research highlight Energy Use Patterns in Off-Grid Houses introduction

research highlight Energy Use Patterns in Off-Grid Houses introduction
research highlight
April 2001
Technical Series 01-103
Energy Use Patterns in Off-Grid Houses
introduction
This project is a survey of twelve “off-grid” households across Canada.
The objective is to document off-grid energy use and lifestyle patterns
to determine if there are lessons or examples of energy conservation
that apply to conventional grid-connected houses. The houses in the
study operate on systems using renewable energy as the primary source
of electricity. These systems run the gamut from simple photovoltaic
(PV) installations with diesel generator backup, to complex “hybrid”
systems that use PV, wind and seasonal microhydro for power. Most
of the houses in this study feature all the “mod-cons’’: running water,
stereos, computers, fax machines, etc. People have chosen the off-grid
option for several reasons: political, environmental, financial, and
entrepreneurial. In every case, homeowners cited more than one of
these categories when describing their choice to use a renewable
energy source.
Research Program
Twelve single family dwellings which have been off-grid and occupied
for at least two years prior to the study were identified in three regions:
Nova Scotia, Manitoba and British Columbia. The energy source(s),
the system size and the storage system as well as the possible electrical
load were noted for each house. In most cases the energy used by the
lights or appliances was determined by running each of them and by
noting the draw on the system. In several cases, the homeowners already
had the information, either from the exercise of sizing their system in
the first place, or because of their familiarity with it and the usage
patterns. To determine an approximate actual annual loading, homeowners
were asked to estimate the hours each light and appliance was run on
a daily or weekly basis.Where the water heating source, typically propane,
was also the energy source for cooking, and in some cases, refrigeration,
the kiloWatt-hour equivalent of that fuel source and the efficiencies of
the appliances were calculated and added to the estimated actual annual
load. The energy required for the generator was considered outside of
the load generated by the household. The estimated actual annual
load total was compared to the “baseload” figures described below.
The average electrical “baseload” (the amount of energy used for
lights and appliances) for a standard house of the same vintage in the
same province was determined, as was the energy required for water
heating. Every house used wood for space heating; some included
excellent passive solar heating features in their design, and some used
wood and/or solar for their water-heating source. Because of the variables
involved in wood heat (mix of wood, efficiency of appliances, etc.), space
heating was not included in any of the loading comparisons. Estimates
of off-grid system costs were obtained from each homeowner. An
airtightness test was performed on 10 houses (two houses were not
viable for testing because of renovations).
Research Highlight
Energ y Use Patterns in Off-Grid Houses
Electrical System Configuration and Loading
All twelve houses have renewable energy sources as their primary source of electricity, and most of them have fossil fuel generators for backup. In most
of these houses, the lighting and water pumps were the highest draws on the system. See case studies for details.
#
Location
StartUp
Year
Energy Source(s)
Rated
System
Size, in
Watts*
Power
Storage,
Amp
Hours
Max.
Power
Storage
MJ (kwh)
Possible
Daily
Load, MJ
(kwh)
Actual
% Battery
Daily
Drain/Day
Load, MJ **
(kwh)
# Days
House
Can Run
Off
Batteries
**
1
Yarmouth Co, NS
1998
Wind/PV/Gas
1,000
(5,000)
1,200
54 (15)
42 (12)
19 (5)
35-77
1-3
2
Gulf Islands, BC
1994
PV/Diesel
200
(5,000)
1,200
54 (15)
14 (4)
7 (2)
13-26
4-7
3
Gulf Islands, BC
1997
PV/MH/Wind/Gas
1,920
(3,500)
1,250
54 (15)
38 (11)
20 (6)
37-73
1-3
4
Gulf Islands, BC
1981
PV/Wind/Diesel
830
(3,500)
1,200
52 (14)
18 (5)
11 (3)
21-34
3-5
5
Gulf Islands, BC
1991
PV/MH/Propane
500
(3,500)
1,200
52 (14)
11 (3)
6 (1.6)
11-21
5-8
6
S. Manitoba
1995
PV
125
220
9 (2.5)
2 (0.5)
1 (0.3)
10-19
5-10
7
S. Manitoba
1980
PV
100
100
4 (1.1)
2 (0.5)
0.7 (0.2)
17-38
3-6
8
Antigonish Co, NS
1994
PV/Gas
420
(6,000)
1,400
61 (17)
10 (2.7)
6 (1.7)
10-16
10-6
9
Antigonish Co, NS
1997
PV/Gas
420
(3,500)
880
38 (11)
5 (2)
4 (1)
10-14
7-11
10
Belfast, PEI
1997
Wind/Grid
900
(grid)
840
36 (10)
29 (8)
22 (6)
60-80
1-2
11
Keswick Ridge, NB
1994
PV/Diesel
333
(3,500)
1,200
52 (14)
7 (2)
3 (1)
5-15
7-17
12
Eastern Shore, NS
1994
PV/Wind
900
600
26 (7)
5.8 (1.6)
2.4 (0.7)
10-22
15-10
* The bracketed numbers in column #5 “Rated System Size” are the power ratings of backup generators, in Watts.
** Assuming fully charged battery bank.
2
Canada Mortgage and Housing Corporation
Research Highlight
Energ y Use Patterns in Off-Grid Houses
Comparisons of Light and Appliance Use
The following table outlines the estimated annual actual load for electrical and non-electrical1 appliances for each house and compares those loads to
the baseloads2 for similar houses in the same region.
House # Estimated
Actual Load,
Lighting/
Appliances, MJ
(kWh)
MJ (kWh)
Equivalent, NonElectrical (Not
Including WoodBurning
Appliances)
Water
Heating
Load
Included
Total
Estimated
Actual Load,
MJ (kWh)
1
7,050 (1,960)
31,100 (8,640)
Y
2
2,700 (750)
20,600 (5,720)
3
7,380 (2,050)
4
Average
Baseload, MJ
(kWh)
Difference
Between Actual
and Baseload, MJ
(kWh)
% Reduction from
Baseload
38,150 (10,600) 49,000 (13,610)
10,850 (3,010)
22
Y*
23,300 (6,470)
33,270 (9,240)
9,970 (2,770)
30
10,180 (2,830)
N
17,560 (4,880)
24,500 (6,810)
6,940 (1,930)
28
4,000 (1,110)
15,330 (4,260)
N
19,330 (5,370)
26,470 (7,350)
7,140 (1,980)
27
5
2,080 (580)
21,600 (6,000)
Y
23,680 (6,580)
47,400 (13,170)
23,720 (6,590)
50
6
330 (90)
N
330 (90)
20,450 (5,680)
20,120 (5,590)
98
7
260 (70)
N
260 (70)
20,850 (5,790)
20,580 (5,720)
99
8
2,160 (600)
38,960 (10,820)
Y
41,120 (11,420) 49,000 (13,610)
7,880 (2,190)
16
9
1,340 (370)
22,800 (6,330)
Y
24,140 (6,710)
49,000 (13,610)
24,860 (6,910)
51
10
7,810 (2,170)
13,570 (3,770)
Y
21,380 (5,940)
49,000 (13,610)
27,620 (7,670)
56
11
1,090 (300)
N
1,090 (300)
21,780 (6,050)
20,690 (5,750)
94
12
820 (230)
5,690 (1,580)
N**
6,510 (1,810)
24,500 (6,810)
17,990 (5,000)
73
Average
3,210 (890)
19,820 (5,510)
18,080 (5,020)
34,850 (9,680)
16,770 (4,660)
48
Range
260 – 7,810
5,680 – 38,960
260 – 41,120
20,450 –49,000
6,940 – 24,870
16 – 99
(70 – 2,170)
(1,580 – 10,820)
(70 – 11,420)
(5,680 –13,610)
(1,930 – 6,910)
* An estimated 25% of both the water heat and cooking fuel for this house is derived from an airtight cookstove with a water jacket.The
estimated annual baseload reflects a reduction of 25% in energy use to compensate for this.
** Although the hot water in this house is heated using the propane stove, the amount of hot water used is negligible, as it is only required for
dishwashing and occasional bathing (homeowner uses “solar shower” water bag) for one person. As a result, the water-heating load was not
included for this house.
“Non-electrical”appliances (other than wood burning appliances) in use in the study houses are propane-fired. Assumptions about propane use:
1
26,417 available Btu per litre. Usage figures based on information from Superior Propane (Kentville, NS office) # litres used by appliance annually
(as a proportion of total purchased litres where several appliances are used) * efficiency of appliance * 0.0002929 = kWh equivalent.This figure
divided by a factor of 3.6 gives the MJ equivalent.
