Energy Reports (Nov 2021)
Techno-economic evaluation of building envelope solutions in hot arid climate: A case study of educational building
Abstract
Building energy use is becoming increasingly important worldwide, with the increasing necessity to attain indoor thermal conditions. The high temperatures in hot climates cause human dissatisfaction resulting in higher use of air conditioning systems. As a result, energy in those buildings rises regularly driven by the increase in the air conditioning systems operation. In the non-residential building sector, the air conditioning system consumes the majority of the building’s energy to satisfy the thermal comfort requirements. With this aim, simulations have nowadays become an important tool to fulfill various high-performance buildings. Dynamic simulations have often been used by designers to evaluate buildings’ energy performance to accomplish specific goals, as minimizing energy usage and environmental impacts. This study analyzes the energy savings obtained by the execution of retrofitting measures in an educational building located in Egypt through dynamic simulations of the building performance. The main objective is the creation of a decision matrix to select an optimal solution for the building envelope based on the effectiveness of thermal insulation, cost, and environmental factors. Based on the precise physical characteristics of the building’s vacancy schedule, geographical location, weather conditions, and the nature of construction, overall energy consumption would be determined. A sensitivity analysis is undertaken to assess the key factors that influence building energy consumption through the validated baseline model. The envelope is chosen as it is vital for the building’s energy efficiency and could account for up to 50% of the total heat gain in a building. Thermal insulation is one of the most effective implementations to provide desirable thermal comfort and minimize heat transfer into buildings, resulting in an energy consumption reduction. Two insulation materials are assessed through the building simulation model, the cost of each measure is estimated, and the emissions mitigation produced is obtained. With this information, a decision matrix is created that allows highlighting the best option based on the effectiveness of the measure in Egyptian hot arid climates. Among different insulations surveyed in Egypt, the study highlighted the effectiveness of using Extruded polystyrene insulation (XPS) with a thickness of 25 mm, resulting in reductions of about 16% in Heating, Ventilation, and Air-Conditioning (HVAC) energy consumption and 8% of the overall energy consumption with a payback period of about 25 months and a 29% Return on investment (ROI).
