Why bother buying efficient lights if you are already heating your house? | Hacker News Reader

Why bother buying efficient lights if you are already heating your house?

physics.stackexchange.com

31 pointsfirebaze8 comments

When the question even put arctic circle into a hypothetical example, most of the answers seems to be fairly low quality.

In a well insulated building the heat from the bulb is going to be almost exacly as effective as any other source of electric heat. The heat doesn't have any place to go before it is well mixed into the inside environment. Presumably a building in the far north near the arctic circle would be well insulated.

The question is dumb and so are the answers.

Person who asked this question, should have calculated how many lightbulbs he need to heat up the room - unless he has built tiny room for some pet, then it makes sense to use just one lightbulb.

I would assume, that most of the folks on this site are heating up room using their PC... For me it is clearly a 2-5 degree difference if the room is not heated by PC.

PS Ironically, I use the most energy consuming and brightest lightbulb I could find(among the energy efficient lightbulbs, because there are no other options).

I dont think that's a useful answer. They consider the lightbulb to be supplementing their heater, not replacing it

Not a bad point! Similarly why dont we have electric heaters doing useful work rather than just jumping that energy immediately?

Literally the exact same answer as in the link.

Heat pumps can be up to 4-6x more efficient at heating than simple resistance based heaters.

They can expense 1 watt of energy and heat a room up by 4-6 watts of energy.

You should also take into account the cost of the heat source.

I'm building a house to modern building standards that will have a thermal energy demand of 15W/m2/year. For our heating season and size of the house (160m2), that could easily be supplied by a 2kW electric radiator, at a cost of around €500 per year. So the total cost over 10 years, would be €5000 + the cost of the radiator (~€50).

I'll also have solar, which will produce more electricity than that consumes per year, and we have nearly net metering (need to pay a few c for every kWh consumed), so the electricity bill would actually be a lot less.

However the building codes in my country need you to have a "renewable" heat source, and an electric radiator + solar is not considered "renewable", so we will be going with a heat pump. Over 10 years that will be more expensive, the install cost alone is higher than the total cost of the radiator. Maybe eventually we will break even, but I don't think the heat pump will last much more than 15 years before needing to be replaced.

Thermal energy per m2 of living area seems like a terrible way to calculate heat loss. Unless you mean you have 160m2 of outside facing surface area. Are you sure your numbers are correct?

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