A dwelling is any set of living quarters that is structurally separate from the living quarters of other dwellings and has a private entrance outside the building or a private entrance from a common hall or stairway inside the building. The private entrance must be one that can be used without passing through the living quarters of another dwelling.
There are many types of dwellings across Canada with varying characteristics, such as size and year of construction. The interaction of these dwelling characteristics, in addition to other factors, influences the energy intensity level of a household.
In 2007, more than 60 percent of Canadian dwellings had been constructed in the previous 40 years (see Chart 2). Among these dwellings, an equal proportion, or 19 percent per decade, was constructed in the 1970s and 1980s, while the proportion decreased to 15 percent in the 1990s. The most active period of construction was from 1946 to 1969. The most recent (2000–2007) and the oldest (pre-1946) periods were the least active years of construction.
Year of construction reflects different building codes and is a determining factor in energy consumption and energy intensity analysis (which will be discussed later in this report). The heated area of a dwelling is also a major factor affecting a dwelling’s energy consumption.
The heated area of a dwelling is defined as all space within the exterior walls of a dwelling that is heated, excluding garages and basements.
SHEU-2007 found that the average heated area of a Canadian dwelling was 128 square metres (m²). However, 35 percent of the dwellings had a heated area of less than 93 m², and 31 percent had a heated area larger than 139 m² (see Chart 3).
A regional analysis reveals that the average heated area of dwellings varied significantly by region in 2007. Dwellings in British Columbia had the largest average heated area, at 143 m², followed by Ontario dwellings, which had an average heated area of 136 m² (see Chart 4). The average heated area of dwellings in Atlantic Canada and Alberta was close to 130 m². The smallest dwellings in Canada were in Quebec and Manitoba/Saskatchewan, which were the only regions where dwellings had an average heated area of less than 130 m².
Dwelling size in Quebec was affected by the dwelling types that are prevalent there. In 2007, Quebec was the only region where single detached houses made up less than half of the dwellings. Quebec was also home to 46 percent of the country’s low-rise apartments, which is the dwelling type with the smallest average heated area. Manitoba/Saskatchewan had the third largest proportion of single detached dwellings, at 70 percent, and the second largest proportion of low-rise apartments, at 17 percent.
An exploration of average dwelling size by year of construction found that the smallest dwellings were built between 1946 and 1969, at 112 m² (1201 sq. ft.). As shown in Chart 5, dwellings increased in size in the 1970s and 1980s and decreased slightly in the 1990s. The largest dwelling size occurred in the most recent period, the 2000s.
The average size of a dwelling in a given period is influenced by trends in the mix of dwelling types. Dwellings built before 1946 were larger on average than those built before 1980, partly because there were fewer apartments built during this period than any other. As the next section will show, apartments are the smallest dwelling type.
Across Canada in 2007, 58 percent of dwellings were single detached homes, while double/row houses and low-rise apartments each accounted for 16 percent of dwellings. The remaining dwellings were high-rise apartments and mobile homes, which accounted for 8 percent and 1 percent of all dwellings, respectively.
SHEU-2007 found that the type of dwelling built during each period varied. The types of dwellings that varied the most in this regard were apartments and double/row houses. High-rise apartments were rare before 1946, but accounted for 9 percent of all dwelling types built between 1946 and 1969 (see Chart 6).
Double/row houses, on the other hand, were more commonly constructed than apartments before 1946, then became less common than apartments before rebounding in the most recent period.
Typically, certain dwelling types have larger heated areas than others. In 2007, the average heated area of a most at 130 GJ per household. Ontario consumed single detached home, the largest dwelling type, was 149 m² (1600 sq. ft.), while that for double/row houses, 107 GJ per household, which was just above the national average. Quebec (95 GJ per household) and the second largest dwelling type, was 119 m² (1284 sq. ft.), as shown in Chart 7. These two types of dwellings had much larger heated areas than the average low-rise apartment, which had a heated area of 83 m² (896 sq. ft.). High-rise apartments and mobile homes fell in between and were similar in size, at 95 m² (1024 sq. ft.) and 94 m² (1010 sq. ft.), respectively.
