Buying guide

What features should you look for in an eco home?

The benefits of having an eco-friendly home.

Just as you might be thinking your next car will be a more eco-friendly EV, for those with a reasonably good budget, you may also be mulling the idea of your next home being an eco home. A house that’s smarter about keeping you warm and dry and which, if done right, will repay you with low energy bills in the years to come.

How do you define an eco home? Put a search into Trade Me Property and a wide range of homes will spring up dating from the 1970s experiments to new builds and high end beauties.

A well-established eco home builder in Aotearoa, eHaus, has a handful of “eco values” that it likes to see in its homes. They should have a reduced footprint, be built with non-toxic materials and resource minimisation (reductions in energy, water, material and equipment use on the build). Ideally, the materials should be recyclable at the end of their life and the home will ideally be low maintenance too.

When creating an eco home, says University of Auckland senior architecture lecturer, Bill McKay, you’re constantly weighing up using one material against another.

When it comes to materials, there are a lot of options to consider, he says. What’s the carbon footprint when choosing between a concrete floor or a timber one? The concrete floor has a bigger carbon footprint but it can be used for passive heating, so it’s a balance. When building with timber you use a lot more plastic in the process, he says. Meanwhile, if you’re using steel, glass and aluminium, there’s a lot of carbon footprint in the manufacture of those materials so it’s about taking that into consideration.

The New Zealand Green Building Council is a good reference, advises the Auckland University senior lecturer. It has the Homestar rating system for new builds and the HomeFit one for existing homes. The Passive House Institute of NZ (PHINZ), which certifies passive houses, is another good resource for homeowners and builders. Eco homes are sometimes passive houses, which are all about passive heating and cooling, says Bill.

A certified passive house has to be wrapped in plastic and tested to be airtight. The idea is there should be an air exchange system but that the home is not losing heat. Passive housing is all about performance, explains the architecture lecturer.

The argument for having an eco home is it pays its own way and, if it’s not, well, you’re still doing your bit for the planet, adds Bill.

Start at the beginning when planning an eco house

Andrew La Grouw, Managing Director of Lockwood Homes, which has eco-smart homes, says an eco home starts with site design and good orientation for passive solar gain. Site works should be minimised and destruction of existing flora avoided.

The aim is for energy efficiency with these homes and how good the eco home is, depends on how well the thermal envelope is designed in order to minimise leaking, explains Andrew.

39 Coleridge Street, Cambridge, Waipa

Size matters, stresses the Lockwood MD. “A simple rule for eco-house design is that it’s much easier or more cost efficient to operate a thermally efficient home if the floor area is small to medium, say 180 sq m, excluding a garage,” says Andrew.

Materials are key. Timber sourced from renewable plantations is the most sustainable building material, he explains.

If timber is not an option, then the life cycle of the material should be considered. The Lockwood MD thinks the use of uPVC (unplasticised Poly Vinyl Chloride) in construction will rise because it offers better thermal performance, a lower carbon footprint and it’s recyclable at the end of its use.

An extra feature he would recommend for an eco-house would be rainwater collection, he says.

A Wellingtonian who built his own eco-home

Karl Wakelin is a sustainable design manager at architecture and engineering firm Stephenson & Turner and three years ago, he worked on his own eco home project in Wadestown, and has featured on Grand Designs NZ.

As the NZ Green Building Council describes in its case study on Karl and his family’s story, the house has rooftop rainwater harvesting, as well as 93% heat recovery ventilation, a fully insulated floating concrete slab, insulation which is double the code requirements, and an air tightness and vapour control layer, to name a few.

Karl says he really appreciates the dry and fresh air at home and the low energy bills.

Karl Wakelin's eco home that featured on Grand Designs NZ

“I truly believe my daughters sleep so well because of this, they wake up happy, it enhances their mood because they’re constantly getting nice fresh air,” he says.

The heat recovery ventilation system is like the lungs of the house, says Karl. “It brings in fresh air to all of the living spaces, the bedrooms, living and dining room and extracts air from the bathrooms, laundry and kitchen.”

“It’s 100% balanced so that the same amount of air is going out as is coming in,” explains Karl. An average house, by comparison, has very few air changes.

“You don’t have to open windows and lose energy but you can open the windows when it’s nice,” he adds.

If homes are air tight, he cautions, they must be ventilated appropriately. As the saying goes, “you build tight and ventilate right,” he explains.

Shouldn’t all homes be eco homes?

There’s an argument that any new build in Aotearoa should be an eco home. Karl says, from November this year, new houses will be much better insulated than previously. They won’t be eco houses because there are a few other things to incorporate, he explains. But he recommends, if you have a good building team and they’re insulating and ensuring air tightness, make sure they include a good heat recovery ventilation system.

Karl agrees with Andrew La Grouw, to keep an eye on how big to build your home.

Make it a 170 sq m home rather than a 200 sq m home and you’ll save yourself $90,000 that you can spend on other things, he suggests.

It is possible to retrofit your existing home to be more eco friendly but this can be a big job, he warns.

What are some of the main things eco home owners appreciate?

