In their latest blog, the Washington-bound First Light team give us the low-down on the passive solar design principles they’ll be utilising in the construction of their bach—a bach that will use less than a third of the energy of a typical New Zealand home
The aim of the Solar Decathlon is to design, build and operate a solar powered house but the greater goal is to increase public awareness around the cost saving opportunities of clean energy products. We want to show that by using passive solar design strategies homeowners can save energy and money.
Passive solar design makes the most of the natural climate by controlling the positioning and materials used for walls, floors and windows. If designed correctly these surfaces will collect, store and distribute solar energy to keep the building warm in the winter and cool in the summer.
So how are we using passive solar design in the First Light house?
We have positioned large windows along one side of the house—north facing during its time in the Northern hemisphere and South facing here in NZ. These allow light to flood the interior space in winter and heat the thermal mass floor. In summer, these windows would cause the house to overheat if left exposed. We solved this problem by extending the solar canopy to provide shade for the windows during summer. The solar canopy is a multi-purpose design feature—it provides shade, gives aesthetic appeal and acts to support and cool the solar array.
The heart of our design is the glazed middle section which acts as a bridge between the natural environment and the indoors. This part of the house is open and can be manipulated to suit different occasions making it perfect for socialising and entertaining. Not only is this central section party central, it also acts as the comfort control centre for the house. Large doors on both sides can be opened to allow passive cooling of the house during summer.
The large transparent skylight allows sunlight to penetrate the space to provide heat and light during winter. As with the windows, overheating in the summer can be a problem so a shading system for the skylight has been introduced to allow for total control of the interior climate.
Using passive solar design means the home owner has an active role in how their house functions, they need to be aware of seasonal changes and how they affect the house. This makes a running passive house sound like a lot of work but really it’s no different to how we already live. “Controlling the indoor climate” sounds technical but it’s as easy as opening and closing windows, doors and screens. We have put in thought and effort into the design to make the running of the house as easy and comfortable as possible for the home owner.
You may ask, “what can passive solar design do for me?” The First Light house will use less than a third of the energy of a typical New Zealand home. We have used passive strategies, already covered, and active strategies, which include using photovoltaic panels to create energy for the house. By using passive strategies we have greatly reduced the need for energy overall by cutting down on the need for mechanical heating and cooling of the house. This leads to a reduction in initial set up costs with fewer solar panels needed to power the house, and ultimately leads to savings on power bills. Never seeing another power bill in your life, who wouldn’t want that?
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