This article was originally published in the September/October 1996 issue of Home Energy Magazine. Some formatting inconsistencies may be evident in older archive content.
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Home Energy Magazine Online September/October 1996
Advanced Houses: The Canadian Experience
by Tim Mayo and Robin Sinha
Tim Mayo is manager and Robin Sinha is project manager of the Advanced Houses Program for Natural Resources Canada.
Canada's Advanced Houses are more energy efficient, have better indoor air quality, and use even fewer resources than houses built to R-2000 standards.
The goal of Canada's Advanced Houses program was to build houses that are far more energy efficient, environmentally benign, and healthy for occupants than typical Canadian houses. Energy and indoor air quality (IAQ) monitoring has shown that, for the most part, the houses have met this goal.
Natural Resources Canada (NRCan) launched the Advanced Houses program in 1991. They used the same performance-based approach as for R-2000 (see Canada's R-2000 Standards Get Tougher, HE May/June '95, p. 8), but expanded beyond space and water heating to cover total purchased energy, material selection for indoor air quality, and environmental features.
NRCan selected the 10 house proposals out of 31 plans entered by design teams that included architects, designers, engineers, builders, renovators, manufacturers, suppliers, utilities, and provincial and municipal officials. NRCan funded about one quarter of the total project costs. Each project also received cash, services, labor, and goods from manufacturers, suppliers, trade organizations, consultants, gas and electric utilities, municipalities, and government agencies.
The winners were chosen in early 1992, and all were under construction later that year. During 1993, they were open to the public for a mandatory one-year demonstration period; most were also open to industry tours during construction. The Advanced Houses were then sold and, once occupied, were monitored for at least one year to evaluate their performance.
All houses were required to include room-by-room ventilation, compliance with guidelines for exposure to pollutants, noise limits from mechanical equipment, and humidity control. They were to cut water consumption in half, use federally labelled EcoLogo products and recycled materials, build in indoor recycling facilities, and have a construction waste management plan. Except in refrigerators, no chlorofluorocarbons (CFCs) were allowed.
Overall Energy Performance
The houses were evaluated based on purchased (site) energy, converted to equivalent kWh. There was no calculation of energy use at the power plant for electricity usage, although many designers took source energy into account when choosing equipment for the houses. The typical Canadian house consumes an estimated 50-63 kBtu/ft2 of floor area (160-200 kWh/m2) per year. The target for the Advanced Houses was 17 kBtu/ft2 (52 kWh/m2); actual monitored total energy use was 25 kBtu/ft2 (81 kWh/m2) per year-one-third less than expected of an R-2000 house and a 50%-60% reduction from conventional houses (see Figure 1).
The energy consumption of each house was normalized to account for climate (heating degree days, C). Annual energy intensity ranged from a low of about 2.4 Btu/ft2/HDDoF (13.8 Wh/m2/HDDoC) in Manitoba to a high of 3.7 Btu/ft2/HDDoF (21.1 Wh/m2/HDDoC) in Nova Scotia.
Approximately one-quarter of the space- and water-heating energy was used for domestic hot water. About 13% of the total purchased energy was consumed by fans and pumps. All the Advanced Houses used a forced-air fan delivery system for space heating, cooling, and ventilation.
Figure 2 shows the energy used by electric appliances and lighting. This usage was about 19 kWh per day, close to that observed in R-2000 houses and 75% greater than the Advanced Houses target of 11 kWh/day. Lighting in particular used significantly more energy (almost twice) than budgeted for in the program.
One reason for this is probably that homeowners are using more appliances and lighting than they used to. Also, although the Advanced House builders installed efficient fixed lighting, clothes dryers, and refrigerators, homeowners added lights and other appliances. For instance, the Saskatchewan Advanced House met the target for refrigerator usage with a photovoltaic-powered refrigerator, but the occupants installed a large new refrigerator when they moved in!
Insulating the center of the floor slab achieved relatively little reduction in heat loss through the foundations. Most R-2000 houses already insulate foundation walls and at least floor slab perimeters.
