I'm not used to living in a cold house, especially not a big one. But now when the heat is on, I look at all of the space that's being heated, and realize that I occupy an extremely small fraction of it (~0.05%). On most days I don't even set foot in the two spare bedrooms. Why heat them? Just heating the rooms I'm in is far better.
But even better than heating fewer rooms is just heating a body. Of course, our bodies produce heat themselves. I now wear flannel pajama pants, a sweater, and warm slippers in the evenings in my house to keep the body heat near me. It sounds like I'm 70 years old, but now I'm comfortable with the house at 66 degrees.
And I now have flannel sheets on my bed, as well as a down comforter, so I don't have to run the heat at all at night.
So that's my system for now. I keep the largest unused bedroom closed off so that it doesn't need to be heated, I dress warmly and have a warm bed. I now only need to heat my house to 66 degrees from 6-11pm, and don't run the heat at all at any other time (at least during the week).
Of course that's the low hanging fruit. Now I need to insulate my house better.
Wednesday, December 28, 2011
Thursday, December 8, 2011
The Blower Door Test
I had a home energy audit this morning. It was really educational. Not because the guy was so informative, but because I got to look over his shoulder and see the numbers on his gauges.
The major test he did was a blower door test to measure air infiltration. A blower door is a plastic seal put over your front door, with a large fan on the bottom (see picture to the left). The fan blows air out of the house to create a pressure differential between the inside and outside. This causes air to be sucked into the house via numerous cracks and leaks. While the fan is on, you can go around the house and feel the areas that have obvious leaks. For example, there was air coming out of my light switches - not much, but it was definitely there.
There were several big (and obvious) drafts. First, the chimney flue doesn't really close all the way, so that's a gigantic hole letting my conditioned air escape. Second, I have ten recessed lights that are not sealed, so they're just a bunch of conduits between the living space and the attic (and the attic is likely damn hot during the summer). Third, I have a few holes in the wall where coaxial cable is poking through but there's no cover. So it's just a ~ 1-inch diameter hole where air comes right in.
These were all fairly obvious leaks. What I didn't expect was that my floor leaked. Seriously. I have hardwood floors on a slightly raised foundation and when I put my hand near the floor, there was a very subtle, but real, draft. Apparently, hardwood floors (on raised foundations) are typically more drafty than mine, but still, this opened my eyes a bit.
For the subtle leaks, the guy (inspector?) had a cool contraption that was basically a large plastic hemisphere that you put over something you want to inspect for leaks (a vent, recessed light, etc). The rubber around the edge forms a seal and it reads out the pressure difference between the room and the sealed inside of the hemisphere. The blower door was maintaining 50 Pa (pascals) pressure difference between the inside and outside. If this contraption also measured a large differential between the room and the object of interest, that means it's leaking a lot. For example, he put it over one of my AC vents, and it only read 3 Pa. Not a big difference. However, when he put it over a recessed light, it read 33 Pa. Basically, there was almost nothing holding the air back.
On top of this, you can use an infrared camera to scan the walls and openings to spot obvious places where heat is being transported. It was a very cold morning and the joints between the wall and ceiling were colder than the rest, indicating that some of the cooler air was leaking in there (apparently this is quite common). Unfortunately, the temperature differential between the inside and outside was pretty low, so this stuff was hard to see. I felt a little ripped off because of that.
Anyway, the whole experience was fascinating. But here's the thing - I could have done it myself. I'm a smart guy with basic physics knowledge. I could have figured out how to do this in 5 minutes on the internet. The inspector didn't really have a deep understanding of what he was measuring. When cranking up the blower door fan, he kept saying he was going to crank it up high enough so that there was a "50% difference" between inside and outside, while pointing to the meter. The meter was actually reading the pressure difference in units of pascals, not percentage difference in pressure. A 50% drop in pressure would have been like transporting us to 18,000 ft. elevation in a matter of seconds. That would have done some nasty things to my ears - and it would have really pissed off my cat.
So, yes, I could have done this myself. It looks like it might be possible to rent these blower doors. That would be awesome! It makes so much more sense. Seal up the recessed lights, take the measurement again, seal the fireplace, take the measurement again. You could actually see how much you're improving your home's insulation. The way it works now is, you get the test, they tell you what will help, and then they claim to fix it. But I want to see a before and after. How much have you really helped me out? This is all just making me want to do it myself.
Side note: The inspector was useful in that he helped me realize some quirks about the way my city provides efficiency rebates. That might save me a ton of money.
There were several big (and obvious) drafts. First, the chimney flue doesn't really close all the way, so that's a gigantic hole letting my conditioned air escape. Second, I have ten recessed lights that are not sealed, so they're just a bunch of conduits between the living space and the attic (and the attic is likely damn hot during the summer). Third, I have a few holes in the wall where coaxial cable is poking through but there's no cover. So it's just a ~ 1-inch diameter hole where air comes right in.
These were all fairly obvious leaks. What I didn't expect was that my floor leaked. Seriously. I have hardwood floors on a slightly raised foundation and when I put my hand near the floor, there was a very subtle, but real, draft. Apparently, hardwood floors (on raised foundations) are typically more drafty than mine, but still, this opened my eyes a bit.
