Bridging Material Science and Architectural Heritage: A Critical Review of Silica Aerogel Materials in Historic Envelope Protection

Historic buildings often require thermal upgrading without compromising historic fabric, geometry, moisture balance, or the principle of minimal intervention. This critical review evaluates silica-aerogel materials for historic building-envelope retrofits by linking synthesis and pore-scale characteristics to thermal, hygrothermal, fire, mechanical, and conservation requirements. This review synthesises evidence from material studies and documented applications of aerogel plasters, boards, cavity fills, and fibre-reinforced composites. Silica aerogels commonly exhibit porosity of ۸۰–۹۹.۸%, specific surface areas of ۵۰۰–۱۲۰۰ m²/g, bulk densities of approximately ۲–۵۰ kg/m³, and thermal conductivity of approximately ۰.۰۱۳۶–۰.۰۳۸ W/(m·K), enabling high thermal resistance at limited thickness. Historic-building studies report substantial performance gains: thin internal insulation systems reduced wall U-values by up to ۶۱% in comparative testing; blown-in aerogel reduced a wall U-value from ۱.۷۴۶ to ۰.۴۸۲ W/(m²·K); and monitored retrofit projects reported energy-demand or energy-consumption reductions of approximately ۳۵–۶۰%. Hygrothermal studies also indicate that vapour-open aerogel systems can reduce condensation risk when material properties, substrate conditions, climate, and detailing are considered together. However, brittleness, high production cost, uncertain long-term durability, product-dependent fire behavior, reversibility, and limited multi-decade field evidence remain important barriers. The review therefore evaluates aerogel as a conservation-compatible retrofit system rather than solely as a high-performance material. It identifies priorities for standardized field monitoring, long-term aging studies, life-cycle assessment, and lower-cost scalable production.

کلیدواژه ها:

Silica Aerogel ، historic buildings ، Internal insulation ، Hygrothermal performance ، Energy retrofit