A new eHaus homeowner, Heather, is loving her eHaus eco home, in Kinloch, Taupo which she and her husband moved into in November last year.

“The more I live in it the more I love it,” says Heather.

The air quality is one of the real differences, they notice. “We went away for two weeks in the summer and when they came back, it still smelled fresh,” she says.

They have a heat recovery ventilation system, which means every three hours the air in the house is replenished.

“So there’s never a worry about mould and there’s very little dust,” says Heather.

“It’s like the difference between cotton and polyester,” says the project manager, whose previous home was a new build in Wellington.

Because Taupo has an alpine climate, the couple have gone for triple glazing with their windows to be on the safe side. They get a credit every month on their power bill, she says.

The couple have a soffit or overhang around the house which keeps it cool on hot days.

Heather has learned from her research with eHaus etc that rectangles and cubes are the best shape for eco houses because they have four corners.

Their home is near a forest and Heather says she wanted a home design that looked like part of the scenery. The home is north facing and, spread over 218 sq m, it has two wings, two bedrooms and bathrooms at each end so that when family come to stay everyone has their own space.

The couple, in their late 50s, have also gone solar at their single storey Kinloch home, with 20 solar panels.

“We haven’t paid an electricity bill yet, the hot water is through solar, and we did some extra things like put a water tank in for gardening just to make it reasonably efficient,” comments the former Wellingtonian.

You start to think differently in an eco home. Heather has shutters in part of the house for decorative appeal and she has some curtains to add a soft touch, but there’s no real need for them because there are no draughts in the cosy home, she says.

The responsibilities that come with being an eco home owner

If you want that great air quality, you’ve got to keep on top of the maintenance of the ventilation system and filters, says eco home owner, Lani, who has a beautiful eHaus home in Foxton.

“It’s super easy, quick and much more pleasant than prepping firewood, dealing with damp air and spending mornings wiping condensation off the windows as we’ve done in previous homes, like many New Zealanders I imagine,” she says.

A big game changer for the couple was how consistent the air temperature is across the whole house, adds Lani. “No longer are we confined to the living area huddled around the fire trying to stay warm in winter, avoiding going into the cold parts of the house.”

39 Coleridge Street, Cambridge, Waipa

The couple had lived in a newly built home prior to their eHaus and even that fell victim to heating issues. It was difficult to keep heated in winter and in summer, prone to overheating, so new doesn’t necessarily mean better, she notes.

A particular feature that Lani enjoys is the protection the home gives them against the elements, which will make Wellingtonians prick up their ears.

“Our home is on a very exposed, windy coastal hill and, as I write this, the weather is crazy outside, but it still feels cosy and quiet in here,” says the eHaus homeowner..

“The only downside is that I often underdress when healing out as I don’t realise how bad the weather is outside sometimes!” she adds.

What kind of budget do you need for an eco home?

There’s no doubt, you do have to have a bit more money to spend on an eco home. Jon Iliffe, DesignHaus director and co-founder of eHaus, says that an eco home compared with the cost to do a newly built home that’s being individually built and designed, would probably be another 15% more expensive.

There are more materials because the walls are three times thicker, he explains. At the same time, the home will likely be smaller than a typical new build.

As for the running of the home, energy bills will be that much more reasonable so it’s about the long term value, argues Jon, a member of the Passive House Institute .

Around 40% of the eHaus clients are downsizing and building their forever home, and they don’t want to be wasting money on heating but want guaranteed comfort, explains the design director.

“It’s all about resilience,” says Jon. Once you’ve set the building up, it doesn’t take much energy to maintain it. When you have thin walls with not much insulation in the roof and aluminium joinery, then you’re at the whim of the outside temperature, he explains.

“That’s all we’re doing, building a fabric that helps isolate that temperature difference,” he adds.

Resale of eco homes

The good news is, if you have one of these homes, they “punch above their weight” when it comes to resale, according to Jon.

The best time to sell is in the winter when you can show the power bills and the fact it’s warm in every room. It speaks volumes.

One eHaus home built several years ago in Christchurch with a $900,000 building cost, sold for $2.5 million three years later. It was a 250 sq m, four bedroom home including a garage.

What an agent says

Cambridge, in the Waikato, has more than its fair share of eco homes, thanks to initiatives like the St Kilda housing subdivision which specialises in eco friendly homes with close access to wetland paths.

According to More-Re agent Peter Tong, each house has been designed with eco in mind with covenants in place to ensure the homes have certain features like solar power and north facing living areas, among other things. In one home he’s selling, there’s a water tank which takes rain water alongside town water, the roof water supplying outside taps, toilets and the laundry.

47 Baxter Michael Crescent, Cambridge

“To set up a home in St Kilda would probably have cost an extra $100,000 to $150,000 because of the eco side, but once it’s there, it’s just a dream,” says Peter.

He’s selling two five-year-old eco homes in St Kilda and the larger of the two has a childrens’ lounge which was designed to get the children out of their bedrooms to play in an open area rather than in their rooms.

“Eco is also about lifestyle,” says the Cambridge agent.