An approach to achieve thermal comfort and save energy in heritage buildings using different operating patterns

The effective utilization of natural ventilation in heritage buildings could save a significant rate of electrical energy, as the airflow pattern affects interior comfort conditions; achieving users’ thermal comfort counts as an added value. This study aims to promote an approach in the form of a design strategy for a developed optimal annual operating schedule for heritage buildings, targeting the best operating pattern/s for each month. The study was carried out for a typical heritage building in the central district of Alexandria city (a typical Mediterranean Basin city), Egypt, for improving energy efficiency while achieving users’ thermal comfort. The paper adopted a simulation methodology for conducting energy and thermal comfort analyses using DesignBuilder simulation software. The approach was applied to a south-oriented room of the selected residential heritage building, which is the most affected orientation in the temperate-humid (slightly warmer) climate. The developed operating patterns included closed and opened windows, controlled natural ventilation, and HVAC system for cooling and heating with different temperature setpoints. The results showed that using the developed optimal annual operating schedule can save up to 47% of the total cooling and heating electrical energy annually, while achiev- ing 365 thermally comfortable days a year, including 177 days when only natural ventilation operating patterns are used. The study revealed the importance of considering the optimal operating patterns schedule as an approach to improve the environmental performance of heritage buildings. Also, the optimal annual operating schedule resulted in an adjusted base-case that can be used for evaluating the retrofitting scenarios for south-oriented, energy-efficient heritage buildings in temperate-humid climate.