Analysis of the Optical Response of Opaque Urban Envelope Materials: The Case of Madrid

The optical response of opaque materials in an urban envelope plays an important role in a city's energy exchange with the environment as it defines the absorption of radiation and emission of heat. In the present work, the most common surfaces of the finishing materials of pavement and walls in the city of Madrid (Spain) were identified, and their reflectance was measured in situ to determine their solar absorptance and color coordinates. Most of the selected pavement showed a relatively high solar absorptance in the range of 0.87 to 0.60, while in vertical surfaces, the range was 0.85 to 0.29. The variations of the color coordinates obtained for pavement were 27.1, 11.4, and 6.7 for Delta L*, Delta a*, and Delta b*, respectively. Significantly higher values were obtained in the case of vertical surfaces (47.5, 20.5, and 23.6, respectively). The results were included into a database intended to be the seed for a catalogue of the experimental thermo-optical properties of opaque envelope materials in Madrid. The catalogue will be useful for the analysis of the stimuli generated by the urban environment for citizens and for achieving more reliable results from energy simulation tools in the search for strategies to improve urban comfort and sustainability.