The Oil Drum: Canada | Kyoto, Canadians, Energy and the Environment

70 comments on Kyoto, Canadians, Energy and the Environment

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liferaft on February 21, 2007 - 12:01pm

I replaced all the incandescent bulbs in my home and calculated a savings of 80% in electricity usage for lighting. Helping achieve that figure included only replacing 2 bulbs in a 3 bulb fixture, etc.

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assystems on February 21, 2007 - 4:43pm

I've been to lazy to actually do any calculations, but I think the energy savings with compact flourescent bulbs may not be as simple as one might think.

Each incandescent bulb is a small radiant heater, deploying heat into your house. I agree that electric heat is 1)not the most efficient, 2) that the ceiling is not the best place to have a heat source, and 3) that in the summer heat is not required.

However, a radiant heater's placement in a room is not critical, more or less eliminating item 1).

If a house already has electric heat, I would venture to say that during the winter there would actually be a very slight negative savings with compact flourescent bulbs. I say this because of the "cost" of higher environmental impact and the higher cost of the bulbs.

If a house uses another heat source, then it is probably more efficient than electric heat, and hence there would be a savings with the compact flourescent bulbs. However, this would not be an outright savings, but merely transferring energy consuption from one source to another.

If a house requires cooling, then the compact bulbs would get a double payback - you won't be paying to dissipate the heat from the incandescent light/heaters in your house.

We use compact flourescent bulbs in our PV system - that choice is pretty obvious. However, in town we largely use encandescent - we don't see a clear reason why the CF bulbs are better. Our electricity comes from hydropower. Our furnace is natural gas, and we also have a wood stove. Most of the time we don't really heat the house anyhow, but the fewer incandescent bulbs we have, the more heat we will need.

Tyan in Seattle

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liferaft on February 24, 2007 - 3:08pm

I had some doubts regarding the significance of overhead incandescent bulbs on heating a room, and since my house has electric heat, and I decided to run an experiment.

The room I used is very well insulated and the heat control unit has a digit thermometer accurate to +/- .1 degree, located about 5' above the floor with the ceiling at 8'. I turned off the heat, and the room stabilized at 51.8 degrees for an hour. Turned on the overhead lights, which consist of three 60 watt bulbs within a frosted glass bowl. Left the lights on two hours, with no change in temperature. The bowl did get quite warm.

So as I suspected, the incremental heat from the overhead bulbs had no impact on the thermometer, and thus could save nothing in regards to electric heating. I doubt that heat from bulbs in lamps located closer to the floor would have any impact either, as heat rises.

Bottom line is that you would reduce your energy consumption by installing CFLs even if you have electric heat.

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Valuethinker on February 25, 2007 - 2:55pm

Tyan

To the extent that incandescent light goes out of your house via the windows as visible light, you are losing energy. This is not the case with a domestic heating system (which produces heat, not light).

It's also the case that the conversion efficiency of a coal fired power plant is as low as 35%, and there is transmission loss getting the power to your light socket. So it's a very inefficient way to heat your home vs. a modern gas boiler with a conversion efficiency of over 70% (90% is possible with a condensing unit).

If you heat your home electrically, this calculation doesn't apply.

You wouldn't though, just heat your home with lightbulbs. Because heat energy is wasted being turned into visible light.

There are other inefficiences:

- obviously in summer with air conditioning, compact fluorescents are an all-out winner-- a 5th or less of the heating (which has to be in turn cooled)

- incandescents have to be manufactured, transported and distributed to stores (where they occupy shelf space) and then to your house-- all of this takes fuel. CFs last up to 10 times as long, saving all that energy expenditure *plus* the extra volume of waste disposal.

In the end, from a personal point of view, the lifetime of a CF is the best answer. Yes they cost more, but not so much more, usually, that the don't offset the cost of replacing incandescent bulbs every couple of thousand hours.

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