This is a blog post I’ll update as time goes on… But I’ve been wondering how much our utility costs would go up once we moved into a house. Here are the baseline numbers for electrical usage in our old coop. It was 2 bedroom, 2 bathroom, and about 1,350 sq. ft. in a 1939 pre-war (poorly-insulated) building with leaky window A/C units and a Sub Zero fridge:
Summer Average (’07-’09): 29.0 kWh/day
Winter Average (’07-’09): 18.3 kWh/day
Summer I defined as the June 20ish reading through the August 20ish reading. Winter I defined as the September 20ish reading through the May 20ish reading. Actually, winter is a bad term – “non-summer” would be better. So what you see above is the average of three summers (6 total months), and 2 winters (16 total months)
I should also mention that we work from home – so everything you see includes air conditioning during the day – but typically just for the rooms we were occupying, though Dan has a bad habit in the house of opening doors into unairconditioned spaces and cooling more of the house than is necessary. We also have at least one computer on 24 hours a day – since it acts as a server.
From 5/21 to 6/12 we used an average of 36.3 kWh/day (98% over winter average)
From 6/12 to 7/31 we used an average of 37.2 kWh/day (28% over summer average)
From 7/31 to 8/20 we used an average of 54.1 kWh/day (87% over summer average)
From 8/20 to 9/20 we used an average of 41.0 kWh/day
From 9/20 to 10/23 we used an average of 31.4 kWh/day (72% over winter average)
Now, mind you, the house is a lot bigger has more things going on. Instead of 1,350 sq. ft., it’s about 3,200 sq. ft. There’s 180 watts of light bulbs that are on from dusk to dawn (roughly 2 kWh/day). There’s a dehumidifier running the cellar 24/7 – it’s Energy Star certified, but it still uses a fair amount of power. The server we have running is more power hungry. There’s also a booster pump for water pressure, etc. All in all there’s just more electrical demand than there was in the apartment.
The average from 6/12 to 8/20 was 42.1 kWh/day. Since the period started a little earlier than it should have and there were some days we wished we had A/C before July 3 (when it actually got up and running), let’s call the summer average 45 kWh/day – that would be “just” 55% more than at the coop. I’m pretty happy with that, all things considered.
The average up to 6/12 and after 9/20 is 33.4 kWh/day. So once again we see power going up roughly 11 kWh/day for A/C during the summer. That’s great since we’re cooling more space than we did at the apartment with about the same amount of energy. In fact for about 6 weeks during that time Dan had the A/C on 24/7 up in the studio because he was making stuff out of fiberglass and needed to control the temperature. But our building is more efficient and the A/Cs are more efficient.
But the “winter” (non-summer) power is considerably higher. So far, the townhouse seems to consistently use 15 kWh/day more than our old apartment – that’s 80% more power. Electricity seems to be costing about 25 cents per kWh, so that’s less then $4/day, or about $115/month additional. But when you look at the list of stuff (above) that we didn’t have in the old apartment, it sorta makes sense that it costs more to run a townhouse that’s over twice the size of the apartment.
We also have data for our tenant. That’s a roughly 1,050 sq. ft. duplex apartment (basement & half of the cellar):
From 7/31 to 8/20 he used an average of 24.5 kWh/day (15% under summer average)
From 8/20 to 9/20 he used an average of 35.2 kWh/day
From 9/20 to 10/23 he used an average of 20.9 kWh/day (14% over winter average)
Our tenant also works from home. Theoretically his energy usage should be less than our old apartment – the square footage is less, the insulation is better and the A/C is more efficient. Plus, a third of the space is the cellar which almost never needs cooling. But he does have a dehumidifier running 24/7… His usage was 15% below our usage from late July to late August, but then the following month his electricity usage went up considerably for some reason. And then he was 14% over our winter usage in the past month.