Energy myth-busting: Is it cheaper to have heating on all day?

grahamc2003

wantanswers wrote: »

@richard 019,



"which approach is the most energy-efficient for you."

Thermodynamic Laws taken into consideration of course!

That's a contradiction though.

Thermodynamics says the warmer a body, the more heat it loses, which is all you need to know.

It follows very simply that that the subject of this thread is a myth.

The thermal mass of the house has nothing to do with the fact that a body loses more heat the warmer it is. It applies if you have the house with the largest thermal mass or the smallest thermal mass.

You keep saying you don't have to violate thermodynamic laws to make constant heating cheaper than on and off, but I'm afraid you do. Just because you don't realise that doesn't mean it doesn't apply.

zebb

terry2 wrote: »

. Note that the thermal mass is so big that it can take about 48hrs for the walls to actually reach that steady state.

This has rung a bell. We leave the heating on minimal when away but when we return after a week, it often does seem to take a day or two to truely warm up the house. Our external walls are thick concrete (upto 1m in height) and do indeed take a while to warm up. Might well be a convert now to see if leaving heating on for longer on a daily basis might not actually cost as much extra as I thought. Thanks for this. As it seems we have a long cold spell ahead, this should give a relatively constant environment in which to experiment!

Sir_Alan

terry2 wrote: »

cold walls (which are effectively acting as radiators of cold

Surely not? You cannot "radiate cold". I think I know what you meant, though.

My new combi boiler (Viessmann) was supplied with a dual thermostat timer, with recommended settings of 20° (peak) and 16° (off-peak): clearly the maker's intention is to have the system operational 24/7. I actually keep it 1° below these settings, with peak hours 0730-0915 and 1745-2200, and my (poorly-insulated) Victorian house keeps comfortably warm - I am at home most of the day. So far the gas usage seems reasonable, although I have not monitored it closely.

The previous boiler, an ancient Thorn, had no room or radiator thermostats when I bought the place yonks ago. I had radiator 'stats installed, which brought the heating bills down with a bump.

Some of the arguments in this thread ("Yes, it is!" "No, it isn't!" "Yah, boo, sucks to you!") rather remind me of John Wyndham writing in The Day of the Triffids: “It was odd, I felt, how many people seemed to have positive, if conflicting, information upon God's views.”

wantanswers

grahamc2003 wrote: »

Just because you don't realise that doesn't mean it doesn't apply.

What I realise grahamc2003 is that I can play around with my system until the cows come home and try and get the best/most efficient from it as as best i can.

Do I want to keep on doing that? probably not, I would much prefer an installed intelligent system that will do it for me.....but then I've got the missus...she beats the lot!

terry2

grahamc2003 wrote: »

That's a contradiction though.

Thermodynamics says the warmer a body, the more heat it loses, which is all you need to know.

exactly - my house with a lower thermostat setting loses less heat than a warmer one.

The thermal mass of the house has nothing to do with the fact that a body loses more heat the warmer it is. It applies if you have the house with the largest thermal mass or the smallest thermal mass.

you are missing the point - the thermal mass is about where most of the heat goes each time you have to warm the house from cold.

You keep saying you don't have to violate thermodynamic laws to make constant heating cheaper than on and off, but I'm afraid you do. Just because you don't realise that doesn't mean it doesn't apply.

YOU are still missing the point. Thermodynamics is about what happens for real, and not what you would like to believe. Constant heating at a lower temperature IS cheaper for me.
If you want to prove I am wrong then do the measurements on your own property and post the results here.

As with all real physics, measurement trumps theory.

wantanswers

"you are missing the point - the thermal mass is about where most of the heat goes each time you have to warm the house from cold."

In my case with normal switching off times i'm experiencing long warm up times next morning, especially in these cold nights/days. Experimenting over the last couple of nights by leaving the heating on at a lower setting appears to be saving for me and of course its more comfortable!

rgn007_2

I'm sorry, but I disagree on turning your heating off is cheaper.

The reason is based on around 15 years of logging my energy consumption using Excel. I moved in from a house with no central heating and found I could keep warm if I left the core heat at 15 degrees at night but just increasing during the day if I noticed the cold. It was an older system so I had to remember to manually turn down again when I went to bed. I was a mum at home, doing an Open University degree that included science, environment, health etc and also ran a small business with my husband.

I audited therms used in the gas usage over several winters and not only did I find myself freezing cold if I turned off the heating at night, but the core temperature, if left comfortably cool at 15 degrees, also meant I felt less need to keep turning the thermostat up to compensate.

The above clearly showed I used less therms consistently if I never switched off my heating so I ended up leaving it on all year at 15 degrees and it became a familiar sound each autumn when the boiler would burst into life of it's own accord.

I found that on the trial periods I would turn off the heating, we were far more tempted to compensate by turning up to 22 degrees to get the warmth back in as all the furniture and walls were also chilled through and I can only assume absorbed some of the heat from the human inhabitants shivering and waiting for the home to warm up.

I think the Energy agency have not considered everything in their "research" as my home experiments clearly showed I use less energy overall if I never turn off my heating but leave it at a low core heat of 12 to 15 degrees when the house is well insulated.

My boiler is often not in use even though it is never switched off and my annual gas consumption in a 3 bed semi is £42.

grahamc2003

I wonder if there's a similar conversation as this going on in Germany, India, China or Japan? I very much doubt it.

No wonder the UK is falling further and further down the country list of wealth per head.

This is the most depressing thread ever. The ignorance of even the most basic aspects of science is absolutely astounding.

oldskoo1

grahamc2003 wrote: »

I wonder if there's a similar conversation as this going on in Germany, India, China or Japan? I very much doubt it.

No wonder the UK is falling further and further down the country list of wealth per head.

This is the most depressing thread ever. The ignorance of even the most basic aspects of science is absolutely astounding.

I think these threads are the result of people feeling the squeeze with high utility prices, trying to do anything to stay warm for less.

I dont think these questions are asked much across europe, people dont usually rely on mains gas. A lot of people chop, buy and burn wood or even have ground heating.

Some people might not realise but gas prices are a lot more expensive in countries like Sweden where -20c is common right now, day in day out. They have no choice but to run heating 24/7, even with electric boilers.

People may well save running it at 15c 24/7 but comparing this to timed at 21c - it's comparing apples with oranges.

People also need to know how to test correctly.

wantanswers

grahamc2003 wrote: »

This is the most depressing thread ever. The ignorance of even the most basic aspects of science is absolutely astounding.

So can I assume graham uswitch are ignorant as well? even though they suggest experimenting to see what is best for you ie

Post at 5.52pm


"which approach is the most energy-efficient for you."