Energy renovation of an old single-family house

After having identified a large potential for profitable energy renovation of the existing building stock, a demonstration project was carried out in practice. This paper deals with the methods and results from the demonstration project concerning a 161 m² poorly insulated single-family house built in 1927 in DK.

Since the project has been carried out and the documentation thus established in only six months from September 2004 to January 2005, an extrapolation method for the measurement results has been used. Both before and after the energy renovation, detailed monitoring of the indoor environment in terms of room temperatures, air change rates, and relative humidity has been carried out together with monitoring of air leakage and energy consumption.

In addition to the measured energy consumption and savings, theoretical predictions have been made by use of building simulation modelling. The energy saving improvements carried out in the project are “easy to carry out” and cost-beneficial measures such as cavity wall insulation, loft insulation, insulation of walls under windows and a new second window-frame with energy-saving glass.

The work was carried out by professional contractors at a total cost of DKK 157,000. The project has shown that the energy renovation has reduced the gross energy consumption with around 50% from 53,400 to 28,100 kWh per year. This corresponds to a reduction of around 2,500 litre of fuel oil per year or 16,000 DKK per year (assuming a conservative energy price).

If a conservative way of financing the building work of 157,000 DKK is assumed, the first year’s cost equals DKK 8,500 and the house owner will gain a net saving the first year of DKK 7,500.