Annual Space Heating Demand

Hi I’ve using your Heatlossjs tool. ( excellent by the way, the ease with which I can go back & tweek things is really useful, & try different values) . One question , the Annual Space Heating Demand seems to be the same when using room set points of 21c or 17c (even if I turn down the rooms to 10C) ?

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Hello @BrianW and welcome!

Yes the annual heat demand is based on a simple degree days calculation. There’s more on degree days and how to calculate an accurate value for your location and indoor temperatures here:

I used this approach in heatlossjs as it is the approach used by the MCS heat loss spreadsheet that it’s based on. Ideally an integrated calculation that took into account the room set points would be better, similar perhaps to how SAPjs does it

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