To think keeping thermostat at 20 will cost the same as keeping it at 17?

[Cigent]

I know it's said that turning the heating down a few degrees will save money, but how?

If I'm, say, October I set the heating to 20 degrees and leave it like that, and if it falls to 19 degrees it automatically kicks in until the house is up to 20 then switches off, how would that cost any more than keeping it at 17 and it kicking in when it dropped to 16 to heat the house one degree? In both cases it's only kicking in to heat the house by one degree, so how does keeping it lower cost less money?

I understand that if I turn it on when the house is at, say 15 degrees, then it would cost more to get to 20 than 17, but once it's there surely it would be the same to keep it there?

I am now beginning to understand why the whole "insulate your homes" bonanza of financial incentives hasn't really taken off. Fucking hell, this thread is eye opening.

It is worrying how difficult some people find it to grasp. There are a few reasons but surely at least the first 2 of these are common sense

1. the temperature varies each month. You can look up monthly averages but generally if you set your thermostat at 20 all day the heating will come on much earlier in the calendar year than one set at 16

2. obviously it varies during the day also so a thermostat set at 20 will activate the heating earlier at night.

3. It takes time to raise the temperature of the building and all the material in it like bricks etc so it takes more energy to heat to higher temperatures.

4. as many posters have said heat loss increases as the difference between the outside temperatures and inside temperature does so maintaining higher temperature indoors takes more energy

5)as many pp have said insulation reduces the rate of this loss but it can never be completely prevented.

@Cigent do you need to get your bills down? As well as reducing by a degree, you can have it on less often.

At the moment your boiler is running all the time, which uses gas.
If you use the timer on the thermostat, you can run it for a couple of hours a day to heat up water. It will stay hot in the tank.

When you need the heating as well, you can run that for a few hours morning and evening. Most people don't need it at night as they are in bed.

Using it less often will save even more than turning it down a notch. It will be cooler, obviously, but if you are going out or home but active there's no need to heat the house.

Not true

If you are keeping the house at 20 all the time you are constantly adding heat to make up for the heat loss all the time

Say you lose ten units of heat per hour at 20 then you burn 10*24 units of energy every 24 to stay stable

If you say turn it off for 12 hrs at night you lose heat until you reach the outside temperatures and then you stop losing heat. You might lose 40 units if heat - so to reheat would be 40 units not 10*12 = 120 units.

Because heat loss depends on the difference between outside

And inside temperature, If you lose 10 units of heat per hour at 20 you might might only lose 2 unit of heat per hour at 15

Mimimise your energy cost by turning the thermostat down and only using heating when you need it - morning and evening if you are out at work

In both cases turning on half an hour before you need it - so it's nice when you get up - and turning it off an hour before you leave ( and 2+ before bedtime ) in a well insulated home - because you should not notice it getting colder in that time.

The only time keeping a stead temperature helps is if you tend to overheat - blast the heat out - and then turn it off - so you oscillate around an average of 20

Houses must be really badly insulated in the uk.

Here winter temp is anywhere between 0 and -25. Even at -20, our heating goes off at 8pm and on again at 6am. If it’s 21 degrees at 8pm, it only drops to 18/19 by 6am. With no heating on for 10 hours.

Our heating is set to constant 6am-8pm, but when you look at actual times you will see it’s only on for 4/5 hours of that as it clicks of when it reaches set temperature and only back on when below that.

It was though, that's the point.

The fact that people can't work out the "science" of why it costs more to heat a room to 20C rather than 17C.

Jesus Christ.

Whereabouts are you? Yes, it’s very likely your houses are insulated better than those in the UK - they’d have to be, with that temperature differential.

As you can see from the conversation here, the difference between outside and inside temperature is a lot smaller here, overall, so insulation (particularly in much older houses) hasn’t been as efficient, as it wasn’t seen as necessary cost wise. Now, obviously, it is - and of course, people have been saying for years that it’s better for the planet if we insulate more and waste less heating energy. Things are improving but they’re clearly in a different place to houses built to withstand outside temperatures of -25.

Your overnight temperature drop isn’t too different to ours - it probably drops about 3-4 degrees overnight in the winter. And when people are saying they have it on “all day” with a thermostat, it’s not going to be actually on all day - just kicking in when needed. Ours probably varies between 1-3 hours of total heating time in winter months.

@Talipesmum - alps. we have +35 temps in the summer also. So actually about 50 degree difference between summer and winter.

Growing up in uk, our house was always freezing. But we didn’t have central heating, just crappy gas fire ( it’s still the same at my parents)

Yes, I do the same with a pan of water. Keep it near-boiling at 95•C all day, then when I want a cuppa just turn the flame up briefly and I have boiling water in seconds, for only a tiny bit of energy. Great trick to save energy and money.

Made me laugh, brilliant!

There have been loads of really clear, scientific explanations on this thread. But I don't understand why the "is it cheaper to leave my heating on all the time?" threads don't get the same response. Because the science is exactly the same.

I'm not turning my thermostat down. I'd rather be cosy and have toast for dinner than be freezing with a steak.

I'd give up a lot of things before I start side eyeing the thermostat, tbf, but I don't think steak is a menu option for those concerned about heating v. eating Hungrycaterpillarsmummy.

People don't always see those threads of have the time

You know what I mean..

Sorry, I did know what you meant. It was a pissy way to write it - I've clearly been here too long.

@midgetastic thank you for the explanation. It makes sense

Because the relevant delta is that between the inside temperature and the outside temperature. 20 vs 19 compared inside when the outside temperature of 10 will use more energy than 18 to 17 for the same outside temperature, for the same building, unless the building is perfectly insulated.

You can reduce heat loss but almost never eliminate it. There's no need to be snarky.

My comment was about insulating houses - in respect of the OP's discussion about heat loss and house temperature.

Because UK houses are poorly insulated and we need to do something about it.

But thank you for explaining that you can reduce heat loss but can never eliminate it.

Has anyone mentioned heating degree days yet? You may find this article interesting and informative

buildpass.co.uk/blog/what-are-degree-days-and-how-do-we-use-them/

Not a rigid date at all as sometimes the heating didn't come on until mid November if it wasn't needed.

Many people of my generation didn't have heating, depending on an Aga or Raeburn and/or log fires. Our children got used to living at a lower temperature, were rarely ill with colds, sore throats etc unlike their peers in stuffy overheated homes.

I'm perplexed as to why parents these days dress their children in inappropriate clothing for the season then complain their heating bills are too high. How many school children over 5 even own a vest these days? It's also very hard to find decent winter jumpers/ cardigans etc - is it a given by clothing manufacturers that these items are no longer needed because of such highly heated homes?

What we saved by being frugal throughout the year (not only with regards heating but home cooked meals, batch baking etc) allowed us to save enough to give the children a week's holiday abroad pre Christmas, soaking up the sun in a warmer climate.

That's interesting @Svalberg, thanks for the degree days link. That looks like a useful concept for tracking your gas consumption when the weather and temps are so variable in any given month.

I think you're getting hung up on how often it switches on.

Ignore that.

Heating your house to 20 degrees takes more energy than heating it to 17 degrees because it's a bigger difference between inside and outside.

Hello anyone reading,

It's very cold at the moment. Our living room loses a lot of heat, but during the day I have the thermostat set to 17 degrees. It's cold but I'm trying to save monies. However the heating still kicks in consistently during the day to even keep it at that. I put it to 20.5 usually around 4pm until about 11pm as I need a bit of cosiness during the evening.
As a result our heating is on for roughly 9 hours a day during these freezing days, how long is yours on for?

P.s we have a nest smart heating system.