While producing a stylish dwelling and passing the stringent levels for certification made this one of Joe’s more challenging builds to date – another aspect that ‘posed a few issues’ was building to BAL-FZ, since the five-acre subdivision site backed onto a steep gully and was deemed to be a flame zone (the highest BAL regulation).
Some of the materials used to ensure the home was adequately equipped with the right bushfire defences included: a Colorbond corrugated roof in Custom Orb; UPVC aluminum-clad triple-glazed windows and doors (imported from Germany); structural steel (as required for bracing); external cladding in fire-rated Inex Board; plywood and external shutters to BAL-FZ.
Besides these considerations, Joe says that when building a Passive House ‘there are no assumptions, everything is quantified and calculated on the whole lot’.
‘[Sapphire] is a very technical house,’ he says. ‘We worked with our certifier to complete the modelling and just kept at it until we got it right.’
One of the principles of Passive House is eliminating thermal bridges. This refers to points in the building that allow heat or cold to con-duct more quickly than the rest of the structure, compromising the overall performance of the insulation.
‘We had to calculate the thermal conductivity of each screw in the wall so that we would get our insulation correct,’ Joe explains. ‘When you have 3000 screws just on the external cladding, it all adds up! That’s how far the thermal modelling for this house goes.’
Other calculations included air tightness. The required level was a minimum of 0.6 air changes an hour, but the house is performing at 0.39 air changes per hour.
‘The house breathes, but it doesn’t let moisture transfer in and out. It’s important that your wall and roof systems breathe so condensation doesn’t build up.’
Asked if the endeavour was a success, Joe says ‘100 per cent’: ‘High-performance glazing, insulation and an airtight building ensures the internal temperature is constantly kept at a comfortable level ranging from 20–25˚C, with minimal reliance on artificial heating or cooling. We estimate running the entire house is only about 13.3kW per day without solar, so we’ll be putting more into the grid than we’ll be using.’
Joe says it was an ‘intense’ process at times, but not only was the project a first for Blue Eco Homes, The Sapphire is one of the first known certified Passive Houses to BAL-FZ in Australia, and possibly the world, according to the Passive House Association.
‘We’re all very proud about what we achieved. The house looks good and is working tremendously. We built it to teach and show people it can be done, so we’re looking forward to the next one and making it easier for people to obtain.’