The climate crisis is encouraging some property owners, developers and tenants to retrofit, not demolish older buildings. The Government needs to do more.
Number one Queen Street is prime downtown real estate. Opposite the harbour, and next to the new $1 billion Commercial Bay precinct and PwC Tower, the 1972 building “looked like it’s built to withstand a nuclear attack”, says Alain McKinney, project director at building owner and developer Precinct Properties.
That’s probably not a compliment.
When it came to deciding what to do with the half-century-old tower, the usual thing to do would have been to demolish and rebuild. Architects get a blank slate for a new concept, engineers get the opportunity for modern, energy-efficient design.
But that’s not what Precinct Properties decided. Instead the company chose a two-year, $300 million refurbishment of the old building – keeping the core structure and then putting a new and more energy efficient exterior around it. The building should be finished by the end of the year.
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One of the main key reasons for the decision to refurbish, not demolish and rebuild, was trying to reduce the carbon footprint of the project. More precisely, the 'embodied carbon' footprint.
Embodied, also called 'embedded' carbon, involves all the emissions that go into putting up a building: from the extraction, production and transport of building materials, through the construction phase, to the process of deconstructing and disposing of materials.
In the case of One Queen Street, 48 percent of the embodied carbon comes from the energy that's gone into the superstructure, and another 17 percent for the substructure, Precinct's McKinney says. The facade generated 16 percent, the mechanical, electrical and plumbing systems soaked up 15 percent, and the internal finishes the final 4 percent.
The embedded carbon already in an existing building, plus what's needed for a newly-constructed one, is the reason retrofits are so much more carbon-friendly than demolition/rebuilds
In the case of One Queen Street, there was more than double the amount of emissions involved a new build, as the graphic below shows.
That’s the equivalent of planting 43 rugby fields with NZ native forest, McKinney says.
“We realised we had to look at embodied carbon. It made our decision quite straightforward.”
Multiply that by all the buildings in New Zealand, and the numbers are significant. Our ‘built environment’ - buildings and infrastructure - is responsible for 20 percent of the country's carbon footprint, according to figures from the NZ Green Building Council. Emissions from the construction industry increased 66 percent between 2007 and 2017.
Until recently, the main focus for reducing the greenhouse gas in buildings has been around operational carbon - the fossil fuels from our heating, cooling and ventilation systems. Switching from coal or natural gas to electricity for boilers, for example, or improving window insulation so less energy is lost.
But it turns out operational carbon is only half the picture. The other half of the emissions in our buildings are embedded into the structure before anyone even moves in.
And as the world pushes to reach net zero emissions by 2050, things are starting to change in the property sector. In some countries it’s getting increasingly difficult to demolish and rebuild commercial buildings because of the problem of embodied carbon, says Andrew Eagles, chief executive of the NZ Green Building Council.
Late last week the council launched an Embodied Carbon Calculator – the result of 18 months liaising with industry and scientists to come up with a robust formula for exactly how to measure the embodied carbon in, say, a metre of timber or a length of reinforcing steel.
There are calculators in the market already, Eagles says. But three different products might come up with three significantly different calculations - like 50-60 percent different. And that makes it difficult for property owners, developers, architects or regulators to compare different designs and materials when looking for a more environmental solution.
Accurate embodied carbon measurement will only become more important. The latest version of NZGBC’s Green Star commercial building scheme expects teams to prove a reduction in upfront embodied carbon of 10 percent before they get a rating, with higher reductions rewarded with more points.
Meanwhile from 2025, MBIE will start asking for embodied carbon figures for new builds and some refits. Some time later - perhaps 2028 - they will look for reductions, Eagles says.
The World Green Business Council, which champions best practice globally, is calling for all new buildings, infrastructure and renovations to have at least 40 percent less embodied carbon by 2030, and to be net zero in terms of embodied carbon by 2050.
Increasing numbers of property owners, tenants and manufacturers of building materials are starting to put embodied carbon into their calculations, but in many places, including New Zealand, regulation is lagging behind.
Three years after MBIE talked about reductions in operational carbon, industry is still waiting for certainty around exactly how the Government is going to measure that, Eagles says.
So he’s not holding his breath on embodied carbon.
“They need to clarify what they are thinking. If they continue this delay, the sector is not going to be ready.”
There are things the government and councils could do relatively easily to get property owners and developers thinking hard about embodied carbon and putting it into their construction calculations, Eagles says.
They include making sure the tax system incentivises retrofits, not demolition and rebuilding. The opposite can sometimes be the case at the moment.
Second, officials could use subsidy programmes to encourage lower carbon buildings and retrofits – in much the same way the electric vehicles scheme encourages low emissions cars.
Wellington City Council’s Environmental and Accessibility Performance Fund provides up to $500,000 to recognise the strategic importance of green certified buildings.
