Well the heat has been officially kicked on by landlord gods. And, while I have been excited to once again live in a habitable environment, I have also been dreading this moment. Space heating uses a LOT of energy, and while I wasn't sure until now how much exactly that was, I had a feeling that I might be in for some trouble. We don't pay for our heating bill (luckily) but I was able to request the natural gas bills for the last year from my landlord.
The facts are these:
This statement reflects all natural gas use for our entire house; water heating and hydronic radiant heating (we have an electric stove so no gas included). My house is a duplex with equal floor areas of 1,490 sf each, so dividing by 2 gives a rough total for our level. As you can see, the gas is measured in 'therms' and there is a big difference in the winter months from the use in the summer. In the warmer months, the only gas use is water heating, so this gives an accurate picture of how much energy is used to heat water- an average of 34 therms per month for the whole house, so 17 therms for our floor . While I need to include all of the floor area 1,490 sf in my 'energy budget' because I occupy most of this space, I can divide by three for the water heating portion and assume that I use an average of 5.6 therms per month.
By converting therms into kWh, I can compare space heating energy to the other quantities of energy that I am using.....moment of truth:
Remembering back to my earlier graphs of energy use for various things, I've added space heating, water heating and the amount of energy it takes to clean water (1.8 watts/gallon according to a report- "Energy Use At Wisconsin's Drinking Water Faciltiies" Energy Center of Wisconsin (July 2003).
|click to enlarge|
As you can see, space heating trumps all other energy use (of the energy users I have identified so far). Water cleaning is shortly after. Space heating every week is 7.5 times the energy required for transportation. 704 kWh are required for average heating throughout the winter, which is 93.95 kWh each day. My energy budget is 12 kWh per day (the amount of energy we can capture on our roof divided by 2 apartments). Clearly, the energy required for heating requires a much different strategy. Like....not living in Minnesota?
Ok, without jumping to conclusions, there more efficient ways of heating spaces. Passive solar homes come to mind, where heat from the sun is absorbed and trapped inside building materials with sufficient thermal mass. Super-insulated homes such as the Passive House (http://www.passivehouseinthewoods.com/) also have the opporunitity to greater reduce heating energy by reducing the amount of heat lost through wall systems.
My first reaction to these numbers was to feel like nothing I have been doing up to this point has really made any difference. In comparison to how much energy is required simply to heat my space, all of the other energy users COMBINED don't even add up to half. However, there are other major energy users which are not yet represented on my graph. The amount of energy required to eat food from all over the country and world versus eating locally is a big one that I havn't pinned down yet.
My advisor mentioned a while back that many people on raw or vegan diets who want to eat local foods year round have relocated to places where this kind of lifestyle can be accomodated (like california where things GROW). I would speculate that in a post-cheap oil world, we may find ourselves in a position where we are re-evaluating where we have chosen to live- and the price we will pay both economically and energy-wise to accomodate living here.