How to avoid common sustainable design mistakes
Making mistakes in a building project can cost time and money, and leave you well short of the energy-efficient home you planned for. Verity Campbell asks four experienced designers about their top tips for avoiding the most common pitfalls.
Building or renovating a home can be stressful. There are many things that can, and do, go wrong: subterranean ‘surprises’ when the first sod is turned, challenges getting the design through planning regulations, and budget and time blowouts, to name a few.
Aiming for a green home adds another layer of difficulty, so here are some tips from the experts to help you achieve a smoother, more enjoyable and stress-free project.
The first step to getting it right is finding the right team to work with, says Simone from Gruen Eco Design. You need to separate those claiming sustainable design knowledge from those who actually have it. “If a designer or architect says ‘we’re going to put in a rainwater tank and solar hot water and have a six-star house,’ that’s already a good indication they don’t know what they’re talking about,” she says. And if they tell you that all you need is the legal minimum requirement for insulation, you know they’re not aiming for best practice. You need an architect or designer who knows everything there is to know about passive solar design.
Another thing to look out for is cost cutting. “When you have a limited budget, you sometimes have to be innovative or more involved in the whole process if you want to build a really energy efficient house.” This means being involved in sourcing materials, including checking from the outset how amenable the builder is to using salvaged materials or to get your preferred companies (third parties) involved in the construction. It might also mean overseeing the window company to get your new highly energy efficient double-glazed windows installed properly to guarantee their performance. “Some builders are a bit hesitant about this when it comes to their insurance and their warranties.”
Simone recommends you make sure insulation and gap sealing is done properly during the build, to ensure that the performance you’re paying for and expecting is the performance you’ll receive. She says you should insist insulation be checked onsite, and audited if possible. “I would recommend engaging specialist insulation contractors – a third party – to install and certify the insulation.”
Sid Thoo from Sid Thoo Architects says it can help to choose a builder who has a portfolio of sustainable homes. “However, this is no guarantee in itself,” he cautions. “I was once involved in a project where the builder appeared to have a strong history, but it turned out it was the business partner, who had left, who actually had the experience.” And, he advises, don’t overlook the younger generation of builders who are passionate about building more sustainably, even though they may not have much experience.
Sid also suggests homeowners ask “pointy” questions of prospective architects or designers in those early meetings. Questions like: “How will you manage construction waste on site? Will you spend the time to get multiple quotes? Do you know about more sustainable options or selections?”
When putting together the design brief, Sid recommends homeowners identify priorities and must-haves, and budget accordingly. His tip is to create two lists: “One that contains things you absolutely must have in the project (that you aren’t prepared to compromise on), and a wishlist of things you would really like to have, in order of priority, but can live without.”
For the essential items, get cost estimates and prices as soon as possible and clearly identify what brand, size, model et cetera you want, to ensure these are factored into the construction cost estimates. “If any budget issues come up (and they often do), knowing that these items have been allowed for helps to ensure they don’t get left out.
“Don’t assume anything: it has to be specified/identified/noted, or it will be missed!” says Sid. Your architect or building designer will create construction specifications that list all the finishes, materials, fixtures and fittings you want to include in the build. You need to make sure these specifications are comprehensive. “There are many standard or ‘off the shelf’ specifications in use by industry, but when it comes to sustainability and water and energy efficiency inclusions, you’ll really have to write your own to make sure you get exactly what you want.”
Guild Architects’ Penny Guild says it’s important people understand the difference between thermal mass and insulation to help them choose the right architect or designer to work with and to ensure they end up with a home that is thermally comfortable year round.
Penny gives examples of homeowners who have lived in Victorian brick homes, remembering how cool they stay in summer. “They think that’s the brick acting as an insulator, whereas it’s actually the brick acting as thermal mass (and once it heats up it will take a long time to cool down),” she says. The confusion is completely understandable, though: “When I’m tutoring, I see architecture students struggle with the difference between mass and insulation, and I think a lot of architects don’t fully understand the difference either.”
People need to be aware that requesting a brick house with lots of concrete and expecting it to be thermally comfortable year round can be challenging. “You’ve got to be thoughtful about where the mass is and whether it can be exposed to sun or other passive heating source in winter particularly. And if you’ve got mass, it’s got to be insulated on the external side,” she adds. And don’t forget that in cooler climates, heating is the larger part of the energy load on your house: too much glass on a cold night is going to “suck all the heat out of the room”.
Penny also advises homeowners to think about how, where or even if they will use timber. “Everyone loves the look of timber,” she says, “but you have to understand how much maintenance timber requires.” Clear finishes on exposed external walls require refinishing at least every year, if not more often. The orientation of your wall will also affect how much maintenance it will need, she says. This means the building will weather differently – and even if you opt for a low maintenance, natural finish that greys over time, you’re still going to get uneven weathering. “Anywhere there’s an eave is going to weather differently to walls without eaves.”
“Timber sourcing is a really interesting one, too,” she adds. “It’s really hard to source sustainable hardwood timber in Australia. Every timber supplier says their timber is ‘sustainably sourced’ and there’s a lot of greenwash.” Penny recommends people consider opting for other timber products such as recycled timber, finger-jointed Australian-grown plantation pine, or composite and reconstituted products that ensure every part of the tree is used.
Sven from Maxa Design says homeowners should look out for the hidden costs of using recycled and reclaimed materials. “It seems like a great idea – which it is – to use reclaimed and recycled materials in a project, but homeowners need to be aware that using these materials can increase labour costs.” Laying recycled bricks takes more time and mortar; reclaiming floorboards is a painstaking process of removal plank by plank, then removing nails and preparing the boards for relaying.
If you’re an owner builder, says Sven, you can source, clean and stack recycled materials for your projects – and save on labour costs that way. Or a good half measure, he suggests, is to purchase reclaimed or recycled materials ready for use. “There’s not a huge supply, but they’re ready to go,” he says.
Sven also recommends homeowners make sure they look into minimum allowable house sizes when moving into estates or borrowing from banks. “Sometimes you can’t build a house less than a certain size (large!) in an estate and a bank won’t loan you money for a new build unless it meets the banks expectations on size and cost.”
He also recommends homeowners and their designers make proper allowances for sustainable technology from the earliest stages of design. “There’s no use deciding on a 10kW solar panel system if you haven’t allocated the roof area or right roof aspect in the design,” he says. Just as there’s no use wanting a blackwater waste treatment system if you haven’t given due consideration to access on the site. “It’s important when you’re meeting prospective designers for the first time that you’re asking these questions, and looking for their experience in these areas,” says Sven.
He also suggests homeowners look to the future when planning their build or renovation. “We advocate for a fabric-first approach. Forget the interior finishes to a degree and invest in a great quality build with the best windows you can afford. You can renovate a home over time but, realistically, you are never going to redo that fabric. Build it once with really good integrity and you’ve got great bones to build on into the future.”
Experienced owner-builder Megan Waru from Home Base explains how to get started, and the importance of like-minded support networks.Read more