A multi-criteria decision analysis framework for sustainable energy retrofit in buildings

The construction industry is considered to play an essential role to economic growth. However, it contributes a considerable amount of damage to the environment due to intensive use of materials during the construction stage. Thus, methods of prolonging the service life and increasing the performance of buildings during post-construction are heavily explored. This presents an opportunity to improve the performance of existing buildings by incorporating energy efficient technologies and strategies. The ambitious goal would be to transform aged buildings into Net-Zero Energy Buildings (NZEB). Due to economical restrictions and feasibility concerns, energy retrofit strategies must be designed and planned well to achieve the long-term goals of a building. In this work, a sustainable retrofit framework for evaluating energy retrofit strategies in buildings was developed through Multi-criteria decision tools: Analytical Hierarchy Process (AHP) and VIKOR as the weighting and ranking method, respectively. Environmental damages will be assessed through a Life Cycle Assessment using SimaPro while the economic performance shall be measured by the strategy’s investment cost and payback period. As proof of concept, the National Engineering (NEC) building was used as a case study that involved a whole building simulation using DesignBuilder to determine the effectiveness of energy retrofit strategies and retrofit scenarios. Results showed that NZE is technically feasible on an existing institutional building through an energy reduction of 52 % and a 48 % on-site energy generation strategy. In selecting a retrofit strategy, stakeholders gave preference to the technical performance followed by the environmental and economic performance. VIKOR proposed three compromise solutions consisting of the following retrofit scenarios: on-site generation scenario ranked first followed by the mechanical/electrical, and building envelope scenario, respectively