One of the largest contributors to our environmental footprint is our home. From the materials we use to construct it, the land we cover over with pavement, the species (both plant and animal) we displace, to the energy we use to operate it – our homes have a big impact on our world. If we are going to find a more sustainable balance between us and the eco-system in which we live, we are all going to have find ways to reduce the impact our homes have. Today I’m going to examine the energy we use in our home.
According to Statistics Canada, in 2011 the average two person household in Manitoba used 95GJ (gigajoules) of energy in their home for the year. That works out to .90 gigajoules per m2 in housing area (average home) for a two person family. That’s the energy a family of two would use to heat, cool and light your home; and power all of your appliances and devices for a year. That doesn’t sound like a lot – but it is. 1GJ is a billion joules of energy. The joule is a useful measure of energy because it allows the conversion of energy measures from one type to another. I’ll spare you the pain of having to read my geek-out over how “cool” the joule is, let’s just say it’s a very useful unit of energy measurement. It’s sort of the Rosetta Stone for energy measurements in that you use it to translate energy use from one form to another, ie calories to kilowatts, kilowatts to BTUs, and so forth. Anyway according to Wikipedia, 6GJ is about the energy you get from burning a barrel of oil. So 95GJ represents the burning of almost 16 barrels of oil.
This week I contacted Manitoba Hydro and requested a summary of our energy use for 2013. I provided my email address and within a couple of hours I had a pdf summary report in my inbox. Pretty decent service if you ask me! Anyway – last year we used 16,537 kW.h (kilowatt hours) of electricity for the entire year. That includes the energy used to heat our home as well because when we built our home we were adamant that we wanted electric heating and not natural gas. Sure gas is cheaper, financially, but it’s a fossil fuel and burning it contributes to climate change. In Manitoba, electric heating is far less climate impacting because the vast majority of our electricity comes from hydro generation. Anyway – 16,537 kW.h is what we used to heat, cool and power our home. So how does that compare to the average energy use number I quoted above? Well – since every kW.h is equal to 0.0036 GJ, our energy use in GJ in 2013 was 59.53GJ. That’s only about 63% of the average use for other 2 person Manitoba families.
Using these Statistics Canada numbers the average Manitoba family of two would use 26,388 kW.h of electricity to run their home. A quick Google search on energy use in Canada returns an interesting infographic from Canadian Geographic. In the graphic you can see that the average home energy use per capita in Manitoba is 11,779 kW.h. So with that number a family of two would use 23,558 kW.h per year. Even by these standards Erin and I are almost 30% below the average. Click on the image here to see a larger version of this infographic.
Our energy use is low for a number of reasons. The first is that our home is new and built using new techniques and materials that greatly improve energy efficiency. Also – we take special care to manage our energy use. We actively manage passive forms of heating and cooling. For example opening our south facing window dressing in the winter to let the free solar heat in, while keeping them closed in the summer to reduce the solar heating. We also open our windows strategically in the summer to use airflow to keep our home cooler and we use the furnace fan to circulate cooler air from the basement as well. We also made the decision to build a smaller than average home. Rather than build the average sized new home (1200-1500ft2), our home is 986 ft2. This significantly reduces the amount of energy we use in our home. To get a better measure of how effectively we use energy based on our behaviours rather than simply the smaller size of our home – I’ll calculate the energy we use per m2 and compare it against the average noted above.
Using the handy conversion tool provided by Google – 986ft2 is equal to 91.6 m2. If we take the 59.53GJ we used and divide it by our 91.6 m2 of area, we get an energy use of .649 GJ/ m2. This is about 72% (.649/.9) of the local average. So that tells us that not only is our energy use reduced because of the size of our home, but also because of the construction and the operation of the house as well. These are good number but I know that we can do better.
You might ask yourself why someone would go through the trouble of figuring all this out (I mean beyond the pure joy of doing math and using the Joule measure). Well I did it for a couple of reasons. The first is to quantify our energy use and give that number some perspective (understanding our energy use compared to others). Second – now that I know what we actually use, we can set reduction targets for our energy use and track our progress regularly which will tend to encourage reductions. Remember that old management saying – what’s measured is treasured. Finally – finding out this number was the last piece I needed to purchasing carbon-offset credits. What are carbon-offset credits? Well you’ll just have to read my next post to find out.