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Way of the future: The zero energy house

Way of the future: The zero energy house

The Zero Energy House in Auckland is one of New Zealand’s innovative sustainable projects and exemplary of the country’s leading role in the global green building industry.

March 2015

In New Zealand, the concept of sustainability is increasingly being recognised as good practice supported by the government as well as the private real estate developers.

According to the BCI Economics and FuturArc’s latest report on Green Building in New Zealand, green building principles are now part of mainstream building activity in the country. The three most prevalent motives for companies to pursue ‘green building’ principles when designing or implementing projects were found to be: achieving lower lifecycle costs, contributing to the protection of the environment and attenuate the impact of global warming, and achieving increased building value or marketability.

One of the unique examples of New Zealand’s sustainable buildings is the Zero Energy House in Auckland, designed to achieve net zero energy over the course of the year through energy efficient features and solar energy systems.

THE ZEH PROJECT

The Zero Energy House (ZEH) is, first and foremost, a family home. The owners, Jo Woods and Shay Brazier, wanted a home that was comfortable, healthy and cheap to run. However, they both have experience in the building industry (Brazier has previously worked as a solar engineer, Woods works as an engineer at a leading NZ sustainable design consultancy) and have both worked in the UK. These experiences showed them what was possible in housing, and when they returned to New Zealand they decided to incorporate many of the principles from their work in the house.

The Zero Energy House produces as much energy as the people living in it consume. It generates energy via roof-integrated solar photovoltaic panels and roof-mounted solar hot water panels. It was the first to have integrated PV systems of its type in New Zealand.

“We don’t store energy on-site so at times will rely on a connection to the electricity grid for power. But at other times we’ll push surplus energy generated on-site back to the grid. Over the course of a year the amount of energy we consume from the grid and the amount we push back will cancel each other out to result in a net zero energy balance,” explains Shay Brazier.

While the average Auckland household uses (and purchases) 10,660 kWh of energy annually from external suppliers, in the ZEH it is reduced to zero with three methods: building envelope design which eliminates the need for any heating that accounts for around 30% of a standard home’s energy use; solar hot water heating – the solar system reduces energy needs by a further 25%; solar photovoltaic (PV) panels, 88 of which are laid out on the north-facing side of the roof and which provide the remaining 45% of energy.

In comparison to regular ‘green buildings,’ the Zero Energy House, which has been designed and built in accordance with sustainable principles, seeks to completely eliminate outside energy needs and associated impacts, while green buildings only aim to reduce these.

WHY BUILD A ZEH?

The developers of the Zero Energy House name three main reasons as to why build a ZEH – economic, environmental, and health benefits.

Energy is not only costly for homeowners, it affects the country as a whole. Increasing energy demand will mean increased supply, resulting in the need for more power stations and ongoing maintenance and upgrades to the national grid. The owners of the Zero Energy House which produces more energy than is required to run the house believe that these costs and risks can be reduced by moving towards on-site or locally generated power.

While a large amount of New Zealand’s electricity comes from hydropower, in a normal year people still rely upon non-renewable energy sources for a quarter of their needs. They are also dependent on a vast transmission network to move power around the country that is expensive to maintain and inefficient.

“On-site solar generation reduces dependence on the fossil fuels that make up a portion of electricity supply, reduces reliance on the right weather conditions (solar panels capture energy even on cloudy days), and reduces energy loss by transmitting energy a short distance from the roof to the ground” says Brazier.

Besides, by creating an indoor environment that is warm and dry, the Zero Energy House eliminates health risks. A ZEH doesn’t require heating which means its owners don’t have to worry about spending money on power to stay warm as energy prices increase. Finally, by achieving this result without mechanical heating they are also avoiding the cold spots common in many homes where living areas are heated but other areas (including bedrooms) are not, which can result in serious health effects.

The Zero Energy House owners say that the most exciting thing about their home is being comfortable all year round and at all times of the day. The house has a very stable temperature without the need for heating or cooling, and there is hardly any temperature difference between the living and sleeping areas.

“The little things people notice like finding it hard to get out of bed on a cold winter’s morning don’t happen in our home. One ‘downside’ of this is that we find it hard to know what to wear before leaving the house. We need to actually go outside to feel how warm or cold it is,” comments Brazier.

Another great thing about the Zero Energy House is the ability to generate one’s own energy, the owners say, giving them independence from having to pay someone else for it. They are still connected to the grid like a typical home, but buy and sell energy from an electricity retailer, which has even made them a profit in the first year.

FUTURE PERSPECTIVES

Matt Fordham, co-founder of Evident Connect, a business that emerged from the Zero Energy House project in 2013, is sure that this type of building will become more popular in New Zealand over time.

“We are already seeing that,” says Fordham. “Shay Brazier and I launched a business called Evident Connect that helps to give people control over the performance of their homes during design, build and operation. We are already working with two architecture practices to achieve zero energy for their clients, and receive enquiries every week from people wanting help. As energy prices increase and the cost of solar falls, these buildings will definitely be more attractive here.”

In New Zealand, there are more and more projects being completed that demonstrate to people what can be done in terms of achieving zero energy, both locally and internationally.

“We are working on a multi-building, multi-use net zero energy development that will be a leading case study for a range of green building methods. We also have a strong and growing Green Building Council, and the Auckland Council is incorporating green building outcomes in its development and policy. For example, a large section of Auckland’s waterfront is being redeveloped with new commercial and residential buildings that will deliver high levels of performance. This redevelopment has won design awards internationally and has the potential to be a leading international case study once it is completed. It’s a good time to be part of the green building movement in New Zealand,” concludes Matt Fordham.

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