Calculation notes:
U-value stone walls: The external walls are ~0.65m thick stone walls with 30mm of cellulose fibre insulation on the majority of walls appart from the larder, porch and landing. Assuming a thermal conductivity of 0.935 W/m.K for the stone wall part, 0.65m gives a U-value of 1.44 W/K.m2.
North West ground floor wall calculation does not take into account that the house is built into the bank.
Complicated range cooker inset in North West ground floor is ignored in calculation.
The kitchen, porch and larder have solid tiled floors. The Livingroom has a carpet on a concrete slab. Using the Carbon Coop Open Floor U-value Calculator with: slab on ground, area:37.9, perimiter:24.82, ground:clay or silt, thickness of external walls:0.65, insulation:none. Results in a U-value of 0.680 W/K.m2.
The rooves are insulated with ~200mm of rockwool between timber battons, there are two layers of battons perpendicular to each other reducing thermal bridging. The thermal conductivity of rockwool is 0.044 W/mK and so the U-value at 200mm would be 0.22 W/K.m2.
Calculation assumes secondary glazing U-values of 2.8 W/K.m2, 1.6 W/K.m2 for the double glazed front door and 3.2 W/K.m2 for the back door.
Heat loss calculation:
Room by room heat loss calculation is based on the MCS Heat Pump Calculator that implements the EN12831 heat loss calculation standard.