Rethinking Lifestyle

Energy Efficient Homes

  • Gary Martens, Guest Author
  • Retired Lecturer U of M, Agronomist

How can you contribute to Canada’s goal of reducing its carbon footprint and save money at the same time? The low hanging fruit of energy conservation and greenhouse gas reduction is found in our homes. Energy to move things relies on mobile fuel but homes are stationary and therefore stationary energy sources like wood, natural gas, electricity, geothermal heating and cooling, solar panels, windmills and air source heat pumps can all be used to keep our homes comfortable.

But before we look at energy sources for our homes we should consider the three basic strategies that will give us the biggest bang for our buck in providing an energy efficient home. The first strategy is to insulate the home well. The standard home has around R20 for the walls, R40 for ceilings and R14 for foundation walls. A truly energy efficient home would have insulation of R40 for walls and R60 for ceilings and R22 for foundation walls for our climate.

An aside about snow is that it insulates significantly. Snow has about R1 per inch. I just measured, and I have about 6-8 inches of snow in my yard. That is R6-8 and if shovelled against the house will provide significant insulation on the foundation wall.

The second strategy to make your more home energy efficient is to make it more air tight. The average Canadian home has cracks that accumulated into one space would be about a one square foot hole. If that hole was in one place it would be easy to close, however the holes are scattered throughout the house in tiny cracks. Sealing all those cracks is a complex job however you might start with sealing up electrical outlets, switches and any other obvious cracks and air leaks. Seal around windows, both inside and outside the house and replace weatherstripping on doors. The average Canadian home has 6.8 complete house air changes per hour (ACH) through all these cracks. An excellent airtight home might have as little as 0.8 complete air changes per hour. An energy advisor can measure your ACH with a blower door test.

An airtight, well insulated home may only need 15 Kwatts/m2 energy per year. You can check your energy usage by going to your account at Manitoba Hydro. They give you energy use statistics for your home. Divide the number of Kw of energy you use by the square meter size of your house to get a comparison of your house to a highly energy efficient one. If you use natural gas you can convert cubic feet from your meter to Kw by multiplying cubic feet used by 0.29.

The third basic strategy is to manage the airflow in your home using a high efficiency heat recovery ventilator system (HRV). If you have the average Canadian home you do not need an HRV. The cracks are adequate to supply the fresh air your home needs, but when your home is very airtight you need to manage the airflow to have adequate fresh air. The better HRVs can recover over 90% of the heat in the air before it is exhausted.

Implementing all three of these basic strategies can save you up to 90% of the typical Canadian home energy costs. For example, if you now spend $400 per month to heat and power your house and you reduce that by 75% you would save $300 per month. That would be the monthly payment for a loan of over $50,000 that you could use to upgrade your home.