Design factors for energy-efficient residential extensions

Additional factors which may be considered in the development of extensions to existing dwellings include: • Orientation and glazing: orientation and the amount of glazing will determine how much sunlight a property receives. In considering the rationale of solid to void in residential facades, it is important to achieve an optimal amount of glazing. A balance is required to permit sufficient daylight to the property and to maximise solar gain while minimising heat loss. While south facing windows are recommended, it is necessary to avoid an excessive amount of glazing to avoid overheating and the need for mechanical ventialation. Glazing on north facades should be kept to a minimum and a greater focus on high quality insulation. • Airtightness and insulation: it is important to achieve a reasonable level of airtightness (i.e. minimise air leakage) to ensure a property remains energy efficient and capable of providing comfortable living. Airtightness should be complimented with use of high quality insulation to maintain heat within the building, as well as appropriate ventilation to minimise the risk of condensation or mould