Energy consumed4 by a household is one measure of energy efficiency. This consumption is affected largely by the size and age of a dwelling occupied by a household, in addition to factors affecting climate and the energy consumed by appliances and electronics. Energy consumed per household is important because it demonstrates the household characteristics that change the net energy consumption. That is, it shows the factors that lead one household to use more energy than another. (Another measure of energy efficiency, consumption per square metre, will be presented later, in the section “Energy intensity.”)
The average Canadian household consumed 106 gigajoules (GJ) in 2007 (see Chart 8). Atlantic Canada, Manitoba/Saskatchewan and Alberta consumed significantly more energy per household than the national average, with Alberta consuming the most at 130 GJ per household. Ontario consumed 107 GJ per household, which was just above the national average. Quebec (95 GJ per household) and British Columbia (97 GJ per household) were the only regions below the national average. British Columbia’s low energy consumption per household is interesting because the region has the largest average dwelling size, which should lead to a high level of energy consumption.
British Columbia’s mild climate, which in 2007 had the fewest heating degree-days (HDD),5 partly explains the low energy consumption per household observed despite the average dwelling’s relatively large heated area. Ontario had the second lowest HDD, while Manitoba, followed by Saskatchewan, had the highest.
Many factors can be used to help explain these regional discrepancies. These factors include the types of energy used; general dwelling characteristics, such as year of construction, heated area and dwelling type; and differences in climate.
Trends in housing size, construction standards, techniques and materials vary considerably over time and exert a direct impact on energy use. The influence of these trends on a household’s energy use is evident when the energy consumed per household is compared with the construction period.
Dwellings built between 1946 and 1969 had the lowest energy consumption per household in 2007, at 97 GJ per household (see Chart 9), but they also had the smallest heated area. This finding was unexpected because newer dwellings use the latest technologies.
However, the older dwellings had the smallest heated area. Dwellings constructed during each decade from the 1970s until the 1990s consumed more energy than the previous decade until the current decade (2000s), which showed a slight decrease in energy consumption from the 1990s. One explanation is that dwellings have, in general, increased in size. Dwellings built before 1946 consumed the most energy in 2007. These dwellings were at least 61 years old in 2007 and were on average larger than the average dwelling built between 1946 and 1979.
Based on SHEU-2007 data, the energy consumed per household increases as the dwelling’s heated area increases. This relationship between heated area and energy consumption is evident when dwellings are divided into categories based on their heated area, and the average consumption per household within each category is compared.
Dwellings in the category of smallest heated area, less than 56 m², had the lowest energy consumption at 51 GJ per household (see Chart 10). For a heated area from 56 m² to 93 m², the energy consumed average increases to 75 GJ per household. This trend of increasing heated area and increasing energy consumption continues for all heated area categories. Dwellings in the category of largest heated area, 232 m² or more, consumed 169 GJ per household. This is more than three times the energy consumption of the smallest dwelling size.
Single detached homes consumed the most energy of all dwelling types, at 138 gigajoules (GJ) per household (see Chart 11). This consumption is not surprising given that it is also the largest dwelling type. Mobile homes were the next largest consumers of energy, despite being the second smallest dwelling type. This might be due to less insulation in mobile homes. The remaining dwelling types illustrate the benefit of shared walls because both apartment types and double/row houses had the lowest energy consumption.
A common or shared wall reduces a dwelling’s exposure to the exterior and enables a dwelling to share heat with the adjacent dwelling, thus permitting a dwelling to reduce its energy consumption and improve energy efficiency. Apartments normally have at least two common walls and a common ceiling or floor, and double/row houses have at least one common wall.
Double/row houses were the third largest consumers of energy despite having the second largest heated area. Low- and high-rise apartments consumed the least amount of energy.
