HRV worked with the property owner and other partners, including LG, Resene and Mercury Energy, to renovate the house inside and out.
The master bedroom and en suite on the top storey were removed to create living areas with more natural light.
The ceilings were replaced, foundations corrected, the kitchen moved and the bathroom replaced and a full ventilation system put in it to remove moisture.
Appliances with good energy ratings were installed.
The master bedroom was moved downstairs, reducing the number of bedrooms from five to four, insulation was installed throughout, plus ventilation, heat transfer and water purification systems, soundproofing insulation on the internal walls and LED lightbulbs to reduce the cost of lighting.
The project team wouldn't put a price on the renovation but said the kitchen was the most expensive part.
Boyes said one of the most important changes owners could make was to dry their properties so they could be heated more efficiently.
Heat transfer systems also eliminated a common New Zealand problem of one room being heated well while the others around it remained cold, he said.
The HRV components of the renovation were installed for less than $18,000. Boyes said people who insulated and installed heat pumps and heat transfer systems often found they did not see a large decrease in their power bills but had a healthier, warmer house to live in.
Nic Rowan, of Greenstuf Insulation, said the insulation cost about $5,000. "Insulating is the single most beneficial thing to do to improve a home's energy efficiency."
He said a house insulated to the building standard would be 2°C warmer in winter and 2°C cooler in summer.
It was most cost-effective to plan insulation in a renovation project, he said, and not cut corners. "Spend the time at the start to get it right and it will always be there.
"It's not like an appliance that has a limited life and you're paying for it for that life. It pays itself back pretty quickly."
The house has been fitted with a power use monitor, which predicts the monthly bill and builds a personalised energy-saving plan.
Monitors are free to Mercury Energy customers.
Spokesman Ben Harvey-Lovell said the 100,000 customers using the monitors were on track to save about $2 million on their annual power bills.
He said up to 60 per cent of a typical house's energy bill was for heating and hot water. "Anything you can do to make it easier to heat will result in significant power savings."
The house will be auctioned on May 18. It has a 2011 CV of $980,000 but could get double that now it has been renovated. A neighbouring property recently sold for $2 million after being renovated.
