Green buildings: Reaching beyond energy efficiency to tackle embodied carbon

The buildings in which city dwellers work, live and play produce a huge chunk of climate-destroying global carbon emissions today. Making buildings greener — both in their construction and their running — could significantly affect the impact cities have on climate change.

Already, buildings produce 39 per cent of global carbon emissions, says the World Green Building Council (WGBC). But with rapid urbanisation fuelling an unprecedented need for new buildings globally, floor area is expected to rise 75 per cent between 2020 and 2050.

Set that against the International Energy Agency's estimate that global net man-made carbon emissions must fall to zero by 2050, in order to keep the rise in global temperature below 1.5 deg C, and the problem is clear.

What is Singapore doing?

Here, buildings make up over 20 per cent of carbon emissions. The government aims to green 80 per cent of Singapore's buildings (by gross floor area) by 2030. As at end-2020, 43 per cent were deemed green.

Greenness is set out under the Building and Construction Authority's (BCA) Green Mark ratings scheme which stresses energy efficiency, but also considers how a building uses greenery, manages waste and water and maintains indoor air quality.

Currently, the Green Mark standards certify that buildings are 30-60 per cent more energy-efficient than 2005 levels.

But the government says new buildings must now meet a stricter requirement of being 50 per cent more energy-efficient.

In fact, BCA aims for 80 per cent of new builds to be Super Low Energy ones that boast best-in-class energy efficiency, run on renewable energy and deploy intelligent energy management systems.
 

How can architects help?

Much of the push towards greener buildings is devoted to minimising the energy needed to keep a building running.

From the start, architects can now use digital modelling systems to design a building to work with rather than against the local climate, such as sun and wind patterns, reducing the energy needed to cool it.

District cooling systems — which pipe chilled water to clusters of buildings for air conditioning — have yielded energy savings of up to 40 per cent here.

Clever use of vertical greenery, rooftop gardens, louvres, eaves and air funnels serve not only to shade and ventilate, but add to aesthetics.
 

Then there are the motion sensors and smart controls that regulate electricity use within a building, or tweak indoor temperatures in response to how hot or cold it is outdoors.

Solar windows — transparent photovoltaic panels that serve as windows while trapping energy for use — and low VOC (volatile organic compounds)-emitting materials for use indoors are among emerging green technologies that Associate Professor Kua Harn Wei from the Department of the Built Environment at the NUS School of Design and Environment believes "will be decisive in defining green buildings in the next few years".

Such green building solutions work to reduce what WGBC terms "operational carbon" — what's produced from buildings being used. This accounts for 28 of the 39 per cent of carbon emissions that buildings contribute to the global total.
 

What role do construction materials play?

Often overlooked but now increasingly in focus, however, is the other 11 per cent: embodied carbon — what's emitted in construction and the creation of steel, concrete, glass and other building materials.

With mounting advocacy for buildings to be assessed on environmental impact using a whole-life approach — more developers, engineers and architects are now paying attention to the embodied carbon of the buildings they dream up.

Typically, that embodied carbon is a chunky 30 per cent of a building's lifetime emissions. But, in a city like Singapore, where buildings tend to have shorter lifespans due to urban renewal and condominium developments' en bloc cycles, these upfront emissions can make up a higher 40 per cent of lifetime emissions, says the Singapore Green Building Council (SGBC).

Awareness and acceptance of more sustainable construction methods such as Prefabricated Prefinished Volumetric Construction, as well as lower-carbon building materials, is now on the rise.

More sustainable concrete and steel — produced with carbon capture, utilisation and storage technology — are also gaining prominence, says Tang Kok Thye, SGBC president and associate partner of architecture firm ADDP Architects.
 

Can wood, green concrete be solutions?

Wood has experienced a resurgence in popularity as a building material - thanks to advances in technology and strong, fire-resistant engineered wood products such as cross-laminated timber.

Wooden high-rise buildings have sprung up in concrete urban jungles of late, from Vancouver to Vienna. And timber skyscrapers — an 80-storey one in central London and a 70-storey one in Tokyo — have already been proposed.

In addition to being greener, these prefabricated timber frames are lightweight and quick to install — raising construction productivity. In fact, such mass engineered timber has already been used in buildings in Singapore — from a sports hall at Nanyang Technological University to Eunoia Junior College.

