Homes that raise the bar
This is a part of the Sustainable design feature
A Christchurch-based designer has proved that clever integrated design can provide sustainable modest homes that are affordable and accessible to more people.
ARCHITECTURAL DESIGNER Bob Burnett of Eversun Homes has overseen the completion of two innovative and affordable eco-homes designed to achieve an 8-star Homestar rating, making them among the more energy-efficient homes in the country.
Two 8-star homes
The first is a modest 113 m2 timber-frame home with four bedrooms and two bathrooms (see cover). Variations in ceiling heights provide a perception of space making it feel larger than you would assume, given the size of the footprint. Burnett says they are targeting zero energy use through excellent thermal design and the use of PV solar panels to provide more than enough power.
The other is a 152 m2 2-storey home built using insulated precast concrete panel thermomass construction carefully detailed to eliminate thermal leakage, for example, bolts are nylon instead of steel to avoid thermal conductivity. It too features PV solar and high-performance glazing and has a solar wall (collector) to prewarm fresh air, which is then fed into an ERV (energy-recovery ventilation system).
Both houses incorporate key dimensions and features of the Lifemark standards for enhanced functionality and safety for all ages and abilities.
Thicker wall framing standard
The timber homes Bob Burnett designs have thicker wall framing as standard. These are multi-purpose – they improve thermal performance by getting more insulation into the walls.
‘We’re also wrapping the house with a proprietary rigid air barrier so that it’s really well braced and about 200% of Building Code. It’s solid, making it unlikely to be damaged and gives you a more airtight house, too,’ says Burnett.
Innovations filter down
The idea behind Eversun Homes was to draw on some of the cost-effective innovations developed in Burnett’s mid to high-end architectural design practice over the last 12 years and filter them into a range of not-so-big homes that are affordable and accessible to more people.
‘People are starting to realise they can get something much better than the average, standard Kiwi home without it costing a lot more. The obvious compelling benefits of a sunny, warm, dry, more healthy and comfortable energy-efficient home are now being seen as more attainable. Particularly when on-going cost savings that can help pay off the mortgage faster are considered, it makes complete sense.’
Design rather than technology
However, Burnett warns homeowners still need to be aware of pitfalls when going down the energy efficiency route. ‘There is a lot of greenwash out there, and the right advice is critical. There is a fine line between getting energy-efficient designs right – and not.’
He says the whole house should be considered as a system. Adding energy-efficient features that are not fully integrated or complementary simply won’t work.
‘The key is to take an integrated design approach from the earliest concept stage when around 90% of the important decisions need to be made. People are often surprised that clever design, as opposed to incorporating a whole lot of expensive technology, is the first essential element of an energy-efficient home.’
Factor in running costs
Eversun uses 3D computer thermal modelling to analyse the home’s solar gain and heat losses for different months of the year. This process provides solid data that allows designers to estimate the new home’s future power bill. Previously, designs were created just through experience of what works in practice.
‘Once built, the real proof of a home’s energy efficiency is the power bill. That’s why people should always think about their new homes as having two prices – the price to build it and the annual running costs. A lot of money can be spent on big houses that don’t necessarily perform well.
‘As a certified Homestar practitioner and assessor, I’m particularly enthusiastic that Homestar becomes recognised in New Zealand, leading to not only better buildings but also future-proofed homes with high ratings which will have increased value. And they must be appealing designs which are chic and eye-catching,’ says Burnett.
Better-performing homes
Burnett says most New Zealand houses are built to only 3 to 4 stars. ‘Many Kiwi homes are viewed by people from overseas with dismay. They are seen as notoriously poor performers, often cold, damp and unhealthy.’
But Kiwis are starting to catch on with a growing readiness in the New Zealand market to embrace eco-friendly, safer and more energy-efficient homes.
For more Visit www.eversun.co.nz, www.bobburnett.co.nz and www.homestar.org.nz.
For more Visit www.eversun.co.nz, www.bobburnett.co.nz and www.homestar.org.nz.
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