How to work out BTUs with a vaulted ceiling

[kevyt]

Hi
I have put an extension onto the rear of my bungalow , and now when you enter from the front I have vaulted the ceiling to the ridge line of the roof.2 velux windows for light. Insulated with Tri Iso Super. I now cant find any way to calculate the BTUs. DO i work out the requirement for the standard room and then add the vallted area as another "room "and add them together?

Any assistance thankfully received

K

 

[Phill Peck]

Work it out at the ceiling height of the highest point?

Or you could work it at the highest and lowest the deduct 50% of the difference

If it's well insulated working it out as standard should be fine

 

[TCCHeating]

Time to dust off the old pythagoras. The volume of the roof space is (1/2 x base x height x length). Then just add it onto the room volume

 

[ChrisR]

Be generous especially for the Velux windows. The air up there is the warmest in the room so the heat loss is proportionately greater.
Even if that's not the reason, ceiings like that always seem to need more than the numbers say.