By Donna Kelly
6 December 2012 — ABC TV’s Gardening Australia presenter and environmental scientist Josh Byrne has started on his most ambitious housing project yet – the design and construction of two 10 Star Nationwide House Energy Rating Scheme energy efficient family homes in the Fremantle suburb of Hilton, WA.
Mr Byrne said he and his colleagues were tired of hearing that sustainable construction had to cost more so wanted to prove that resource efficient homes could be built at comparable cost and timeframes to regular houses.
And the Josh’s House project was under way.
The three bedroom, two bathroom homes will be thermally comfortable year round, without the need for airconditioning or additional heating. They will generate more electricity than they use, and will harvest and recycle water. In addition to private garden areas, a common productive garden will supply both houses with fresh food.
“The project also demonstrates a more sensitive approach to residential subdivision that has considered maximising effective garden area around the homes to allow for natural shading, children’s play spaces and local food production – important health and lifestyle benefits that are rapidly disappearing from our suburbs”, Mr Byrne said.
In addition to the 10 Star NatHERS achieved for both homes, the development has undergone further scrutiny to assess their environmental impact, sustainability and liveability credentials.
Mr Bryne has engaged two local companies to help. One company eTool undertook a life cycle and carbon accounting assessment while ARCActive assessed the project across a broad range of sustainability criteria including energy, water, materials and biodiversity.
The homes are expected to use less than 10 per cent of the energy of a typical Australian new house, saving the occupants an average of $2000 per year in energy costs. The houses will emit less than 10 per cent of the greenhouse gas emissions normally created by Australian dwellings and use around 40 per cent of the scheme water of a typical Perth home, while still supporting a diverse and productive garden.
“This project is all about providing an inspiring and practical example of how to create beautiful and resource efficient homes that are accessible to the broader community,” Mr Byrne said.
“Key to the project’s success will be the industry partnerships that we will form and foster throughout the process to help share ideas and promote the outcomes.”
Already on board are builder Highbury Homes, Solar Dwelling’s Griff Morris, the Water Corporation and the City of Fremantle.
The building and landscape plans can be downloaded for free here and factsheets on various aspects of the build will made available during the construction period. There will also be a research component to the project to assess the thermal performance, as well as energy and water efficiency of the homes and landscaping once they are completed and operational.
The houses are scheduled for completion by May 2013.
The key solar passive design principles employed include:
- East-west orientation with maximum glazing to the north for winter solar gain (shaded in summer) and minimal glazing to the east and west to minimise summer heat entry.
- High thermal mass materials used on the inside of the buildings to absorb winter solar gain and stabilise internal temperature during summer.
- High insulation value to roof and walls to minimise uncontrolled heat loss/gain, and pelmeted curtains on the windows to reduce heat loss in winter.
Meanwhile, a combination of reverse brick veneer and double brick walling has been used in order to increase internal thermal mass where it was needed. Where this wasn’t required, timber framed walling was used because the materials have a lower embodied energy value and therefore a lower carbon footprint.
Low emissivity glazing was chosen throughout to regulate heat flow. Surprisingly, only one double glazed window was required in each house to achieve a 10 Star rating and this was in the kitchen where the use of curtains to keep in winter warmth wasn’t practical.
Lighting will be provided by a combination of LED down lights in the bedrooms and living areas – kitchen, dining living room and activity room, and compact fluorescent globes in occasional use areas – bathroom, laundry, toilet and hall way. Reversible ceiling fans will also be installed in the bedrooms and living areas to provide downward cooling and upward circulation of warm air in winter.
Each house will have a 3 kiloWatt grid connected photovoltaic system installed which will generate more power than required to run the homes, as well as gas boosted solar hot water systems. Solar tubes will help to “daylight” internal areas such as walk-in robes to reduce the need for artificial lighting.
High efficiency shower heads and tap ware have been selected, and the low volume dual flush toilets have integrated hand basins which use tap water fills the cisterns.
The landscaping will also help address a number of pressing urban sustainability issues including improved household energy efficiency through appropriate shading, habitat provision with local native plantings, as well as local food production with an extensive shared vegetable garden, home orchard, poultry and composting and worm farm system.
The hard landscaping works will incorporate locally sourced and salvaged materials, including items from the demolition of the original cottage. Permeable, rather than sealed surface treatments will be used where possible to allow for localised storm water infiltration and paving will be laid to direct water in to garden beds.
Both houses will have direct diversion greywater systems to provide irrigation to selected areas, as well as rainwater tanks for internal usage, with mains water back up for dry periods. The productive garden will be watered from a shared bore and state of the art centrally controlled irrigation system, incorporating both soil moisture monitoring and weather monitoring to maximise water efficiency.