Business South August 2021

86 | Whitehouse Builders BUILDING Passive homes help the planet Passive houses defuse the buildings heating and cooling effects and cut energy bills by around 90%, according to Robert Whitehouse. Hugh de Lacy T he very notion of the energy efficient house was so novel when Robert Whitehouse migrated to New Zealand in 1999 that he was able to label one of the residential building companies he established in Christchurch just that: Energy Efficient Homes Ltd. Robert came from a building-related manu- facturing background in the United Kingdom to residential building in New Zealand with two companies, the other being Whitehouse Builders Ltd. The second company builds conventional houses while Energy Efficient Homes targets the growing market for environmentally friendly dwellings. Between them the companies run five two-or-three-man teams working on ten to 12 sites at a time, turning out 20-odd homes a year ranging from bespoke energy-efficient architecturally designed ones on the hills to low-cost multiple dwellings on the flat. But it’s the energy-efficient side of his business that captures most of Robert‘s atten- tion, and the key to building them lies in five passive house design principles, the first being insulation – and it goes further than the Build- ing Code requirement of R2.8-rated batts. “Energy Efficient Homes replaces the stand- ard non-waterproof building paper with a Ger- man-made impervious wrap called Pro Clima that is 100% moisture resistant and prevents the insulation – Earthwool, made of recycled glass – from absorbing moisture from the outside,” Robert says. “We install another paper, a vapour barrier, on the inside of the frame and fully seal it, and its role is to stop the home’s own humidity from damaging the insulation from the inside. “We add a 45mm batten to the interior of the exterior wall to accommodate services and extra insulation, and the Gib board ap- plied over that gives the wall an R4.2 insula- tion rating.” The second distinctive element in the Energy Efficient Home is European-designed windows which, as well as being double or tri- ple-glazed, lock tight shut when closed, using a tilt-and-turn mechanism that incorporates six locking points. “Then there’s the question of airtightness, which boils down to preventing unwanted draughts,” Robert says. “To ensure airtightness Energy Efficient Homes carries out blower-door tests where the interior of the house is pressurised to 50 pascals, then de-pressurised to measure how much air the structure is losing. “To meet the passive house standard it’s allowed to lose 0.6 of the total volume of air over the total insulated area per hour.” The fourth passive house element is mechanical ventilation, which sees air ex- tracted from the bathrooms, toilets, laundry and kitchen areas and put through a heat exchange unit, taking out the moisture and extracting heat that would normally go to waste. “It also brings in fresh air through a filtra- tion system that eliminates nasties like pollen, and feeds it into the living areas and bed- rooms round the clock, recovering up to 85% of the energy. “It has the added benefit of keeping the whole house at an even temperature at a cost of just $75 a year to keep the fan running.” The fifth element in the Energy Efficient Homes formula is thermal bridging, based on the principle that heat will always go towards cold, and it will also find the weakest point, the so-called thermal bridge. “Keeping the thermal bridges to a minimum will make the house perform much better in both summer and winter,” Robert says. He puts the energy efficient home in a global perspective by noting that 38% of the world’s carbon footprint is caused by the heat- ing and cooling of buildings – “48% if you add the carbon generated by the actual building process. HIP D Providing Expert Electrical Solutions for All of Your Domestic, Commercial, & Light Industrial Needs with a Prompt & Efficient Service Guaranteed. Concrete Masters Ltd Blaise Chamberlain Phone: 027 222 1600 Architectural concrete works | Driveways, Patios, Courtyards | Full landscape works provided Email: info@concretemasters.co.nz Website: www.concretemasters.co.nz WWW.DYERSROADITM.CO.NZ Proudly supporting Whitehouse Builders