Energy Modeling:- The energy modeling of the house on certified software ensures that the thermal performance of the structure in conjunction with its orientation and the nature of it openings is such that it complies with the energy efficiency requirements of the National Building Regulations, SANS 10400 part XA. The actual building is modeled and compared to a reference building “on the basis of annual energy consumption and maximum energy demand. This comparison is made on the basis of the energy required to maintain a set temperature range in both the actual and the reference buildings. In order to facilitate this comparison, both buildings are simulated as being air-conditioned spaces, with a controlled temperature range of 19-25°C. If the energy intensity (annual energy consumption per square meter) values for the actual building are below those of the reference building, the building is deemed to be compliant.”
The electrical load on the house is reduced with the use of gas cooking, a heat pump to augment the hot water supply, biomass ducted heating, extensive natural lighting with low energy LED lighting throughout the house. The main electrical distribution board is also wired to be Solar PV ready. Once the house’s annual consumption is assessed phase 2 is to retro fit a solar photovoltaic panel array on the garage roof with the inverter and battery storage in the garage. The new concrete roof has rigid foam insulation between the slab and screed, the pop-up roof and all dry walls have fibrous roof insulation and all external brick walls have a cavity. Together with the optimal solar orientation for this site, roof overhangs and the additional fixed screens and shutters the house has an energy intensity of 71,42 (KWh/m2) which is just lower than the reference model. This energy efficient performance was also achieved using single glazing and aluminium frames, which indicates some that good early planning and considered design can generate a simple but smart green home.
Words & photos – Stuart Thompson & Matt Pretorius