Green and cool? Office buildings in hot countries
Why are hot countries important for the building sector? What are the greenhouse gas emissions associated with office buildings? And finally, how can we decrease them?
Office buildings are a special type of buildings, with lots of people and appliances, all producing heat. They usually have big windows that allow lots of sunlight to enter. And while this additional heat can be advantageous on a cold day, it usually means that office buildings need much more cooling than residential buildings.
In the future, most office buildings are expected to be built in developing countries. These economies are growing, meaning that more and more people will be employed in the service sector, likely increasing the demand for offices. At the same time, developing countries typically have very warm climates!
The green: greenhouse gas emissions
Now we know — office buildings in warm climates are important. But how much do they impact the environment in terms of greenhouse gas emissions?
We tried to answer this question in our new study (Krych et al. 2021). We analyzed the life cycle of a building. Actually, not one, but 1000 buildings! Each of them had slightly different characteristics. We considered ten parameters, including climate, cooling system efficiency, and frequency of replacement.
The main results can be seen in the figure below. Not surprisingly, the right panel shows that the highest emissions are caused by operational energy use, particularly cooling. But surprisingly, paint pops up as the hotspot of material replacement emissions! The decisive factor is its frequency of replacement, on average every 8 years.
The cool: cooling systems
Cooling in buildings requires lots of energy, causing greenhouse gas emissions. How do we decrease the emissions while still keeping the buildings cool?
Typically, office buildings are kept cool using mechanical air conditioning (AC). But it uses lots of energy! Wouldn't it be better to open the windows to get some fresh cool air and only use the AC when necessary? That's the idea behind mixed-mode ventilation.
Our findings suggest that the mixed-mode strategy can offer a 14% reduction of greenhouse gas emissions on average. By opening windows, we can decrease the environmental impacts of cooling in buildings. Just don't forget to first turn off the AC!
Krych, K., Heeren, N., & Hertwich, E. G. (2021). Factors influencing the life-cycle GHG emissions of Brazilian office buildings. Buildings and Cities, 2(1), 856–873. https://doi.org/10.5334/bc.136