There was a small reduction from the R-2000 average in the utilization of free heat from lights and appliances, in keeping with the modest reduction in purchased energy for these end uses. More surprising is that the passive solar contribution was less than in R-2000 houses, although the houses incorporated passive solar design. A likely explanation is that in the shoulder seasons when passive solar energy is most available for offsetting space heating, free heat from lights and appliances was more than sufficient to match the very low heat load of the house. Thus there was little opportunity to utilize passive solar, except in colder periods when free heat cannot contribute enough to offset the heat load, and these months (typically December and January) have the fewest sun hours.
Nonetheless, all of the results were at or below Health and Welfare's recommended action level of 0.1 ppm. Additional measurements under occupied conditions will provide a clearer picture of the actual levels of formaldehyde homeowners will be exposed to over the long term, and how occupants contribute to formaldehyde levels.
A whole-house approach also goes beyond energy. For example, high-performance windows resist condensation, reducing the potential for peeling paint, wood rot, and mold growth. Their warmer interior surfaces make occupants feel more comfortable and eliminate the need for heating outlets beneath the windows.
In two Advanced Houses, designers reported that the savings in ductwork offset the increased cost of the high-performance windows. Good windows and small heat loads mean air-flow volumes can be lower. The 2-inch-diameter, high-velocity ductwork used in the Ottawa Advanced House was originally intended to provide fresh-air ventilation, but it has the capacity to meet the reduced heating and cooling loads. However, small-diameter ducts mean higher-velocity air and a higher pressure drop across the fan, requiring more fan power. Observers did notice higher fan energy usage in this house (although the efficient electrically commutated motor [ECM] lessened this impact). The ducts did not prove to be particularly noisy, another concern with smaller diameter ducts.
Engineered wall framing technologies have significant potential. The slightly higher cost of a 2 x 6 I-stud or an open-web truss should be largely offset by savings from reduced warpage, twisting, and shrinking (resulting in reduced callbacks to repair popped wallboard screws). The open-web truss nearly eliminates thermal bridging through the web. Also, engineered studs require less material and can be made with wood scraps or lower-quality trees.
Insulating the open-web truss walls with loose fill can be difficult. In one house, the installers needed to put cardboard blocking between the cavities so that they could blow in cellulose to a high enough density. However, Icynene sprayed-in foam used in another house worked well in the open-web truss wall.
Insulation levels in these houses are above conventional practice but are not excessive-typically R-30-R-45 walls and R-50-R-60 ceilings. Every Advanced House provided full insulation under its basement floor. The most common insulating material was wet-spray cellulose, blown in place with a latex binder to prevent later settling.
Canadian building codes now distinguish between vapor diffusion retarders and air barriers. All Advanced Houses bettered the airtightness requirement of 1.5 ACH at 50 Pascals (Pa) with a variety of techniques; their success was largely a result of careful installation.
The trend appears to be toward exterior air barriers, which eliminate many of the problems associated with penetrations through interior air barriers. Two new exterior air barrier systems have recently entered the market-a polyethylene-laminated fiberboard with joints taped on site and a gasketed styrene foam insulation board developed by the Maison Novtec Advanced House.
All ten Advanced Houses used high-performance windows featuring various combinations of multiple glazings, low-e coatings, gas fills, insulating spacers, and low-conductivity frames. The design teams used the Canadian Window Energy Rating standard to guide the selection of their windows, including selection of windows by orientation in some houses. The rating is a heat balance for the product-solar gains in, minus heat loss and air leakage out-and is measured in watts per square meter of total window area. Windows in the Advanced Houses have Energy Ratings (ER) as high as +12 for fixed models and +4 for opening models, compared to about -15 to -30 for a conventional double-glazed window.
Still, no completely integrated package is yet available. Current practice is to assemble off-the-shelf components and combine their operation and control. All ten Advanced Houses used heat recovery ventilators (HRVs) and installed the ventilation system according to Canadian Standards Association (CSA) standard F326 Residential Mechanical Ventilation, with fresh air supplied to living rooms and bedrooms and stale air exhausted from bathrooms and the kitchen (see Mechanical Ventilation for the Home, HE Mar/Apr '96, p. 13).
