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A. Azarnejad, A. Mahdavi:
"Implications of facades' visual reflectance for buildings' thermal performance";
Journal of BUILDING PHYSICS, 42 (2018), 2; 125 - 141.

The surface properties of building facxades have implications for thermal performance of buildings and might also influence outdoor thermal comfort conditions for pedestrians. A surface property, which is frequently used by building engineers and specially architects, is the visual reflectance. In this article, effects of facxades´ visual reflectance on thermal aspects of building performance have been investigated in two parts. In the first part, the result of a field study is presented. The study explores the relationship between the visual reflectance of actual building facxades and the corresponding surface temperatures. A number of
buildings with diverse facxade colors were selected. Surface temperatures were measured via infrared thermography. Facxades´ visual reflectance was derived via simultaneous measurement
of the illuminance on the facxades and their luminance. Furthermore, incident solar radiation, ambient air temperature, and relative humidity were measured. The results of the field study display a non-random relationship between the building facxades´ visual reflectance and their surface temperatures. The second part of the research involved the deployment of a calibrated simulation tool toward exploring the impact of facxades´ visual reflectance on thermal performance of buildings. The results suggest that the magnitude of visual reflectance has little impact on indoor temperature and heating demand in case of
facxades with external insulation layer but may influence cooling loads in case of noninsulated buildings.

(kein deutscher Abstract) The surface properties of building facxades have implications for thermal performance of buildings and might also influence outdoor thermal comfort conditions for pedestrians. A surface property, which is frequently used by building engineers and specially architects, is the visual reflectance. In this article, effects of facxades´ visual reflectance on thermal aspects of building performance have been investigated in two parts. In the first part, the result of a field study is presented. The study explores the relationship between the visual reflectance of actual building facxades and the corresponding surface temperatures. A number of
buildings with diverse facxade colors were selected. Surface temperatures were measured via infrared thermography. Facxades´ visual reflectance was derived via simultaneous measurement
of the illuminance on the facxades and their luminance. Furthermore, incident solar radiation, ambient air temperature, and relative humidity were measured. The results of the field study display a non-random relationship between the building facxades´ visual reflectance and their surface temperatures. The second part of the research involved the deployment of a calibrated simulation tool toward exploring the impact of facxades´ visual reflectance on thermal performance of buildings. The results suggest that the magnitude of visual reflectance has little impact on indoor temperature and heating demand in case of
facxades with external insulation layer but may influence cooling loads in case of noninsulated buildings.

Building facades, visual reflectance, surface temperatures, heating and cooling loads, overheating

http://dx.doi.org/10.1177/1744259117731287

http://journals.sagepub.com/doi/full/10.1177/1744259117731287