Keeping buildings cool in a warming climate

BRING up green solutions, and most people think of electric vehicles and solar panels. Far less attention is paid to the reduction of emissions by increasing energy efficiency.

Yet, as Singapore attempts to reduce its carbon footprint, the carbon emissions of buildings will come into greater focus.

According to the United Nations Economic Commission for Europe, buildings in the developed world account for 40 per cent of primary energy consumption and 40 per cent of carbon dioxide emissions from combustion.

With cooling systems consuming up to 40 to 50 per cent of energy within buildings, there is much that can be done to help reduce the amount of energy and greenhouse gas emissions that are emitted.

"As Asian countries move towards meeting their ambitious COP26 targets, improving the energy efficiency of buildings is especially impactful as buildings and construction projects have been identified to be significant contributors, accounting for 39 per cent of total global CO2 emissions," said Karunia Tjuradi, head of the sector solutions group at UOB, citing data from the Global Alliance for Buildings and Construction.

"However, overall adoption of energy efficiency projects is low despite the significant benefits for building owners, which range from positive environmental impact to direct positive financial contributions."

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For the head of the sustainability and resiliency office at urban and infrastructure consultancy Surbana Jurong, Praveen Chandrasekar, cooling and lighting considerations begin with the design process for buildings. That is when architects, structural engineers, and mechanical and electrical engineers gather to make informed decisions about a building's design.

"We don't use a checklist; Rather, we believe that any certifications will be a byproduct of good design," Chandrasekar said, noting that most of the company's projects score more points than necessary for certifications such as the BCA Green Mark.

Some passive design factors that can change a building's cooling efficiency include the choice of building materials. Glass, while aesthetically pleasing, actually lets in more heat than other building materials, making a building less efficient.

To mitigate this warming effect, Chandrasekar said a building's glass facades can be oriented to face away from the East and West where sunshine is likely to be harshest. If a glass window needs to be placed facing such a direction, a deep overhang could be employed to block some of the sunlight entering the building.

A building's semi-formal spaces, such as its lobbies and corridors, can also be naturally ventilated if possible, he said. Wind simulations can be conducted for these areas to check if this is feasible and, if so, suggestions can also be made for architects to design different forms of shading to reduce the amount of heat gained from the Sun.

Cooling-as-a-service

After a building is designed well, it also needs to be cooled efficiently. Kaer, a company that has been providing cooling-as-a-service since 2013, believes the key to this lies in leveraging customer data to deliver cool air when it is needed.

Headquartered in Singapore, the company services more than 10 million sq ft of space across the region. When Kaer's services are engaged, the company starts by taking over the ownership and operations of a building's air-conditioning assets - freeing the facilities manager to focus on other tasks.

Then, the company installs sensors and meters as part of its patented building monitoring and control system. All this data is sent back to Kaer for analysis, so its engineers can decide how to run the air-conditioning more efficiently. If a lower load is detected, engineers can reduce the amount of cooling delivered.

In the case of air-conditioning at a school, Kaer has even worked with school administrators to integrate its systems with class bookings and ensure that rooms are cooled only when needed.

The company employs its own brIQs machine learning technology to do autonomous optimisations to the parameters of a cooling system. Chief executive officer Justin Taylor said such adjustments can be as much art as they are science.

"I think the power comes from putting the people with the data. The computer can do all of these adjustments, but the person will be able to say: 'It's Chinese New Year next Tuesday.'

"If you think about every building we have as an R&D facility, in that sense we're learning everyday," he added.

Paradigm shift

To truly make a difference, however, it will be necessary for cooling optimisations to go beyond individual buildings.

Chandrasekar of Surbana Jurong noted that Singapore needs to start preparing for a much warmer world - with temperatures potentially hitting a high of 40 deg C, up from the current 33 to 36 deg C.

This would require a large shift in the way we think about cooling, he said. For instance, the form of district cooling being used at commercial buildings in Marina Bay, which saves about 30 to 40 per cent of energy consumed, could be adapted to HDB flats.

Currently, individual households have their own compressor and air-conditioning units. "Because you have a stack of outdoor compressor units that are blasting out hot air, it can really increase outdoor temperatures. If you're still willing to use fans and open the windows to sleep at night, it'll be more difficult," Chandrasekar said.

In October last year, 1,000 households signed up for a centralised cooling system (CCS) in the upcoming Tengah Build-To-Order flats. With the CCS, chilled water is piped to homes from centralised chillers. Users can also look forward to saving 15 to 20 per cent in upfront costs and 30 per cent in life cycle costs according to SP Group, which runs the system.

Data centre cooling

Another major concern is data centres, which are poised to consume a greater share of energy in the future. According to the Frost & Sullivan 2020 Data Centre Services Market Forecast, data centre capacity within the Asean region is expected to grow by a compound annual growth rate of 18 per cent from 2020 to 2025.

Michael Murphy, a director at multinational consultancy Linesight, said companies need to think about how they can build data centres more efficiently and reduce carbon emissions in the process.

If a company has plans to build many data centres, it may consider making its design repeatable. Doing so would allow it to modularise different segments of the building and prefabricate these segments in a more controlled environment, leading to less wastage.

Because Singapore is connected to many undersea data cables, and has high quality infrastructure, a highly educated workforce and a stable political outlook, Murphy said the country will remain a very attractive place to set up data centres, even as the government has paused new data centre construction since early 2019 and been in consultation with companies on the sector's sustainability.

With Singapore's tropical climate, 35 to 40 per cent of energy consumed by a data centre would be on cooling alone. In countries with temperate climates, data centres can leverage cooler weather in the winter months.

Kaer said its brIQs technology has helped data centre clients improve the energy efficiency of their cooling systems. David Mackerness, a director at Kaer, said its systems are 15 per cent better than current BCA Green Mark Platinum benchmarks.

Murphy of Linesight said there have been other innovations in the data centre cooling space. One is the use of StatePoint Liquid Cooling (SPLC). It uses outside air to induce evaporation, which helps cool the water and remove heat from the air headed to the data hall.

SPLC was developed by Meta Platforms (formerly known as Facebook) and Nortek Air Solutions. It is said to reduce the need for mechanical cooling such as air-conditioners and reduce peak water usage by more than 20 per cent.

This technique is being applied with several others at the Sustainable Tropical Data Centre Testbed, a S$23 million research programme that is being established with the National University of Singapore, Nanyang Technological University and other local data centre industry stakeholders.

Another way data centres can take advantage of natural resources is by sinking them underwater. In September last year, Microsoft released a report on Project Natick - its attempt to sink a sealed container of data centre servers in the Pacific Ocean.

Not only did the data centre save energy thanks to the cooler temperatures of the sea, but it also saw one-eighth of the failure rate that it normally would record on land.

The project group hypothesised that pumping the sealed container with nitrogen, a less corrosive gas than oxygen, and the absence of people bumping into the servers' components helped its reliability.

A similar project to harness the sea's cooling potential is Keppel's Floating Data Centre Park, which will increase cooling efficiency by up to 80 per cent.

Said Linesight's Murphy: "With data centres… anything that can be done to make that more effective and more efficient can only be a good thing."

This is the 14th in a 20-part Green Business series, in collaboration with UOB, exploring sustainability trends across businesses and industries.