Te Kauwhata Passive Solar House in Waikato, New Zealand, has been designed to optimise rural views, while maximising northern passive solar gain and buffering from cold south westerly winter winds. The house utilises environmental principles throughout; it is passively self-heated during winter, self-cooled over summer and employs green materials and technology. The floor plan area is 240sqms, situated on a 2 acre property in the north Waikato, with sweeping views of pine forests and farmland.

Orientated due north for maximized passive solar gain the house takes full advantage of the low angled winter sunlight that passively heats north facing exposed insulated concrete floor slabs and exposed internal concrete block walls. A centralised clerestory works as a climate chimney creating a natural stack effect, naturally ventilating and cooling the house during warmer months. Top light windows are strategically located throughout the house to further assist the passive cooling design.

The energy use is approximately 3000kWhs annually or an annual energy index of 12.5kWh per/ sqm. Powered by a 3.2 kW grid connected solar panel system, this generates power during the day which is fed into the main public power grid. Power is then withdrawn from the main public power grid during the evening. Internal temperatures passively peak at 24⁰ during later afternoon mid-winter, with the extreme low being 17⁰ during early morning.

Green technologies and features which have been incorporated into the house are a passive hot water heating system that is located on the roof, providing all the hot water requirements of the house. Building materials include untreated Lawson Cyprus timber for exterior cladding, untreated Macrocarpa timber for interior shelves and architraves, natural bio-paints for the interior finishes, and wool/polyester composite insulation. Above code building insulation has been used for floors, walls and ceilings, and as well as insulated glass windows. The house collects rainwater for drinking and reduces water consumption through water efficient fixtures.

The combination of passive design strategies, passive solar, passive cooling, energy efficient technologies and 3.2 kW solar panel system renders the house energy self-sufficient.

Location:  Waikato, New Zealand
+ Programme: Family and Retirement House
+ Client: Private Owner
+ Site area: 2acres
+ Built area: 240sqm
+ Status:  Built
+ Award: First Place equal in The Residential Concrete Sustainability Awards sponsored by Cement & Concrete Association of New Zealand (CCANZ)
+ Credit: Duncan Firth, Milti Stefadouros, Helen Richards
+ Photographer: Francis Oliver