As the concept of sustainable houses becomes increasingly mainstream, many homeowners are looking at ways of creating or renovating a dream home that not only meets their design and lifestyle requirements but is easy on the planet.
If you're thinking of designing a sustainable house or making your existing home more sustainable, there are a few things to bear in mind.
Firstly, a holistic view is key, meaning there are a number of guiding principles you should deploy when creating your sustainable house. Things to consider might include the site itself; is it on a slope, does it have trees or other forms of natural shading? Other considerations might include solar passive design through a northerly orientation; cross flow ventilation, enabling the house to be cooled rapidly in summer; thermal mass, balanced with insulation; and the size of the house - houses that are correctly sized to meet owners' needs help conserve energy both in building and running the home.
Solar hot water, a specialised plumbing system for waste water, rainwater tanks and double glazed windows are all key to successful eco design, along with thoroughly considered site orientation.
Most sustainable houses have some critical design elements that provide benefits during construction and for the lifetime of the house:
€ Environmental sustainability: the house is designed to reduce greenhouse gas emissions, save water and energy usage, and reduce waste.
€ Social sustainability: the house has built-in safety features to prevent injuries, as well as security features to reduce crime and improve the occupants' sense of security.
€ Economic sustainability: the house is designed to save money and avoid the need for major renovations. Costs of energy use, water use and maintenance will be reduced.
Overall the ideal sustainable house should be designed to minimise environmental impact, maximise year round comfort and reduce running costs.
Passive ventilation 101:
We're all aware of the continued rise of energy costs, and in Australia, where extremes of climate are so prevalent, this awareness appears to be reaching a critical point.
A large number of homeowners are becoming increasingly conscious of the need to control their energy costs, not just from the perspective of their bills, but also due to increased awareness of the environment.
To be comfortable, buildings in all Australian climates require some form of cooling at some time of the year, so effective alternatives to traditional approaches to cooling, such as costly air conditioning, are needed.
There are a number of ways homeowners can achieve what's called passive (non-mechanical) cooling in their homes, as well as hybrid approaches which utilise mechanical cooling systems. The most effective passive cooling solutions include ventilation, windows, shading and insulation.
The efficiency of the building envelope can be maximised in a number of ways to minimise heat gain:
€ shading windows, walls and roofs from direct solar radiation
€ using lighter coloured roofs to reflect heat
€ using insulation and buffer zones to minimise conducted and radiated heat gains
€ making selective or limited use of thermal mass to avoid storing daytime heat gains.
Remember, direct sun can generate the same heat as a single bar radiator over each square metre of a surface, but effective shading can block up to 90 per cent of this heat. A variety of shading techniques can help, from fixed or adjustable shades, to blinds, cellular or Honeycomb shades, shutters and more.
It's also important to note that as cooling requirements are dictated by climate, distinctly different approaches to passive cooling are required for:
€ hot humid climates where no heating is required
€ temperate and warm climates where both heating and cooling are required
€ cool and cold climates where heating needs are more important.