Life cycle cost analysis of residential energy Retrofits: Achieving near-zero energy homes in desert climates

Climate change mitigation necessitates energy retrofitting of inefficient existing building stock. However, financing such retrofits remains a significant barrier, particularly in countries with desert climates relying on energy-intensive cooling systems, such as Saudi Arabia. A notable gap in understanding and knowledge regarding the whole life cycle costs of retrofitting exists in both literature and industry, resulting in minimal retrofitting activity in the country. This study addresses this gap by conducting a Life Cycle Costing Analysis (LCCA) of energy retrofitting existing homes in Saudi Arabia towards Near Zero Energy Homes (NZEHs). Focusing on villa and apartment units, which represent 70 % of the national residential building stock, the research utilizes Building Information Modelling (BIM) to investigate case studies implementing eight energy efficiency measures and a rooftop photovoltaic system. The LCCA is computed using Compound Payback Period (CPP) and Net Present Value (NPV) methods. Findings suggest that energy consumption in existing homes can be halved through retrofitting, with solar energy potentially providing almost 40 % of the reduced demand. The average CPP for retrofitted buildings is five years across studied cities. However, the NPV indicates a negative investment for most cases, highlighting the need for additional financial incentives. To enhance financial outcomes, we propose measures including abolishing electricity tariff subsidies, potential tax breaks, and government financial support. This study elucidates the whole life cycle costs associated with energy retrofitting and has the potential to catalyse the crucial transition to NZEHs in Saudi Arabia, providing valuable insights for policymakers and stakeholders in the building sector.