Energy efficiency strategies for retrofitting existing buildings towards net zero energy: evidence from the Sri Lankan construction industry

Abstract

By 2050, a significant proportion of the buildings expected to be in use will have already been con-structed. Given the substantial energy consumption associated with the construction industry, the adoption of energy efficiency strategies is essential. Net Zero Energy Buildings (NZEB) play a critical role in reducing energy use and carbon emissions. Despite the growing emphasis on NZEB, limited studies have focused on prioritizing the most effective energy efficiency strategies for retrofitting existing buildings in the Sri Lankan context. This study aimed to identify and prioritize energy efficiency strategies suitable for retrofitting existing buildings to-wards NZEB in Sri Lanka. A mixed method approach was adopted. Initially, a literature review was conducted to identify energy efficiency strategies, followed by preliminary interviews to validate their applicability in the Sri Lankan context. Subsequently, a questionnaire survey was administered to assess the criticality of each strategy, and the data were analyzed using one sample t-test. The findings revealed that eleven out of twelve strategies were critical, with natural ventilation, energy audits, and energy-efficient windows identified as the most impactful. The study provides actionable insights for practitioners and policymakers to guide effective retrofitting interventions and support sustainable, low-carbon building practices in Sri Lanka.