Calculating optimum room temp

toolmaker28

I have been gathering useful information here for a few months and have a question for those on here who I follow for their words of wisdom, I wont name any names because for fear of embarrassment but followers of this section of the forum will know who I mean.

I have searched the forum but cant find the info which I know has been posted on here, what I am looking for is to find the most economical temperature to heat a room. In case my question is not very clear hopefully I can explain better, if its 0 degrees outside and with no heating on inside its 9 degrees, and I heat the room to 15 degrees, how would I find the optimum temp for the room. If I try to get it up to 22 degrees and hold it there, what becomes my optimum temp before I am just wasting energy to get it to a temp where the heat I am putting into the room is just escaping through the walls.
We moved into the property 3 years ago, it needed alot of work, we had it double glazed (windows wood and falling out) unfortunately its solid brick so no cavity wall, I put up polystyrene wallpaper as backing before the main wallpaper on the outside walls for some insulation but cant afford the central heating yet and we are using oil filled and convector heaters for heating. As electricity is expensive I dont want to have it escaping through the walls.

Hope I have made my question clear I am sure I saw some formula on here or a test I can carry out to find the best temp for each room.

jd87

For every degree warmer you have it inside relative to outside, you will always need to put more and more heat in to keep the temperature at that level. There is no "optimum" temperature as such. The warmer you make it, the greater the "temperature gradient" between inside and outside, and the quicker heat is lost.

The temperature at which there is a minimum loss of heat to outside, is the outside air temperature.

Cardew

There is no 'best temperature'.


If it is zero(0C) outside the cheapest temperature at which to maintain a room is zero(0C)

All heat from a room escapes through walls, ceiling, floor, windows and door. Every degree you raise the temperature of the room will cost more money. However the higher the temperature of the room the greater amount of energy(heat) is required to raise the room by, say, 1C. i.e. It takes far more energy to raise the temperature of a room from, say, 22C to 23C than it will to raise from 12C to 13C. This is because the higher the differential between two bodies(i.e. outside and inside) then the higher the rate of heat transfer - which in this case is heat loss. Or to put it another way the heat escapes faster.

I think the formula you have seen is to calculate the amount of heating required to heat a room to a specific temperature. If you want to heat a room to 21C with outside temperature at 0C you need to know size, standard of insulation etc and you can calculate that it requires x.x kW.

jd87

That's what I said. :P

grahamc2003

toolmaker28 wrote: »

I have been gathering useful information here for a few months and have a question for those on here who I follow for their words of wisdom, I wont name any names because for fear of embarrassment but followers of this section of the forum will know who I mean.

I have searched the forum but cant find the info which I know has been posted on here, what I am looking for is to find the most economical temperature to heat a room. In case my question is not very clear hopefully I can explain better, if its 0 degrees outside and with no heating on inside its 9 degrees, and I heat the room to 15 degrees, how would I find the optimum temp for the room. If I try to get it up to 22 degrees and hold it there, what becomes my optimum temp before I am just wasting energy to get it to a temp where the heat I am putting into the room is just escaping through the walls.
We moved into the property 3 years ago, it needed alot of work, we had it double glazed (windows wood and falling out) unfortunately its solid brick so no cavity wall, I put up polystyrene wallpaper as backing before the main wallpaper on the outside walls for some insulation but cant afford the central heating yet and we are using oil filled and convector heaters for heating. As electricity is expensive I dont want to have it escaping through the walls.

Hope I have made my question clear I am sure I saw some formula on here or a test I can carry out to find the best temp for each room.

The cheapest temperature is the outside temperature, which costs you nowt.

The optimum temperature (i.e. the lowest cost realistic temperature) is the lowest temperature you can tolerate, and that is irrespective of outside temperature. It's just that to maintain the optimum temperature under that definition means it costs more the lower the outside temp.

It'll be one hell of a lot cheaper if you can make the lowest temperature you can tolerate around 19C rather than the 24C which is the minimum some people claim.

DVardysShadow

toolmaker28 wrote: »

If I try to get it up to 22 degrees and hold it there, what becomes my optimum temp before I am just wasting energy to get it to a temp where the heat I am putting into the room is just escaping through the walls.

Once you reach a steady temperature, ALL the heat you put in goes through the walls. This is an inevitable consequence of Physics. The trick is to manage the heat input to get the temperature you want.

toolmaker28

Thanks for all the replies I understand it better now, I am comfortable at
17 degrees and it seems that when its freezing outside the temp of the unheated rooms is usually about 7-8 degrees so I am only looking at getting it up by 10 degree which I can easily do with a convector heater.
as that uses less electric than the oil filled because they take longer to heat up the room.

Cardew

toolmaker28 wrote: »

Thanks for all the replies I understand it better now, I am comfortable at
17 degrees and it seems that when its freezing outside the temp of the unheated rooms is usually about 7-8 degrees so I am only looking at getting it up by 10 degree which I can easily do with a convector heater.
as that uses less electric than the oil filled because they take longer to heat up the room.

Sorry, but I am afraid you have that completely wrong again.

Your convector heater won't use any less energy(electricity) than an oil filled radiator for the same running cost.

All electrical heaters produce EXACTLY the same amount of heat as each other for the same running cost.

So a convector heater of any power(kW rating) will use a certain amount of electricity(kWh or units) to maintain the room at 17C.

An Oil filled radiator of any power(kW rating) will use exactly the same amount of electricity(kWh or units) to maintain the room at 17C. So the cost for using both will be the same.

jd87

OP, it doesn't matter how you get the heat into the room (it doesn't matter what type of heater you use, or how quickly you heat the room up), all that matters is how much heat (technically how much energy) you have to put in. So the only thing that matters is the target temperature and insulation.

toolmaker28

But I have one of these plugin monitors and if i have the convector heater on for an hour, then try the oil filled on for an hour the convector heats quicker and my hours electric is less for the convector so is that not saving me money by using the convector for an hour.