Quote Originally Posted by m_c View Post
Irving, where did you get the info for calculating heat loss/heating requirements?
Ummm, one of the civil engineering websites... IHeat Loss through Building Elements due to Transmission

but when I googled I also came up with this: Heat Loss Through Enclosure Walls Equations and Calculations - Engineers Edge which I've not tried to see if it gives the same answer.

Also I found stuff on the concrete supply industry website..

I was doing the calcs for my own proposed workshop and 75mm on the walls, 100mm in the roof and a DPC in the floor are almost essential... I reckon my 6m x 4m build (no up n over door and double glazed, with uPVC personnel door) will require only 600 - 800W to maintain temperature. Given I only have a 32A breaker on a 20A feed I don't want to be using 12A for a 3kw heater.. i want to be able to power everything with some margin. I also plan remote heating control so I can maintain a background temperature in there to ward off condensation and remotely bring it up to working temp fairly quickly