Another measure of efficiency is the total amount of energy consumed per unit of heated area, which is expressed in gigajoules per square metre (GJ/m²). The energy intensity level of a household depends on the interaction of many factors, but it is known from past surveys of household energy use that GJ/m² generally decrease as the size of a dwelling increases. SHEU-2007 enables the isolation and study of some individual factors that influence energy consumption per square metre.
Based on SHEU-2007 data, the inverse relationship between heated area and energy intensity is evident when dwellings are divided into categories based on their heated area and the average intensities of dwellings within each category are compared.
Households in the category of smallest heated area, less than 56 m², had the highest energy intensity, at 1.09 GJ/m² (see Chart 12). Households in the category of largest heated area, more than 232 m², had the lowest intensity, at 0.57 GJ/m². The only break in this trend occurred with the category of 93 m² to 139 m².
This inverse relationship between the heated area of a dwelling and its energy intensity level might be explained by the fact that many energy-consuming products, such as refrigerators, are considered necessities and are used by a high proportion of households regardless of their heated area. Obviously, these types of products have a greater impact on the energy intensity per square metre of a smaller dwelling than a larger dwelling, because the energy consumption of these appliances is distributed over a smaller space.
Another possible explanation for the decline in energy intensity per square metre as the heated area increases is the tendency for larger dwellings to have been constructed during the most recent periods, which are after 1980. As is discussed later in this section, dwellings constructed during these periods were, on average, the most energy-efficient dwellings built in Canada on a per-square-metre basis.
The average household energy intensity per square metre in Atlantic Canada (0.88 GJ/m²), Quebec (0.85 GJ/m²) and Ontario (0.79 GJ/m²) was relatively close to the Canadian average (0.83 GJ/m²), as shown in Chart 13. The same can not be said for Manitoba/Saskatchewan and Alberta, which were well above the national average, and British Columbia, which was well below it. Manitoba/Saskatchewan’s high energy consumption per square metre is due to its having a high percentage of single detached homes, the second smallest average dwelling size in the country and a cold climate. In contrast, British Columbia had the lowest energy intensity with a ratio of 0.68 GJ/m², which may be attributed to its having the largest average dwelling size and a more temperate climate.
SHEU-2007 found that in general, the newer the dwelling, the lower the energy intensity ratio. This can be seen by observing the decline in the ratio: from 0.89 GJ/m² for dwellings built before 1946, to 0.77 GJ/m² during 1980–1989 and to 0.74 GJ/m² during 2000–2007 (see Chart 14). The break in the overall trend in the 1990s coincided with a decrease in the average size of the heated area between the 1980s and the 2000s. The 1970s break cannot be explained by average heated area because dwellings built during 1946–1969 were smaller. But the proportion of apartments, which are the least intensive dwelling type, decreased from the 1960s to the 1970s. Another possibility is that some of the dwellings built before 1970, which were at least 38 years old in 2007, underwent a retrofit,6 which would have improved their energy efficiency.
In 2007, the average mobile home, which has no common walls, had the second smallest heated area among dwelling types, and smaller dwellings generally had higher energy intensity ratios than larger dwellings. Thus it is not surprising to see that the dwelling type with the highest energy intensity ratio was mobile homes, at 1.05 GJ/m² (see Chart 15).
Because of the inverse relationship between dwelling size and GJ/m², it might be somewhat unexpected to observe that double/row houses and low- and high-rise apartments had lower intensity ratios (0.73 GJ/m², 0.53 GJ/m² and 0.46 GJ/m², respectively) than single detached houses (0.93 GJ/m²). These three more energy-efficient dwelling types all share at least one wall with another dwelling.
4 SHEU energy consumption is a summation of household electricity, natural gas, heating oil, propane and wood consumption in 2007. For this survey, household energy consumption excludes energy consumed for transportation and gas-powered equipment.
5 Natural Resources Canada, Comprehensive Energy Use Database, 1990 to 2007, oee.nrcan.gc.ca/corporate/statistics/neud/dpa/comprehensive_tables/index.cfm?fuseaction=Selector.showTree.
6 A retrofit is any type of improvement of the efficiency of energy-consuming appliances or thermal characteristics of a dwelling.