Evaluation of a solar thermal system using building louvre shading devices Ana I. Palmero-Marrero, Armando C. Oliveira * Department of Mechanical Engineering, Faculdade de Engenharia, Universidade do Porto, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal Received 21 September 2004; received in revised form 30 March 2005; accepted 7 April 2005 Available online 13 May 2005 Communicated by: Associate Editor Matheos Santamouris Abstract External louvres are increasingly used to provide solar protection for building glazed surfaces. The integration of col- lectors into the external louvres of buildings offers a means of reducing system cost as well as providing architects with more freedom to integrate the technology into their designs. This work concerns the modification of existing louvre designs to integrate a solar collector in the shading device. The evaluation of a thermal solar system for water heating is assessed in this paper. A numerical model for the integrated solar collector was developed for different configurations and the collector efficiency is quantified for each configuration. System thermal performance was obtained for the climatic conditions of Lisbon (Portugal) and Tenerife (Spain). Economic and environmental viability of the system is assessed. Ó 2005 Elsevier Ltd. All rights reserved. Keywords: Solar collector; Louvre shading; Building integration; Efficiency; Water heating; Economic and environmental viability 1. Introduction Solar energy systems have an important role in build- ings. Its use in building renovation has been studied for different cases and the importance of integration of the solar system in the building was concluded (Dalenba ¨ck, 1996; Voss, 2000). The integration of solar systems in the building envelope often is a necessity if the systems are to be economically feasible. Solar elements should not be separate elements that are added after construc- tion. They must rather replace other building elements, thereby serving dual functions and reducing total costs (Hestnes, 1999). The integration of collectors into the external enve- lope of buildings, offers a means of reducing system cost as well as providing architects with more freedom to integrate the technology into their designs. Louvres are traditionally used as shading devices to reduce the solar (heat and light) gain in a building during the cooling sea- son. The louvres are ideal for the integration of photo- voltaic cells, as the blade is exposed to provide full ventilation and can be tilted to maximise efficiency (Bpsolar, 2002). Photovoltaic cells (PV) are laminated onto the glass louvres to collect solar radiation, also providing a significant reduction in energy consumption within a building. These PV-louvres may track the path 0038-092X/$ - see front matter Ó 2005 Elsevier Ltd. All rights reserved. doi:10.1016/j.solener.2005.04.003 * Corresponding author. Tel.: +351 225081763; fax: +351 225082153. E-mail address: acoliv@fe.up.pt (A.C. Oliveira). Solar Energy 80 (2006) 545–554 www.elsevier.com/locate/solener