Intuitively, a stricter U-value requirement translates into a thicker layer of insulation and therefore a thicker wall. The cost for thicker insulation is threefold: the cost of additional material, cost of additional installation time onsite and the hidden cost of floorspace taken up by the additional insulation. A thicker insulation build-up reduces the amount of floorspace within the building's footprint. This, in turn, directly affects the property's value. The raw material cost of advanced insulation materials is higher than that of traditional insulation materials: both when we consider £/m3 and price / U-value. However, this case study shows that the additional cost is greatly outweighed by the value of Net Internal Area that is added to the floorplan by using more efficient insulation and thus, a thinner wall buildup. 13