator Valves (TRVs)
1 2 3
A thermostatic radiator valve (TRV) may be installed instead of the hand wheel valve.
The TRV has a number of settings which adjust the flow of heating water to the heat
emitter, according to the temperature of the room. So, for example, in rooms where a
high level of heating is required, the TRV will be set at the top setting. Conversely, if only
background heating is desired, then the valve will be at its lowest setting.
A motorised valve may be used along with the hand wheel valve. It is activated by
a thermostat located in the room. However, while motorised valves may offer more
effective heat control than a conventional TRV, they are also more expensive.
Control of the hot water system
As has been previously outlined, domestic hot water supply may be provided from a
central storage cylinder, from local storage or from an instantaneous source. There is
scope for energy saving in the way hot water is produced and used.
Control of central storage cylinder
The hot water cylinder should be supplied with heating water from the boiler via a
separate circuit from the space heating circuits. Two aspects of a hot water cylinder that
should be controlled are (i) the times that heating water is circulated from the boiler to
the coil heat exchanger and (ii) the temperature at which the hot water in the cylinder is
stored.
Point of use control
It is recommended that domestic hot water should be stored at 60ºC. However, water at
this temperature is too hot for showers. The process of mixing hot water from the storage
cylinder with cold water from the cold water cistern can be automated by installing
a Thermostatic Mixing Valve. Once set at the desired temperature, the shower water
temperature always remains the same, provided the water in the storage cylinder is at or
above the desired temperature. This minimises energy and water wastage.
Instantaneous DHW at isolated users
In large houses, distributing heat energy and water from a central storage cylinder causes
wastage. Installing a local hot water system at points of usage eliminates this waste.
Local systems may be either (i) storage or (ii) instantaneous. They use natural gas, liquid
petroleum gas or electricity.
19
Problem solving
Heat generation and distribution systems are prone to a number of issues which can
affect their performance. It is therefore recommended that your heating system is
serviced regularly.
For a list of the issues, problems and answers that may affect your heat generation and
distribution systems, please refer to the Question and Answer section in the SEAI website:
www.seai.ie/yourhome
Maintenance
An annual boiler safety check and boiler service, carried out by a professional service
engineer ensures that your boiler is functioning properly. If your oil or gas boiler hasn’t
been serviced recently, then you could be wasting money. In fact, by servicing your
boiler, you could improve your overall efficiency by 10%.
The benefits of servicing your boiler
Ë
Saves you money - reducing your heating costs
Ë
Reduces CO2 emissions - benefiting the environment
Ë
Gives you peace of mind - improving your boiler’s reliability and safety
For more information on servicing an oil or gas boiler visit www.seai.ie/boilers
All heating systems including those fuelled by renewable energy will perform more
efficiently, and therefore more economically, if they are well maintained and serviced on
a regular basis. Your system will come with a user’s manual and a service schedule. These
are set out by the manufacturer and we would recommend that you follow these to
ensure that your heating system works at its optimum level all the time.
20
The BER Scheme
What is a BER?
A Building Energy Rating or BER is similar to the energy label on your fridge with a
scale of A-G. A-rated homes are the most energy efficient and G the least efficient.
From 1st January 2009, a BER certificate became compulsory for all homes being sold
or offered for rent. If you are buying or about to rent a house or apartment now, you
are entitled to a BER – so ask the seller/landlord or their agent for it.
What are the benefits of a BER?
A BER makes the energy performance of a home visible to prospective buyers and
tenants and enables them to take energy performance into consideration in their
next house purchase or rental decision.
For more information on BER please visit www.seai.ie/ber
Home heating is the major contributor to domestic energy
use, so adopting the recommendations in this SEAI booklet
will reduce the amount of energy used to heat your home,
and produce a better BER for your property. It is imperative
that all of us put these actions in place now. Not only will this
help the environment through lower CO2 emissions, it will also
benefit homeowners through greater home comfort levels and
reduced home heating costs.
Read our other publications, visit www.seai.ie/yourhome
21
Sustainable Energy Authority of Ireland
Wilton Park House, Wilton Place, Dublin 2, Ireland.
t +353 1 808 2100
f +353 1 808 2002
e [email protected]
w www.seai.ie
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