Experimental validation of a methodology to assess PCM effectiveness in cooling building envelopes passively

• Validated methodology for cases with heat gains and low inertia or insulation.
• Inappropriate method for cases with low heat gains and high inertia and insulation.
• Intensity of thermal discomfort is the most significant indicator.
• ITD must be based on comfort zone rather than comfort temperature.
• New indicators are required to fully characterize the benefits and behavior of PCM.

Energy consumption presents increasing trends during last decades, presenting a great challenge. The building sector contributes to a high proportion of the energy consumed and therefore efforts should be focused to improve energy efficiency of buildings. For such purpose, the use of phase change materials in building envelopes has been extensively studied and its benefits were demonstrated. However, there is a lack of simple evaluation tools to assess these benefits. In this paper a previously proposed methodology based on four indicators, which were tested through simulation only are experimentally validated using brick, concrete and timber constructions, incorporating PCM. Results show that the methodology is successful for buildings with heat gains and having low thermal inertia or insulation. However, for highly insulated buildings with significant inertia and low heat gains the method fails to assess the potential benefit of the PCM. Moreover, the ITD indicator is found to be the most accurate in assessing PCM benefits compared to other parameters studied. In this paper the ITD indicator will be modified to take into account an upper and lower comfort temperature levels rather than single set temperature.