According to a recent UK study, as a building goes up in height, its carbon emissions increase.
In fact, found the University College London’s (UCL’s) Energy Institute study, high-rise buildings not only use more energy per square metre than their medium and low-rise equivalents, but also emit up to twice as much carbon at the same time.
Breaking the figures down, the researchers found that electricity usage was nearly two and a half times greater in office buildings that were above 20 storeys compared to buildings of six storeys, while gas use for the same structures was found to be 40 percent higher.
Funded by the UK’s Engineering and Physical Sciences Research Council (EPSRC), The High-Rise Buildings: Energy and Density project analysed energy consumption data from 610 office buildings across the UK and looked at the total energy consumption used both to produce the building materials as well as in the construction process.
Speaking to phys.org, Professor Philip Steadman from UCL’s Bartlett School of Energy, Environment and Resources, found that while air-conditioning was a factor in the results, it was not the only reason for the higher figures.
"The use of air conditioning plays a part in but does not provide a complete explanation of these results. On average, carbon emissions from air-conditioned offices are found to be 60 percent higher than those from offices with natural or mechanical ventilation,” he says.
"It is not the case, however, that the high-rise buildings in the sample are air-conditioned and the low-rise are not. The sample includes buildings of both types, of all heights. The increase in emissions with height is seen in buildings with and without air conditioning."
“Taller buildings are more exposed to strong winds, as well as to more hours of direct sun,” says Steadman, adding that, “energy use for heating and cooling would be increased. But these hypotheses have yet to be tested.”
Another part of the study looked at different forms of building designs in relation to their densities, and found that it was not always necessary to build vertically to achieve high densities, while building different forms with fewer storeys can actually reduce net energy consumption.