U-values (W/m2/K)
Walls 0.45-0.60.12
   solid masonry wall2.4  
   outer wall: 9 inch solid brick2.2  
   11 inch brick-block cavity wall, unfilled1.0  
   11 inch brick-block cavity wall, insulated0.6  
Floors 0.450.14
   suspended timber floor0.7  
   solid concrete floor0.8  
Roofs 0.250.12
   flat roof with 25 mm insulation0.9  
   pitched roof with 100 mm insulation0.3  
Windows  1.5
   double-glazed, 20 mm gap1.7  

outside of the building


Energy loss and temperature demand (degree-days)

Since energy is power × time, you can write the energy lost by conduction
through an area in a short duration as

energy loss = area × U × (ΔT × duration),

and the energy lost by ventilation as

13 NV × (ΔT × duration).

Both these energy losses have the form

Something × (ΔT × duration),

Table E.2. U-values of walls, floors, roofs, and windows.