A home energy enigma

Eight years ago, I was confused and dismayed to see that our household water usage had been gradually creeping upward over time. Where once we had consistently been in the lowest tier for water usage, we were getting one, two, even three bills a year that put us in the middle tier. What upset me most wasn't the higher bill, but the fact that I couldn't for the life of me figure out where all this water was going. We hadn't added any water-hogging appliances or landscape plants, and we hadn't changed our everyday habits significantly (e.g., showering more frequently), so what the heck was going on? Even though our bill ended up dropping back down the following summer, I still never found a really satisfactory explanation for what had bumped it up in the first place.

Today, I find myself in a similar position with regard to our household energy use. Our local utility, PSE&G, has added a "MyEnergy" feature to its website, which allows you to enter some details about your home and then receive an insert with your bill that shows how your energy use compares to other homes in your area. If your electric or gas usage seems to be outstripping your neighbors', the insert includes a few tips on how to get it back in line.

When I signed up for this, I assumed that it would probably just reinforce what I already know: Our electric and gas usage are both well below average, and there's not much we could do to reduce them further. But instead, for the last two bills running, the message has been, "Congratulations! Your household is among the most energy efficient in your area for electric use; but a little behind in gas savings." Then it presents a little chart to show that, compared to other homes similar to ours — built between 1961 and 1971, between 1,400 and 2,000 square feet, with non-electric heating — our household electric use (133 kWh) was well below both the average home (235 kWh) and a typical energy-efficient home (199 kWh). But when it comes to gas use, our usage of 96 therms puts us above the average (87 therms) and well above the energy-efficient home (71 therms).

This is all the more baffling since we're actually at the low end of this size category: technically, our home has about 1,400 square feet of heated space, but that includes the basement level, which we only heat to 54 degrees. The main level is only 936 square feet, and we only heat it to 67 degrees. And I know our insulation is superior to most of the homes in our neighborhood, because after a snowfall, snow melts off their roofs right away but stays on ours much longer (because less heat is leaking out through the roof). And our boiler is less than seven years old and supposedly 83 percent efficient. So what gives here? Do our neighbors actually have their thermostats turned even lower? Do they all have much more efficient heating systems? Or are they actually heating their homes with oil, which is "non-electric" but doesn't add to the gas bill?

One thing's for sure: it's definitely something to do with heating that's causing the problem. The MyEnergy insert also included a couple of line graphs to show how our electric and gas usage have looked over the past year, and during the warmer months (mid-March through mid-November), our gas usage was below not just the average house but the theoretical efficient house as well. It was only after the heating system went on that it jumped above the "efficient" level, and it still remained below the "average" level until January, when it got really cold. So it's clearly our heating system that's to blame. But how? 

PSE&G's report sheds no light on this question. Last month, its suggestions for reducing our energy use last month were to "Maintain your ducted heating and cooling systems," which we don't have; this month's are all about saving on hot water use by doing things we already do, like washing our laundry in cold and not letting the water run while shaving or doing dishes. And even if these tips were useful, they'd only save us 5 percent on our hot water usage, which itself is only an estimated 5 percent of our total energy bill. That's never going to make the difference between outperforming and underperforming our neighbors. Even the more detailed "Home Energy Analyzer" on PSE&G's website offered only such lukewarm tips as "open west- and south- facing window coverings during the day to let the sun in and close them at night to keep in heat" (which, duh, we already do); replace the pilot light in your heating system with electronic ignition (which we already have); and "don't set your thermostat too high" (which I doubt anyone would ever accuse us of doing).

And it gets weirder: when I went to PSE&G's website to add more details about our home, thinking maybe this would give me a clearer picture, it suddenly started telling me that both our gas and electric use for this month were below average. Our usage (96 therms) was exactly the same, but now it said the average usage was 186 therms and the efficient usage was 154. For a smaller house than it was comparing us to before. Apparently, our neighbors in smaller houses, around 1,200 square feet, are all using much more energy than those in houses between 1,400 and 2,000 square feet. And when I adjusted our numbers again to say that our home was 1,400 square feet, all of a sudden it was back to telling us we were less efficient than average. How could 96 therms for a 1,400-square-foot house be not just less efficient, but much, MUCH less efficient, than 96 therms for a 1,200-square-foot house?

Perhaps the simplest explanation here is that PSE&G's comparison tool is just plain broken, and the most useful thing to do is ignore it. But that just leads to a new mystery: how in the world did they come up with these bogus numbers? What formula could they possibly be using that leads them to conclude that a small home using 96 therms of gas is much more efficient than a slightly larger one using the same amount? And, perhaps more to the point, is there any way to get them to fix it and give us some numbers that are actually useful?