Adobe versus concrete: Passive energy analysis in residential buildings in the hot and arid climate of Kashan city
Peyman Naghipour, Afshin Naghipour, Tarana Bakirova, Farazin Soltani Gerd Faramarzi, Faraneh Soltani Gerd Faramarzi
Abstract
Hot-arid regions, such as central Iran, face extreme summer temperatures exceeding 40 °C and mild winters, creating significant cooling and heating demands in residential buildings. Modern construction in these climates predominantly uses reinforced concrete, which has high thermal conductivity and limited capacity to moderate indoor temperatures. In contrast, adobe-a traditional, locally sourced material with high thermal mass-has been largely overlooked in contemporary housing despite its passive climate-adaptive properties. Previous research has rarely conducted year-round, simulation-based comparisons of adobe and concrete in such environments, leaving a clear knowledge gap. This study hypothesises that adobe can substantially reduce annual energy loads compared to concrete in a representative hot-arid climate. A novelty of this work is the integration of full-year OpenStudio simulations, validated by DesignBuilder (R2 = 0.999), using real meteorological data from Kashan and a standardised residential prototype. Results show that adobe reduced total annual thermal loads by 74–78% (≈7325 kWh) and lowered peak summer cooling demand by 81.7% (August) as well as winter heating demand by ~80% (January). Optimal performance was achieved at a 45 cm wall thickness, balancing thermal benefit and material use. Over 10 years, these energy savings translate into an operational cost reduction of about 5860 USD and avoid approximately 16,750 kg CO₂/year, supporting adobe as a low-carbon, cost-effective option for hot-arid housing.