Passive cooling design, as well as natural refrigerant-based air conditioning, are vital to achieving sustainable cooling in buildings, according to Anna Braune, Director of Research and Development at the German Sustainable Building Council (DGNB), a Stuttgart, Germany-based NGO.
Braune delivered this message in her policy presentation at the ATMO/DTI Technical Conference, an online event hosted by shecco (publisher of this website) and the Danish Technology Institute, on June 23-24.
DGNB’s life cycle assessment (LCA) calculator offers guidelines for evaluating the sustainability of a building over its lifetime, and can be used to certify a building’s sustainability generally.
One way to earn LCA points is to operate without active cooling by employing passive cooling features.“Passive design methods can be used to get a good thermal quality in the building, by not using any active sort of cooling measures,” said Braune.
Passive cooling utilizes design features such as natural shade and can be incorporated into the building from the design stage on, according to the DGNB blog.
For an architect, “it’s about talking to the client, saying ‘You know it’s really nice to have this super large window, but thermally, no,’” said Braune.
Other passive cooling elements include insulation, reduction of IT and lighting loads, green facades, appropriate comfort standards, and use of cooling towers and ground water.
Braune also suggested that building owners “pay somebody for coming into the building at three or four o’clock in the morning and opening the windows” to take advantage of nighttime cooling. She compared that to “paying somebody for shoveling the snow.”
Braune noted that not only do air conditioners use significant amounts of energy to cool buildings, most AC units use polluting greenhouse gases.
Thus, the DGNB gives incentives “either not to use them, or to use alternative refrigerants,” Braune said. In particular, refrigerants with a GWP greater than 150 – such as R134a, R407C and R410A – should not be used.