Analysis of Alternative Building Envelope Solutions to Improve Energy Efficiency

Improving the building envelope can play a central role in energy efficiency (E.E) and embodied carbon (EC) emissions reduction during the building life cycle. Such a kind of improvement can be achieved by choosing low-embodied carbon building materials and specifying the appropriate thickness for walls to control the U-value. The main objective of this paper is to determine the appropriate U-value for building walls that should be used to achieve better thermal performance for the building and the least E. C. emissions. Different scenarios of building envelope design were considered for the assessment in terms of thickness and U-value using common clay brick, concrete masonry hollow block units (CMU), expanded polystyrene (EPS) sandwich panels, and autoclaved aerated concrete blocks (AAC). A layer of polyurethane (PU) was added to the clay brick and the CMU wall to enhance their thermal insulation. EDGE (Excellence Design for Greater Efficiency) and One Click LCA tools were used to calculate the energy efficiency savings and the total embodied carbon emissions reduction of the building. The findings showed that achieving the U-Value of the exterior walls in a range between 0.38 and 0.86 W/m²K could minimize the energy use by 10-15%. It was achieved by using polyurethane as insulation material in the traditional clay brick and the hollow concrete block, while the AAC and EPS sandwich panels were more effective wall designs, as they achieved about 10% and 15% energy savings and also contributed to about 32% and 35% reductions in the total embodied carbon of the building, respectively. The study clarifies that there are many sustainable alternative local materials that could be used to enhance the building's performance and facilitate a mandated building envelope strategy for the building sector in Egypt.