Credit: Mirvac

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A concept for a new ultra-energy efficient house has been unveiled in Melbourne this week. A 9-star energy rated house named Harmony 9, designed by Australian company Mirvac, incorporates a multitude of smart internal and external features that generate energy for the house, reduce the need for cooling and heating, save water and decrease the embodied CO₂ in the construction materials.

The construction and occupation of homes is responsible for about one-quarter of Australia's energy and greenhouse gas emissions, 14 per cent of its water use and 40 per cent of the country's solid waste. Recognising the emerging importance of sustainability to the housing market Mirvac designed Harmony 9 as a showcase house at the Waverley Park development in southeast Melbourne.

Mirvac Design Director, John Eckert, likened Harmony 9 to the idea of a concept car in the automotive industry. "Not everything we have learnt is suitable for implementation straight away, but our knowledge paves the way forward for the entire development industry".

Though the house is not yet complete, the design has already received 9.2 stars on the Nationwide House Energy rating Scheme. Other houses at the Waverley Park development are rated 6+ stars.

Low Energy Requirements

Energy requirements in the house are low due to a number of factors, starting with the orientation of the building. The house is positioned to take advantage of the sun in the winter, but features shading and adjustable louvers to restrict summer sun. The use of double glazed windows helps stabilise temperatures and they are located to provide optimum ventilation.

A large spine in the centre of the house is constructed of bluestone and brick. This large mass will soak up heat in the summer, but in winter nights it will dissipate the heat it gains from daytime sun.

The same principle is applied to the external walls. They are constructed with timber clad conventional stud frame on the outside, a layer of insulation in the middle and plastered bricks on the inside.

All of these concepts reduce the need for electricity-intensive cooling and heating systems, but the roofs are fitted with 30 m² of photovoltaic panels to provide electricity for efficient appliances and low energy LED lights inside.

Carbon Savings

The use of recycled construction materials for the house helps keep embodied energy and greenhouse gases to a minimum. A unique one hundred per cent recycled concrete slab floor was poured at the beginning of the build and recycled and sustainable materials such as timber and plasterboard are used throughout.

Local materials have been important in this respect, too, reducing emissions from transportation. Distinctive bluestone cladding features, for example, originate from a quarry less than 100 kilometres from the site.

Water Saving

Mirvac claim that based on the Moreland Council STEPS rating tool, Harmony 9 has the ability to save 125,000 litres of water per year in mains water usage. It does this through a number of innovations:

• Water fittings are rated to the highest possible Water Efficiency and Labelling Standards (WELS)
• There is a 20,000 litre underground tank to capture rainwater for use flushing toilets, washing clothes and irrigating the garden
• The rainwater is cleaned by the rain garden before it runs into the tank
• A recycling system is also included to clean greywater to supplement the rainwater supply

Smart metering

Recognising that all the hard work designing the house is wasted if occupants don't use it correctly, a smart metering system is included. It provides real-time information about the water, electricity and gas consumption helping residents keep a check on their resource use.

Harmony 9 will not be for sale just yet but it will be open for viewing from the middle of this year.