UPDATED: A Nationwide House Energy Rating Scheme (NatHERS) rating of 8.7 for a Queensland home is always worthy of investigation in The Fifth Estate’s books. But we were interested to discover that there was nothing particularly radical or expensive about this Brisbane home designed by dion seminara architecture, and that the high thermal performance rating came down to “really good design”.
Many people wanting to build their dream home think energy efficiency and sustainability come at a major price premium thanks to costly add-ons.
But a home in the Brisbane suburb of Sherwood designed by Dion Seminara and his team was completed on a tight budget for a retiree client.
It is well insulated, has double-glazed windows and a special colour coating on the roof that reflects heat, as well as 62 solar panels on a roof pitched to maximise power generation (the client is a solar enthusiast). But Seminara told The Fifth Estate all of these features were manageable under the tight budget.
The secret to achieving the high thermal rating without breaking the bank was simply “really good design” by the architects, but it helped to engage a high-quality energy rating assessor, SUHO, which is based in Adelaide.
The consultancy recommended a few “minor tweaks”, such has the positioning of the insulation, which helped push the rating up still higher.
“An 8.7 NatHERS rating is blitzing it.”
He said the home might have even achieved a few extra decimal points with a different slab but that was too expensive.
“You have to weigh up the costs and decide if it’s worth it.”
The high thermal performance rating for the home which, compared to a typical 6-star rated home, uses about 80 per cent less energy to cool or heat, came down to basic energy-conscious design around orientation, layout, cross-flow ventilation and shading. In Brisbane’s hot, humid climate this included big overhanging eaves and some external screening on certain windows on the east to try and block the sun.
The home is also laid out to get the “maximum benefit for the majority of the major rooms of the home,” with the garage on the back of the property in the worst corner.
Seminara, who takes a holistic approach to sustainable design, also says it’s important to consider the social sustainability of a home. He works hard to put the entertaining and living areas in the best spots in all his projects.
The client is a big user of airconditioning, but as a retiree, will be able to take full advantage of the extensive solar array as they will use most of their energy during the day.
Seminara expects very low power bills for the client, who was interested in a sustainable home for a number of reasons, including a financing agreement that offered a discount if certain sustainability measures were met.
The flat site was selected by the client to get the most out of the solar panels, with no vegetation from neighbouring properties shading the site. However, the architects have encouraged the client to plant vegetation to help shade the house.
Note: An earlier version of this article implied that the high peformance design was attributed to the energy consultant, rather than the architects.