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How ‘eco-friendly’ is our new house?

Some students from Te Wānanga o Aotearoa are interviewing me tomorrow about whether we built an eco-house. I thought it might be useful to list the ways I think it is and isn’t ‘eco-friendly’.

11196325_10153250715811273_8827879323077468267_nHouse Site:

  • We chose a building site next to Penu Pa, Tarsh’s marae we lived at for 14 months while the house was being built. That was partly determined by cultural imperatives – we were keen to be close to the pa and able to help out by keeping a close eye on it, opening up when necessary and helping out, fielding enquiries if people dropped in, etc.
  • It also had some financial benefits: we were able to utilise the marae septic system that already had a resource consent – we just need to pay for it to be cleaned every two years instead of every three; we can also utilise the free public internet (WaiWhai) that the pa offers; the new house proximity to power lines was also a lot cheaper than our preferred site up the hill which was going to cost $50,000 just to run an electricity cable to.
  • We are about 10km south of Ruatoria, so there is some transport impacts to consider – school, health clinic and shops use more energy to get to than if we had a house closer or in the township. But you can’t choose where your marae is! Some families further out of town than us occasionally ride their horses to town, so I guess that’s an eco-friendly option we can pursue regardless of how soon we’re all driving electric vehicles.

Energy:

  • We designed the house with a lot of large windows and positioned it facing north so it is a sun trap. As I sit writing this at 8am two days out from the Winter equinox, there is a heavy frost outside but I am bathed in sunlight and getting quite hot. The house is designed as two boxes – one side for sleeping/washing and the other for eating/living/working – joined by a small foyer.
  • We installed a wood burning stove in both sides, one is an oven with wetback to heat the water, the other a small heater for the sleeping side. Both fireplaces do a great job of warming the inside areas – if we load them up before bed, even on frosty nights (we live at the bottom of a valley) they keep the house warm overnight. We’re finding the wetback stove is over-efficient, so if the fire has been going full bore for more than 4-5 hours it heats the water too much and the hot water gets dumped outside so cold water can cool the cylinder. That’s a waste of precious water, so we’re looking at installing an additional cylinder to store the hot water or may just run the hose into the bath so it gets dumped there instead.
  • We looked at solar options but our building budget didn’t stretch far enough so that’s something we can save for as it is quite easy to install solar retrospectively. It was going to cost close to an extra $50,000 for a stand-alone off-grid system or $20,000 for a decent grid-connected system.
  • We use the wood oven for nearly all our cooking – we have a BBQ outside that is used more in summertime and we have a few electric appliances like a slow cooker and rice cooker. We have a gas hob beside the wood stove but hardly ever use it, maybe in summer when we don’t have the fire going as long it will be used more. Ideally we’ll replace that gas hob with an electric option to reduce reliance on fossil fuels.
  • We used LED lights throughout the house – they are heaps more energy efficient, though a bit more expensive to start with. I did the lighting design which has turned out to be probably at least a third more lighting than we really needed as the LEDs I chose are brighter than I realised. We have dimmers on abut half of them so that saves power consumption as well as creating nicer lighting options.
  • We have polystyrene underfloor insulation and pink bats in the walls and ceiling. With more time and money we would’ve used wool or hemp insulation products.
  • The house is double-glazed aluminium windows and doors throughout. Aluminium isn’t very eco-friendly of course, but it is the most air-tight house we’ve ever lived in. Because of the double-glazing we just use custom-made vinyl roller blinds on most of the windows and doors as we have no need for thermal drapes. Vinyl isn’t very eco-friendly either.

Materials:

  •  The foundations are non-eco-friendly H4 treated pine and the external ‘ShadowClad‘ ply and flooring is H3 treated pine. Some nasty glue is used to seal the ply to the floor, wall and ceiling framing – along with a million nails. Ply uses a lot of nasty glues to seal the sheets of wood cut from the logs but we used untreated EcoPly for interior linings.
  • We were planning to use an Osmo eco-friendly natural oil product on the outside but had to send the 30 litres back after using over a litre for one coat on one of 80 sheets it was just too expensive. I used a water-based stain from Resene in the end.
  • The interior was finished with Aquatec Wood Coat by Cotec – a water-based polyurethane.
  • Our flooring is half synthetic carpet and half vinyl strips. In retrospect I wish we’d gone with the wool carpet but got talked out of it by the flooring guy. There wasn’t a huge difference in cost, it was more an aesthetic decision about how much it would fade in direct sunlight and a durability decision about how quickly it would wear out.
  • The roof is ColourSteel by New Zealand Steel, not the most eco-friendly option compared to something like a soil and grass living roof. The stormwater downpipes are recyclable PVC by Marley and feed two 30,000 PVC water tanks by Promax – who don’t seem to provide much sustainability information about their products.
  • The kitchen uses natural wood (macrocarpa) bench tops and plywood for the joinery facings with the standard chipboard for the internal linings. We reduced the need for hardware on kitchen joinery by cutting hand holes in the ply, but used standard aluminium hardware on all the internal doors.
  • The bathroom units are all fairly standard off the shelf products.
  • Decking timber is standard pine decking. We could have gone with Kwila decking but even though some of it has FSC accreditation, the products imported to NZ have had terrible environmental impacts.

I think in retrospect if we’d planned the build better by starting much earlier (like a year before we moved rather than after we moved into caravans so the pressure was on), then we would have made better environmental choices and/or saved more money to afford the eco-options or a longer build.

Anything else?

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