Design and drama may take centre stage on The Block NZ but the quiet hero of this year’s homes are the eco-friendly elements. The Block NZ site foreman Peter Wolfkamp talks us through the details
The Block NZ 2017 is embracing high-density living with four teams building semi-detached terrace housing in Northcote, Auckland. While not typical eco-builds, this year’s properties go above and beyond the Building Code. Site foreman Peter Wolfkamp fills us in on the eco-friendly systems and materials adopted by this season’s crews – from adding extra insulation to installing rooftop gardens – and we also suggest a few extra ways to make your home or renovation more eco-friendly.
If you are building new or extensively renovating, the cladding you choose can make a difference. “The exterior of The Block NZ homes have a mixture of different cladding types including brick, cedar and Shadowclad, a plywood product,” says Peter. “The great benefit of plywood is that it uses more of the log, so as a cladding type it is actually quite environmentally friendly.”
Ensure your home is well insulated by waterproofing thoroughly, suggests Peter. At The Block “there is extremely good waterproofing underneath the slabs so the concrete slab is not in contact with the ground and the building does not lose as much heat”. This includes a polystyrene layer underneath the concrete and a waterproof membrane.
Double-glazed windows are essential for thermal retention and are required in all new-builds. The windows in The Block houses have been double glazed with low-E (low-emissivity) glass which is more thermally efficient than standard double glazing. “Double glazing works in two ways,” explains Peter. “Whether it’s warm outside and you want to keep the house cool, or it’s 7°C or 8°C outside and you want your house to be a nice, toasty 21°C, double glazing will be far more effective at stopping or reducing the transfer of heat.”
“This year The Block site focuses on high-density living (in semi-detached terrace houses) rather than the quarter-acre dream,” explains Peter. “For growing cities like Auckland and many other main centres, this is the future. This effectively is The Block meets the Auckland Unitary Plan – where before there was one three-bedroom dwelling on the property, there will now be four family homes, each 250 square metres in total. It’s a lot more people on the same amount of land, which is intensification.
“One of the great features of the homes is going to be the rooftop terraces. Admittedly, our site coverage is greater than we would normally expect, so the trade-off for that is to give each of the homes its own roof terrace to allow occupants to enjoy fresh air and views and potentially homegrown veges.”
The Building Code is often seen as an acceptable standard while others regard it as the bare minimum and always aim to go “above spec” (ie use materials that perform at a higher level than the legislated requirement). This is why choosing builders and designers with a track record in sustainability can help to make sure your home is as environmentally friendly as possible. “
Unless you’ve got a passive house certification, there are no eco credentials as such,” says Peter. “Increasingly we are starting to see builders adopt some of the principles found in the New Zealand Green Building Council’s Homestar scheme. But I have to say that we’ve got a long way to go. There are various rating schemes available for materials. Locally sourced materials would get a higher rating and imported materials would potentially get a lower rating.”
Central heating is an efficient way of heating a space and an effective way of transferring heat from a source to a room, says Peter. “If you’re blowing hot air through a pipe, you lose a lot of energy in the pipe. But this way we are circulating hot water throughout the house and receiving the maximum benefits when it hits the radiator.
The radiator system that we’re using is probably my favourite in terms of heating sources. It runs off a gas-fired boiler, is a very efficient form of heating, and is really nice, quiet and still. This is combined with the insulation and double glazing, and the fact that we use 13mm Gib plasterboard throughout the house instead of 10mm (thicker walls mean more heat retention).”
A warm, dry house is essential and spending more on insulation will help to save on heating and maintenance costs. At The Block NZ, builders have installed high-performing Knauf Earthwool Glasswool throughout the buildings at a higher spec than required, says Peter, reducing noise pollution as well as heat loss.
“In many areas we’ve used 140mm x 45mm framing which allows us to put more insulation into the exterior walls,” he says. “All the internal frames in all levels of the building are insulated well above the code, so instead of using R2.6 we’re using R2.9 and instead of R3.8 we’re using R4.1. Right throughout the building we’re doing more insulation than is required by the Building Code.
