Demolishing and rebuilding commercial property generates massive amounts of carbon pollution. Building regeneration can be a cheaper, greener option that can deliver a better result than new construction. Beca’s Ben Masters presents the environmental and business case for up-cycling our existing building stock.
A recent report has suggested buildings could be belching out 20% of New Zealand’s carbon pollution, rather than the previously estimated 2-5%. The new estimate is so much higher because it includes building construction: the impact of extracting raw materials, manufacturing components and treating construction waste.
In response, the New Zealand Green Building Council is now flagging building construction as a "hugely significant" area for action on climate change. To date, this action has largely seen new projects consider the emissions inherent in new construction materials.
While this is all very laudable, it’s kind of missing the point.
If our current property market trend is contributing so much to our carbon footprint, surely we should look for other options to provide the commercial buildings people want – options that don’t involve new construction at all…
Greening existing properties with minimal carbon emissions
Rather than turning our cities into building sites, why aren’t we up-cycling our existing building stock first?
At Beca, we’ve proved that you can regenerate an unloved, untenantable building to create a fantastic 5.5 Star NABERSNZ-rated building that tenants love. And, you can do this at far less cost and with far fewer carbon emissions than demolishing and building anew.
Delivering award-winning environmental performance
Last week, our regenerated Wellington office, Aorangi House, won the Leadership in Sustainable Design & Performance Award in the Commercial category, as part of the World Green Building Council’s Asia Pacific Leadership in Green Building Awards.
In 2005, the original 1970s building had been vacated due to issues with heating, cooling and ventilation. The single-glazed windows leaked, and the complete lack of insulation made the building unbearable in winter. The property was about to be slated for demolition, when a design team of Beca building services engineers and Studio Pacific Architects suggested all the building’s issues could be solved with a major refurbishment using a passive solar design approach:
- Natural ventilation – with both manual and automated opening windows, which is still rare for a 12 storey building
- Solar gain control – with new solar control double glazing and external solar shading to improve natural ventilation performance
- Reduced heat loss – with external wall insulation applied to the existing concrete structure and concrete walls and soffits left exposed internally to, again, improve natural ventilation performance.
This strategy significantly minimised the energy required to control environmental conditions.
Continuous Monitoring & Building Tuning
Unlike most new buildings, where energy efficiency quickly falls apart, continuous building tuning has reduced energy consumption and greenhouse gas emissions even further. Along with improvements to heating, ventilation and lighting controls, replacing the fossil fuel gas boiler with much more carbon-efficient heat pump plant has significantly reduced emissions.
The regenerated building now consumes 64% less energy than a typical NZ office building! In fact, the revitalised building has a better energy performance than most new commercial properties. Aorangi House is NZ’s first certified refurbished building to achieve a 5.5 Star NABERSNZ energy performance certification.
Creating buildings that improve tenants’ comfort and wellbeing
A true measure of a sustainable building must also consider users’ perceptions. Aorangi House is not just energy-efficient, it’s also beloved by building users. An internationally recognised (BUS) Post Occupancy Evaluation by Victoria University measured tenants’ perceptions of a range of factors: from temperature, air quality and lighting; to health and productivity. The building received excellent ratings in terms of overall comfort and its perceived influence on users’ health and productivity, placing Aorangi House at the top overall of the NZ dataset.
Avoiding energy and emissions from rebuilding
The regeneration project also saved significant embodied energy and embodied emissions compared to a new construction project, avoiding:
- 662 tonnes of embodied CO2-e emissions that would have come from new concrete and steel structure
- 2,870 tonnes of demolition waste that would otherwise have gone into landfill
- 10 million litres of potable water that would have been needed for new concrete.
Every seismic upgrade is a regeneration opportunity
Right now, hundreds of earthquake-prone buildings in Wellington are listed for seismic upgrades to bring them in line with current legislation. Rather than doing the bare minimum to get these properties up to code, we should be encouraging owners and developers to seize the opportunity to regenerate these buildings.
If tenants have to move out anyway, this is the perfect moment to turn each of these properties into a high-performing, energy-efficient, comfortable building – for comparatively minor additional investment.
If we are serious about reducing our nation’s carbon footprint, it’s time to draw a line in the sand and push back against the carbon-hungry strategy of “demolish and re-build”. Wherever possible, we should be up-cycling our existing building stock, harnessing building regeneration to dramatically reduce NZ’s carbon emissions and help regain our ‘clean green’ reputation.