چكيده به لاتين
Today, the large ratio of existing buildings to new constructions in large cities like Tehran has led to considerable energy consumption in the building sector, primarily due to envelope inefficiencies. Retrofitting the building envelope, especially the building façade that accounts for great thermal transmittance, can significantly reduce energy consumption and the consequent environmental problems. However, various retrofit measures and the different thermos-physical properties of existing facades, on the one hand, and limited budgets available for facade retrofit, on the other hand, make the selection of energy-efficient retrofit solutions challenging in existing buildings.
The main problem of the research is to strike a balance between multiple and contradictory research objectives to find effective solutions that reduce energy demand and requires the least necessary retrofit costs with a relatively shorter payback period. Therefore, in the first step, the efficiency of façade retrofit measures in reducing cooling and heating demand in existing office buildings in Tehran was scrutinized. Also, the possibility of energy demand reduction by using various façade retrofit measures such as thermal insulation, efficient windows, shading, window to wall ratio (WWR), and low-emissivity coating on the north and south existing facades have been investigated.
Since the methodological approach of the present study is quantitative, this study is completed by simulation methods using Energy Plus and Open Studio. It is based on parametric modeling using Rhinoceros software and Grasshopper plugin and connected to the energy calculation engines by Ladybug and Honeybee plugins. Also, a comparative study method has been used to compare the energy consumption in existing buildings before and after the façade retrofit. This research takes a step further and tries to find the optimal scenarios that minimize energy demand, retrofit costs, and payback periods. The Pareto optimal has been used to find the optimal solutions that meet the three objectives criteria.
The results show that the energy demand in existing inefficient office buildings could be reduced by up to 50%. In south façades with 30% or less WWR, the shading, window type, thermal insulation, and low-emissivity coating should be prioritized in façade retrofit, respectively. Thermal insulation, window type, and low-emissivity coating should be prioritized in the north façade. Retrofitting the south facade retrofit takes precedence over the north facade due to higher energy efficiency and lower payback period. However, the façade retrofit of south façade requires 1 to 2.5 more budget than that of the north façade. In the south façade, energy efficiency is not always achieved with more investment. But in north facades, the results improve by increasing the retrofit investments. Façade retrofit is not economical in all scenarios. When the WWR is increased to more than 40% in the south and more than 50% in the north, the façade retrofit is not economical.
