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sauprankul t1_iv75rl4 wrote

Reply to comment by Comprehensive_Leek95 in Researchers designed a transparent window coating that could lower the temperature inside buildings, without expending a single watt of energy. This cooler may lead to an annual energy saving of up to 86.3 MJ/m² or 24 kWh/m² in hot climates by mossadnik

Heating is way more efficient than cooling, so on average, this is still better. And the thermal energy lost through glass at night is significant. You lose heat from the building via radiation. If this coating keeps heat out, it'll keep heat in too.

EDIT: see comment thread below. Cooling might be more efficient than heating, so it actually would be better to let as much heat in as possible during the day during winter.

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Lknate t1_iv7eh9k wrote

I live in Florida and absolutely use this principle. Once I have to start having to run heat, I start cooking a bunch. I'm talking about baking bread, roasting pork butts, large stock pots of gumbo and running my antique tube radio all the time. During the summer I actually run the toaster oven and air fryer outside because they are so expensive to pay to heat and cool at the same time.

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winkapp t1_iv81a0z wrote

>Heating is way more efficient than cooling,

While the rest of your reply makes sense, this is just completely wrong. Cooling is way more efficient than heating, by a difference of 3.5x.

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sauprankul t1_iv82ouo wrote

That's not what the abstract says at all. It says that places that get really cold like Minneapolis spend more energy than places like Miami, where it's livable year-round. That's where the 3.5x number comes from. I'll read the paper later when I have time, but I'm still standing by what I said.

"This finding suggests that, in the US, living in cold climates is more energy demanding than living in hot climates."

I'm open to evidence that shows I'm wrong. It'd have to be something like "it takes x% more energy to raise the temperature of a home by 1 degree than to reduce it by 1 degree".

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winkapp t1_iv83e57 wrote

It literally says what you asked for.

> Another way of stating this is that it takes less energy to cool down an interior space by one degree than to heat it up by one degree. This is the case, because (in layman’s terms) it takes less energy to transfer heat (air conditioners) than to generate heat (furnaces and boilers).[…]

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Staerebu t1_iv87egx wrote

The 3.5 times comparison is because it's comparing a heat pump (air conditioning) with heat generation (a regular heater, furnace etc.).

A heat pump transfering heat in would also be more efficient (depending on the outside temperature).

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_Rand_ t1_iv8gmlc wrote

Also the fact that its a lot easier to be comfortable when its cold(ish) than when its hot will probably lead to lower heating costs.

Like, I can put on a sweater or throw a blanket over my lap and keep my house at 18-20c quite easily and not be uncomfortable, but when it its 35c out my AC can’t keep enough to get the inside temp below 25 or 26 and it’s absolutely miserable.

So while heating might be less efficient than cooling on a degree by degree basis, the need to heat/cool to specific levels may not at all be the same.

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