Assessments: Main House

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.

  • Cellulose (blown/sprayed): 0.040 W/m.K
  • Timber battens: 0.16 W/m.K
  • Combined U-value 30mm x 30mm timber battens at 400mm spacing with cellulose insulation: 1.63 W/K.m2.
  • 10mm Plaster board: 0.17 W/m.K, U-value: 17 W/K.m2
  • Combined U-value of all components: 0.73 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.

• No uplift factor taken into account in radiator & heat pump sizing.

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.