We've been in this house for a bit more than a year now, so now we're able to do same month year-to-year comparisons of our energy use. We've been steadily working on making the house more energy efficient, so I've been curious to see what the impacts are. We've replaced the windows, one of the toilets, clothes washer, dryer, boiler, fridge, dishwasher, and stove. Basically, the only things left to do are the hot water heater and the air conditioner...
So, the envelope please...
- Electricity -- Dominion Virginia Power has a handy-dandy button on its site that generates various comparisons for you once you've logged in. It shows how much you paid in a given month compared to the previous month and the same month the year before, and divides the change out among different temperatures, different number of days in the billing cycle, change in prices, and "customer-controlled use." So, we paid $71.20 in May 2008, down from $95.02 a year previously. And the rates went up in that period, so they claim that customer-controlled use saved us $27.28. So, a decent percentage savings, but not that impressive in absolute dollar amounts. Even with the forthcoming 18% rate hike, it's going to take us a long time before the improvements pay for themselves. (Obviously, the energy savings were not the primary reasons we made these changes, so we're not upset by this.)
- Gas -- Washington Gas doesn't offer this kind of comparison, so I have to sort of eyeball things. We used 13.2 therms last month, versus 63 therms a year ago. That's because it took us a while last year to figure out how much energy our old boiler was using keeping water hot even when it wasn't sending any into the baseboard heaters. Once we figured out that we needed to shut the boiler off in the summer, it dropped down to 32 therms. (The remainder is for the clothes dryer and water heater, both of which are gas-powered. Our new stove is also gas powered, but you'd have to work really hard to spend more than a few dollars that way...) The more impressive comparison is February to March, when our use dropped from 258 therms to 151 when we installed the new boiler. That improvement clearly is cost-effective, since our February bill was close to $400.*
- Water -- We get billed quarterly for water, and haven't paid more than $100 per quarter. While the washer and dishwasher use less water than the old ones, I don't expect it to make a noticeable difference on our bills. We put in a low-flow showerhead but I'm guessing that it impacts the gas bill more than the water bill.
Dominion is making a big deal out of their new conservation plan, but I'm pretty skeptical. Based on my results, my guess is that just showing people how much their energy use costs won't significantly affect usage unless they also adopt variable rate pricing, where electricity costs a lot more during peak usage times. (Dominion does not appear to be doing that, since their demo says you'd be entering the rates from your bill.) I think this is mostly an attempt to convince politicians to give them approval for the transmission lines and coal-burning plant they want to build.
* When I see stories like this one about people with $400 monthly electric bills, I have to assume that they have electric heat, and very poor insulation. I'm not sure I could run up a $400 electric bill in this house even if I ran the air conditioning with the windows open.
Cross-posted to my home blog. Also, note the new "Environment" category -- I'll go back when I get a chance and add the tag to some of my older posts.