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 by the UN’s Environment Commission has found that fossil fuel use in buildings accounted for 36% of total global energy consumption in the year 2016 and 39% of total Greenhouse Gas emissions. Whilst progress towards reducing emissions is advancing, the giant pipeline of construction activity around the world is largely negating these improvements.

In Australia, buildings are collectively responsible for 18% of the nation’s emissions, a figure expected to decline to 16% by 2030 as energy efficiency technology improves and appliances switch from gas to electric sources.

In New Zealand, the New Zealand Green Building Council (NZGBC) has found buildings could be belching out 20% of the country’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 construction waste.

In response, the NZGBC is now flagging building construction as "hugely significant" to climate change and is encouraging new projects consider the emissions produced by new construction materials and options such as timber construction.

While this is all very laudable, it’s kind of missing the point.

If our current global property market trend is contributing so much to our carbon footprint, surely we should look for other options – ones that don’t involve new construction at all…

Rather than turning our cities into building sites, why aren’t we up-cycling our existing building stock first?

We’ve proved that you can regenerate an unloved, untenantable building to create a fantastic building that tenants love. And, you can do this at far less cost and with far fewer carbon emissions than demolishing and building anew.


Aorangi House - achieving award-winning environmental performance

In September, 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 demolished, 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 a 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.

The importance of regenerating this existing asset with enhanced energy efficiency outcomes, rather than rebuilding from scratch, is underlined by recent International Energy Agency findings. These findings indicate the global construction sector needs to improve energy intensity per square meter (m2) on average by 30% by the year 2030, in order to meet global emissions reduction ambitions as outlined in the Paris Climate Change Agreement of 2015.


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 building upgrade is a regeneration opportunity

Whenever tenants vacate a building there is an opportunity to regenerate urban space that would otherwise lay dormant, actively contributing to a more vibrant city life for all.

The end of a tenancy is the perfect moment to turn properties into a high-performing, energy-efficient, comfortable buildings – for comparatively minor additional investment.

For example, there are hundreds of earthquake-prone buildings in Wellington right now which 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, owners and developers should be incentivised to seize the opportunity to regenerate.


If we are serious about reducing our global carbon footprint, it’s time to draw a line in the sand and push back against bare minimum upgrades or the carbon-hungry strategy of “demolish and re-build”. Wherever possible, we should be up-cycling our existing building stock and harnessing building regeneration to dramatically reduce our carbon emissions.


About the Author
Ben Masters

Principal - Sustainable Buildings

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