Research paper Performance of a window shutter with phase change material under summer Mediterranean climate conditions Tiago Silva a, * , Romeu Vicente a , Fernanda Rodrigues a , Ant  onio Samagaio b , Claudino Cardoso a a Civil Engineering Department, University of Aveiro, Portugal b Environment and Planning Department, University of Aveiro, Portugal highlights  Incorporation of phase change materials into window shutter.  Resourcing to PCMs as a thermal regulator of indoor temperature.  Analysis of the thermal energy storage system using PCMs.  Experimental campaign of a window shutter incorporating PCM. article info Article history: Received 26 September 2014 Accepted 26 March 2015 Available online 4 April 2015 Keywords: Phase change materials (PCMs) Energy performance Indoor thermal comfort Window shutter Heat flux Thermal energy storage abstract The building sector is the largest final end-use consumer of energy in the European Union. Substantial heat losses in buildings occur through glazing areas, so it is crucial to mitigate the energy transfer be- tween through these areas. The use of phase change materials (PCMs) is presently a technology advanced solution to improve the energy performance of building elements, particularly with window blinds or shutter protections. This paper presents the results of an experimental campaign of a window shutter containing PCM during the summer season. The shutter prototype was applied in an outside cell test composed by two compartments (side by side) and oriented to South. It was monitored and analysed the indoor air temperatures, the outside weather conditions and the heat flux of the interior wall partition. During the experiment, the range of the external air temperature changes from 13  C to 25  C and the average solar radiation recorded is 237 W m 2 to 306 W m 2 . The measured results shows that the compartment with the PCM window shutter can reveals thermal regulating capacity of the indoor temperature about 18%e22%. The maximum and minimum temperature peaks decreased 6% and 11%, respectively. Besides the improvement of the indoor temperatures, the compartment with PCM increased 45 min the time delay to achieve the minimum temperature peak and 60 min to attain the maximum temperature peak, compared to the reference compartment (without PCM). © 2015 Elsevier Ltd. All rights reserved. 1. Introduction Presently, the environmental concerns and the energy efficiency are two widely compatible main research topics. According with the International Energy Agency (IEA) the buildings sector in the European Union is simply the largest final end-use consumer. The energy consumption of this sector is 470 Mtoe (million tonnes of oil equivalent) of 1194 Mtoe which represents about 40% of the total energy consumption [1]. Not considering the emissions associated with the electricity use in the building sector, the CO 2 emissions represent 12% of the total CO 2 emissions produced in 2011 [1]. Recent studies show that a good building refurbishment combined with correct operation and installation of monitoring devices with well-designed active systems, can improve the buildings energy efficiency up to 60% [1,2]. Nowadays, the building design frequently includes large trans- lucent areas, mainly in offices and commercial buildings. However, the use of large façade glazing areas could lead to thermal and * Corresponding author. Tel.: þ351 234 370 845; fax: þ351 234 370 094. E-mail addresses: tiagomsilva@ua.pt (T. Silva), romvic@ua.pt (R. Vicente). Contents lists available at ScienceDirect Applied Thermal Engineering journal homepage: www.elsevier.com/locate/apthermeng http://dx.doi.org/10.1016/j.applthermaleng.2015.03.059 1359-4311/© 2015 Elsevier Ltd. All rights reserved. Applied Thermal Engineering 84 (2015) 246e256