Error! Reference source not found. shows the main dwelling types in Wales and the percentage of the total housing stock that each type occupies. It can be seen that the semi-detached house is by far the most common residential property type, accounting for 44% of the total housing stock, excluding year 2000 onwards properties. The data in bold type shows the building types modelled in this project. These models can be seen to represent around 50% of the total housing stock. A suitable Case Study of a pre-1919 terrace could not be found, but if we were to model this as well then 66% of the housing stock type would be covered.

No data for post-2000 dwellings

Rhodes et al [3] provides greater detail of the housing stock, including physical properties, improvements, etc., but it is clear that a large percentage of the housing stock was built before energy efficiency was a serious consideration.

From figure 1, taken from the Renewable Energy Route Map for Wales [1], we see that the domestic sector accounted for 23% of the total carbon emissions in Wales in 2003. The breakdown between electrical and thermal demand is not known.

For this paper the annual electrical demand for each of the dwellings is taken to be 3090 kWh [8].