Resumen de "Anàlisis tècniques i físiques del comportament de les cobertes ""fresques"" (cool roofs): el cas de Catalunya"
This document is about cool roofs. This is a relatively new term and refers to those roofs that are able to keep its surface temperature similar to the air¿s temperature in spite of solar radiation. Cool roofs could be flooded roofs, green roofs, and obviously roofs with high reflection and emissivity index.
The project described in this paper aims to demonstrate that cool roofs are a good strategy to reduce cooling demand in buildings in the area around Barcelona, as well as on the Mediterranean coast and in the Iberian peninsula. It is not the intention to demostrate this from a theroretical perspective based in numerical simulations ¿this work has already been done- but by testing cells and real common materials used in roofs and modifying their properties of reflection and emissivity.
To assess these materials, the methodology followed was the observation and systematic measurement of the samples under real weather conditions. The temperature was measured in three points: in the upper surface, under surface and indoors. These data and weather data were combined to compare different samples.
This approach facilitated the observation of materials under real weather conditions and provided information with regard to: - Day-night or summer-winter cycles - The effect of dirt and pollution - What modification the coating of roof¿s materials need to improve cool roofs The first step was carried out in the ETSAV¿s roof in Sant Cugat del Vallès. We used 6 cells (called the PAUS cells) measuring 2,2x2,2x2,2 m each.
The second step implemented previous evaluated solutions in real buildings. The buildings were 3 ALGECO modules (each one measuring 15m2) and were located in the ¿Universitat Laboral de Tarragona¿. Different cool roof solutions and materials were assessed. The study demonstrated the benefits of cool roof in modular constructions.
This project has been undetaken under the point of view of an architect. Therefore, although the measurements of reflection or emissivity were obviously important, the main emphasis was placed on concepts closer to architecture such as: - Applicability in different scales, from the entire city to a single building - Replicability of different solutions - Comfort and improvement of thermal efficiency in buildings - The final image of cool roofs in a building
