Energy performance of air conditioned buildings and summer comfort can be improved with high solar reflectance and high emittance of building envelopes. Widely used for roofs, this technique known as cool roof, has a direct impact on the external surface temperatures peaks which reduces both heat transfer to the building and to the environment. In this paper, this technique used with facades is experimented in a confined environment similar to a typical urban scene. This reduced-scale of 4 street canyon rows is designed in order to give realistic measurements of thermal confinement. Then, the temperatures of a street canyon with brown cool selective paint facades are compared with a standard brown coating on another street facades, and with an asymmetrical configuration. The analysis of thermal effects on both buildings and outdoor environments gives interesting prospects for urban heat island mitigation. (C) 2011 Elsevier B.V. All rights reserved.