Achieving net negative sensible heat release from buildings

Abstract

Heat is added to the surroundings as a result of replacing natural landscapes with buildings. This includes waste heat from air conditioning systems and heat transferred into the environment from exterior surfaces. Here, we propose a new concept of “negative sensible heat release” from buildings—that is, buildings that put less sensible heat into the environment than that released from the unbuilt terrain upon which the building was constructed. We explore the potential for net negative sensible heat releasing buildings through simulation studies in hot arid and humid cities—Phoenix, and Houston. Results show that it is possible to achieve net negative sensible heat release from low-rise office buildings by simply increasing roof and wall solar reflectance using existing technologies. While typical 2-story office buildings can generate average heat fluxes of around 100 W/m2 (based on building footprint area), by simply increasing solar reflectance of the roof from 0.2 to 0.9 and solar reflectance of the walls from 0.2 to 0.65, the same building can generate net negative sensible heating of 20 to 40 W/m2. Increasing building insulation and energy efficiency of appliances and air conditioning equipment can further reduce the heat release from buildings. This points to a compelling mechanism whereby buildings can be designed or retrofitted to have a beneficial impact on the local thermal environment.