Architect Carl Elefante once quipped: "The greenest building is one that is already built."
It's a bold statement, one that draws attention to how keeping and rejuvenating an old building for new uses avoids the carbon emissions that would otherwise be released in the process of demolishing and rebuilding.
To raze or retrofit is a decision that hinges at times on factors beyond sustainability.
But the opportunity in retrofitting is undeniable - technology makes it possible for existing buildings to be creatively brought in line with high standards of energy efficiency and other measures, giving them a new lease of life and a hand in limiting climate disruption.
"Embodied carbon" - what's emitted in construction and the manufacturing of steel, concrete and other building materials - makes up 11 of the 39 per cent of global carbon emissions attributed to the built environment.
That's a sunk cost in existing buildings. What's changeable is the "operational carbon" released in the ongoing running of a building that makes up the 28 per cent balance. This is what efforts to green existing real estate seek to reduce.
Why Singapore needs to retrofit its buildings
Retrofitting existing buildings, or "retrogreening", will be critical as Singapore works towards its 2030 target of greening 80 per cent of buildings by gross floor area.
As at end-2020, 43 per cent of buildings had hit the green mark. The remaining 57 per cent have an average age of 26 years, according to the Building and Construction Authority (BCA). Of these, a third are non-residential buildings, two-thirds are residential.
Earlier this year, BCA raised the higher minimum energy performance requirements for buildings undergoing major retrofitting. From 2022, they will have to be 40 per cent more energy-efficient than 2005 levels post-renovation - up from 25 per cent under current rules.
What are the challenges?
Singapore Green Building Council (SGBC) president Tang Kok Thye points to space constraints.
Additional technology needs space that might be scarce in a building not designed to hold energy-efficient equipment. Running services in the space above ceilings, filled with other mechanical and electrical services, may mean having to divert existing services.
For other building owners, the difficulty may lie in identifying suitable retrofits.
"With the myriad of green technologies out there, one of the key challenges that building owners may face is simply how or where to start the retrofitting process," says Associate Professor Kua Harn Wei, of the Department of the Built Environment, NUS School of Design and Environment.
He recommends the BCA's published guide that helps owners understand the baseline performance of their buildings, set targets, and then select possible solutions.
Engaging the right team of certified experts to guide owners on the path of green retrofit is important too, Assoc Prof Kua adds.
There is also the issue of minimising disruption to building operations, which could mean carrying out works at night, on weekends and in phases.
"To overcome these challenges would incur both additional time and cost," says Mr Tang.
However, he sees a growing awareness that green buildings make good economic sense, particularly when a building's entire life cycle is considered. He says numbers from a 2018 BCA energy benchmarking report make a strong business case for green buildings.
How going green saves money
Commercial buildings showed a 14 per cent improvement in energy efficiency compared with 2008. That improvement, from across 1,000 commercial buildings, translates to 1,000 gigawatt hours in energy, or $200 million saved a year. In other words, retrofits often pay for themselves over time in reduced energy costs.
SGBC runs a Zero Capital Partnership Scheme with BCA that provides smaller building owners with the expertise of an accredited energy performance contracting firm, which serves as a one-stop shop for minor and major retrofit projects, provides financing options and facilitates applications for grants or incentive schemes to fund such projects.
The demand is there. BCA's Green Mark Incentive for Existing Buildings - a $100 million fund started to co-fund the adoption of energy-efficient design, technologies and practices in existing buildings - has been fully committed, as has a separate $50 million fund that aims to do the same for small and medium enterprises.
BCA still runs the Building Retrofit Energy Efficiency Financing scheme, which helps building owners access loans of up to $4 million, or 90 per cent of the upfront costs of energy retrofits of existing buildings such as the cost of equipment, installation and professional fees.
How to green a building
Boosting energy use efficiency
Changing light fixtures and bulbs to efficient and longer-lasting LEDs is a relatively affordable move. Replacing old windows with glazed or treated ones that filter out heat, or incorporating blinds and shades also serve to lighten the demand on air-conditioning systems.
Assoc Prof Kua thinks the "lowest hanging fruit is actually using sensors and automated control systems that control the use of electricity".
Home dwellers and building owners alike can tap on smart energy management systems and thermostats for real-time information to modify the ways they use their buildings.
Air-conditioning systems can be upgraded to more efficient water-cooled package units rather than air-cooled ones, and more efficient motors for pumps, fans and compressors.
Other pricier projects include installing solar panels or retrofitting building-integrated photovoltaics, panels built into the exterior of a building in place of windows, skylights and roofs, to harvest energy for use.
Optimising water use
There are innovative systems available to harvest rainwater for safe use, such as cleaning or the irrigation of plants.
For households, you can use thimbles to regulate the flow rates of taps and showerheads, more water-efficient flushing systems and smart water shower devices.
Plants - whether they adorn rooftops or cover facades exposed to intense sun - can help mitigate indoor temperatures, some studies say, by 3-5 deg C. Apart from reducing energy needed to cool a building, vegetation on and surrounding buildings can also mitigate urban heat accumulation.
Improving waste management
Building occupants or users can separate their recyclable materials from waste if appropriate systems are introduced. Commercial buildings and hotels could also set up processes to compost food waste, or collect it for recycling into biogas fuel.
Enhancing indoor air quality
The Covid-19 pandemic has led to a spike in demand for green building solutions that tackle indoor air quality and health. "These include self-isolation, community management, elevator disinfection, environmental cleaning, open windows for natural ventilation, etc," says SGBC's Mr Tang.
The council, which maintains a directory of certified green building products and services, has seen growing interest in "building-based air treatment solutions that are able to help arrest pathogen transmission".
It has also seen higher demand for ultraviolet germicidal irradiation systems as an option to sanitise spaces.
UOB's Green buildings
The iconic UOB Plaza 1, 280m-tall and completed in 1992, remained one of Singapore's three tallest skyscrapers until it was overtaken in 2017. But neither age nor height has prevented it from going green.
Speaking about retrofits in general, UOB chief sustainability officer Eric Lim, says: "Making existing buildings green requires considerable investment as it entails refurbishment and replacement of equipment."
Across UOB's three main buildings in Singapore, energy efficiency initiatives have slashed its annual energy consumption by some 9.3 million kilowatt-hours, yielding estimated cost savings of close to $2.3 million each year.
The bank aims for all the buildings it owns - including those in other cities - to be certified green by 2030.
This is the fourth of a 15-part series in collaboration with