Suburbia 1, Kyoto 0 Why Canadians must link home to environment to achieve Canada s Kyoto targets by Louise St.Germain In recent years, much awareness has been raised around the world about climate change and its relationship to greenhouse gas (GHG) emi ssions, and populations are beginning to react by greening certain elements of their daily lives. However, Canada is nowhere near its Kyoto target, which is to reduce its GHG emissions to 6% below 1990 levels by 2012. As of 2004, Canada s GHG emissions were 27% greater than the 1990 levels [1], meaning that to achieve the Kyoto target, GHG emissions in all of Canada must be reduced by over one -third in the next five years. Achieving anything even close the Kyoto target will obviously require action and serious commitment from all levels, from the federal government and large corporations right down to each individual resident. While individual residents are generally well aware of recycling programs, improved weather-stripping and insulation, and initiatives to switch over to compact fluorescent (CF) bulbs, they can tend to overlook the importance of the relationship between their homes and the environment in which the homes are situated. Resistance to GHG mitigation measures is usually due to the perceived expense of the measures. When building new houses, the opportunity exists to build housing which works with, rather than against, its local environment, an opportunity which is often wasted in the current paradigm of suburban development. In the UK, up to 85% of domestic electricity use is for low-grade heat such as space and water heating [2]. In Canada the situation is similar, though space cooling also accounts for a significant use of electricity [3]. Electricity is a high -grade form of energy; using it for low-grade applications like heating and cooling is an inefficient use of the resource. T h e next section illustrates some ways in which the application of simple physics can substantially reduce the electricity requirement of a Canadian home, for little or no extra cost. The subsequent section considers these principles in reference to the neighbourhood of South March, in the outskirts of Ottawa, Ontario. The Interaction of Home and Environment The first phenomenon to be kept in mind is the difference in the properties of glass and of other construction materials. Glass is transparent to both visible light and shortwave infrared, but is opaque to long-wave infrared radiation [2]. Light absorbed by surfaces inside a home is then re -radiated as heat, in the form of long-wave radiation. Since glass is impermeable to this radiation, it remains trapped inside the building until it leaves through another heat loss mechanism somewhere in the house. In winter, this greenhouse effect due to solar gain is desirable, because it contributes to home heating and reduces the need for additional heating. In summer, this is 1
undesirable, as it increases the temperature indoors and thus increases the energy required for cooling. Regulating the solar gain through south- and west-facing windows can be easily accomplished using deciduous trees. In the summer, the leaves of the trees provide shade from the sun; in winter, the trees lose their leaves, which then allow the windows to be exposed to the sun to take advantage of the greenhouse effect. The second important principle is that the tilt of the Earth by 23.4º on its axis relative to its plane of orbit around the sun means that the sun is higher in the sky in the summer than in the winter. For the community of South March, at a latitude of just over 45º N, the midday sun reaches an angle of 68.2º on June 20, but is down to just 21.4º by December 20. In the hot temperatures of summer, windows facing the sun should be shielded as much as possible, to avoid solar gain through them. This can be accomplished by providing an overhang deep enough to shade the window in summer. The advantage of overhangs is that whe n the sun is low in the sky in winter, the overhang does not prevent exposure to the sun, allowing for some passive heating of the home, as illustrated in Figure 1. Figure 1 - An overhang will protect the window in summer, but allow sunlight in winter. On the right is a good example of this principle, on a house in Normandy. This house remained cool inside while outside temperatures soared above 35ºC in the summer of 2003. The last principle to discuss before moving to the South March case study is the effect of wind and exposure in the winter. Heat transfer can occur either by conduction, convection, or radiation. These can all contribute to the overall heat loss by a specific building material, and this overall value is specified by the material s U-value, which is the heat loss per unit area per degree Celsius [2]. The lower the U-value, the better the insulation properties of the material. Windows typically have higher U-values than an insulated wall, so it is advantageous to reduce the window exposure to northern winds. This can be done by planning the home design and location to avoid large North-facing windows. Reducing exposure to the winter winds by planting evergreen trees North of the house can also reduce the heating requirement for the house. 2
With these three simple principles in mind, let s examine a case study in a small neighbourhood. What Could Have Been, and What Is: a Case Study of South March South March is a small neighbourhood in the west end of Kanata, which is the City of Ottawa s most western suburb. Like much of Canada, the temperatures in this area swing between extremes in winter and summer there is a 36ºC span between the average daily minimum in January and the average daily maximum in July, and approximately 76ºC between the record high and record low [4]. Figure 2 shows the predicted temperature profile for 2007 and the corresponding predicte d electricity usage for the Province of Ontario. Energy Demand, MW 25,000 24,000 23,000 22,000 21,000 20,000 19,000 18,000 17,000 16,000 15,000 40.0 30.0 20.0 10.0 0.0-10.0-20.0 07/01/2007 07/02/2007 07/03/2007 07/04/2007 07/05/2007 07/06/2007 07/07/2007 07/08/2007 07/09/2007 Temperature, degrees C 07/10/2007 07/11/2007 07/12/2007 Time of Year Energy Demand Peak Day Temperature Figure 2 - Energy demand in response to temperature in the Province of Ontario: prediction for 2007 (data from [ 5 ] ). Unlike other places in the world, where there is a single period of high energy demand due either to summer space cooling (in hot climates) or to winter heating (in temperate climates), the Ottawa area experiences two peak periods: one in winter for heating, and the other in summer for cooling. In the 1970s, likely as a reaction to the oil crisis of that era, a site in the Village of South March was earmarked for development as North America s first entirely planned energy-conserving residential community coupled to a district heating system [6]. The original Plan for the South March planned community, as outlined in [6], included the following key energy -saving measures: 3
