Design Considerations for
A combination of high energy costs and deteriorating housing stock has highlighted the need for energy efficient housing in Canada's northern and remote communities.
For housing to be successful in severe climates, it must address a number of competing needs. It must be affordable to build and operate, durable, comfortable, and easy to maintain. It must be capable of meeting the needs of the occupants and it must be energy efficient.
The following discussion focuses on those aspects of design which must be considered when developing new residential and commercial buildings.
Climate and Weather
Climate and weather are possibly the most important elements to consider when choosing low-energy design features. Climate is the average total of rain, snow, wind and sun an area is likely to receive over a period of time; weather is how much of those things you receive on any given day.
One useful measure of climate severity is the number of Heating Degree Days (HDD). The HDD figure is a measure of how much and for how long the mean daily temperature is below 18°C in a year. Inuvik, for example, has 10,174 Heating Degree Days compared to Vancouver's 3,005.
Weather also affects material and labour transportation, and the length of the building season.
The colder the climate, the greater the thermal resistance value (RSI value) of insulation required. Walls and roofs should be insulated to at least RSI 5.0 (R28).
The direction and strength of the wind should be carefully considered when designing building shapes and site planning. Keep the shapes simple, with few projections, and place doors so they are not blocked by drifting snow. The roofs must be designed to withstand wind and snow loads.
Figure 1: A Super Insulated Wall. Enlarged Image
Soils, Vegetation and Landscape
Soils, vegetation and the natural landscape can have a major influence on design and construction.
Common northern soil types include muskeg, clay, permafrost, and various granular materials. Each requires a site-specific foundation design which will prevent shifting or settlement.
Figure 2: A Vegetation Wind Block and South Slope Exposure. Enlarged Image
Soil tests are a must, especially in areas of discontinuous permafrost. Site preparation such as gravel pad construction may require one or two years to allow the soil to stabilize.
Choose sites with the best drainage to reduce moisture related foundation problems. Soil movement can be accommodated by using adjustable foundations or systems such as a space frame foundation.
Site selection should consider natural land forms. Vegetation can act as a wind deflector and slope stabilizer and also help to reduce snow drifting.
Material Selection and Transportation
Materials should be chosen to suit local conditions and preferences. Final selection will also depend upon availability and performance. Pre-planning is essential to ensure materials are ready when construction begins. Use local materials wherever possible. Components that can be repaired or replaced using local skills and materials should be given preference.
Transportation costs are also an important factor. Weight, material size and distance will determine the most cost-effective method of transportation. Shipping and transportation by road are less expensive than transportation by air, but are restricted by a short operating season (although some communities are accessible during the winter months via ice road). Transport by road or water can accommodate items of almost any shape or size. Fixed-wing aircraft and helicopters are the most expensive modes of transportation but can operate in most weather conditions. The size of item which can be carried by air is limited.
Labour Skill Levels
An additional consideration for material and design choices is the labour and skills required. If a project uses building crews from Aoutside@, a design which requires the least labour time will be more attractive. The use of pre-finished materials or prefabricated components may produce a lower total cost when the reduced labour requirement is considered.
On the other hand, if part of a project's intent is to use local labour to provide skills training and employment, the emphasis may switch to customary construction methods using local or conventional materials.
Energy Requirements and Cost
The long term cost effectiveness of any low-energy design depends largely on the cost of fuel. In northern and remote regions fossil fuels and electricity are expensive. By careful attention to detail at the design and construction stages, a home's space heating energy requirements can be reduced by up to two-thirds.
Although solar gains throughout the winter months are meagre at best in the North, many areas receive enough sunlight for some heating and lighting during the spring and fall. Designs should focus on taking advantage of the Afree@ energy available during these periods.
High levels of insulation and properly functioning air and vapour barriers contribute significantly to reduced space heating requirements.
Cold porches and air lock entries reduce the amount of heated air that escapes when doors are opened. They also provide extra storage space.
Wherever possible, use locally available fuels, like wood, in certified heating equipment. The choice of fuel also influences certain design decisions. If wood is to be used, wood drying areas and storage facilities must be provided.
Ensure that furnaces and wood stoves are properly sized. Tighter, more energy efficient houses require smaller equipment. An oversized furnace operates less frequently and is less fuel efficient. All equipment should receive regular maintenance.
High thermal performance windows, using double or triple sealed glazing with low-e coatings and an inert gas filling, significantly lower heat loss. Keep windows as small as practical.
Most windows should face south to take full advantage of solar radiation. Ensure that they will not be shaded during the heating months. North facing windows should be kept to a minimum. If possible, place the building on a south-facing slope to further increase the southern exposure.
An open plan with few full-height partition walls in the living areas will allow heat to circulate naturally. Sunlight will also penetrate more deeply into the home.
Overheating during the summer can be a problem. Keep the total glass area to no more than 10 percent of the floor area and provide shades which can block the summer sun. Windows on the west side are difficult to shade properly.
Cost effectiveness calculations should be based upon life-cycle expenses for materials and energy use.
Lifestyle and Layout
Location, the level of services, family size and the time between food and goods restocking all affect the amount of storage space required. Greater work space will be required by families that rely on traditional income activities like hunting, trapping or artistry.
In some cases lifestyle needs are at odds with the low-energy requirements of the house (eg. need for privacy versus ease of heat distribution). Careful attention to the layout of the residence will provide a spacious feel and the least wasted floor space.
Case studies have revealed that the most successful designs involved input from the future inhabitants. This may not always be possible but a flexible design, with movable interior partitions, can be as successful.
The basic living requirements must be met for:
Design the floor plans with few partition walls in the living areas to give a feeling of openness and assist heat distribution. Grouping the kitchen, dining and living spaces together creates a large area which can accommodate a variety of activities. Southern exposure for these areas gives plenty of light and passive solar heating.
Utility and storage rooms, bathrooms and other spaces which need fewer windows should be placed on the north side of the house.
Mechanical equipment should be isolated from the living and sleeping spaces to reduce noise.
One-storey houses are best for small floor areas. One and a half-storey houses take advantage of the otherwise unused roof space. Two-storey houses are more energy-efficient than single-storey ones of comparable floor area.
Figure 3: Maximize Solar Gain. Enlarged Image
ResourcesRemote and Northern Energy-Efficient House Design Catalogue, prepared for the Remote Community Demonstration Program of Energy Mines and Resources Canada, prepared by REIC Ltd., March 1989.
Contacts | Northern Related Links | Bulletin Board
Upcoming Events | Jobs
Please send any comments or suggestions to AHFC.