For the subtle leaks, the guy (inspector?) had a cool contraption that was basically a large plastic hemisphere that you put over something you want to inspect for leaks (a vent, recessed light, etc). The rubber around the edge forms a seal and it reads out the pressure difference between the room and the sealed inside of the hemisphere. The blower door was maintaining 50 Pa (pascals) pressure difference between the inside and outside. If this contraption also measured a large differential between the room and the object of interest, that means it's leaking a lot. For example, he put it over one of my AC vents, and it only read 3 Pa. Not a big difference. However, when he put it over a recessed light, it read 33 Pa. Basically, there was almost nothing holding the air back.
On top of this, you can use an infrared camera to scan the walls and openings to spot obvious places where heat is being transported. It was a very cold morning and the joints between the wall and ceiling were colder than the rest, indicating that some of the cooler air was leaking in there (apparently this is quite common). Unfortunately, the temperature differential between the inside and outside was pretty low, so this stuff was hard to see. I felt a little ripped off because of that.
Anyway, the whole experience was fascinating. But here's the thing - I could have done it myself. I'm a smart guy with basic physics knowledge. I could have figured out how to do this in 5 minutes on the internet. The inspector didn't really have a deep understanding of what he was measuring. When cranking up the blower door fan, he kept saying he was going to crank it up high enough so that there was a "50% difference" between inside and outside, while pointing to the meter. The meter was actually reading the pressure difference in units of pascals, not percentage difference in pressure. A 50% drop in pressure would have been like transporting us to 18,000 ft. elevation in a matter of seconds. That would have done some nasty things to my ears - and it would have really pissed off my cat.
So, yes, I could have done this myself. It looks like it might be possible to rent these blower doors. That would be awesome! It makes so much more sense. Seal up the recessed lights, take the measurement again, seal the fireplace, take the measurement again. You could actually see how much you're improving your home's insulation. The way it works now is, you get the test, they tell you what will help, and then they claim to fix it. But I want to see a before and after. How much have you really helped me out? This is all just making me want to do it myself.
Side note: The inspector was useful in that he helped me realize some quirks about the way my city provides efficiency rebates. That might save me a ton of money.
Tuesday, December 6, 2011
The 32 Watt Vampire
In a previous post, I suggested that we should all go around the house and measure our appliances' power consumption. I did this when I first moved in, but I didn't have DIRECTV then. I finally got around to measuring the power used by the DIRECTV digital video recorder (DVR). When the DVR is on, it uses ~26 watts. I thought that was a little high, but it's only on for an hour or so per day. But what does it use when powered off? 24 watts! And worse, the coax cable is plugged into a switch that also uses 8 watts at all times. Great. 32 watts on 24 hours a day.
Last month, my average electricity use was 200 watts at all times. That means this damn DVR accounts for 16% of my electricity use right now. It doesn't have to be that way. I assume it's on all the time so that it can monitor the programs so it knows when to start recording shows. But it knows the show times well in advance. Why can't it power on once a day to update the show times and then only turn on when a show is starting? That would save a huge amount of energy.
What's worse is that this is their newest set-top box and the damn thing is supposedly EnergyStar qualified - says so right on the front. But it's not true. Read for yourself. In "single room" configuration (which is the configuration in my house and probably most houses), it is NOT EnergyStar qualified. The DVR part of the set-top-box just uses too much power for one TV unit to ever get an EnergyStar rating.
On top of all of this, DIRECTV recommends that you do NOT repeatedly power off the box by unplugging it. great.
There's got to be a smarter way - possibly a solid state drive that powers on only when it needs to record a show. I'm sure Apple could design something that uses a factor of three less power. Actually, maybe they are.
Anyway, I'm going to call DIRECTV tomorrow to complain. Maybe if enough people complain, they'll actually do something about it. They probably don't get enough complaints at the moment because electric power is too cheap. At the current rates in my area ($0.1035/kwh), this only amounts to about $2.40/month. Imagine if it were three times higher. You can be damn sure DIRECTV would be hearing about its inefficient set-top boxes then.
Last month, my average electricity use was 200 watts at all times. That means this damn DVR accounts for 16% of my electricity use right now. It doesn't have to be that way. I assume it's on all the time so that it can monitor the programs so it knows when to start recording shows. But it knows the show times well in advance. Why can't it power on once a day to update the show times and then only turn on when a show is starting? That would save a huge amount of energy.
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| Image from Seattle City Light |
On top of all of this, DIRECTV recommends that you do NOT repeatedly power off the box by unplugging it. great.
There's got to be a smarter way - possibly a solid state drive that powers on only when it needs to record a show. I'm sure Apple could design something that uses a factor of three less power. Actually, maybe they are.
Anyway, I'm going to call DIRECTV tomorrow to complain. Maybe if enough people complain, they'll actually do something about it. They probably don't get enough complaints at the moment because electric power is too cheap. At the current rates in my area ($0.1035/kwh), this only amounts to about $2.40/month. Imagine if it were three times higher. You can be damn sure DIRECTV would be hearing about its inefficient set-top boxes then.
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