Baseload figures are derived from “Home Energy Retrofit in Canada: Overview and Opportunities”; NRCan & CMHC, March 1994. ISBN 3662-22198-2
2
Canada Mortgage and Housing Corporation
3
Research Highlight
Energ y Use Patterns in Off-Grid Houses
Reasons for Going Off-grid/Lifestyle
and Energy Use Pattern
Implications of Energy Use
Patterns in Off-grid Houses
Reasons for going off-grid ranged from the practical (remote location)
to the environmental/political (renewable energy). Of the 12 installations,
eight were at sites sufficiently remote to warrant an off-grid installation
based on a straight cost comparison between going off-grid and bringing
the utility line to the site. Four sites were within reasonable distance
of existing power lines, but the homeowners’ choice to be off-grid was
directed in part by long-term savings versus rising conventional energy
costs, or for environmental/political reasons. Three of these four nonremote locations are owned by individuals who are “in the business”
of consulting on renewable energy projects, or selling the systems and
components themselves, and had a vested interest in living off-grid, as
well as being “presold” on the concept. The last non-remote home was
designed to be off-grid because the homeowner is a seasonal worker
who wanted minimal operating costs during his downtimes (as well
as simply not wanting to “give money away” to the local utility). Most
of the homeowners named concerns over environmental damage from
fossil fuel generation processes as a prime-motivating factor in choosing
to be off-grid, and all homeowners considered the initial cost of the
systems as “pre-buying” power, especially those in remote locations.
It is difficult to quantify energy use with precision in this study, because
there is a mix of energy sources that cannot be metered, such as wood
and propane and efficiencies of older appliances etc. All figures should
be taken as close proximations. The key issue in the study is the fact that
these homeowners, due to the limits of their energy supply, have easily
modified or re-arranged their energy use patterns to adjust to that supply.
In some cases, the degree to which homeowners have chosen to reduce
their energy consumption would be extremely uncomfortable and
untenable for most people accustomed to a typical North American
“standard of living.” However, there are several examples of more or less
typical house-hold lighting and appliance mixes that are significantly
below the baseload figure.
Lifestyle and energy use patterns included timing activities that require
major draws on the system (washing machines, vacuums, etc.) with
either optimum energy gathering times, or when the generator is run
(only in houses where the generator runs regularly). Another pattern
noted was shifting the activities so that only one major draw occurred
on one day, helping to “balance” the energy required for these
activities over several days.
Many homeowners noted that their connection with the weather and
the seasons had become more obvious or important after going offgrid, an awareness of these factors being crucial to how their household
energy use was being replenished or depleted. For some, this awareness
has increased their personal commitment to environmental issues.
4
Canada Mortgage and Housing Corporation
House 1 and House 10 were designed with larger systems that reflect
the mix of appliances and lighting typically found in grid-connected
houses (including full-size electric refrigerators and freezers, as well as
computers, fax machines and TVs. Even so, these houses show a reduction
in energy use of 22 per cent and 24 per cent respectively for
lighting, appliances and hot water use (hot water in both houses
supplied by propane).
House 6 and House 7 are examples of more “bare-bone” systems,
which suit the lifestyle needs of a small cross-section of rural
homeowners. House 11, while not as spartan as Houses 6 and 7, is still
comparable to a specific rural lifestyle. However, all three houses, with
an average reduction of over 90 per cent in energy use, offer some
excellent insights into efficient and effective use of energy, especially in
cost-effective refrigeration possibilities. The total system in House 12 is
not powerful enough to run a hairdryer, yet the energy needs of a
family of four have been handily met in the past – showing another
excellent example of conscientious energy use.
In total, an average energy use reduction from the typical baseload is about
44 per cent. Of the six houses with propane or electric refrigerators,
the average reduction is closer to 30 per cent, and of the six houses
without refrigerators, the average reduction is around 70 per cent,
showing the impact of these appliances on energy requirements.
Research Highlight
Energ y Use Patterns in Off-Grid Houses
One of the big-ticket items in terms of energy use is refrigeration. All
bemoaned the fact that refrigerators of any ilk were too expensive both
to buy and to run. There were several solutions to refrigeration needs.
Houses 1 and 10 have typical electric refrigerators, while Houses 3, 4,
and 5 have propane refrigerators. Apparently, new propane units are
not as good as old ones for maintenance and longevity. The most energy
efficient–and highly usable, easily adaptable systems–were found in
Houses 6, 7 and 8. Houses 6 and 7 feature vented walk-in cold rooms,
while House 8 has a “California cooler,” a thermally isolated locker
with a cold air vent running up from the crawlspace and a top vent to
create a cold air “chimney.” This arrangement brings consistent cool
air to food products which need to be kept cool (for example dairy,
fragile greens, etc.), with minimal or no energy use. Houses 8, 9 and
12 had chest coolers, the 12-volt direct current (VDC) type that can
be placed in a car and plugged into the lighter socket. These are
typically kept in a non-heated room or a basement and not plugged in
unless the weather is very hot, as they cycle on and off constantly when
plugged in. Freezers were not found in any houses but House 10, which
had two. In terms of energy efficiency, freezers are a fairly constant
draw, and add dramatically to the cost of an off-grid system, as they
result in higher overall loading. However, super energy efficient models
such as the “Vestfrost ConServe,” draw one-third of the energy of typical
freezers (45 W versus 125W, in House 10). Some homeowners share
space in a neighbour’s freezer, or a community freezer.
Adequate, energy efficient refrigeration was the biggest issue for all
houses, along with finding a decent AC water pump that doesn't have
a huge amount of startup surge. Electromagnetic coupled AC motors
offer a great boon to energy efficient operation, but are costly and
difficult to find, as far as the homeowners in the study are concerned.
Other issues surrounding “odd” appliances/motors and lighting
fixtures are: cost to purchase, ease of installation, ease of repair and
maintenance and availability of parts.
In terms of water heating, propane or coils/jackets off woodstoves
were the norm. One major issue that came up in terms of energy use
was the thermal coil ignition for new propane appliances. It is difficult
to time the big loads with water heating cycles so as to not blast the
inverter. This is especially true for the thermal coils in propane ovens,
which cycle on and off constantly through a baking or roasting period.
There are two elements that are economically discordant: compact
fluorescent lighting costs have not decreased in the last decade, while
the market share of these fixtures has risen exponentially. The same
applies to PV panels: the price point remains similar to that of 10
years ago, even though the market has boomed (these are still “specialized”
or niche markets, obviously, but cost is probably one of the reasons
why they remain so). If the initial costs came down, these items would
be more utilized, and more obviously feasible to install. As it is, the
manufacturers are, as one homeowner said “just putting my energy
savings into their back pocket.”
The following energy saving themes echoed throughout the interviews:
Lighting
1. Lights should be turned off when they are not in use.
2. Task lighting means lower wattage, as the light can be closer to
the work surface.
3. Having the outside of the house lit up all night is a wasteful use
of energy, and you can’t see the stars very well, either.
4. Work or study areas set close to S or SW/SE windows increase
daylighting in those high-use areas.
5. “Lightpipes” or “suntubes” in darker work areas or commonly
used rooms increase the overall daylighting.
6. Compact fluorescent light fixtures should be used adequately:
their life cycle and efficiency are reduced dramatically when they
are turned on and off constantly. They should be in places such
as hallways, kitchens, stairwells, exterior fixtures, where they are
going to be turned on and left on for one- or two-hour stretches.
Appliances
1. Appliances should be unplugged when not in use; don't rely on
digital clocks or timers in every room.
2. It is important to buy the most energy efficient appliances you
can afford (ideally those without digital clocks or timers).
3. The overall system can be smaller if high-energy draws can be
staggered (i.e. don't do the washing while vacuuming), or timed
so these appliances are used on clear days or when the generator
is running (for battery equalization, etc.). This doesn't affect
general grid connected homeowners, but it does have an impact
on lifestyle patterns for those who are on time-of-use programs.
4. More efficient sources of energy should be used where possible.
Avoid large thermal resistance loads.
5. Before you buy, ask yourself: Do I really need another gadget?
Canada Mortgage and Housing Corporation
5
Research Highlight
Energ y Use Patterns in Off-Grid Houses
Energy Use Patterns in Off-Grid
Houses – Case Study 1: Yarmouth
County, NS
House Description
A 16 x 8 m (52 x 26 ft.) bungalow with full basement, this energy
efficient “package” house was built in 1998 for a family of four (two
grown children are now part-time residents). The house takes advantage
of good passive solar orientation and of a well-treed area to the north to
reduce the impact of cold winter winds. An airtight stove (3 cords
wood/yr) augments the solar space heating.