“Most New Zealand houses don’t have insulation in their internal walls or mid-floors, because you technically only have to insulate the exterior of the building. We’ve insulated everything. It makes individual rooms warmer and easier to heat. The other benefit is that it makes houses quieter, and I think we underestimate the impact of noise pollution inside houses. If you can hear somebody taking a shower or you can hear the kids’ music, those sorts of things make for a less enjoyable living experience.
“Being able to use 13mm plasterboard gives us one-third more thickness on both sides of each wall. We’ve used Ecoply Barrier (a rigid air-barrier system behind the cladding) on the exterior of the house, which helps to seal the building more effectively. The air barrier gives us weathertightness really early on in the process so the building starts to dry out a lot earlier. I think it’s more robust than a traditional building wrap and it gives us extra thickness on the outside of the building. And while it’s not part of the insulation calculations, I actually believe that it does help.”
Green space is important, especially as our cities become more densely populated. The Block NZ houses each have rooftop gardens, which the teams will be able to customise. “There is an option for the contestants to harvest rainwater, even if it’s as simple as having a small tank which water from the roofs can be diverted into. That way, in summer when you’re watering your vege patch or herb garden, you’re not actually drawing resources from the water system,” says Peter.
“We might also see people doing some composting, and I expect that most people today want the option of being able to go into the garden and take a couple of veges. It doesn’t have to be a big area – even a square metre will help feed a family.”
Rebuild vs renovation
While renovating can be more sustainable than building new in terms of the quantity of materials and resources required, a new-build can be more energy-efficient in the long run. “In the end, you have too many compromises during renovation unless your renovation is a rebuild,” says Peter.
“The great advantage of being able to do a new-build is that every step of the way you can be thinking, ‘Where is my house going to leak air?’, ‘What can I do to increase the thermal performance of the building?’ or ‘What can I do over and above the Building Code to get better performance?’. One thing we’ve done consistently in this build is to say, ‘Okay, we know what the minimum standard is – let’s go above that.”
Easy ways to be eco-friendly at home (even if you’re not renovating)
- Use high-energy appliances such as dryers at off-peak energy-consumption times (eg 11pm-7am). Some power companies offer cheaper power (or even a free hour) at these times.
- Dry your washing outside when possible.
- Use natural products for cleaning, laundry, gardening and toiletries.
- Reduce water and heating costs by minimising how many loads of washing and dishes you do; and do laundry on a cold wash.
- Have shorter showers.
- Invest in good-quality insulating curtains.
- Turn lights off when not in use and don’t keep appliances in standby mode (turn them off at the wall).
- Swap single-use plastic bags and packaging for reusable bags and containers.
- Switch plastic straws for paper or metal ones.
- Purchase items (even toilet paper and toothbrushes) made from recycled or sustainable materials such as bamboo.
- Recycle, reuse and compost.
- Buy less – try to only buy what you need.
- Replace disposable dish cloths with washable cloths or rags.
- Plant a vegetable garden and some fruit trees.
- Use energy-saving light bulbs.
- Install extractor fans and ensure appliances are vented in the bathroom, kitchen and laundry.
- Check your hot water temperature and lower the thermostat if too hot.
- Block draughts around doors and windows; seal an unused fireplace.
Top tips for renovating
- Insulate your ceiling or loft as well as walls and floors.
- Consider low-flush or composting toilets, grey-water recycling, rain harvesting, passive solar design (designing your home around the sun) and solar heating.
- Build smaller homes and avoid unnecessary renovations.
- See energywise.govt.nz for tips and information about the Warm Up New Zealand: Healthy Homes insulation grants available for low-income homeowners and some landlords.
- Use locally sourced building materials and local tradesmen where possible (cuts down on petrol use/emissions).
- Purchase recycled or sustainably produced homeware, furniture and building materials.
- Make sure materials, paints and finishes are safe and environmentally friendly.
- Choose durable products that will last.
- Ask your builder to recycle where possible. Demolition and building materials can be sold on Trade Me or donated to a reuse shop at the landfill.
- Visit ecodesignadvisor.org.
Created by: Fiona Ralph. Photography by: Tom Hollow.