Quantifying improvement of building and zone level thermal resilience by cooling retrofits against summertime heat events

Abstract

Quantifying building resilience to extreme weather conditions helps identify the capability of a building system to tolerate disturbances and recover from extreme events. The robustness of building retrofit strategies can also be evaluated through their contributions to building resilience. In this study, building thermal resilience to summertime heatwaves is defined based on the concept of resilience trapezoid. The Thermal Resilience Index (TRI) with several labeling classes (Class F to Class A+) is proposed to quantify the resilience levels with respect to the relative improvement from original indoor thermal conditions. In addition to evaluating the overall resilience of a building, the resilience of each thermal zone in the building can be quantified with the proposed TRI criteria. A quantification framework is proposed by using the Standard Effective Temperature (SET) index as the performance indicator, and the entire procedure is demonstrated with a long-term care building of five stories. Four retrofit measures and their combinations are implemented to improve the building resilience to heatwaves. The results show layered multiple strategies are necessary to improve both the overall resilience of the building and the resilience of its component thermal zones. The resilience of the building can achieve the level of Class B after the combined strategies are applied, providing an improvement of 50%–70% in the degree of resilience. The proposed TRI index and spatial distribution analysis are useful in evaluating the overall and zonal resilience of a building.