P574 SAP External Walls

U-value calculation for an external wall was produced using Stroma U-value Calculator (version 0.92) and the BS EN ISO 6946 method, printed on 17/06/2019. The wall build-up totals 355 mm and includes internal surface resistance, 12.5 mm plasterboard, a 15 mm plaster dabs cavity, 100 mm Celcon Solar block, 75 mm Celotex CW4000 insulation, a 50 mm unventilated low-emissivity cavity, 102.5 mm outer brickwork, and external surface resistance. Limited bridging elements are included for the plaster dabs cavity, Celcon block, and brickwork with stated fractions. The overall thermal resistance is calculated with an average of 5.06 m²K/W (range 4.922 to 5.197). No U-value correction factors are applied. The resulting wall U-value is 0.198 W/m²K, rounded to 0.20 W/m²K.