System Performance
The load on the system includes lighting, refrigerator, water pump,
vacuum, washing machine, computer, fax machine, 26” TV with
satellite system and several small appliances. The total possible daily
load on the system is approximately 42 MJ (12 kWh), while the
actual load is estimated to be 19 MJ (5 kWh). Propane is the energy
source for water heat, clothes drying and cooking. Approximately
1,470 L of propane is purchased annually. The 5 kW genset, which is
housed in a small shed to the west of the house, is run an average of
1,092 hours, providing 5,460 kWh of power for the house. The
genset has a remote start mechanism installed for convenience.
Annually, the actual electrical use in this house is about 7,050 MJ
(1,960 kWh).When the kWh equivalent of the propane appliances is
included in the actual energy use in this house, the figure is approximately
38,150 MJ (10,600 kWh). The average annual lighting and appliance
energy use for vintage house in Nova Scotia is 24,500 MJ (6,810 kWh).
Water heating accounts for another 24,500 MJ (6,810 kWh)1, for a
total of 49,000 MJ (13,620kWh). There is a difference of 10,850 MJ
(3,010 kWh), for a 22 per cent reduction. These figures do not
include space heating.
Thermal Envelope Summary
AC/H@50 Pa: 2.77
Walls: 2x6 framing w/RSI 3.5 (R20) (bare conc. basement.
walls, no ins. @ slab)
Ceilings: RSI 7 (R40)
Windows: low-E, argon fill, insulating spacers
Doors: steel polyurethane core
System Description
Power is supplied by a 300 W PV array and an Air 303-12 wind
generator. A 5 kW gas generator is used as backup. Energy is stored in
a bank of 10, T2200 golf-cart type batteries, wired to produce 12 VDC
(1200 Ah). A Trace DR2412 modified sine wave Inverter/Charger is
used to produce 120 VAC throughout the house (there are no DC
loads). The cost to install the system was $15,000 CAD.
Home Energy Retrofit in Canada:Overview and Opportunities;NRCan,CMHC,March 1994 ISBN 0662-22198-2
1
6
Canada Mortgage and Housing Corporation
Research Highlight
Energ y Use Patterns in Off-Grid Houses
Notes From Homeowner @ System Operation:
Windbreak @ N of house is interfering with the wind generator, the
height is to be increased from 6.7 m to 15 m (22 to 50 ft.). The solar
array was recently put on turntable to see if daily output can be increased.
Another five panels are to be added to the system to reduce the use of
the genset, which is currently run about three hours every evening.
Energy Use Patterns in Off-Grid
Houses – Case Study 2: Gulf
Islands, BC
Homeowner’s reasons for going off-grid:
As part of the homeowner’s business, he felt it was necessary to show a
“normal” house with an off-grid system, even though the cost of grid
connection on this site was minimal. Homeowner has been interested
in wind and PV since the 1970s, with a focus on PV for these reasons:
no moving parts, quiet, minimal maintenance. The downside of PV is
the toxic materials used in panels, and their susceptibility to radiation
damage (“browning” or “mirroring”). Small-scale residential wind
installations are typically high maintenance and site specific. Homeowner
would not have recommended wind generator for this site for a client,
but he had one in stock and wanted to show it to potential clients.
Homeowner’s observations on living off-grid and
energy use patterns:
It is difficult to find new gas appliances without thermal coil
ignition, which creates a large draw on the system.
Wired-in smoke detectors can overheat or short out due to the
modified sine wave of the inverter.
With modified sine wave inverters, any digital clock or timer
that takes its signal from the utility 60 hz cycle will not tell
proper time, and any appliance that runs with an AC motor is
noticeably louder (microwave, ceiling fan, etc.) in operation.
Computer, phone/fax and office lights are all on a separate
inverter and sub panel with an impulse phase correction that
prevents the computer from rebooting.
Laundry is done when the generator is on, or on a clear day. It
is possible to complete two or three loads at a time this way.
It is important to install appliances, lights and system
components that are standard, replaceable and repairable.
Microwave cooking with modified sine wave inverter takes
twice as long because the microwave is designed for peak power
of 160 VAC on demand.
House Description
A 17.7 x 7.3 m (58 x 24 ft.) bungalow on an open crawlspace with a
5.5 x 7.3 m (18 x 24 ft.) second storey addition. The house was built
in 1960 and barged to its new island site in 1981 as a retirement home
for a couple. The primary axis is N-S, with view windows to the west.
A wood stove and a cookstove (9 cords softwood/yr) heat the house.
Thermal Envelope Summary
AC/H@50 Pa: 17.28
Walls: 2x4 framing w/RSI 2.1 (R12) (+/- 25% crawlspace RSI 1.4/R8)
Ceilings: RSI 2.1 (R12)
Windows: single pane, sashless sliders, thermopane patio doors and
one upper window
Doors: solid wood with storm door
System Description
The power is supplied by a 200 W output PV array (4-50 W panels)
which was installed in 1994. A 5 kW diesel generator is used as
backup. Energy is stored in a bank of 10, Canadian National
“Performer” batteries, wired to produce 12 VDC (1,200 Ah). A Trace
DR2401 Inverter/Charger is used to produce 120 VAC. The original
power system to this house was the 12 VDC diesel genset with
propane and kerosene for refrigeration, cooking and some lighting.
The genset was kept to backup the PV system. The original wiring in
the house was for the 12 V genset system. After the PV was installed,
wiring for new AC loads was added. The cost of the system (with the
genset system) was $7,000 CAD.
Canada Mortgage and Housing Corporation
7
Research Highlight
Energ y Use Patterns in Off-Grid Houses
use for this vintage house in British Columbia (1981) is 21,450 MJ
(5,960 kWh), with water heating adding another 22,900 MJ (6,360 kWh).
It is estimated that wood heat accounts for 25 per cent of cooking and
water heating. Allowing for a corresponding reduction in baseloads, the
total average annual baseload is 33,270 MJ (9,240 kWh). There is a
difference of 9,970 MJ (2,770 kWh), for a 30 per cent reduction.
These figures do not include space heating.
Notes From Homeowner @ System Operation:
Two “sunpipes” were installed in the kitchen (which is on the east face
of the house) to increase the daylighting potential in the afternoon/evening.
Initially, the cooking was done on the woodstove and in a large microwave.
However, the owners found that the microwave was noisy and the
inverter didn’t supply enough power to the microwave. A propane range
was installed and the microwave use reduced. The battery bank is typically
charged before noon on clear days, and the homeowners switch over
to using just the available PV when this happens.
Homeowners’ reasons for going off-grid:
System Performance
The load on the system includes lighting, water pump, vacuum,
washing machine, dishwasher, microwave, computer, two small TVs
(AC/DC) and several small appliances, as well as an air compressor,
table saw and radial arm saw in the workshop. The total possible daily
load on the system is approximately 14 MJ (4 kWh), while the actual
load is estimated to be 7 MJ (2 kWh). Propane is the energy source
for the refrigerator and range (one pilot kept on, light pilot when oven
is in use), and a much-used barbeque. There is a propane clothes dryer
in the house, but it is not hooked up. Approximately 870 L of propane
is purchased annually. The running of the genset, which is housed in a
small shed to the east of the house, has been logged since 1996. In four
years, the homeowners have only required the genset to run for 540
hours, which averages to less than 1/2 hr/day. However, the typical
usage pattern is periodic equalization of the batteries, which means the
genset is often not used for months at a time, depending on the season.
The actual electrical use in this house is about 2,700 MJ (750 kWh)
annually. When the kWh equivalent of the propane appliances is included
in the actual energy use for this house, the figure is approximately
23,300 MJ (6,470 kWh). The average annual lighting and appliance
8
Canada Mortgage and Housing Corporation
This is a retirement home. The homeowners had bought the diesel
genset as the affordable, convenient option. Their son gave them the
PV system. The homeowners enjoy the quiet operation of the PV system
and the reduced fuel costs associated with using renewable energy.
Homeowners’ observations on living off-grid and
energy use patterns:
With modified sine wave inverters, any appliance that runs with an
AC motor is noticeably louder (microwave, ceiling fan, etc.) in
operation.
Newer propane fridges don’t have the longevity nor maintenancefree operation that older models offer.
Laundry is done on a clear day and hung out to dry.
Living off-grid has emphasized the need to turn off lights and unplug
appliances when they are not being used. Original light fixtures are
12 VDC, all 120 VAC fixtures are low wattage incandescent or compact
fluorescent. Visitors are not aware of power limitations, and visiting
family or friends who are grid connected is quite a different experience:
grandchildren wonder why the homeowners always turn out lights
and unplug things wherever they go.
