No heaters required
Randal and Pam Greenbank have nailed winter-zero power bills, in their new, air-tight rural retreat. By
While Pam Greenbank was out walking the farm dealing to the weeds, she came across the perfect site for a new house.
She came back to the farmhouse and told husband Randal who agreed it looked promising. And, to cut a long story short, the couple subdivided and sold their Te Kauwhata dairy farm, saving the prime spot for themselves.
But there was a hitch – the couple were quoted $110,000 to have a power cable laid all the way up their 850m-long driveway to the house. So they went for a better solution. They chose to build an off-grid passive house powered by solar energy.
First, however, there was an inordinate amount of research undertaken by Randal Greenbank, who says a friend in Palmerston North had built a passive house with eHaus.
‘‘We went down and had a look at their house and ended up signing up with eHaus Waikato builder Ross Brown. And we did go to a lot of show homes to be sure we got the right home we wanted.’’
But there was also a lot of research required for the solar power. ‘‘Our friend was off-grid, but his system was not a very good one. We saw a few houses, picked the brains of all the owners and chose to use Able Solar in Takanini.
It’s fair to say the couple have never looked back. Their brick and plaster-clad house has been built to German Passivhaus principles, which means it is airtight – the airtightness was tested every step of the way during construction, Ross Brown says. ‘‘The house features very efficient, thermal bridge-free European glazing – the windows have extremely high insulation values and are very, very airtight. The whole house is highly insulated.’’
A mechanical heat recovery ventilation system introduces fresh air, replacing the entire volume of air in the house every three to three-and-a-half hours, with filtered air that is preconditioned to the same temperature as the air already inside the house. Humidity is also removed.
‘‘After we have been staying with my son in Tauranga, we can feel the difference walking into this house,’’ says Greenbank. ‘‘This is definitely better than a standard house.
‘‘We had an enormous amount of sunshine over the summer. When it was 30 degrees Celsius outside we would leave the heat pump going all day on auto – it didn’t cost us a cent, and the house was as cool as a cucumber.’’
Inland Waikato does get temperature extremes, and the Greenbanks have yet to face their first winter in the house, but Brown isn’t concerned.
‘‘It will be just lovely and warm all winter – they will hardly need to turn on the heater. We did have a frost one morning recently; there was white frost everywhere. I went up to see them later, and they said they didn’t even think to turn on the heater.
‘‘The guests were all overdressed. They were pulling off layers all evening. If Randal and Pam do turn on the heater, they won’t be using it for long.’’
The Greenbanks have an app, so they can track their power use, and see exactly what is happening, but they are not concerned: ‘‘We’ve paid our power bill already in advance. The price can’t go up,’’ says Randal Greenbank. ‘‘And our battery life is 16 to 20 years.’’
The couple have a back-up generator in case the batteries get too low – to avoid possible damage.
‘‘Pam was a bit unsure about going off the grid at first. Now that it’s all up and working, it’s not a problem.’’
And there is the other ‘‘upside’’. The couple have the perfect private country retreat. Around four years ago, they planted native specimens right along the long drive up to the house, and these are now wellestablished, adding to the rural charm of a lifestyle far away from the rat race.