Unfortunately, the Advanced Houses did not avoid installation problems. Although HRVs themselves have efficiencies in the 70%-80% range when tested to the CSA standard in the labs, many systems were observed to be imbalanced, resulting in reduced system efficiencies in the field.
The British Columbia Advanced House featured a sealed-combustion, condensing natural-gas hot-water heater, with remote fan-coil units providing space heating through the forced-air duct system. These combination space and domestic hot water (DHW) products have a rated efficiency of better than 90%.
The midefficiency natural-gas furnace/HRV combination unit in the Waterloo Green Home is a prototype by the Canadian Gas Research Institute. Production prototypes are now being field-tested, and the product should be commercially available in 1996. The combined efficiency is expected to be 85%.
The oil-fired combination system in the Nova Scotia Advanced House addressed the issue of short-cycling and the resulting inefficiency of typical oil systems in low-energy houses. The low-mass boiler heats the water in a 60-gallon water tank, permitting a longer firing time for peak efficiency. The water tank feeds a separate DHW tank and two fan coils to provide forced-air space heating for two zones. Steady-state efficiency is predicted to be 80%-85%.
Several houses used electrically commutated motors in variable-speed blowers. ECMs maintain a high efficiency over their entire range of speeds and hold air flow steady at specified levels regardless of changes in static pressure. In a typical furnace installation, they can save almost 60% of electricity consumption.Appliances Some of the Advanced House builders went beyond currently available technologies and installed prototype appliances not yet on the market. A prototype sealed-combustion direct-vent gas stove, designed by the Canadian Gas Research Institute, was installed in several Advanced Houses. Two houses also used a prototype sealed-combustion direct-vent gas clothes dryer.
Some houses also used home automation systems to help reduce peak loads. Two homes used the Consumer Electronics Bus (CEBus), which shifts operation of high-usage electrical appliances to off-peak times and monitors the performance of some mechanical equipment.
Water consumption. Total water consumption appears to have been cut by more than half, and hot water consumption showed a small reduction. Cold-water consumption was reduced substantially indoors with low-flush toilets, and outdoors with a combination of drought-resistant landscaping and rainwater cisterns.
Construction waste management. Construction waste management made a significant reduction in the 2.7 tons (2.5 tonnes) of waste that a typical new house sends to landfill. One house reported no construction waste-except for two green garbage bags, it was all recycled or reused. The Nova Scotia Advanced House reported that of the 7,536 lb of construction waste it produced, only 2,467 lb was sent to landfill. The rest was either reused or recycled. The Nova Scotia Advanced House also calculated the amount of recycled materials used in its construction-a total of over 20,000 lb.
One innovation was the use of crushed, recycled glass mixed with gravel for foundation drainage. Laboratory testing of a sample from the Manitoba Advanced House showed that a half-and-half mixture of gravel and crushed glass outperformed all other types of drainage material.
Advanced House builders also learned that they have a strong influence on how green the occupants can be. In addition to their own efforts during construction, builders provided a range of recycling facilities, including in-house storage for paper, glass, and plastics; kitchen compost storage; and outdoor composters.
Industry awareness and acceptance of the benefits of innovative green technologies is strong, and public response has been good. Several builders of Advanced Houses have added environmental features or are offering environmental upgrade packages to all their houses.
The Waterloo Green Home's builders estimated the construction costs (excluding land and builder profit) for a similar conventional house with the same market appeal features-upgraded interior finishes, hardwood flooring, appliances, and landscaping-at about $125,000 Can ($93,700 US). The actual construction costs for the Waterloo Green Home were $147,600 ($110,700 US), due to the additional energy, environmental, and IAQ features.
The Advanced Houses have shown that significant reductions in energy consumption are possible, improved indoor air quality and comfort can be achieved, and that both builders and homeowners can contribute to reducing the impact of housing on the environment. The program is now promoting the adoption of technologies used in these houses (such as high-performance windows, integrated mechanical systems, and energy-efficient motors) in the existing housing market and new multifamily housing.
The Advanced Houses Program offers one- and two-day seminars on the program and the technologies used. Contact Tim Mayo at (613)996-3089.
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