Te Awamutu couple's energy efficient Ehaus

Chris and Sue Kay at the construction site of their eHaus.

Chris and Sue Kay have invested more than $1 million to build an energy-efficient eHaus in Te Awamutu because they want a comfortable home within walking distance of everything they might need for their retirement years.

Hamilton-based eHaus licencee Ross Brown says the project was the seventh of his company's projects in the Waikato and the first in Te Awamutu of its eHaus 'Pacific' range. While eHauses cost about 15 per cent more to build than a standard home, they are designed around the climatic conditions of the area and are 90 per cent energy-efficient. This means that the additional cost will be recouped in eight to 10 years.

Ross says the eHaus appealed to a wide variety of people, with the market book-ended by the young and environmentally aware and people getting on in life who wanted to leave a legacy.

Chris says he and Sue went looking for a new house they could live in for the next 20 years and were impressed by the home of eHaus national director Jon Iliffe in Wanganui — which only required one small wall heater to keep it warm.

Extensive ventilation circulates fresh air, removes moisture and filters dust and pollen.

"We wanted something that was going to be comfortable," says Chris.

"We did some research around homes and building design and thought this would be the ultimate in comfort technology including insulation and ventilation with very little energy required to heat and cool.

"There is also a heat-pump system to provide hot water — it costs four times as much (as a standard hot water system) to install but costs only 25 per cent as much to run.

"A computer simulation of location, weather patterns and living style is used to come up with design specifications."

The couple purchased a property in Te Awamutu within walking distance to town and eventually removed the existing home when they were ready to build.

The eHaus is built to international PassivHaus standards with key points in construction including — a level of thermal insulation which exceeds the building code and high-quality joinery in Upvc, wood and thermal aluminium.

"The home is wrapped in an airtight layer which sits behind the insulation and has a high-quality ventilation system which constantly extracts stale air and introduces fresh air," says Ross.

"The whole air volume of the house is replaced every three and a half hours which keeps humidity low and constant," says Chris.

"It also filters out dust and pollen and extracts surplus moisture to reduce condensation and eliminate conditions which create mold."

Walls have an airtight layer and thermal insulation which exceeds the building code.

So far 60 eHauses had been completed nation-wide with another 57 under construction.

These included a more-than $10 million co-housing project of 21 dwellings in Dunedin.

"More people are becoming aware that using less energy is important," says Jon.

"We use building science and undertake climate modelling to international standards."

Chris and Sue have been living in their motorhome and a cabin on a property they own at Parawera, so are looking forward to their new eHaus, which should be complete within the next few months.