Research Highlight
Energ y Use Patterns in Off-Grid Houses
Energy Use Patterns in Off-Grid
Houses – Case Study 3: Gulf Islands, BC
120 VAC. The lights in this house are all 12 VDC fixtures, as is the
fridge. The remainder of the wiring is for 120 VAC appliances. The
PV
WIND
genset
charge
controller
M/Hydro
battery
bank
House Description
A two-storey 7.6 x 15.2 m (25 x 50 ft.) house with walkout basement.
The family of four moved in 1997. A 7-sided two-storey passive
solar greenhouse wrapped around the SE corner is the main source of
space heating. A vacuum tube collector and tank with integral heat coil
supply most of the hot water. A combination wood furnace with
water coil and cookstove built around a massive central chimney heat
the house and the water (3 cords wood/yr) when there isn’t enough
solar gain. The high mass construction includes a 100 mm concrete
slab on the lower floor and 50 mm concrete overpour on the main
floor. The lower walls and north facing stairwell are built of stone with
an interior insulated stud wall. The remaining walls are standard 2x6
framing.
Thermal Envelope Summary
AC/H@50 Pa: n/a, as one window and a door were not in place
Walls: lower stone walls w/vermiculite, RSI 2.4 – 3.2 (R14-18), upper
walls 2x6 framing, RSI 3.5 (R20),
Ceilings: RSI 3.5 (R20)
Windows: thermopanes in wood frames
Doors: solid wood
System Description
The power is supplied by a 620 W output PV array (8-60 W and 435 W panels); a 1,000 W Whisperlite wind generator and a 25 W
microhydro system which runs seasonally (November through May)
from a pond overflow. A 3.5k W gas generator acts as backup. Energy
is stored in a bank of 6, P23 golf cart batteries, wired to produce 12 VDC
(1,250 Ah). A Brutus pure sine inverter/charger is used to produce
inverter
DC load
AC load
centre
system cost $10,000 CAD to install.
System Performance
The load on the system includes 12 VDC lighting and fridge, 120 VAC
water pump, built-in vacuum, an energy efficient front-loading washing
machine, microwave, two computers (one PC and one laptop), a fax
machine, a stereo, a TV, an air cleaner (Bionaire type) and several small
kitchen appliances as well as music equipment in the studio. The total
possible daily load on the system is approximately 38 MJ (11 kWh), while
the actual load is estimated to be 20 MJ (6 kWh). Propane fuels the
cooktop and oven. Approximately 250 L of propane is purchased annually.
The genset, which is housed in a small shed to the north of the house,
is run once a week for one to four hours (approx. 4.5 L gas @ 4 hrs).
Clothes washing, vacuuming, flour grinding or other high-load
activities are done when the generator is on.
The actual electrical use in this house is about 7,380 MJ (2,050 kWh)
annually. When the kWh equivalent of the propane appliances is included
in the actual energy use for this house, the figure is approximately
17,560 MJ (4,880 kWh). The average annual lighting and appliance
use for this vintage house in British Columbia is 24,500 MJ (6,810 kWh).
There is a difference of 6,940 MJ (1,930 kWh), a reduction of
28 per cent. These figures do not include space or water heating.
Canada Mortgage and Housing Corporation
9
Research Highlight
Energ y Use Patterns in Off-Grid Houses
Notes From Homeowner @ System Operation:
The installation of the PV on the roof has turned out to be awkward
for maintenance. Another two 75 W panels are to be installed within
the coming year.
Energy Use Patterns in Off-Grid
Houses – Case Study 4: Gulf Islands, BC
Homeowners’ reasons for going off-grid:
Homeowners wanted to live on this remote island, it was never an option to
have a generator “plunking away". There was a long-standing desire to
live off-grid “as if we were on grid”. The result is an interesting juxtaposition
of low-tech and high-tech solutions (passive solar and wood space and
water heating with PV/wind/microhydro system; low-tech microhydro
system built specifically for the site; modified 12 V fridge on timer).
Homeowners’ observations on living off-grid and
energy use patterns:
Living off-grid has emphasized the need to turn off lights and unplug
appliances. 12 VDC lighting is much more efficient use of power.
Gas appliances (cooktop/oven) have low AC startup draw too small
for the inverter to detect. Research has found no new “non-load”
gas cooktop/ovens.
Insurance companies don’t like houses heated with wood, and want
a guarantee of 24 hour, 100A electrical service or the rates are
incredibly high. The phenomenon of “24/7” electricity supply is
relatively new to the world in general, yet it has become the norm.
Homeowners had a mishap with a housesitter and a homemade
charge controller, where the shunt failed in open position and drained
the batteries completely. Seven years later, the solar array (due to a
manufacturing defect) and the same batteries failed at the same time.
There was no problem replacing the panels from the manufacturer
and new batteries were purchased. The lesson learned was: a good
controller is indispensable, and roof-top mounted panels (whether
PV or collectors for a water heating system) are difficult to get at
for repair, maintenance or replacement.
10
When planning to be off-grid, you have to put more emphasis on
the infrastructure of the house (for example, dual wiring for 12 VDC
lights and 120 VAC appliances). These homeowners look at their
off-grid installation as “prepaid” electrical bills.
When installing a PV system, put in as many panels in your array
as you can afford, and build-in room for more.
Canada Mortgage and Housing Corporation
House Description
Originally a 1 1/2 storey 4.6 x 7.6 m (15 x 25 ft.) float home, in 1980,
this was converted into a house on a crawlspace foundation. A 7.3 x
6.7 m (24 x 22 ft.) single storey addition on an open crawlspace was
built on the SW side of the original structure. A 3.7 x 7.3 m (12 x 24 ft.)
greenhouse was built onto the SE face of the addition. An unheated
porch area buffers the NW side of the house. The site has good solar
access and is well protected to the N and NW by trees. It was chosen
for the wind/water/PV potential. An airtight cookstove provides cooking,
space and water heat (5 cords wood/year), with a drain down solar
DHW system used in the summer. Two adults live in the house.
Thermal Envelope Summary
AC/H@50 Pa: n/a, as float home section fragile Walls:
float home, RSI 2.1 (R12) addition, RSI 3.5 (R20)
Ceilings: float home RSI 2.1 addition, RSI 4.9
Floors: float home: RSI 3.5 (R20)
Windows: float home, single plexiglass; addition, thermopane
Doors: solid wood
Research Highlight
Energ y Use Patterns in Off-Grid Houses
PV
WIND
genset
controller
M/Hydro
The actual electrical use in this house is about 4,000 MJ (1,100 kWh)
annually. This figure does not include the nonelectric appliances used
in the house.When the kWh equivalent of the propane appliances is
included in the actual energy use for this house, the figure is approximately
19,300 MJ (5,370 kWh). The average annual lighting and appliance
use for this vintage house in British Columbia is 26,470 MJ (7,350
kWh). There is a difference of 7,140 MJ (1, 980 kWh), a reduction of
27 per cent. These figures do not include space or water heating.
Notes From Homeowner @ System Operation:
battery
bank
inverter
load dump
DC load
The wind generator needs to be shifted from its current position, as
the trees have grown up around it. A load dump shunts power to other
functions when the batteries are full. In the spring, a heating coil is
run under seedbeds in the greenhouse, and in the summer a heavyduty ceramic resistor is used (water could be heated with this extra
load in the summer). Heavy-duty wire from the microhydro to the
house reduces the power loss.
Homeowners’ reasons for going off-grid:
AC load
centre
System Description
The power is supplied by a 280 W output PV array (8-35 W panels);
a 400 W Aerofoil 3 wind generator; and a seasonal 150 W
microhydro system (runs November through May, 24 hr/day) from a
source 0.4 km from house. A small generator is used for seasonal
backup. Energy is stored in a bank of 12 salvaged forklift batteries,
wired to produce 12 VDC (1,200 Ah). A Trace 1512 modified sine
wave inverter produces 120 VAC. There is a combination of 12 VDC
and 1,200 VAC wiring. The system cost approximately $7,000 CAD.
System Performance
The load on the system includes AC lights, water pump, washing
machine, microwave, a computer, an answering machine, two cordless
phones, a mini stereo, TV/VCR, and small kitchen appliances as well
as power tools in the workshop. The total possible daily load is
approximately 18 MJ (5 kWh), while the actual load is estimated to
be 11 MJ (3 kWh). Propane fuels the fridge and a cooktop. There is a
propane-fired hot water tank in the house, but it is not hooked up.
