HawthornHaus is a PassiveHouse retrofit-renovation of an 1890 timber cottage, with a poor 1980’s extension, in a heritage overlay area. The project aim was to create an attractive, healthy, sustainable, energy efficient and resilient all electric home fit for the 21st century.
More than 25 tonnes of carbon has been saved by recycling construction materials and minimising waste, as well as minimising cost. Use of low embodied energy, low V.O.C. materials and timber has been maximised throughout, while steel has been eliminated and only a minimal amount of “green concrete” was used, to minimise the embodied carbon footprint.
Timber/alu windows are triple glazed with openable clerestory windows for night purging. Living areas are designed to capture winter sun and exclude summer sun. Natural light has been maximised and all rooms have access to nature. A mature Silver Birch has been saved to shade the west elevation and an existing green wall on the north boundary has been salvaged to enhance the views from the north facing windows.
The highly insulated, airtight thermal envelope and heat recovery mechanical ventilation [HRV] system ensure that the temperatures remain comfortable and the internal air quality is great. The HRV system provides constant filtered fresh air.
Compared with the original house, the annual energy costs have been reduced by over $3,000. A battery has recently been added to the 6.6kW solar array, which will make the home close to net zero.
