Post-works assessment

Owners’ feedback

Limited data was available on fuel consumption at the time of the study as the project had just been completed. The house is felt to be very comfortable with very little heating input up to October with the solar panel providing the majority of the domestic hot water demand.

Impact on BER rating/fuel bills

The extended and retrofitted building achieved an A3 building energy rating (and an energy value of 73kwh/m2/yr). The original house had a BER of G (505kWh/m2/yr). This is an energy value improvement of 85%. The project is illustrative of what can be achieved in a detached house with a large heat loss area.

Impact of works on architectural heritage

The works included the extension and reconstruction of the rear of the house, alteration of the original plan form, external insulation to the gable walls of the original house and internal lining of original walls. The works have had the following impacts on the heritage value of the house:

• The composition of the house, roof profile and internal plan form of the house (including the proportion of original rooms) have been significantly altered.
• The external appearance of the house has been radically altered to the rear. The appearance of the front of the house has also been modified by the addition of a set-back first floor level extension and external insulation to the gable of the existing house which are visible from street level.

While the house is not a protected structure, the works have been handled sensitively with the front façade, setting of the house and its relationship to the road and adjoining houses retained. The rear elevation forms a coherent entity with appropriate window to wall ratios and a much-improved relationship between the living spaces and the rear garden. The scale and massing of the overall house is appropriate to its context and site area.

This type of design brief is one that architects face with increasing regularity. There is an inevitability that higher modern energy performance targets and modern living space requirements will have an increasing impact on heritage buildings, particularly those that are not afforded protection status. A variety of concepts and approaches to retrofits and extensions are illustrated by this project that maintain the key characteristics of the house.