How should one maintain the temperature in the house??

tomstickland

1carminestocky wrote: »

Think about it.

I spend a lot of time thinking about a lot of things.
The accepted laws of thermodynamics show that heat flow from a building will be higher if it is kept at elevated temperatures compared with being allowed to cool down when empty.

Cardew

tomstickland wrote: »

I spend a lot of time thinking about a lot of things.
The accepted laws of thermodynamics show that heat flow from a building will be higher if it is kept at elevated temperatures compared with being allowed to cool down when empty.

Tom,
You are just playing The Troll's game by bothering to respond. He is only interested in winding people up - he contributes nothing.

red_flump

mech wrote: »

Housing varies quite considerably. The only way to eliminate such variables entirely would be to measure the consumption using each method in the same house for a whole heating season.

The Canadians have done this:

http://irc.nrc-cnrc.gc.ca/pubs/fulltext/nrcc48361/nrcc48361.pdf
http://www.cmhc-schl.gc.ca/odpub/pdf/63816.pdf

Two identical test houses built next to each other to the latest insulation standards.
One house thermostat set to 22C
The other they tried 22C day 18C 23:00-06:00 night setback
also 18C day 09:00-16:00 and night setback
and 16C day and night setback

Biggest savings found with the 16C night and day setback up to 21%

However with these highly insulated houses designed to cope with -20C nights the savings with an outdoor temperature above 4C was minimal. The R-2000 standard for house insulation is I think better than our current buiding regs.

Conclusion
The experiments showed that thermostat setback has significant
potential as an effective and inexpensive energy-saving method,
even in an energy-efficient house.

Red

Cardew

Red Flump,

Excellent - thanks.

The conclusion should be repeated every time this issue is raised; to at least demonstrate that the laws of thermodynamics are not broken.

It also shows that if our houses were built from scratch with the sort of insulation found in these Canadian houses, then in our climate, the constant or timed discussion would be almost academic.

1carminestocky

tomstickland wrote: »

I spend a lot of time thinking about a lot of things.
The accepted laws of thermodynamics show that heat flow from a building will be higher if it is kept at elevated temperatures compared with being allowed to cool down when empty.

That's in no way what I was getting at, Tom. What I was suggesting is the 'you don't leave your heating on when you are on holiday so that answers the question' is a flawed argument in the sense that there is absolutely no need to have your heating on because there is no need for warmth due to the occupants being elsewhere. When you are living in the property there obviously IS need for warmth so that's when this argument comes into its own, the best/cheapest way to keep your house warm when you are residing in it - do you have it timed or leave it on 24/7? A completely separate argument to when you require absolutely no heat.

We all know having absolutely no heating an at all will save you money.....

red_flump

Cardew wrote: »

It also shows that if our houses were built from scratch with the sort of insulation found in these Canadian houses, then in our climate, the constant or timed discussion would be almost academic.

In my Victorian mid-terrace with full loft insulation the living room will drop from 19C to 14-15C on a mild (above freezing) night (the bathroom with its three 9" non-cavity walls can drop to 10C). The new boiler on full (with a smart thermostat Honeywell CM927) will get the house back up to temp in 1.5 hours max (and the thermostat adjusts its start time to compensate)
If I set the thermostat low for an evening (ie not to come on at all) because I know I''l be out - after the heating has "caught up" the following morning, the gas used for the preceding 24 hours has been about 26-32 kWh compared to 48-60 kWh for both evening and follwing morning. On the last Tue where the thermostat was set for 9pm-10:30 rather than 6:30-10:30 the daily consumption was 35 kWh.

These readings are from Nov, with _my_ house (with a fast recovery time, but medium to high heat loss) I always save gas when the following happens:

When it is warmer.
When the heating is on for less hours.

(the last sub zero evening I think I used 77 kWh)


Red

Idiophreak

Cardew wrote: »

to at least demonstrate that the laws of thermodynamics are not broken.

I'm no expert, but all your jibbajabba about thermodynamics seems to be somewhat short-sighted/flawed to me...Sure, something that's hot loses more energy than something cold - but, equally, something that's hot takes less warming than something that's cold...So, if your house is well enough insulated and stores enough heat, it may well lose less energy through being "hotter" than the extra energy it'd take to warm it back up from cold...

