Empowering being off grid

A new house on a rural block near Tarras has underfloor heating and other mod cons, but the owners do not expect to receive any power bills - ever. Mark Price investigates.

A Wellington family with a love of camping and roughing it on Central Otago holidays have taken self-sufficiency to a whole new level.

The family - Duncan Kenderdine, Suze Keith and their children Caitlin and Phoebe, and Duncan's mother, Shonagh, have just completed a 200sq m house that runs without relying on electricity companies.

It has all the usual electrical and heating devices of a modern house - including underfloor heating and a dishwasher - but the family have found other ways to make them function.

There are solar hot water-heating panels, photovoltaic panels, batteries, a wood-burner with a wetback, an lpg oven and fridge, a huge, heavily insulated hot water tank and, for when all else fails, a large diesel generator.

It is a far more complex house than the average, but the family is confident it will provide all their energy needs without having to pay for electricity from the grid.

Shonagh Kenderdine is a Dunedin-born former Environment Court judge, now of Wellington, and is chairwoman of the New Zealand Historic Places Trust.

Her son, Duncan, is a qualified architect who works for Downer Group and lived in Dunedin while working on the Otago Corrections Facility at Milburn.

For many years, the Kenderdine family had a small, uninsulated cottage at Luggate - "a classic Kiwi bach", according to Duncan.

But eight years ago they bought a piece of land on the bank of the Clutha River near Tarras where, until now, their Central Otago holiday accommodation was a small tin shed and tents.

Duncan said, "It's a lovely way to be. Very simple, away from the crowds."

A few weeks ago, they moved into their new straw-bale home - still lacking many finishing touches, including its exterior coat of cob - but operating independently off the grid.

The family's eight-year journey towards a house self-sufficient in electricity began with the news it would cost them $35,000 to hook up to high-voltage power lines near their property.

"As we sit here in an off-the-grid straw-bale house wasn't where we started," Duncan said. "Being super-sustainable wasn't the driving force. It's just where we've ended up."

Part of their thinking was to make use of Central Otago's high sunshine hours.

That led to the installation of an evacuated-tube solar hot water system and an array of photovoltaic panels on the roof of the garage, angled for the winter sun, with a battery bank below and a "pretty serious" diesel generator out the back.

"You could be quite brutal about it and say, well, you are just going to have the photovoltaic system and no backup, but last week the average temperature for five days was -3degC and it was cloudy."

Mr Kenderdine said the photovoltaic panels were in place before work on the house began and on some days, full construction was going on with people using saws and concrete mixers, all running off the panels.

Their hot water system, which also heats the house, cost $15,000.

The photovoltaic system with six panels and six batteries, including the generator, cost about $30,000.

But Mr Kenderdine said every time the price of power from the grid went up, the payback period for their system became shorter.

He did not expect the technology they were using to be "immediately cost-effective".

"You've got to be prepared for a long-term return. So if you are looking to sell the house in four years, you might not do it, because you don't get the return."

Ms Keith describes being off the grid as "exceedingly empowering".

"It's a really nice feel and the straw bales are an exceedingly nice environment to live in."

The family are quite relaxed about having to balance their use of energy between heating water, heating the house and running appliances, and liken it to the decisions that come naturally while camping.

They have had little experience living with the systems yet.

Ms Keith says with a laugh that, some days, the choice might be between being "smelly but warm" or "clean but a little bit chilled".

- mark.price@odt.co.nz