Following certain recommendations, such as using steel frames and choosing cladding in multi-storey buildings to reduce carbon emissions and operational energy, could save up to six gigatonnes of carbon by 2050, according to a new study.
Researchers at the University of Cambridge and Bath in the United Kingdom designed a computer model and used it to estimate that these recommendations could also save 28 to 44 percent of annual heating and cooling costs, using the technology currently available. Their findings are reported in the journal Applied Energy.
The construction and operation of buildings accounts for more than one-third of global emissions and energy consumption. While buildings are a big part of the current problem, they are also a significant lever for change, the researchers said.
Impact on the embodied carbon
For their study, the researchers looked at the shape, size, layout, structural system, windows, insulation, ventilation and usage parameters for both residential and office buildings in different climates. The researchers found that the choice of structural frame type has a large impact on the embodied carbon and costs of both residential and office buildings.
They also found that cheaper frames tend to have a high carbon content and vice versa, indicating a trade-off. Cross-laminated timber floorboards with laminated beams or steel frames are the lowest-carbon solutions, they say. They also say that as the number of floors increases, so do the carbon values.
For cladding, brick cladding leads to significantly higher embodied carbon and costs compared to lighter sheet or tile cladding options, they said. Brick buildings were found to be up to 20 percent more carbon intensive and 15 percent more expensive than buildings clad in sheet metal or tiles. The more trim, the more bulk needed in the frame to support the trim load, they said.
In terms of building operational energy, researchers have found, by examining the effect of climate on the sensitivity of building design variables, that it is much more challenging to reduce energy use in hot and humid climates than in cold and temperate climates.
However, for the tropical climates of Singapore or Lagos, for example, high humidity and high temperatures mean reliance on cooling. The more occupants in a building, the more cooling energy is needed to dehumidify the supply air, the study says.
For temperate climates like London’s, building shape and window configuration are the most influential design decisions for heating and cooling, the study said. In Cairo’s hot, dry climate, window-to-wall ratio decisions are critical, the study said. This is because the more windows there are, the more the building is heated by sunlight.
The researchers also found that smaller windows and a lower solar heat gain coefficient the fraction of sunlight transmitted through a window had a greater effect on the efficiency of office buildings than residential buildings.
This is due to the fact that the former has a larger number of inhabitants and heat-emitting appliances. The use of mechanical ventilation with heat recovery is one of the most important levers to reduce heating and cooling energy, researchers say, especially for office buildings in hot, humid and cold climates.
Written by: Vaishali verma
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