Approximately 400 L of propane are purchased annually. The genset
runs regularly September through November during the shift from
solar and wind to microhydro.
One person in this household has lived off-grid for 20 years, as a
conscious lifestyle choice. The other member moved into this off-grid
house eight years ago.
Homeowners’ observations on living off-grid and
energy use patterns:
Being off-grid raises awareness of power consumption, and how
power fluctuations and different loading scenarios can stress
motors, reducing their useable life. Modified sine wave inverter
doesn’t run such things as “Walkman” style tape recorders.
Installing and fabricating your own module mounts, salvaging and
reusing existing equipment from other installations can reduce the
cost significantly.
When the weather and the seasons generate your power, you tend
to be more conscious of what’s going on out there.
Microhydro systems require water licenses.When the homeowners
applied for a license for their 150 W system (which they share with
another household), they couldn’t get one, because the lowest
listing available for a microhydro/run of river system was 1 kW,
and anything below that mark is “unfeasible”.
Propane appliances such as fridges are expensive to purchase and
run (approximately 1 L/day). New ones are difficult and expensive
to get fixed. If the propane hot water tank was connected, the
household would use 100 L of propane in 3 weeks vs. 3 months.
A cool cupboard is a cost-effective way to store food at lower
temperatures, perhaps allowing for a smaller, more efficient fridge
to be installed.
Canada Mortgage and Housing Corporation
11
Research Highlight
Energ y Use Patterns in Off-Grid Houses
To increase the efficiency of the conventional top-loading washing
machine by 40 per cent, the homeowners removed the 120 VAC 2
speed motor and replaced it with a 90 VCD permanent magnet
motor. In older model washing machines, the motors bolt in, so
the retrofit is relatively easy to accomplish, but it is important to
get the right pulley size, otherwise the water in the machine gets
tossed so violently that it overflows the drum of the machine.
An inverter produces 120 VAC, and the whole house is wired for
standard AC lights and appliances. The system cost approximately
$15,000 CAD.
Energy Use Patterns in Off-Grid
Houses – Case Study 5: Gulf Islands, BC
House Description
A 9.1 x 12.2 m (30 x 40 ft.) 1 1/2 storey house on an open crawlspace
was built in 1991, on the high side of a steeply sloping south-facing
site with excellent solar access and winter wind protection from tree
cover at the top of the mountain. An airtight woodstove provides
space heat (3 to 4 cords wood/year, unless winter holiday taken, then
2 cords, primarily arbutus) for the single occupant (and guests).
Thermal Envelope Summary
AC/H@50 Pa: 15.14
Walls: RSI 3.5 (R20)
Ceilings: RSI 3.5 (R20)
Floors: RSI 2 (approx) (R12)
Windows: thermopanes
Doors: solid wood
System Description
The power is supplied by a 360 W output PV array (6-60 W panels)
and a seasonal 240 W microhydro system (runs November through
May, 24 hr/day) from a source 0.4 km from house. A propaneconverted generator is used for seasonal backup. Energy is stored in a
bank of 6, 85T13 batteries, wired to produce 12 VDC (1,200 AH).
12
Canada Mortgage and Housing Corporation
System Performance
The load on the system includes 120 VAC lights, water pump,
washing machine, vacuum cleaner, a computer, laser printer and
modem (heavy use for several hours a day), a cell phone, a stereo, two
radios, TV/VCR, and small kitchen appliances. The total possible
daily load is approximately 11 MJ (3 kWh), while the actual load is
estimated to be 6 MJ (1.6 kWh). Propane is the energy source for the
fridge, range, water heat and generator. Approximately 1,300 L of
propane is purchased annually. The genset runs regularly September
through November during the shift from solar to microhydro, and
sometimes on winter evenings when the homeowner is working late
on the computer.
The actual electrical use in this house is about 2,080 MJ (580 kWh)
annually. When the kWh equivalent of the propane appliances is included
in the actual energy use for this house, the figure is approximately
23,680 MJ (6,580 kWh). The average annual lighting and appliance
use for this vintage house in British Columbia is 24,500 MJ (6,810
kWh).Water heating accounts for a further 22,900 MJ (6,360 kWh),
Research Highlight
Energ y Use Patterns in Off-Grid Houses
for a total of 47,400 MJ (13,170 kWh). There is a difference of
23,720 MJ (6,590 kWh), a reduction of 50 per cent. These figures do
not include space heating.
Energy Use Patterns in Off-Grid
Houses – Case Study 6: Southern
Manitoba
Notes From Homeowner @ System Operation:
A load dump shunts excess power to two heat coils in the bathroom;
grow-lights are used during the winter to absorb power as well as grow
plants. The generator is also frequently required in the summer for
early morning garden watering, as the sun doesn’t hit the PV until
mid-morning because of the surrounding trees and the slope of the
hillside. Batteries are typically full by 1 p.m., year round. The only
limitation is the water pump can’t be run at the same time as the
printer or the vacuum cleaner.
The microhydro provides continuous 20A service at the house, over
0.4 km of 110 cable from the end of the driveway, which is stepped
down to 12 V for the batteries and then stepped back up again
through the inverter for household use. There is a problem with the
microhydro system when too much water flows down the hillside,
bringing rocks with it which pile over the intake valve. The site is such
that the intake valve cannot be set into a more protected area.
Homeowners’ reasons for going off-grid:
Knew about PV before buying the land. Fell in love with site. Would
have cost $1/2 million to bring in-grid connection. Reread Harrowsmith
and gathered information from technical manuals for six months before
beginning construction. Thought of using propane for lighting as well,
but needed to run the computer and didn’t feel comfortable with the
generator for hours at a time, so went with the PV/microhydro system.
Homeowners’ observations on living off-grid and
energy use patterns:
Being off-grid raises awareness of power consumption, power
fluctuations and different loading scenarios (that is, can’t operate
pump and printer together).When your power is generated by the
weather and the seasons, you tend to be more conscious of what’s
going on out there.
House Description
House #6 and House #7 are located on the same farm, which has
seven off-grid houses, five of which are permanently occupied. All the
systems on the farm are small, but very efficient.
House #6 is a 4.9 x 6.7 m (16 x 22 ft.) 1 1/2 storey house on a pole
foundation built in 1995. Four people occupy the house (two are
children). The house has good solar access and some protection to the
north and the NW from trees and the screened porch/insulated cold
room. An Enterprise cookstove provides cooking, space and water heat
(4 cords wood/year). The house was built from recycled wood, the
double stud walls allow 200 mm (8 in.) of fiberglass insulation. A
solar cooker is also used for baking and slow cooking.
Thermal Envelope Summary
AC/H@50 Pa: 7.22
Walls: RSI 4.9 (R28)
Ceilings: RSI 5.6 (R32)
Floors: RSI 3.5 (R20)
Windows: triple pane, no openers (adjustable vents for fresh air)
Doors: solid wood
Canada Mortgage and Housing Corporation
13
Research Highlight
Energ y Use Patterns in Off-Grid Houses
System Description
The power is supplied by a 125 W output PV array (6-40 W panels).
Energy is stored in 2, 6 V golf cart batteries, wired to produce 12
VDC (220 Ah). All lighting is 12 V, several of which are site-built
fixtures which use 3 W automotive bulbs. A 150 W Statpower
modified sine wave inverter produces 120 VAC for a few small
appliances. The system cost approximately $1,500 CAD.
The cold room, a large walk-in cooler/pantry which replaces a fridge,
takes up the NW corner of the house. It is completely insulated and
isolated from the rest of the house. It is kept at a constant temperature by
a sensor that causes an exterior venting system to open when the
temperature exceeds 8°C (46°F), allowing cold air in from outside until
the temperature drops to 5°C (41°F). An interior venting system opens
when the temperature is below 5°C, bringing warmer air from the
interior of the house into the cold room. The sensor closes the interior
vent when the temperature reads 8°C (46°F). The small 12 VDC motors
that operate the venting system run for a few seconds at each opening/
closing sequence, drawing hardly any discernible load.
Notes From Homeowner @ System Operation:
The system is designed to carry the house through several short days of
poor solar gain during the winter months, resulting in too much power for
the rest of the year. The homeowner ran out of power on the original
50 W system once during a 3-week cloudy spell when one of the children
was a newborn. The system was boosted with a 20-minute charge from
another off-grid source on the farm. The largest load on the system is
the water pump, which is the motor out of a windshield wiper assembly.
This 12 V motor runs for about 1 hour a day to fill a 225-L (50 gal)
container. Water is taken from this container and used in the house (heated
on the cookstove) or in the garden. The summer watering needs of the
garden are the largest draw on the system, matched well with the availability
power from the sun.
