Part of that involved a design approach that would not change the existing building, but rather see the addition of a new envelope within the building. This structure used insulated walls, double-glazed windows and air-tight membranes to enhance the natural thermal responsiveness of the home.
Indeed, while this is Australia, winters in Melbourne can get exceptionally chilly (by Aussie standards). Despite the often gray and cold winters, homes in the city are often designed with balmy climates in mind.
“Achieving air tightness and thermal improvements can be challenging on a retrofit, but we built a second structural wall and new skin inside the existing brick walls, giving us the opportunity to create a continuous, well-insulated envelope without thermal bridges. Adding new high-efficiency timber double-glazed units and air-tightness membranes throughout has had a big impact on thermal comfort,” Sewall added.
All the windows are double-glazed, and the insulation throughout means the envelope is airtight. In terms of air flow and ventilation, the walls were fitted with a HRV system (Heat Recovery Ventilation system) which featuresan in-line fan and ceramic honeycomb structure). This is a trickle ventilation system which allows the building to maintain good air quality by exhausting CO2, while also retaining internal temperature. This, in conjunction with excellent air tightness and insulation, works to eliminate the need for additional air conditioning and heating. “There is now no mechanical heating or cooling in this house, because the thermal envelope and HRV keep the building comfortable without the need for it” Sewall said. In the kitchen, living and dining areas, windows are operable not expressly for the purpose of cross-ventilation, but to provide access to pockets of garden.