how do i calculate the energy required to heat a room

[traclenin]

Is there a calculation i can use to work out the cost of energy needed to heat a room to a comfortable room temperature for 8 hours /day please.Obviously it would depend on the number of cubic metres being heated and the cost of energy so Im looking for a energy unit/cubic metre/degree centigrade I think .Can you help,thanks in advance.

[Vagrant]

Depends what the room's made of, how many outside walls, window area, type of glass in windows, insulation in floors, ceilings, etc etc ... Try googling for central heating / radiator calculators

[rov1200]

The cost really depends on the heat loss. If in 1 hour your room temperature goes from 20oC to 15oC without any boiler input then you need to calculate what it costs to reheat that room to its former level. As an analogy to heat a 3Kw kettle should take 4 minutes. Electricity is charged per kw/hour. Your CH boiler is also rated. Therefore based on this rating and the time it takes you could find how long to reheat the room.
The boiler manufacturer always quotes the BTU's whether its 40 or 60 btu's/hour.

Simply said if the boiler is on for 1 hour to reheat from 15 to 20oC then the amount fuel used can easily be calculated and this will give the cost. If this cycle is repeated for 8 hours then the calculation will be x8.