What's the cost of building green?

Michele Powles
What's the cost of building green?

Award winning author Michele Powles may not have any house building experience, but she and her family are learning fast. After buying a section in West Auckland last year, Michele and her husband James started the daunting building process and blogged about their experience on a Stuff blog How to build a house and on her website Building Boxes.

As she explains here, one of the big learning experiences was how to make the home as energy efficient as possible without blowing the budget. 


A growing trend

Building or buying a home with sustainable or environmentally friendly products in New Zealand is growing in popularity. Up around 15% according to a 3 year Homestar/RealEstate.co.nz survey. And as new home builders, we definitely wanted to incorporate as many environmentally smart principles as we could afford. But the key word in there is afford.Powles Family

Proponents of environmentally smart products, like Thomas van Raamsdonk from Proclima, argue that you can't afford not to make sure your house is as efficient and environmentally friendly as you can make it. A fierce advocate for ensuring architects and builders think about ventilation options to ensure Kiwi asthma rates drop, van Raamsdonk’s products do, however, cost more than traditional options.

SEE ALSO: No energy bill in 9 months: The 'ideal house' revolution

The argument is that over time the products pay for themselves, with benefits to health and your power bill. The trouble of course, is that it’s difficult to quantify those sorts of savings.

A build firm who is trying to do just that has recently completed a 230m2 home in Tauranga. Iain Gleaves, Commercial Manager of the Belvedere Group, says “We have calculated our 10 Homestar home would save the average 4-person Tauranga family $3,198.68 per year.”

While there is a cost, an 8-9% premium for the 10 star home compared to a comparative home with 7 stars, (which also provides energy savings,) year on year those sorts of savings stack up and make a real difference to the household budget.

House frame

A balancing act

In our build however, we had to make choices on the products we're using based on the initial cost now, as well as the cost recovery in the future. We've chosen to use a more expensive Zehnder heat recovery system to ensure we have a warm dry home, and have a Proclima airtightness membrane to make the absolute most of all the insulation we've put into the walls, ceiling and floor.

But we couldn't, for example, afford to include thermally broken windows in our design, (rather than standard double glazing) because the cost – an extra $10,000 – was just too much for our budget to handle.

It’s the same with solar panels. We plan on being in our new home for the long haul, 20 years if everything goes to plan, but even then we might not quite make back our investment in the current market. This differs to overseas payback periods because there are no feed-in tariffs for power in New Zealand.

However, environmental build technologies, especially solar, are developing quickly and dropping in cost, so we've chosen to build in the capacity for solar in the future, but not tip our budget over the edge for now.

Father and kids


Remember every house is unique

I mentioned Homestar earlier: an independent rating tool that measures and rates the performance of New Zealand homes. It estimates that there is only a 2.2% increase in the cost of bringing a standard Building Code compliant new house (about 3-4 stars) up to 6 stars. On that basis, it seems worth the investment to me.

However, this assumes you will build a certain type of home – likely one with smaller windows and certain types of products and layout.

In our build we wanted to make the most of the glorious southern view, while maximising the Northern sun. This meant bigger windows, and a bigger price tag.

We also had to deal with a sloping site and significant groundworks, and this dictated the design as much as our desire to use environmental materials. Using passive design principles on our site meant we poured a suspended concrete floor to ensure thermal mass, for example.

We'd estimate that the costs of following passive design principles and using sustainable materials has added an extra 15% to our overall budget, and that’s not going all the way with PV, and thermally broken windows.



A second opinion helps

Homestar advocate using their design principles at the very start of the design process, but as a very new system we went with our architect's (great) suggestions instead.

Homestar is a system set up for bigger developments too, so there are points available for building in a community setting (being within walking distance to amenities for example) which only certain types of buildings will be able to take advantage of. But as it gets more established, Homestar should provide a good guide for integrating energy savings and increasing the health of ordinary Kiwi homes.

For us then, we've tried to find a balance between the cost outlay now, and environmental efficiency in the long term. In a one off design I would estimate the cost of more efficiency is definitely more than 2.2%, but with so little empirical data to go on, it’s difficult to quantify exactly how much yet.

In my (non-expert) opinion though, I think there is the possibility to build green on a budget, you might just need to build smaller, be part of a development, and/or be selective on the materials involved depending on your build.


SEE ALSO: No energy bill in 9 months: The 'ideal house' revolution

Michele PowlesMichele Powles

Despite training in law (or perhaps because of it) Michele has been a dancer, choreographer, producer and all round arty type in various countries for most of her life.

A full time writer and full time mother (yes, that’s busy) Michele has published widely in New Zealand and overseas and was the 2010 Robert Burns Fellow.

She is currently penning a weekly column each Tuesday about her family’s house build project on stuff.co.nz and buildingboxes.co.nz.


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