Retrofit Measures Evaluation Considering Thermal Comfort and Energy Efficiency in School Buildings Using Design of Experiments

Abstract

An evaluation of retrofitting public school buildings for energy-efficiency without sacrificing thermal comfort was investigated using the design of experiments. A current school building was used as a case study for this research. Three building codes were applied to improve energy efficiency in school buildings in Jordan. These codes are the Jordan building code, The Pearl Rating System for Estidama ‘’Emirate of Abu Dhabi’’ and Jordan Green Building Council booklet. By using the three codes, six-building construction cases were derived by changing the U- values to enhance the thermal insulation for buildings, such as changing the material used in external walls and roof or Window to Wall Ratio ‘’WWR’’. A statistical factorial analysis was performed to understand the main effect of each variable on the heating and the cooling load and if there is any interaction between these variables. The seven parameters used in the statistical analysis were; U-roof (0.18-1.963 W/m2. K), U-wall (0.24-0.682 W/m2.K), U-glass (3.63-6.11 W/m2.K), WWR for north, south, east and west (33.5%-50%). After keeping the U-wall constant (UW= 0.682 W/m2.K ) based on the payback period results, a second statistical analysis was performed on other parameters such as external shading (no shade or 1.6m shade from building surface) and U-roof ( 0.18-1.963 W/m2.K), U-glass(3.63-6.11 W/m2.K), WWR for north, south, east and west (33.5%-50%). An optimization technique was finally utilized to summarize all the relations between variables and the cost of materials by using Lagrange multipliers; an equation was written and solved by EES software.