The world of sustainable materials is ever-expanding. Heard of transparent wood?

It could be the next energy-efficient building material now that researchers in the US have discovered a method to turn wood clear, yielding a final product that's greener, stronger and lighter than glass.

Closer to home, Assoc Prof Kua and his team at NUS have successfully recycled excavation waste into an ultra-high performance green concrete that is 20 per cent stronger than mortar and 16 per cent less water permeable.

There is both demand and supply. One report estimates the global market for green building materials to have been worth US$238 billion (S$322 billion) last year. That is projected to swell to US$425.4 billion (S$574.9 billion) by 2027.

More evidence of green building traction: the WGBC's Net Zero Carbon Building Commitment — to slash operational carbon of direct assets to net zero by 2030 — has Singapore companies among its signatories, including ARA Asset Management, Atelier Ten, City Developments Limited and Surbana Jurong.

SGBC's Mr Tang expects more as the need to go low-carbon gains recognition. "But they'd need to have concrete plans and initiatives to address both operational and embodied carbon emissions in place, which might be too early for companies just starting out on their sustainability journey."

That is why locally, SGBC has launched its own Singapore Built Environment Embodied Carbon Pledge — to raise awareness that in greening buildings, the process of building matters too.

Are consumers willing to pay more?

A 2016 study commissioned by the Building & Construction Authority of Singapore (BCA) on attitudes towards green buildings painted a positive picture. Among other findings, 70 per cent of homeowners believed a green building offers better resale value and 54 per cent were willing to pay a premium of 3-4 per cent for a Green Mark-certified property.

A more recent survey of senior executives in Singapore's real estate sector by the National University of Singapore Real Estate (NUS+RE) similarly found that most expect prospective home buyers to pay a 0-5 per cent premium for residential projects awarded the top Green Mark tiers.

However, two-thirds of the real estate executives surveyed also expect building such homes to cost 11-30 per cent more — implying that the economic returns of investing in building greener homes aren't commensurate.

Still, SGBC's Mr Tang sees a silver lining for sustainability amid the ongoing global pandemic.

"It has shown us what can be achieved when we work together towards a common goal. Climate change is an even greater existential threat facing mankind."

As for the built environment sector, he says: "The industry is growing more cognizant than ever before of the importance of sustainable development, and more stakeholders are galvanised to seriously look into bettering the environmental performance of our places and spaces."

Demand for sustainable financing solutions

Building green does not always cost more. In fact, some greener construction methods and energy efficiency improvements are accompanied by lower costs and higher productivity.

But, barriers to finance do exist for manufacturers investing in high-capital low-carbon technology, or for builders wishing to try novel techniques or circular business models that recover and recycle resources used to make their products. That is, if they are assessed on traditional risk criteria.

The good news is that banks are increasingly rolling out sustainable financing solutions. UOB for instance, was the first Singapore bank to roll out a lending framework for the real estate sector in 2019. Specific eligibility criteria apply. In Singapore, buildings must achieve Green Mark Gold Plus or Platinum certification to qualify for green loans under the framework.

That such conditions are stringent "reinforces UOB's considered move to ensure that our financing activities will help result in actual and positive environmental impact in areas such as energy efficiency, water efficiency and the shift to renewable energy", says the bank's head of group wholesale banking and markets Frederick Chin.

The bank's Smart City Sustainable Finance Framework also lays out criteria for extending loans to contractors, service providers, and equipment and building material suppliers involved in building a green building.

Green financing deals UOB was part of this past year include a S$780 million club green loan to Sapphire Star Trust, which owns Green Mark Gold Plus-certified Waterway Point, and a S$100 million loan to Ascendas India Trust which has terms tied to the environmental, social and governance performance of its portfolio of buildings in India.

As for the future of green projects and sustainable financing, Mr Chin says: "With consumers and investors continuing to place greater emphasis on sustainability, we believe more companies will accelerate their sustainable development agenda and this will sustain the rising demand for green projects and sustainable financing."

Building Sustainable Cities is a series sharing insights on how individuals and businesses can take action to forge a cleaner, greener tomorrow.

Source: The Straits Times © SPH Media Limited. Permission required for reproduction.