Sustainable Habitat Construction

Building a Better Way

‘Low energy houses for the NZ climate ’.

Not until the 1950’s with the wide spread development of roads, global infrastructure ,fossil fuel distribution, and industrialisation were we able to turn our backs on the sun and wind as providers of light, heat and air for the houses and buildings we occupy. As a consequence, in just a few decades we have experienced an exponential growth in consumption of natural resources, production of pollution and waste. Fortunately, for New Zealand 60% of energy required to run our country comes from renewable resources; however this is not enough with talk of nuclear power a lively topic and numerous wind farms planned or under construction throughout the country. With the melt down and re-structuring of the global economy in 2008 the connection between cheap energy and resources is now becoming more apparent. Current price increases in New Zealand, either directly or indirectly related to GST are set on a upward trajectory which unfortunately the consumer is now unable to escape footing the bill for. Some say this is the beginning of the end for consumerism and will lead to the better use of resources.

In response to these new economic and cultural avenues there is opportunity and a joint movement of designers and architects who are creating houses that solve the wider and complex issues of global warming and climate change. The New Zealand climate offers some unique qualities that can be utilised to achieve low energy or zero energy houses without great costs.
New Zealand homes are for families and should be built around lifestyle and enjoyment of living. During winter time we are based indoors and try and keep ourselves as warm as possible, during summer time we like to open our houses up for outdoor living and the maximum benefits of nature.
The New Zealand seasons and latitude gives it an ideal orientation to the sun suited for passive solar gain, a typical mid day winter sun angle in Northland is around 30 degrees, during summer it is 77 degrees. That’s a 47 degree sun angle difference over seasons and allows for low angled winter sun to penetrate deep into a house, if designed correctly. A few hours of sunlight on thermal mass (exposed concrete) is sufficient to provide the majority of heating for a house. During summer sunlight needs to be kept out of the house preventing it from overheating. This is achieved by correct orientation and layout which is fundamental for a successful passive solar low energy house. Prevailing winds can be utilised to give good natural ventilation by either cross ventilation techniques or a centralised climatic chimney which creates a natural stack affect (hot air rising), this keeps the interior cool and comfortable during summer. With leaps in insulation and glass technology over the past decade we are able to economically retain the openness and light qualities of a traditional New Zealand home while increasing our temperature comfort levels during winter.
A typical Northland house uses about 8000 kilowatt hours per year for its total energy consumption (cooking, fridge, TV, computer, water, heating, lights etc), a correctly designed passive solar energy efficient house can reduce this to about 3000 kilowatt hours and achieve internal temperatures during winter of around 17 degrees Celsius. With this amount of energy reduction it then makes it affordable to implement a photovoltaic system (solar panels) which will render the house self sufficient energy wise.
Written by Duncan Firth who is a Design Director at ‘Powered Living’, which is a design company that specialises in passive solar energy efficient architecture.

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