SIP thickness for year round garden office

[Jamie McNaught]

Love the forum... cannot believe how helpful and friendly everyone is!

 

Quick question (hopefully) for a year round garden office that i am building in Cambridgeshire.

 

Quick specs... approx 5m x 3.5m, 4.8m bifolds and 2m x 1m sky light.

 

Planning on 100mm SIP's for walls, 150mm for roof and 100m celotex for floor.... with maybe (still trying to clear my conscious) a 12000 btu aircon unit for heating and cooling.

 

Any ideas if this will be warm enough through an east anglian winter or do i need to beef up the sips?

[Nickfromwales]

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Edited October 9, 2020 by Nickfromwales
Moved post

[AliG]

Around a quarter of the outside of the building will be the bifolds (excluding the floor which will lose a lot less heat if it is on the ground).

 

Assuming a U-value of 1.2 for these versus 0.25ish for the walls and 0.2ish for the roof, you will lose almost as much heat through the doors as through the rest of the room put together.

 

So if you want to make it easier to heat I would make the bifolds smaller, or better insulated.  Changing the wall U-value would make negligible difference to the amount of heat required. Even when considering the bifolds, as it is just one room, spending a lot of money to reduce the cost of heating would not pay for itself. For example improve the U-value of the walls to 0.2 would save around £5 a year, I am assuming you don't even heat the room half the time.

 

However 12000 BTU is enough to heat an entire house, it would be multiple times what is needed to heat this space so you can certainly keep it warm enough.