After 20 years renovating other people’s houses and gardens to demonstrate his sustainable design ideas, Josh Byrne (Environmental Scientist & presenter on ABC TV’s Gardening Australia) is undertaking his most ambitious house project yet – the design and construction of two 10 Star energy efficient family homes in the Fremantle suburb of Hilton.
The homes will be thermally comfortable year round, without the need for air conditioning 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.
What sets this project apart from many others is that the building designs have achieved a 10 Star energy efficiency rating*, whilst intentionally using conventional building materials and construction methods so that they can easily be replicated by industry and the wider community. “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”, says Josh Byrne.
ABOUT THE HOUSES
Josh describes the homes as “a new take on the classic Hilton brick and weatherboard look”, with a mix of modern rendered finishes, old style weatherboards and heritage red brickwork in high impact areas. The sympathetic roof lines, combined with the generous building setback of the front house will fit comfortably with the 1950’s feel of the suburb.
The floor plans are typical of many family homes – three bedrooms, two bathrooms, with an open planned kitchen, dining and living room area, plus an activities room, but there are a few subtle points of difference. Firstly the orientation of the houses, window location and internal layout has been done on the basis of maximizing the solar passive performance.
Consideration has been given to universal access, by keeping to one level, opting for slightly wider doorways (870mm) with flush thresholds to all external doors, and hobless showers.
The external walls of the homes are a conscious combination of double brick, reverse veneer brickwork and lightweight timber framing. All external walls are insulated with a combination of bulk insulation and closed cell foil insulation. Low-e type glazing has been used throughout to regulate heat flow, with only one window on each dwelling (the kitchen) requiring double glazing to achieve the 10 Star NatHERS rating. The roof is conventional timber construction using light coloured reflective roof sheeting with insulated foil underneath. The ceiling will be lined with bulk insulation to achieve an R4.0
The northern living areas will feature a decorative concrete slab finish to soak up and store the heat from the winter sunlight
and to help stabilize internal temperature during summer. Internal walls will generally be plastered single leaf brickwork with some double brick walls used to add additional thermal mass to the main living areas, as well as sound insulation to selected rooms.
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 hallway). Reversible ceiling fans will also be installed in the bedrooms and living areas to provide downward cooling in summer and upward circulation of warm air in winter.
Each house will have a 3kW 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 tapware have been selected, and the low volume dual flush toilets have integrated hand basins which use tap water, which then fills up 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, composting and worm farm system.
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.
In addition to the 10 Star NatHERS rating achieved for both homes, the development has undergone further scrutiny to assess their environmental impact, sustainability & liveability credentials. Josh engaged two local emerging companies to assist with this process – eTool, who undertook a life cycle and carbon accounting assessment and ARCActive who assessed the project across a broad range of sustainability criteria including energy, water, materials and biodiversity amongst others.
Overall the project rated very well, with the homes expected to use less than 10% of the energy of a typical Australian new house, saving the occupants an average of $2,000 per year in energy costs. The house will emit less than 10% of the greenhouse gas emissions normally created by Australian dwellings and use around 40% of the scheme water of a typical Perth home, whilst still supporting a diverse and productive garden.
People can follow Josh’s journey via a series of short online films which can be viewed on the project website. The building and landscape plans can be downloaded for free and factsheets on various aspects of the build will made available across 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, with the intention of making the data available to industry and research institutions.
“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” says Josh. “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.”
There has already been significant interest from industry with a number of leading suppliers and industry association partnering with Josh and his team. “We’re thrilled to have Highbury Homes as our builder and to be working with Griff Morris from Solar Dwellings on the design – from concept to completion. The Water Corporation and the City of Fremantle have also got right behind us, as have a number of other organisations”.
* Refers to the Nationwide House Energy Rating Scheme (NatHERS) which is based on a scale of 0-10, with 10 being the highest rating score. 6 stars is the minimum energy efficiency standard required under the Building Code of Australia.