Written by Vicki Holder
Designing a sustainable future
Rising land and water temperatures, wildfires, and droughts are among the climate changes that are becoming regular events around Aotearoa New Zealand. Many of these are the direct result of human activities that cause greenhouse gas emissions – our building industry, for example, is estimated to be directly and indirectly responsible for up to 20 percent of New Zealand’s greenhouse gas emissions.
In 2019, Auckland Council declared a climate emergency to focus on the threat climate change poses to the economy, our environment and way of life. Te Tāruke-ā-Tāwhiri: Auckland’s Climate Action Plan followed with a pathway to reduce greenhouse gas emissions by 50 percent by 2030 and achieve net-zero by 2050.
Auckland’s Unitary Plan encourages a more compact city as one response to tackling emissions, providing people with walking, cycling and public transport options. The council is also proposing new transport and infrastructure options, planting more trees and forests, increasing the zero waste recovery network and encouraging energy efficiency and emissions reduction, funded (between now and 2031) through rates and greater debt.
Critical to this plan is how our built environment performs. Around 1.66 million people live in Auckland. By 2050 the city’s population could reach 2.4 million. To accommodate this growth, Auckland’s built environment will have to change significantly. The decisions we make now determine the extent to which we can have an impact on future emissions, and our exposure to climate risks.
Over the next 10 years, Auckland’s architects will shoulder a huge responsibility for improving the performance of new and existing buildings to support a low-carbon, climate-resilient future. So, are they doing enough to deliver a more sustainable built environment?
Kate Rogan and Eva Nash – Rogan Nash Architects
Sustainability is a fundamental part of the office mantra for Kate Rogan and Eva Nash of Rogan Nash Architects.
This practice aims to deliver innovative and flexible design solutions that support sustainability wherever possible.
“Many of our clients ask for sustainable features, but it’s something we adopt in all our designs anyway,” they say. Eva has a Master degree in Residential Sustainability in addition to her two architectural degrees, so is well-equipped with specific knowledge in this area.
“We bring sustainability into every aspect of the design. It’s something we introduce early in our briefing sessions,” she says.
“In all our projects, we use passive solar principles – obvious things like thermal mass, orienting the building towards the sun and making sure it faces the right direction to encourage air movement,” says Kate.
“For example, in our Bookends project in Waipu, we utilised a concrete slab as a heat store. We put louvres in front so the high summer sun doesn’t reach the concrete slab, keeping it cool in summer. But, in winter, the sun reaches the slab, which holds onto the solar energy for when you need it.
“With the correct orientation, the building is able to capture the sun from the right direction.
“We also put solar panels on the roof to generate electricity and provide hot water. A high level of insulation throughout the house reduces heating requirements. Deep overhangs on the westerly aspect mean there’s no overheating from that angle. Double glazing is a given, of course.“
But they also consider the embodied energy of the building. These are the less obvious, behind-the-scenes aspects that clients may not be aware of. Materials selection is always based on sustainability, whether it’s in Auckland or elsewhere.
“If we use cedar cladding,” says Eva, “we think about how the timber was milled, where it was milled, and how far it has to travel to the site. It’s about the energy needed to get there. We look at all the processes used for making the materials and how they do the finishes.
“For the Bookend house, we used pine weatherboards because they were made in New Zealand and were readily available.”
Such considerations are always integrated into their designs. Then, there are the details that Eva calls add-ons, like photovoltaic panels and solar heating, rainwater catchment systems, and systems for processing sewage.
“We have a lot of projects that have these add-ons, especially outside Auckland. We have used them in Auckland as well, but it’s trickier in an urban context where there’s less space.”
And sustainability doesn’t just apply to new homes. When they’re working on renovations, they think about how to improve the existing home as well, upgrading the insulation and adding double glazing and efficient heating systems.
“It’s a step in the right direction to making it a healthy home,” says Kate.
When a client is thinking about a renovation, sustainability might seem like an expensive add-on. But Kate and Eva say any of these extras are going to improve the house.
Eva says that eventually, the government will force people to make changes to improve their sustainability. However, the ideas are already being introduced gradually.
“There was an outcry when double glazing was introduced. Now it’s accepted because people can see the benefits. The same thing happened when fireplaces became more energy efficient, with less emissions.
“On some of the gulf islands the council makes homeowners collect rainwater. People don’t realise that with decisions like this they’re already building more sustainable homes.”
Then there is the challenge of disposing of construction waste. The New Zealand Green Building Council says construction waste makes up around 50 percent of the waste going to landfills.
Kate and Eva always suggest to clients when they’re demolishing existing homes or parts of them to try to get a second life out of materials like kitchen cabinetry and glazing, which can be recycled. They encourage clients to use Green Gorilla, a waste management company that separates and sorts building materials like timber, gypsum and copper at its waste processing facility in Auckland.
“They’re about the same price as other rubbish collectors because they sell the waste parts for profit. There are whole industries developing as a result of this re-use initiative.”
As well as considering the bigger picture in their architecture, Kate and Eva also focus on the details. When they’re talking kitchens, they look at where and how to include composting bins. When they’re designing a garage, they consider where the EV charger will go.
