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Comment by jll29 | Hacker News Reader

Edinburgh is such a walkable city, I had a fantastic half a decade living there (without a car, apart from the rental one when moving there). This sounds like the right move to maintain the pedestrian-friendliness and to keep the air cleaner.

However, the houses there are often old/historic, with very inefficient heating systems (some even use electricity to heat up a bunch of bricks, which then emits the heat to keep warm) - shocking! Also, windows are not normally with double or triple glass, and sometimes it is not permissible to change these because many buildings are protected.

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Those brick heaters are smart because they use electricity at off-peak times to heat the house for the whole day. What about it strikes you as less efficient than any other direct electric heating?

They're pretty dreadful in that they leak heat while charging up during the night, using (still-expensive) off-peak electricity, when you don't really need the heat, then run out of stored heat quickly during the day, failing to do their job. Maybe in a heavily insulated building they would work better - just my personal experience before ripping them out to install gas central heating.

They’re a suboptimal version of a boiler heat pump.

https://electrek.co/2022/01/05/these-new-affordable-electric...

They don't work particularly well. You're roasting in the night when they heat up, nice and toasty at breakfast, but by the time you're back from work in the evening you're sat in the cold.

How can a heating system be inefficient? Does it generate too much waste heat?

Heating relies on a number of factors:

- Conversion of input energy to thermal energy. Fuel-based or electric resistance heating are both less efficient than heat pumps. The later can deliver several times the heat energy as is used to move it from elsewhere (outside air, the ground).

- Any emissive losses. The electric + brick heat systems seem to be similar to a masonry stove or similar design. If the bricks are on an interior wall, any heat leakage should be into the living space. If on an exterior wall, it's quite possible that much of the heat is radiated to the exterior. Even where placement is central, a wall may leak heat vertically and through the ceiling to the outside.

- Cost of fuels. The electric + brick design would seem to rely on cheaper off-peak electric rates. A more efficient system which more closely follows other electric loads (and hence, uses more high-cost electricity) could cost more whilst utilising fewer kWh of actual electrical energy, for example. Similarly, heat pumps with fallback to electric resistance heat might see similar high-cost patterns during extremely cold weather.

Not sure if this is what OP's talking about, but heat pumps are several times more efficient than traditional heating.

> How can a heating system be inefficient? Does it generate too much waste heat?

Yeah, they do:

1) Heat that's present when people aren't is unnecessary heat.

2) Heat that leaks out of the building is wasted heat.

So isolate the building better...? Yes, of course... But you can never isolate 100%. And heat that's present while people aren't -- see 1) above -- is heat that can (and, to some extent, will!) leak out before ever warming anyone.

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