Abstract:
Improving the thermal behavior of old buildings’ external envelope to meet current standards is a subject that every country needs to tackle when talking about eco-efficient building design. In cities, buildings constructed several decades ago account for a substantial percentage of the total residential buildings. The same applies to the Mediterranean city of Beirut, the capital of Lebanon. Retrofitting the external walls of old buildings aims to decrease the energy consumed to maintain comfortable conditions inside the residential space. This study assesses the thermal behavior of four different walls located in the Makassed Schools in Beirut, three are made of sandstone and the other is made out hollow concrete blocks. The goal of this study is to propose modifications on the current constructions to enhance the thermal comfort inside of each classroom. To do so, recorded temperature data were analyzed, and the thermal behavior of the walls was described using the thermal time lag and decrement factors. Furthermore, energy models for the four spaces were created using the OpenStudio application and the Sketchup plugin. These models were calibrated according to the standards set by ASHRAE and validated for a full year. Subsequently, unretrievable construction data, mainly the density and the specific heat of the building envelope, were estimated using the Markov Chain Monte Carlo method by the means of the interface linking python and the building energy simulator EnergyPlus. The calibrated models were used as a basis to compare the thermal performance of various passive energy saving techniques available in the Lebanese market. The results show that extruded polystyrene, double window glazing, and rock wool insulations are readily available options capable of significantly enhancing the thermal comfort of the classes without relying on mechanical ventilation.