“We bring it into every aspect of the design,” says Kate. “There are lots of simple things you can do. It’s like with the plastic bags, even though it’s a simple change, if we all do it, it makes a difference. We should all adopt sustainable ideas in our homes. We can lead by example. If we make good choices, there’s a follow on.”
Dave Strachan – Strachan Group Architects
In 2020, Dave Strachan was awarded a gold medal by the New Zealand Institute of Architects for his contribution to architecture. His multi-award-winning practice is known for its highly detailed sense of craft in developing sustainable, elegant designs.
His own home in Mt Eden already meets the Royal Institute of British Architects (RIBA) 2030 Sustainable Outcomes Guide for water and energy use. It offers many lessons on how to create a beautiful, eco-friendly, living environment.
Partially using thermal mass, the solid concrete components of the home make the most of the sun, soaking up heat during the day and radiating it at night. Double layers of German ‘super insulation’ and a heat pump-operated, hot water, hydronic heating system keep the home warm. To cope with dry Auckland summers, tanks hold 15,000 litres of rainwater, and solar panels are fixed on the roof.
Rather than having lawns that need to be mown, creating carbon emissions and requiring water and fertiliser, coprosma ground covers are used in the garden.
Dave is living the sustainability dream, and since 2000 his practice has had a 12-point matrix of sustainability goals that it tries to apply to most of its projects – such as minimising CO2 emissions, energy demand and resource use, responding to the climate, selecting materials based on life-cycle analysis, reducing, recycling, collecting and creating healthy environments. Good ventilation practices ensure SGA homes maximise natural air conditioners and breezeways by drawing breezes across the surface of water or through vegetation to pre-condition and cool air in the hotter months.
In the past five years, Dave’s seen many changes to residential architecture in Auckland.
“There are higher standards of thermal performance for homes such as the Homestar rating, while other performance standards set better targets for water use and solar generation, and many homes are being located near public transport as a result of the Unitary Plan densification.”
Gaining traction, too, is the German Passiv Haus system. “That’s primarily focused on an incredibly airtight thermal envelope for buildings with Mechanical Heat Recovery Ventilation (MHRV) systems that use excess energy and control air flows in and out of buildings.”
He says architects are now having to confront issues of sustainability beyond just using LED lights. The NZIA even has a sustainability statement as part of the Awards submissions, with measurable factors so it’s not just “greenwash”, and includes looking at the embodied energy used in building construction.
Although the government has a policy on sustainable architecture, he says that no government will ever sort out the climate problems that we face. “It must be driven by the people and the industry.”
And the biggest roadblock to the uptake of sustainable building, he says, is affordability. “With the New Zealand material supply chain duopoly and Covid-related shipping costs, the prices of building products have trebled. So putting capital into buildings to promote better performance and the embodied energy picture either can’t happen or doesn’t get priority.”
Jonathan Smith – Matter Architects
Jonathan Smith believes architects are generally very aware of the need to improve sustainability levels in the building industry. He says, in many cases, they lead the way, from providing sustainable design through to methodologies on site.
“Architecture is a dichotomy of sustainable ideas working in an industry of consumption. Good architecture responds to the context of the site, the conditions and the client, allowing homes to work with the environment. As with all industries, the execution of these design formatives results in the use of resources and creates waste.”
The good thing, he says, is the shift in consciousness among clients who are now aware of the need for sustainability and the need to make changes on the micro that apply pressure on the macro, from heating through to cladding.
“In our industry, we’re in a fantastic position to provide input on all the options.”
But, he adds, we can always do more.
“Initially, we can continue to refine our practices, reduce wastage on site, build more efficiently, and work with local materials. Many systems can be applied to measure the success of a building and the impact it is having on the environment.”
Building for the long term, not just for the next 50 years, is important. He also thinks architects should get involved at government policy level to ensure equality of living standards, and they should take a harder line with material and spatial requests. Though, he says, it’s a fine line to balance desires and investment.
As a practice, Matter Architects is always reflecting on the way it practices, reducing wastage on site, building more efficiently and working with local materials.
For homeowners, the best time to begin the sustainability conversation is right at the start of the project, whether it’s working with an architect on a new build or renovating a home.
Sustainability was a driving force in its Railway House, in particular prioritising retaining the existing home and materials as much as possible. Timber wall framing was removed, reconditioned and re-used as benchtops and exposed timber slats and battening.
Litecrete panels were chosen for their thermal mass, pre-cast and insulation properties. The panels were also used to mitigate privacy and sound, and set up a discourse between old and new.
“On one of our current sites, we are working with the main contractor to improve awareness and educate the workforce on construction waste management, with the provision of waste skips for specific materials (waste segregation). Where possible, standardising design and materials also helps reduce wastage.”
Over the last five years, Matter has observed big changes in client and supplier awareness. “Today, people are more willing to consider and implement sustainable options where possible,” says Jonathan.
Everyone – homeowners and those in the building industry – can make a personal contribution to ensure we’re building energy-efficient homes, reducing carbon emissions, and working together towards creating a more liveable city for future generations.
Questions to ask your architect
• Do you have a sustainability or passive house accreditation?
• What sustainable design processes do you use?
• Do you source materials locally?
• How can we recycle existing materials?
• What other eco-friendly systems can we add to our home?
• How do you minimise waste on site?