A certified Passive House stands in Thornleigh, on Sydney’s upper north shore, and a second in the Blue Mountains.
Airtight construction stands at the core of the Passive House building standard, developed in Germany as Passivehaus. This is paired with a dependable mechanical ventilation system complete with heat recovery, ensuring exemplary indoor air quality, minimal energy usage (usually less than 80 per cent of the energy needed to heat and cool a typical home) and minimal noise penetration from the exterior.
Joe Mercieca of Eco Homes, the design build team responsible for the Blue Mountains display home, says he was seeking his next big challenge in sustainable homes, which inspired his interest in Passive House.
He calls this concept sustainability on steroids.
Mercieca has earned his qualification as a certified passive house tradesman, and chose as his first project, the Sapphire Passive House in the Blue Mountains.
He says that this building standard runs counter to traditional teachings in carpentry.
Australian carpenters are generally instructed that homes have to breathe, but a passive house must be airtight.
The Sapphire home is sealed so tightly that the gaps open for air to escape are no more sizable than the tip of a small finger. Mercieca states that the bulk of the air is seeping from keyholes. So the challenge becomes to create a breathable but non permeable membrane that water can’t infiltrate.
The correct materials must be used in the appropriate location.
The result is an amount of power consumption per day, sans solar, that costs less than the cost of a coffee.
The house’s internal temperature is maintained at a comfortable level, varying from 20 to 25 degrees, with little reliance on artificial heating or cooling. A ventilation system disperses filtered clean air throughout the home to prevent carbon dioxide accumulation.
The home also comes complete with a 5.2kW LG solar PV system with battery storage, and is constructed in accordance with the highest Bushfire Attack Level rules.
Both houses were constructed using traditional Australian building techniques.
The Thornleigh home is the work of Envirotecture architect Andy Marlow, who says that he is very happy to see his first Passive house project completed and certified. He notes the fact that a third of all their new projects are now being delivered in accordance with the Passive House standard.
The airtight construction and exemplary windows will protect residents from the noise created via overly congested local roads and a local train line.
The two-storey residence also wraps around a tall tallow wood tree that will supply shade in the summertime.
The home contains 10 internal water tanks that help control internal temperature. They will serve as a room divider while filtering sunshine through a sizable north facing window that comes complete with a retractable shading blind to control the level of sunlight filtered during the summer months.
The tanks will be filled following construction and are not connected to other rainwater tanks, as the rainwater temperature can be low and pose a condensation risk if placed directly into a building.
The windows – uPVC with an aluminium exterior skin – are imported and are triple glazed as standard–more cost efficient than a a special order of double glazing.
The resulting residence is a house 44 times less leaky than the typical Australian house.
Blue Eco Homes’ Mercieca states that the newly certified homes should allay any concerns that Passive House is not suited to the Australian climate, as the calculations for Passive House are specified to every project climate.
Mercieca says that his company is soon to tackle its second Passive House project, and hopes to build many more in the future.
The certification of these homes elevates the quantity of Passive House Certified buildings in Australia to 18—with hundreds of Passive House buildings in different stages of planning and construction.