09 December 2010

Green House, Warm Bed

In early November, I mentioned that it still hadn't gotten cold enough for our heater to kick in. (It would dip briefly into the 40s overnight, but the cold couldn't penetrate our well-insulated walls, and between the warmer daytime temperatures and the passive solar heat coming in through the windows, we stayed nice and toasty.)

Over the last week or two, it got cold enough.

And while we haven't gotten our first electric bill with heating on it, so far we're really pleased with the system. As you may know, we opted for a geothermal heat pump, which gets most of its heating power from the constant temperature of the earth 275 feet below our house (learn more about it here, here, and here, although the best I understand is that our house is being heated and cooled by magic).

Despite nearly doubling our square footage from our old condo, our electric usage this summer was only 2/3 what we used in the condo (thanks to green building measures like better insulation, the hugely efficient heat pump, and CFL bulbs throughout the house). I expect that our winter bills will be a bit more difficult to compare, as the condo had gas heating, but we still should see some good savings. (We had planned to install solar panels on the roof, but with our summer bills as low as they are (no more than about $60 in electrical usage per month), it's hard to justify the expense.)

As with every component of the new house, we considered lots of HVAC possibilities. Before we settled on the geothermal system, we knew that we wanted multiple zones. Although the house is pretty modest in size, we had three zones in mind: the great room, the master bedroom and bunny room, and the less-used bedroom wing. The most important consideration was that the bunnies needed air conditioning during the day in the summer, when we wouldn't be cooling the whole house. As it turned out, that wasn't too big a deal, as we kept all three zones around 78-80 degrees but with the humidity turned down to 50%. (It's amazing how reducing the humidity makes the house feel so much cooler; the built-in humidistat and dehumidifier allow the HVAC to work less hard to keep us comfortable.)

But now that it's cold, we're really seeing the difference the zones make. Last night, the master bedroom zone was set to 74 until we went to sleep. The rest of the house, which Steve hasn't programmed to come on at all (until and unless the house reaches the thermostat's preset minimum of 60) was somewhere around 70, which was chilly but nothing a bit of Jimmy Carter action (long sleeves and a pair of socks) couldn't remedy. This morning, after overnight temperatures in the mid-30s, the master bedroom was a toasty 72 while the rest of the house was a wintry 67. Bottom line: as long as we keep the bedroom door closed, we can get away with heating less than a third of the house most days. Since the thermostat is in our room, we can even leave the bunny room doors open for easy access to bunny snoogles. Which is the whole point of having bunnies, really. (Click here if you like bunnies.)


  1. I'm envious of your green construction. Our house in DFW is almost 30 years old, and has 20-foot ceilings in the living room. With both of us working at home, a back wall that is floor to ceiling (all 20 feet) windows, and seven million computers (or ten) you do NOT want to know what our electric bill is like.

    I try not to use the heat. I hate the dryness.

    Is your house the one in your blog picture?

    -- MissMeliss

  2. It's the rendering that we used as the starting point for our plans because I loved (and love...probably even more now) the front facade. We changed the roof material (metal), the color (medium green), and little things like the door style and window sizes, but it's pretty close. We'll replace the picture in the header with an actual photo eventually, but we don't have any landscaping yet, so it's still looking pretty rough: http://greenhousegoodlife.blogspot.com/2010/10/compare-and-contrast.html

  3. My wife and I are looking forward to building our dream house in the next couple years. We've got a lot of green ideas, but we're still settling on exactly what we're going to do.

    I'd imagine there's somewhere on your blog where you've discussed more fully the features of your house and your building process--can you point me to them?

    (I wandered over from Holidailies)

  4. I posted about various green features as we made decisions, and then again as they went in during construction, so they're throughout the blog. I was pretty good about labeling posts, though, so you might try the "green" label (which is all of the green building stuff; "green living" is for non-building topics) or individual component labels (water heater, insulation, windows, etc.). I think the one post that addresses the widest variety of issues is this one: http://greenhousegoodlife.blogspot.com/2009/08/green-building.html. If you have any questions, I'm happy to answer them (or at least try).

    Good luck with your dream home! It was a long and, at times, difficult process, but also really fun and so rewarding.