Homeowner’s reasons for going off-grid:
Homeowner chose to move from an urban environment to a rural one. The
choice to be off-grid came from political and environmental convictions.
System Performance
The load on the system includes 12 VDC lights, water pump, two small
motors to operate the vents in the cold room, washing machine (not
used much), vacuum cleaner (not used much), a cordless phone (fitted
with an energy saving feature) and a stereo. Small kitchen appliances run
off the inverter: blender, mixer and sewing machine. The total possible
daily load is approximately 2 MJ (0.5 kWh), while the actual load is
estimated to be 1 MJ (0.3 kWh).
The actual electrical use in this house is about 330 MJ (90 kWh)
annually. The average annual lighting and appliance use for this vintage
house in Manitoba is 20,450 MJ (5,80 kWh). There is a difference of
20,120 MJ (5, 590 kWh), a reduction of 98 per cent. These figures do
not include cooking, space or water heating.
14
Canada Mortgage and Housing Corporation
Homeowner’s observations on living off-grid and
energy use patterns:
There is an adjustment to make to lower levels of light, when offgrid and no yard lights, etc.
Pumping water and having to heat it over stove requires a large
change in water consumption habits. Instead of bathing, the
homeowners use a sauna.
An indoor composting toilet system further decreases the water
requirements in the household.
Seasonal changes are more obvious as power needs go up during
winter and power generation goes down.
Research Highlight
Energ y Use Patterns in Off-Grid Houses
Energy Use Patterns in Off-Grid
Houses – Case Study 7: Southern
Manitoba
System Description
The power is supplied by a 100 W output PV array (2-50 W panels).
Energy is stored in 2, 6 V RV batteries, wired to produce 12 VDC
(100 Ah). All lighting is 12 V, several of which are site-built fixtures
which use 3 W automotive bulbs. A 150 W Powerstar modified sine
wave inverter produces 120 VAC for a few small appliances. The
system cost approximately $1,500 CAD.
House Description
House #6 and House #7 are located on the same farm, which has
seven offgrid houses, five of which are permanently occupied. All the
systems on the farm are small, but very efficient.
House #7 is a 15 x 4.9 m (60 x 16 ft.) one-storey house with a sleeping
loft, built on a pole foundation in 1980. The house has been occupied
by one person for several years. The house has good solar access and
some protection to the north. An Enterprise cookstove provides cooking,
space and water heat (3 cords wood/year). The original part of the house
(a 6-sided structure of approximately 28 m2/300 sq. ft.) is 2x4 framing.
The newer “wing” additions to the west (4.9 x 3.7 m/16 x 12 ft.) and
the east (3.7 x 3.7 m/12 x 12 ft.) are 2x6 framing. A 4.9 x 1.2 m (16 x
4 ft.) greenhouse on the west addition helps to keep the living space
comfortable, with a site-built venting system operated by a temperature
sensor and a small 12 VDC motor. There is a cold room with the same
operating system as House #6.
Thermal Envelope Summary
AC/H@50 Pa: 5.63
Walls: Original, RSI 2.1 (R12);
Additions, RSI 3.5 (R20)
Ceilings: RSI 3.5 (R20)
Floors: RSI 3.5 (R20)
Windows: double pane/combination
Doors: solid wood
System Performance
The load on the system includes 12 VDC lights, small motors to
operate the venting systems in the greenhouse and cold room, as well
as a fan for a food dryer in the greenhouse, a water pump and a stereo.
Small appliances run off the inverter: blender, shaver, glue gun and
soldering iron as does a 22 W fluorescent fixture in the “summer
kitchen” (screened-in area where food is processed during harvest
season). An electric lawnmower is charged off this system during the
summer. A 10 Ah motorcycle battery in the summer kitchen powers
the washing machine. The total possible daily load is approximately 2
MJ (0.5 kWh), while the actual load is estimated to be 0.7 MJ (0.2 kWh).
The actual electrical use in this house is about 260 MJ (70 kWh)
annually. The average annual lighting and appliance use for this
vintage house in Manitoba is 20,850 MJ (5,790 kWh). There is a
difference of 20, 580 MJ (5,720 kWh), a 99 per cent reduction. These
Canada Mortgage and Housing Corporation
15
Research Highlight
Energ y Use Patterns in Off-Grid Houses
figures do not include cooking, space or water heating.
Notes From Homeowner @ System Operation:
The system is designed to carry the house through several short days
of poor solar gain during the winter months, resulting in too much
power for the rest of the year. The largest load on the system is the
water pump, which runs for two hours a day, using 30 W. Water is
taken from this container and used in the house (heated on the
cookstove) or in the garden. The summer watering needs of the
garden are the largest draw on the system, matched well with the
availability power from the sun. Sauna replaces showering or bathing.
House Description
A 6.7 x 10.4 m (22 x 34 ft.) 2 1/2 storey house built on a
combination basement/open crawlspace foundation. This house has
been occupied by a family of five (now six) full-time since 1994. The
house has reasonable SE to S solar access (concession to the view to
the SE) and good protection to the north from a treed hillside. An
airtight woodstove provides space heating for the whole house (4 cords
wood/year). The original part of the house was constructed in 1988 as
a seasonal residence, with a typical “cottage” PV system. In 1994, when
the family moved in, the house and the system were as described below.
Thermal Envelope Summary
Homeowner’s reasons for going off-grid:
Homeowner chose to off-grid, simplified living because of political
and environmental convictions. The homeowner is one of the original
co-operants on the farm, established in the late 1970s. This system
was originally on a manual tracker, but there was not enough difference
in power generation to warrant the effort to move the array.
AC/H@50 Pa: 11.24 (one bedroom and loft area not finished)
Walls: 3.5 RSI (R20), double wall construction in progress to upgrade
Ceilings: RSI 4.9 (R28)
Floors: RSI 3.5 (R20)
Windows: double pane Doors: steel polyurethane core
System Description
Homeowner’s observations on living off-grid and
energy use patterns:
A feeling that quality of life was diminished by the proximity of
loud equipment and all-night yard lights was part of a co-operative
decision for the farm to remain off-grid during the mid 1980s,
when 30 people were living in the community. Some members left
to establish a gridconnected farm after this.
A 960 W wind generator functions on the farm, but it is used to
grind grain, not produce power, because no farm members require
more power than their small household systems produce. The wind
generator grinds up to 13.5kg/day.
DC is a “friendlier” power – the low voltage poses little hazard for shock.
Energy Use Patterns in Off-Grid
Houses – Case Study 8: Antigonish
County, NS
Canada Mortgage and Housing Corporation
16
The power is supplied by a 420 W output PV array (4-105 W panels).
Energy is stored in 6, 6 V L-16 batteries, wired to produce 12 VDC
(1,400 Ah). All lighting is 12 V, including compact fluorescent,
halogen and hi/low car taillight type. A Trace square wave inverter
produces 120 VAC for certain appliances (washing machine, battery
charger, skilsaw). A 6 kW gas generator provides backup power. The
system cost approximately $10,000 CAD.
Research Highlight
Energ y Use Patterns in Off-Grid Houses
System Performance
The load on the system includes 12 VDC lights, a water pump,
TV/VCR and three “personal” stereos. Small kitchen appliances run
off the inverter: blender, food processor as well as a computer and a
household stereo. The total possible daily load is approximately 10 MJ
(2.7 kWh), while the actual load is estimated to be 6 MJ (1.7 kWh).
Propane fires an instantaneous (demand) water heater and the range.
Approximately 1,700 L of propane are required each year. The
generator runs approximately six hours/week during November and
December, and two hours/week through January and February, for a
total of about 64 hours/year. There is no fridge, but a chest cooler is
situated in the basement. The cooler sometimes requires ice to keep
the temperature down during July and August.
The actual electrical use in this house is about 2,160 MJ (600 kWh)
annually. The kWh equivalent of the propane appliances and water
heater is 38,960 MJ (10,820 kWh), for a total of 41,120 MJ (11,420
kWh). The average annual lighting and appliance use for this vintage
house in Nova Scotia is 24,500 MJ (6,810 kWh).Water heating
accounts for another 24,500 MJ (6,810 kWh) for a total of 49,000
MJ (13,620 kWh). There is a difference of 7,880 MJ (2,190 kWh), a
reduction of 16 per cent, without a refrigerator. These figures do not
include space heating.
found many more off-the-shelf options for lighting sources, such as
inexpensive porcelain “pigtails” that convert a standard
incandescent fixture to a halogen fixture (in Canada, halogen
fixtures are available in a typical track lighting assembly). Site-built
adapters can be made, but they are still more expensive than the
“pigtails”. Lighting is the number one issue/load after water
pumping: difficult to find affordable, good, efficient equipment for
either.