A super- block grid pattern, with the main mixed-use street down the centre. The grid is sized such that it is neither too dense (high -rises) nor too sparse (sprawl) for comfort, efficiency, and ease of public transit. Compact land use and higher net density. No detached houses were included in the plan. District heating, the distribution of which would be aided by the logical, gridlike layout of the community. The fuel for the heating could be anything from oil to municipal refuse. Both active solar systems and passive solar design. Purposeful orientation of homes would reduce the requirement for heating and cooling loads, and an active solar hot water system would supplement the district heating. Energy-efficient building design, such that houses would be designed for the environment in which they were built. Examples include overhangs on windows for summer shade, the option for thermal shutters, and putting the l a rge windows on the south side, away from the arctic winds. Figure 3 shows the original 1970s plan; the layout that has actually been built to date is shown in Figure 4. Note that in the current community, the entire area in the square bounded by Old Carp Road, March Road, 2 nd Line Road, and Terry Fox Drive is residential. There is one regular bus route and one express bus route (peak period, Monday-Friday) through this entire neighbourhood. To shop or get to work, the vast majority use a personal vehicle. Figure 3 - The 1970s- era plan for South March, based on map in [6]. 4
Figure 4 - Th e c u r r e n t l a y o u t f o r S o u t h M a r c h / M o r g a n ' s G r a n t, b a s e d o n G o o g l e E a r t h i m a g e centred on 45º20 57.94 N and 75º56 21.70 W, at an eye altitude of 2.32 km. Compared to the proposed plan for the community in the 1970s, the community as it is actually being built differs in many respects. As seen in Figure 4, the layout of the streets is irregular, typical of the outer suburbs in the Ottawa area and in North America in general. There is no grid pattern and no general trend of East -W e st streets to take advantage of southern exposure for the winter months. While the 1970s plan considered detached houses to be the least energy-efficient type of housing, and were therefore entirely excluded from the plan, the bulk of the housing in this area today is detached housing, as seen in Figure 5. Figure 5 - Houses typical of the South March/Morgan's Grant neighbourhood. These particular houses face East. 5
Furthermore, while the proposed ene rgy-efficient building design specified overhangs to protect south-facing windows in summer when the sun is higher in the sky, many houses do not have this protection, especially on the upper levels, as in Figure 6. Figure 6 - The windows on these south- facing houses do not have overhangs to protect them from sun exposure in summer, nor are there many deciduous trees to provide shade. The houses in Figure 7 face Northwest (i.e., into the prevailing winter winds), and are wholly unprotected by any other homes or evergreen trees. There are also many large windows on the houses that face into the winter winds. Planting some evergreen trees for wind protection would be a simple solution, though a better solution would have been to think about the location and orientation of these houses during the construction phase and account for them in smart home design. Figure 7 - These houses face Northwest and are unsheltered from prevailing winter winds. District heating and active solar systems (e.g., photovoltaic panels and/or solar hot water heating), while an important part of the 1970s plan, are completely absent from this neighbourhood. Active solar systems c ould be retrofitted onto existing homes, but implementing district heating would be difficult and expensive at best. In conclusion, as with this South March community, homes and suburbs all over Canada are often ill -designed for their environment, though simple solutions are available both through foresight and hindsight. Canada s commitment to its share of GHG emission reduction will be dependent, in part, on its citizens recognizing opportunities for improvement through some simple physics based on sun, shade, and shelter from cold winds. 6
References [1] "2006: Canada s Fourth National Report on Climate Change: Actions to Meet Commitments Under the United Nations Framework Convention on Climate Change," Environment Canada [Online doc ument], [cited Available HTTP: http://unfccc.int/resource/docs/natc/cannc4.pdf. [2] G. Boyle, Renewable Energy: Power for a Sustainable Future. Oxford: Oxford University Press, 1996. [3] "Ele ctricity Usage by Ontario's Residential Sector," Ontario Power Authority Conservation Bureau [Online document], [cited 2007, December 25], Available HTTP: http://www.conservationbureau.on.ca/page.asp?pageid=122&contentid=153 9&SiteNodeID=168. [4] "Canadian Climate Normals 1971-2000, for Ottawa CDA," Environment Canada [Online document], [cited 2007, December 25], Available HTTP: http://www.climate.weatheroffice.ec.gc.ca/climate_normals/results_e.html?pr ovince=all&stationname=ottawa&searchtype=beginswith&locateby=pr ovince&proximity=25&proximityfrom=city&stationnumber=&idtype=ms C&CityName=&ParkName=&LatitudeDegrees=&LatitudeMinutes=&Longitu dedegrees=&longitudeminutes=&normalsclass=a&selnormals=&stnid=4 333&. [5] " 1 8 -Month Outlook: Ontario Demand Forecast from January 2007 to June 2008," Independent Electricity System Ope rator (IESO) [Online document], [cited 2007, December 26], Available HTTP: http://www.ieso.ca/imoweb/pubs/marketreports/18month_odf_2006dec.pdf. [6] R. Lang and A. Armour, Planning Land to Conserve Energy, vol. 25. O t t a w a : Environment Canada Lands Directorate, 1982. 7