Wednesday, April 22, 2009

Energy Use and Usefulness

Hi Gang - thank you for hanging in there with us. We're getting ready for the Mpls/St Paul House Tour this weekend and HGTV to come film next week for the second series of World's Greenest Homes (2) and we're all a flutter. A little cleaning, a little touch up painting and watering the green roof and lawn because we've had no appreciable rain yet this spring and things are drying out. We'll get rain all weekend I'm sure.

SO - We've been busy measuring our energy use and production for the past 6 months - and while it's still a little early to be conclusive, I can say that our home is performing well.
The solar hot water panels seemed to produce nearly 100% of our hot water needs from July - October and the solar PV panels have produced an average of 25% of our whole house electrical energy needs and nearly 50% of the house load if we discount the energy used by all of my office equipment - which is 380 kwh a month - not a typical load in most people's homes!
Given that the balance of the electricity used by the house that we haven't produced ourselves is purchased through Xcel Energy's Windsource program - we're feeling pretty good about our carbon footprint.

A fun little fact - our house uses less energy than the former house does even though it is nearly twice as big. I'll wait to give an exact percentage until we have a full year's worth of data. What I can tell you right now is that our new and improved home uses 47% less electrical energy per square foot and 63% less gas per square foot than the original house did. I expect these numbers to improve as we move through Spring and early Summer - when we'll need very few lights and very little cooling.

I'm also in the process of tying our kilowatt hours of electricity and ccf of gas into an average kBTU/carbon emissions total and square foot for the house. It will be great to be able to see if we use more or less than the amounts predicted by our energy model (HERS score 52, Energy Star Rating 5 stars plus). I hope we'll be below the predicted use. I think we will be. Look for that post in a few months.

The solar panels get the headlines and ooohs and ahhhs, but most of the energy savings are coming from simple, smart design decisions that everyone can do. We've been talking about all of these things in this blog so I'm sure you're familiar with them. Use better insulation with higher R Values and good air sealing, use high performance windows and passive solar strategies; limit the amount of glazing to the west and north, protect the south glazing from solar gain in the summer, maximize it in the winter, use high efficiency energy star rated equipment, use CFL and LED lights, turn your lights off when you leave the room, have heat recovery system on your furnace exhaust, caulk around windows and doors, set your thermostat higher in the summer and lower in the winter....and all the other basic stuff that leads to better energy savings.


modernemama said...

Can't wait to see the house "in action"

alister said...


It was good post.

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