Comparative Thermal and Techno-Economic Assessment of Residential Building Envelope Systems with Renewable Energy Integration

Abstract

The need for enhanced thermal efficiency in residential buildings cannot be overstated, as it plays a critical role in lowering energy consumption, reducing operational costs, and increasing sustainability. Although superior walling systems can help decrease heating and cooling demands, they also tend to be more expensive. The use of renewable energy systems presents a possible alternative for providing cost-effective thermal comfort. This study aims to comparatively assess the thermal and economic efficiency of four different residential walling systems-namely, Cavity Brick (CB), Insulated Cavity Brick (ICB), Insulated Brick Veneer (IBV), and Insulated Reverse Brick Veneer (IRBV)-and to examine the viability of integrating renewable energy systems to improve the performance of building envelopes at a lower cost. Monthly heating and cooling demands were calculated using Autodesk Ecotect Analysis software. Construction material costs were analyzed in PKR, and economic viability was evaluated using Net Present Value (NPV) analysis with a 20-year lifecycle, a 6% discount rate, and a 3% inflation rate. The ICB module demonstrated the highest thermal efficiency but incurred an additional construction cost of PKR 1,504,366 compared to the least expensive IBV module. Although ICB resulted in annual energy savings of PKR 41,937, the NPV of these savings (PKR 629,144) did not offset the additional capital cost. Renewable technologies, particularly a 2 m² solar air heater and a 1 kW PV system, were identified as economical options for space heating, with total 20-year costs below PKR 198,097, making them more viable than the envelope upgrade alone. The findings suggest that integrating renewable technologies with cost-effective building envelopes provides a more favorable thermo-economic approach than relying solely on insulation upgrades.