Many AC appliances such as portable stereos, etc. are originally 12
VDC appliances fitted with adaptors. Cutting the adaptor out of
the system turns the appliance back into DC, which can then be
plugged directly into a wall socket wired for DC.
Inverters are the weak link in any system: they can short out or
overload. Newer models are better protected, and it may make
more sense to have several smaller inverters throughout a house to
carry smaller loads.
Energy Use Patterns in Off-Grid
Houses – Case Study 9: Antigonish
County, NS
Notes From Homeowner @ System Operation:
The house is primarily wired for DC, using a “modified buss bar”.
Large DC cables run up to the second floor through a concrete chase
and travel to outlets on short runs of smaller wires. There are four AC
runs throughout the house. Fuel usage should decrease as two new
panels were installed this year, and two more will be installed next
year, for a total system output of 720 W.
Homeowner’s reasons for going off-grid:
PV installations are a part of the homeowner’s business. PV is virtually
maintenance free (requires someone to sweep snow off the array, turn
the panels occasionally, and turn the inverter on or off ), making it
easy for non-technical members of the family to live with the system.
The house began as a low-use seasonal dwelling and kept being added
on to until it became a full-fledged dwelling.
Homeowner’s observations on living off-grid and
energy use patterns:
Know what is “best” for your lighting fixtures: compact
fluorescents have a lower lifespan and efficiency if they are cycled
on and off too frequently. Halogen fixtures make excellent task
lighting and are readily available at hardware/home centre stores.
From the homeowners’ travels in the U.S. and Mexico, they have
House Description
A 6.1 x 9.1 m (20 x 30 ft.) one-storey house built on an open
crawlspace. This house has been occupied by a family of four full-time
since the fall of 1997. The house has reasonable solar access. An
airtight woodstove provides space heating for the whole house (4 cords
wood/year).
Thermal Envelope Summary
AC/H@50 Pa: 13.22
Walls: 3.5 RSI (R20)
Ceilings: RSI 3.5 (R20)
Floors: RSI 4.2 (R24)
Windows: single pane wood sliders w/storms
Doors: steel polyurethane core and wood
Canada Mortgage and Housing Corporation
17
Research Highlight
Energ y Use Patterns in Off-Grid Houses
System Description
Homeowners’ reasons for going off-grid:
The power is supplied by a 420 W output PV array (4-105 W panels).
Energy is stored in 8, 6 V golf cart batteries, wired to produce 12 VDC
(880 Ah). All lighting is 12 V. A 250 W Trace Statpower inverter
produces 120 VAC for the house. A 3.5 kW gas generator provides
backup power. The system cost approximately $5,000 CAD.
One of the owners is a seasonal worker, and wanted a house that would
allow the family to have minimal annual costs, to be able to “coast”
through the winter months when minimal income would be coming
in. The cost of grid connection was a factor as well. Not wanting to
give money to the utility company played a part in the decision.
Energy Use Patterns in Off-Grid
Houses – Case Study 10: Belfast, PEI
House Description
System Performance
The load on the system includes 12 VDC lights, a water pump. The
inverter powers a 13” TV, a VCR and a stereo. The total possible daily
load is approximately 5 MJ (2 kWh), while the actual load is estimated
to be 4 MJ (1 kWh). Water heat and cooking is provided by propane.
Approximately 1,490 L of propane are required each year. The generator
is run from five to 60 hours/month, for an estimated total of 365
hours/year. There is no fridge.
The actual electrical use in this house is about 1,340 MJ (370 kWh)
annually. When the kWh equivalent for propane water heating is included,
the total load is 24,140 MJ (6,710 kWh). The average annual lighting
and appliance use for this vintage house in Nova Scotia is 24,500 MJ
(6,810 kWh). Water heating accounts for a further 24,500 MJ (6,810
kWh) for a total of 49,000 MJ (13,610 kWh). There is a difference of
24,860 MJ (6,910 kWh), for a reduction of 51 per cent, without a
refrigerator. These figures do not include space heating.
18
Canada Mortgage and Housing Corporation
A 1 1/2 storey house built on a slab foundation. The main house is
7.3 x 9.7 m (24 x 32 ft.), the sunroom/office section is 4.9 x 7.0 m
(16 x 23 ft.), and the workshop/studio section is 5.5 x 7.3 m (18 x 24
ft.), with 1.8 x 3.7 m (6 x 12 ft.) indoor wood storage area. The total
heated area is 279 m2 (3,000 sq.ft.). It was built as an affordable
alternative to the PEI Advanced House Project (sponsored by NRCan).
This house has been occupied by a family of five full-time since the
fall of 1997 (currently three are full-time). The house has good solar
access. An airtight woodstove provides space heating for the main section
of the house (3 cords wood/year) and preheats the water. In-floor hydronic
heat is installed in both main and upper floors, but only used in office
and studio (upper floors). This alternative energy system is different
from the other houses in the study, as it is connected to the grid. See
below for details
Thermal Envelope Summary
AC/H@50 Pa: 2.19
Walls: 3.3 RSI
Ceilings: RSI 7.4
Floors: RSI 1.4 under slab
Windows: 3/8” space, low-E, argon casement and single hung
Doors: steel polyurethane core
Research Highlight
Energ y Use Patterns in Off-Grid Houses
System Description
System Performance
Power is supplied by a World Power H900 wind generator, rated at
900 W output. Energy is stored in 4, Surrette “Big Red CS25” batteries,
wired to produce 124 VDC (840 Ah). A 4,000 W Trace SW4024
inverter produces 120 VAC for the house. A grid-connected sub-panel
provides backup power. The system cost approximately $18,000 CAD.
The load on the system includes lights, a water pump, a fridge, two
freezers, laptop computer w/printer, fax machine, portable stereo, TV/VCR
unit, clothes washer, vacuum, iron, sewing machine, toaster and popcorn
popper. The total possible daily load is approximately 29 MJ (8kWh),
while the actual one is estimated to be 22 MJ (6 kWh), with the renewable
energy system typically supplying 2 kWh per day. Water heat is provided
seasonally by the water coil off the airtight stove. Cooking and the
remaining hot water for the house is provided by propane. Approximately
600 L of propane are required each year. The grid connection is used
to carry the house over times when the batteries are charging.
The actual electrical use in this house is about 7,810 MJ (2,170 kWh)
annually. When the kWh equivalent of the propane appliances is included
in this figure, the total is 21,380 MJ (5,940 kWh). The average annual
lighting and appliance use for this vintage house in PEI is 24,500 MJ
(6,810 kWh). Water heating accounts for another 24,500 MJ (6,810
kWh), for a total of 49,000 MJ (13,620 kWh). There is a difference
of 27,620 MJ (7,670 kWh), for a reduction of 56 per cent. These
figures do not include space heating.
Notes From Homeowner @ System Operation:
It is important to note that the grid connection is not used to charge
the batteries, rather it is used to carry the house through periods when
the batteries are being recharged by the wind system. Although the
wind generator is rated at 900 W, it acts more like a 600 W generator.
A higher tower would result in better performance, but the homeowner
feels that the wind unit is overrated. In 2001, the following changes
will be made to the system: a new 1 kW-rated wind generator will be
installed, as will a 1 kW PV system (16-75 W panels). This will bring
the overall cost of the system to almost $30,000 CAD (less the sale of
the original wind generator).
Homeowner’s reasons for going off-grid:
The homeowner wanted the house to provide a demonstration of an
effective renewable power system, to achieve energy self-sufficiency,
and to reduce electrical use from non-renewable sources.
Homeowner’s observations on living off-grid and
energy use patterns:
Hybrid systems are best suited to the Maritime region, as there is a
good seasonal match between higher winter wind speeds and fewer
sunlight hours.
Wind generators typically give you more power per dollar invested.
The estimated baseload figure for a house of this vintage is 24,500 MJ (6,810 kWh).A reduction of 2,720 MJ (760 kWh) was made from the baseload
1
to compensate for the absence of an electric range. 24,500 – 2,720 = 21,780 MJ (6,050 kWh).
Canada Mortgage and Housing Corporation
19
Research Highlight
Energ y Use Patterns in Off-Grid Houses
Energy Use Patterns in Off-Grid
Houses – Case Study 11: Keswick
Ridge, NB
House Description
A 8.5 x 9.1 m (28 x 30 ft.) 1 1/2 storey house built on a vented crawlspace
with an unheated 4.9 x 6.1 m (16 x 20 ft.) summer kitchen/storage
area off the east face of the house. The house was built in 1994 and is
occupied by a farming couple. This well-insulated timber-framed
house was situated to maximize the passive solar gain available on the
site. A high-mass combination wood heater with water jacket/cookstove
assembly (2 cords hardwood/yr, one each for cooking and heating) on
the main floor provides space and water heat as well as all cooking
requirements.