The whole thing's going to depend on how long the heating's set for, what temperature, what your house is made of, how cold it is outside and a whole host of other factors. I really think it's just a case of individual experimentation to work out what's best for you...

As an example...think of a thermos flask. You make your coffee in the morning. Stick it in the flask. By the end of the day, it's only going to take a very little energy to heat it back up to original temperature (if you wanted to, probably wouldn't improve the taste of the coffee ). Now, replace that flask with a regular bottle - come the end of the day, the coffee will be cold and you'll have to reheat it completely from scratch, using much more energy. The two things behave completely differently, just as different houses behave differently. You can't say that thermodynamics have broken because the coffee stayed hot in the thermos...that's just bonkers.

Totality

powerRIP wrote: »

I leave my heating on low when I go away particularly if there is a chance of the pipes freezing. In fact, in the past, when I have rented property, a minimum temperature is specified in the terms and conditions for this very reason.

Yep that's in my tenancy agreement also.

Cardew

Idiophreak wrote: »

I'm no expert, but all your jibbajabba about thermodynamics seems to be somewhat short-sighted/flawed to me...Sure, something that's hot loses more energy than something cold - but, equally, something that's hot takes less warming than something that's cold...So, if your house is well enough insulated and stores enough heat, it may well lose less energy through being "hotter" than the extra energy it'd take to warm it back up from cold...

The whole thing's going to depend on how long the heating's set for, what temperature, what your house is made of, how cold it is outside and a whole host of other factors. I really think it's just a case of individual experimentation to work out what's best for you...

As an example...think of a thermos flask. You make your coffee in the morning. Stick it in the flask. By the end of the day, it's only going to take a very little energy to heat it back up to original temperature (if you wanted to, probably wouldn't improve the taste of the coffee ). Now, replace that flask with a regular bottle - come the end of the day, the coffee will be cold and you'll have to reheat it completely from scratch, using much more energy. The two things behave completely differently, just as different houses behave differently. You can't say that thermodynamics have broken because the coffee stayed hot in the thermos...that's just bonkers.

Idiophreak,
So are you contending that the Energy Saving Trust input see below is 'jibbajabba'?(which I assume means wrong?)

Question
Is it more economical to leave my heating on 24hrs in the winter?

Answer
No. It is a common misconception that it is cheaper to leave your hot water and heating on all the time. Boilers use more power initially to heat water from cold, however the cost of this is greatly exceeded by the cost of keeping the boiler running all of the time.

The best solution is to programme your heating system so that it comes on when you need it most (possibly early morning and in the evening), and goes off when you don't need it (when you are out of the house or asleep). There are a range of controls that can be used and your heating engineer will be able to provide you with the most appropriate solution.

Depending on your circumstances it may be necessary to keep the heating on all day during winter but it will cost more than if you turn the heating off when you don't need it.

Of course the factors you speak of above (what your house is made of, how cold it is outside and a whole host of other factors) are important. Again as stated above all these factors will affect the rate at which the property loses heat.

However the important point is they don't affect the principle.

Your analogy with a thermos and a bottle is flawed.(I hesitate to say bonkers;) )

To compare heating a thermos with a bottle is, in the context of this thread, like comparing heating a well insulated house(the thermos) with a heating a tent(the bottle).

To make the analogy have any relevance you would need to compare the energy used to keep the water in the thermos at a the same constant temperature(option 1) against the energy used to bring it back up to temperature after a period of time(option 2).

The same with the bottle, you would need to compare the energy used to keep the water in the bottle at a the same constant temperature(option 1) against the energy used to bring it back up to temperature after a period of time.(option 2)

In both cases option 2 will use less energy than option 1.

Take the figures given by red flump in post #28.

His 19C living room temperature drops 4C or 5C over night; his less well insulated bathroom drops 9C.

There surely can be no question that should he wish to maintain both rooms at a constant 19C it would take more energy.

To quantify how much additional energy it will take to keep a house at a constant temperature will depend on the factors you mention in your post, but it will always take more energy.

lilac_lady

My central heating is old and has to be worked manually. I switch it on and off a lot and find that I have lower gas bills than my friends who have more modern timed systems. If I get a new system I'll keep switching it on and off with the timer.