Technical Series 01-103
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.
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).
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.
* The bracketed numbers in column #5 “Rated System Size” are the power ratings of backup generators, in Watts.
** Assuming fully charged battery bank.
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.
*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.
1“Non-electrical” appliances (other than wood burning appliances) in use in the study houses are propane-fired. Assumptions about propane use: 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.
2Baseload figures are derived from “Home Energy Retrofit in Canada: Overview and Opportunities”; NRCan & CMHC, March 1994. ISBN 3662-22198-2
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 non-remote 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.
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 off-grid, 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.
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.
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% and 24% 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% 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%. Of the six houses with propane or electric refrigerators, the average reduction is closer to 30%, and of the six houses without refrigerators, the average reduction is around 70%, showing the impact of these appliances on energy requirements.
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. Electro-magnetic 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:
Energy Use Patterns in Off-Grid Houses
|Project Manager: Don Fugler
Research Consultant: Shawna Henderson, Abri Sustainable Design
Housing Research at CMHC
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