Water-related deterioration risk assessment for sustainable conservation of heritage buildings in the Forbidden City, China

Abstract

A suitable hygrothermal environment is imperative for sustainably conserving movable and immovable cultural heritage. This paper proposes a combined method for quantitatively assessing water-related deterioration risks in heritage buildings, validated employing the Forbidden City in China, a UNESCO World Heritage site. The approach emphasizes combining hygrothermal coupled transfer simulation with conventional environmental monitoring for systematic risk assessments. Key findings include identifying predominant causes of year-round deteriorations of salt weathering, freeze–thaw damage, microorganism growth, and physical cracking. Secondly, it underscores the persistent dampness at the bottom, stemming from capillary rising in building foundations, rendering the present environment unsuitable for the conservation of single-story heritage buildings. Lastly, in the Forbidden City, significant deteriorations manifest just a few millimeters or centimeters beneath the surfaces of brick walls and floors. Suggested measures include reducing shallow groundwater and enhancing airtightness. This study establishes a scientific framework for deterioration risk assessment and sustainable cultural heritage conservation.