Thermal envelope analysis for new code compliance of Saudi Arabian dwellings.

• The performance of Saudi houses is compromised by weaknesses in the building envelope. • Walls formed with insulated concrete blocks do not comply with the Saudi Code 2018. • The thermal bridging increases the thermal transmittance considerably. • 39% of energy consumption is attributed to heat loss from thermal bridging. • External insulation improves the U-value and reduces the impact of bridging. Electrical energy usage in Saudi Arabia is high (~300 TWh/yr) and is increasing (>5%/yr). The residential building sector is responsible for approximately half of the total electricity usage. Past studies have shown that up to 70% of the electric energy used in buildings in Saudi Arabia is consumed in the air conditioning of internal space. This study investigates this significant cooling requirement, particularly concerning the building envelope in typical detached villa housing. The paper concludes that walls formed using insulated concrete blocks only, as is common in Saudi Arabia, do not ensure compliance with the minimum requirements of the Saudi Code 2018. Thermal bridging of the building's envelope, which is currently not given due focus in the code, undermines the performance further. Bridging caused by the mortar joints between blocks, and by the cast concrete structural elements, increases the thermal transmittance through the envelope by a factor of two, relative to a non-bridged insulated concrete block wall. Simplified methods for thermal bridging calculation are referenced in the Saudi code, and these are evaluated here with reference to a detailed finite element study. Modelling studies show that the neglection of thermal bridging could underpredict building energy load by approximately 54 kWh/m2/yr – from 139 to 85 kWh/m2/yr. A 55 mm thick continuous external insulation layer is proposed to improve the performance considerably, reducing the wall-averaged thermal transmittance from 1.27 W/(m2·K) to 0.34 W/(m2·K) and hence achieving compliance with the latest building code. [ABSTRACT FROM AUTHOR]