Thermal Envelope Summary
AC/H@50 Pa: 5.36
Walls: 3.5 RSI (R20)
Ceilings: RSI 7.0 (R40)
Floors: not insulated
Windows: thermopane, single hung openers
Doors: steel polyurethane core
System Description
Power is supplied by a 333 W rated PV array (10 re-used “Arco” panels –
3=100W – slightly mirrored, probably operating at 90 per cent of rated
output). Energy is stored in 12, 6V Trojan T105 batteries, wired to
produce 12 VDC (1,200 Ah). A Trace DR1512 modified sine wave
inverter produces 120 VAC for the house. A diesel generator supplies
backup power. The system costs $6,000 CAD.
20
Canada Mortgage and Housing Corporation
System Performance
The load on the system includes lights, a water pump, a computer, an
answering machine, turntable and stereo system, TV/VCR unit, blender,
juicer and food processor in the kitchen and skilsaw, sander and chainsaw
(summer use only). A 360 W block heater is used on the tractor three
or four times a year. The total possible daily load is approximately 7 MJ
(2 kWh), while the actual load is estimated to be 3 MJ (1 kWh). Water
heat is year-round off the heat coil within the heater/cookstove assembly.
The actual electrical use in this house is about 1,090 MJ (300 kWh)
annually. The average annual lighting and appliance use for this vintage
house in New Brunswick is 21,780 MJ (6,050 kWh). There is a
difference of 20,680 MJ (5,750 kWh), for a reduction of 94 per cent.
These figures do not include space or water heating.
Notes From Homeowner @ System Operation:
Generator is only used once or twice a year to equalize the batteries.
Other than that, the PV array provides all electrical needs for this house.
Research Highlight
Energ y Use Patterns in Off-Grid Houses
Homeowners’ reasons for going off-grid:
House Description
The remote location resulted in very high grid connection costs,
however, this was not the motivating factor to be offgrid. The
homeowners planned to be off-grid at any site they chose, because as
environmentalists (that is, conservationists), they wanted to set an
example of low energy use, especially in New Brunswick, with it’s
nuclear power generation plant.
A 9.7 x 7.3 m (32 x 24 ft.) one-storey house built on an open
crawlspace. The house was built in 1994 and is currently occupied by
a single individual, but was previously inhabited by a family of four.
The bulk of the glazing is to the south. The N and NW facade of the
house are protected by trees, which reduce the rated output of the
wind generator. An airtight stove (3 cords wood/yr, one softwood, two
hardwood) on the main floor provides space heat.
Homeowners’ observations on living off-grid and
energy use patterns:
This house doesn’t have a fridge. A “California Cooler” is installed
on an exterior wall of the kitchen. This assembly is typically a small
locker that has a venting system that brings cool air from below
ground. In this case, the cool air comes in from the root cellar
under the summer kitchen (which has a dirt floor) into the bottom
of the locker, which is thermally isolated from the heated part of
the house. A second vent set high in the locker acts as a chimney to
pull warm air out of the locker and keep the cool air passing over
the stored food. This, plus a large walk-in pantry isolated from the
heated portion of the house suffice to keep all stored food in good
shape. This approach to food storage is probably more successful in
a vegetarian household.
Energy Use Patterns in Off-Grid
Houses – Case Study 12: Eastern
Shore, NS
Thermal Envelope Summary
AC/H@50 Pa: 3.72
Walls: 3.5 RSI (R20)
Ceilings: RSI 5.3 (R30)
Floors: 5.3 (R30)(cats have dislodged some of it)
Windows: thermopane casements
Doors: steel polyurethane core
System Description
Power is supplied by a 50 W PV panel and a 750 W (rated output)
“Wind Baron” wind generator. Energy from these sources is stored in
a 600 Ah battery bank and fed to a Trace 800 modified sine wave
inverter for large loads. Two “mini-circuits” are also in place for small
loads. Each of these consist of a 50 W PV panel connected to a 300
Ah battery bank feeding a 125 W Statpower modified sine wave
inverter. The house is wired for 12 VDC and 120 VAC. A 1 kW gas
generator supplied backup power until two years ago, it was sold when
the load was reduced. The self-installed system cost $5,000 CAD.
Canada Mortgage and Housing Corporation
21
Research Highlight
Energ y Use Patterns in Off-Grid Houses
System Performance
The 120 VAC load on the system includes lights, TV, battery charger,
vacuum, laptop computer, and a cell phone. The 12 VDC load
includes a marine water pump, rechargeable power tools, VCR and
chest cooler. The total possible daily load is approximately 5.8 MJ
(1.6 kWh), while the actual load is estimated to be 2.4 MJ (0.7
kWh). Propane is used for cooking.Water is heated on the stove.
Approximately 240 L of propane is used annually.
The actual electrical use in this house is about 820 MJ (230 kWh)
annually. The average annual lighting and appliance use for this
vintage house in Nova Scotia is 24,500 MJ (6,810 kWh). When the
kWh equivalent of the propane use is included, the total load is
6, 510 MJ (1,810 kWh). There is a difference of 17,990 MJ (5,000
kWh), a reduction of 73 per cent. These figures do not include space
or water heating (water is heated on the propane stove, but is used
only for dishwashing and the occasional shower. The single occupant
uses a “solar shower” bag for regular showering).
Notes From Homeowner @ System Operation:
The battery bank has partially failed due to being drained beyond the
50 per cent level, and also because poor quality batteries were
purchased. It is important to install the best quality batteries possible,
with the longest life cycle noted. Extra cost on the batteries could
possibly be counteracted by adhering to the 1 per cent rule (from
marine applications) which is: no charge controller is required for the
battery bank if the bank is 100x bigger numerically than the 12 V
output (in Amps) of your PV array.
22
Canada Mortgage and Housing Corporation
Research Highlight
Energ y Use Patterns in Off-Grid Houses
Homeowners’ reasons for going off-grid:
Bringing power to the remote location would have cost $30,000.
Wanted to create an affordable, energy efficient offgrid house that
would allow the owners to enjoy their lives without being in debt or
having to work to keep up to operating costs.
Homeowners’ observations on living off-grid and
energy use patterns:
Sales of both energy efficient compact fluorescent lighting and PV
panels have increased dramatically over the last 10 years, but the
price-point of both of these products has not dropped in a similar
fashion. The manufacturers are in a sense pocketing the energy
savings that consumers are gaining by using compact fluorescent
fixtures and going off-grid.
There are no thermal coil resistance appliances in this house,
allowing the system to be designed cost-effectively.
The biggest load in the house was high computer use, but the
solitaire game was erased and a deck of cards bought. Now laptop
(with 90 minutes of battery time) is used for no more than four
hrs/day, and is hooked directly into the PV panel during the
brightest part of the day. The cell phone is a steady four-hour load
in the evenings, and is not plugged in during the day, to save both
power use and money on phone bills.
The chest cooler has to run full-time so it will be hooked up to its
own 40 W collector on a tracker.
Canada Mortgage and Housing Corporation
23
Research Highlight
Energ y Use Patterns in Off-Grid Houses
CMHC Project Manager: Don Fugler
Research Consultant: Shawna Henderson, Abri Sustainable Design
Housing Research at CMHC
Under Part IX of the National Housing Act, the Government of Canada
provides funds to CMHC to conduct research into the social, economic
and technical aspects of housing and related fields, and to undertake the
publishing and distribution of the results of this research.
This fact sheet is one of a series intended to inform you of the nature and
scope of CMHC’s research.
To find more Research Highlights plus a wide variety of information products,
visit our website at
www.cmhc.ca
or contact:
Canada Mortgage and Housing Corporation
700 Montreal Road
Ottawa, Ontario
K1A 0P7
Phone:
Fax:
1-800-668-2642
1-800-245-9274
62669
©2001, Canada Mortgage and Housing Corporation
Printed in Canada
Produced by CMHC
27-10-2006
Revised 2006
Although this information product reflects housing experts’ current knowledge, it is provided for general information purposes only. Any reliance
or action taken based on the information, materials and techniques described are the responsibility of the user. Readers are advised to consult
appropriate professional resources to determine what is safe and suitable in their particular case. Canada Mortgage and Housing Corporation
assumes no responsibility for any consequence arising from use of the information, materials and techniques described.
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