“Think of green buildings as giant N95 facemasks, protecting you from harmful toxins the moment you step inside,” said Dr Ho Nyok Yong, president of the Singapore Green Building Council (SGBC), in a webinar in May.
“Building-based prevention and control measures have become one of the most important methods of fighting against the effects of the Covid-19 pandemic,” Dr Ho told his audience of 600 building and construction industry stakeholders.
As cities start to reopen their economies and people return to work, installing green building technologies in shopping centres, offices, factories and other shared spaces can help to limit the spread of the coronavirus within them and stand them in good stead against future disease outbreaks, experts have told Eco-Business.
When commercial real estate services firm CBRE surveyed 264 tenants in Asia Pacific from March to April on their industries’ response to the Covid-19 crisis, nearly half said that it will lead to a stronger preference for buildings with wellness and environmental features.
This bodes well for green buildings, which place a strong emphasis on indoor air quality and well ventilated indoor spaces. Even before the Covid-19 outbreak, SGBC, a non-profit that supports sustainability in the built environment, had been working to raise awareness of how buildings affect people, with its Better Places for People programme.
Retrofits such as adding ultraviolet lights to air-handling units and switching to demand-controlled ventilation can reduce the transmission of airborne viruses and bacteria while increasing the buildings’ energy efficiency, said experts such as Mark Yeo, CBRE’s chief operating officer of property management in Singapore and Southeast Asia.
In the longer term, new buildings can further shrink their carbon footprint and aid in disease prevention by maximising natural ventilation or making use of innovative ventilation systems that are already deployed in cities such as Singapore, the experts added.
Making buildings healthier
Even before the emergence of Covid-19, more hospitals were starting to use ultraviolet-C (UV-C) light to disinfect surgical suites and other rooms and surfaces because it kills or inactivates microorganisms.
“Some buildings are now looking into installing UV-C lighting in their air-handling units to remove airborne bacteria, viruses and germs to improve the indoor air quality,” said Yeo.
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Think of green buildings as giant N95 facemasks, protecting you from harmful toxins the moment you step inside.
Dr Ho Nyok Yong, president, Singapore Green Building Council
Over time, organic materials usually build up on the surfaces of the units’ cooling coils and other components, degrading their energy efficiency and leading to higher energy use and costs. Having UV-C lights in the units also prevents this and lessens the need for maintenance. SGBC certifies such innovations to ensure the general health and well-being of building occupants.
Refining ventilation systems is another key to minimising disease transmissions while saving electricity. In most commercial buildings, the heating, ventilation and air-conditioning (HVAC) system recirculates up to 90 per cent of the indoor air because drawing air from outdoors and conditioning it is energy-intensive. This practice, however, could enable contaminants such as bacteria and viruses to persist within the premises.
Demand-controlled ventilation pairs HVAC systems with carbon dioxide or other sensors to vary the intake of outdoor air depending on the buildings’ occupancy. When there are more people, more air is brought in, diluting the concentration of airborne contaminants and making infections less likely. Conversely, when there are fewer people, the smart systems draw in less air, decreasing their energy use.
Different parts of a building may benefit from different ventilation and sensor strategies. “In basement carparks, ductless jet fans’ activation can be linked to carbon monoxide sensors. This will help to both guard against viruses and make the building more sustainable,” Yeo said.
A fresh (air) approach
As new buildings are constructed, they can also take advantage of state-of-the-art ventilation systems that may be too difficult or costly to install for existing properties.
The National University of Singapore’s (NUS) net-zero energy building, for instance, uses a hybrid cooling system that combines air-conditioning with ceiling fans. The system supplies only conditioned outdoor air, but at higher temperatures and humidity than conventional HVAC systems to reduce its energy consumption.
“Even though the temperature is warmer at around 27 degrees Celsius, the ceiling fans circulate the cool air which makes it comfortable for people,” explained Professor Chandra Sekhar, co-director of NUS’s Centre for Integrated Building Energy and Sustainability in the Tropics.
Prof Sekhar, along with Professor David Cheong, the centre’s other co-director, and Professor Tham Kwok Wai, another colleague in the NUS School of Design and Environment’s Department of Building, also patented an energy-saving system that improves ventilation, called the Single Coil Twin Fan (SCTF) system, that is installed in the Singapore Building and Construction Authority Academy’s Zero Energy Building.
In traditional HVAC systems, air drawn from outdoors and recirculated indoor air are mixed into a single stream before being conditioned and distributed across the building. In the SCTF system, the two air flows are treated and distributed independently to various rooms. When a room is occupied, more outdoor air and less recirculated air is supplied, and vice versa, enabling energy savings.
Conditioned outdoor air is also sent directly to each employee’s desk through ducts integrated into the furniture and controllable speaker-like devices on each desk that vent the air as needed. “Such personal ventilation technology uses the smaller volume of cleaned outdoor air more effectively by creating and maintaining healthy microenvironments around each workstation,” said Prof Tham.
With sensors, the personal ventilation system can also save more energy by delivering the air only to occupied desks. “This would be especially useful for offices and other buildings with high variability in occupancy, including co-working spaces,” said Prof Tham.
Rethinking buildings
The experts noted that building owners may be able to seek government funding for some of the retrofits. For example, Singapore’s Green Buildings Innovation Cluster Building Energy Efficient Demonstrations Scheme finances up to 70 per cent of the cost of installing novel technologies that use at least 20 percent less energy than their best commercial counterparts.
Prof Sekhar added that the Covid-19 pandemic is likely to spur urban planners, architects and property managers to reconsider how they design, operate and maintain buildings to safeguard occupant health and wellbeing.
“Apart from sterilising access points and other practices, such as safe distancing, to minimise the spread of infections, we will expect building systems themselves to offer some inherent protection to the people who are in the buildings,” he said.
“By taking advantage of innovative systems, buildings will be able to adjust to the post-Covid-19 environment with improved safety and sustainability.”
