Thermal behavior and energy saving analysis of a flat with different energy efficiency measures in six climates

Researchers at Cadi Ayyad University in Marrakesh, Morocco, have modelled the thermal discomfort levels and energy loads for a reference building after various energy efficiency measures are implemented in 6 types of Moroccan climates. Using simulations verified with experimental results, it was found that high thermal insulation in the façade walls can undesirably result in higher cooling loads during the summer, and that the cavity wall technique is sufficient to achieve acceptable energy efficiency gains.

greenTEG’s U-Value Kit was used to measure the in-situ U-value of the cavity wall and verify the researcher’s calculated values. This paper represents a significant contribution to the continuing optimisation of building energy efficiency measures and techniques in different climates and conditions, which is important for the ongoing effort against preventing and mitigating climate change.

Authors: El-Hadi Drissi Lamrhari, Brahim Benhamou

Building Simultation

Abstract

This article aims at studying the impact of many construction parameters of a flat on its energy performance and thermal comfort. The studied parameters are: the envelope thermal insulation, the orientation, the floor level, the ground coupling, the roof and the external walls absorption coefficient and the controlled mechanical ventilation. The TRNSYS based numerical study is performed in six different climates ranging from cold to desert one. The numerical model has been validated against experimental results obtained from summer and winter long term monitoring campaigns of the flat located in the Marrakech city, Morocco. The apartment’s heating and cooling loads as well as thermal discomfort indexes are calculated for the possible eleven configurations combining the studied parameters. The results show that high thermal insulation of the walls leads to an apparent summer overheating with an increase in the flat’s total thermal load by up to 18% in all the considered climates, except for the cold one. It was found that the walls’ light thermal insulation resulting from the cavity wall technique is sufficient to reach an acceptable level of thermal comfort thus preventing summer overheating. Similarly, thermal insulation of the slab-on-grade floor was found to perform an increase in thermal load for hot and moderate climates by at least 67%. The best combination of all the studied energy efficiency measures for each climate conditions was evaluated via comparison to a reference case that represents the actual apartment.

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