I have recently moved into a property that needs refurbishment and insulation. It has late 60s - early 70s cavity walls.
I wanted to work out what the current U value is across the property and what EPS insulation in the cavity would do to improve it based on published thermal conductivity values. I have also added calculations for the loft space, using a base layer and top-up layer of insulation.
Walls Outer leaf value Brick 0.90 W/m.K Outer leaf thickness 102.50 mm Outer leaf R value 0.11 m²K/W Insulation value EPS 0.03 W/m.K Insulation thickness 100.00 mm Insulation R value 3.23 m²K/W Inner leaf value Block 0.20 W/m.K Inner leaf thickness 100.00 mm Inner leaf R value 0.50 m²K/W Total R value 3.84 m²K/W Total U value 0.26 W/m².K Loft Tiles value Tile 0.56 W/m.K Tiles thickness 20.00 mm Tiles R value 0.04 m²K/W Insulation value Bottom 0.04 W/m.K Insulation thickness 100.00 mm Insulation R value 2.27 m²K/W Insulation 2 value Top up 0.04 W/m.K Insulation 2 thickness 170.00 mm Insulation 2 R value 3.86 m²K/W Total R value 6.17 m²K/W Total U value 0.16 W/m².K Windows (stated in brochure) Total U value 1.40 W/m².K Sliding doors (stated in brochure) Total U value 1.60 W/m².K
Am I roughly along the right lines for my calculations? There are some pretty big tolerances based on the type of brick and some confusion around how to get a total U value for a combination of layers. I'd love to nail these values so I can show measurable improvement in the property's heat retention credentials.