24 BCD SPECIAL REPORT ON HISTORIC CHURCHES 32nd ANNUAL EDITION The Spoure monument at St Torney’s, North Hill: environmental monitoring indicated that this area regularly reaches 100% RH even in the summer months. (Photo: Meriel O’Dowd) to assess climate change risks considers hazard, exposure and vulnerability plus sensitivity, adaptive capacity and significance. This is a rapidly developing area not only in the heritage sector but throughout the built environment. Climate change is most often summed up by hotter drier summers and warmer wetter winters; but how hot is hotter? And how wet is wetter? It is possible to move beyond this generic statement to a more granular assessment. UK Climate Predictions 2018 (UKCP18) data1 can be used to analyse potential future conditions nationally and regionally allowing more specificity to local changes. The Met Office’s Hadley Centre publishes 2.2 km-scale predictions from 12 models operating under different Representative Concentration Pathways (RCPs). These can be averaged to glean monthly predictions for relevant climate variables over a range of years; 2021–2040 and 2061–2080, for example, with a 1981–2000 baseline period. This data set can also be used to interrogate potential weather extremes. Climate change hazards include higher rainfall, heavy downpour events and flooding, more frequent and intense droughts, higher humidities, storms and rising sea levels. All these hazards multiply the occurrence of building defects and worsen their impact, increasing risk to fabric, collections and landscapes. For example, higher temperatures can lead to cracking of materials such as glass, metal and stone, and seasonal variations can worsen the shrinking and swelling (‘soil heave’) of clay subsoils beneath historic buildings. Higher relative humidity (RH) for prolonged periods increases incidents of fabric decay, microbiological growth and attacks from insect larvae. Higher levels of rainfall, along with heavy downpour events, will increase saturation of building fabric and potentially impact the rate of deterioration and decay. It is, therefore, important to understand what type of climate hazards are likely to impact a site and determine the effects of these threats in order to develop suitable conservation management strategies and a record of any historic fabric that is likely to be lost. The setting of a building impacts how it will be affected by the changing climate. Understanding the building in relation to its setting and how the two interact is key to determining its potential vulnerability and resilience. For example, urban environments with little green space intensify periods of high temperature and hard surfaces (urban or not) can increase surface water flood risk. Reviewing location-specific details, materials information, and, where available, building monitoring data supported by local climate modelling allows the determination of potential future conditions, impacts and vulnerabilities. CCT CLIMATE CHANGE ANALYSIS A study carried out for the Churches Conservation Trust, which cares for over 350 redundant churches across England, illustrates typical issues of relevance to historic places of worship of all shapes and sizes across the UK. The study reviewed local and regional climate change hazards that may impact the building fabric, monuments, systems and services for churches in three locations: North Hill in Cornwall, Hamstead Marshall in Berkshire and Berrington in Shropshire. The aim was to provide a strategic view of climate-related risks for the sites, highlight vulnerabilities and support future maintenance planning. Different climate variables were modelled using the Met Office data sets to establish current and future weather conditions and identify the most likely changes. This article looks at St Torney’s, North Hill, in detail where hydrological, geological and geotechnical assessments were undertaken along with a combination of site visits and desktop reviews of existing reports. The site’s significance was assessed with fabric condition and repair requirements ascertained to establish potential risk, vulnerability and resilience. ST TORNEY’S, NORTH HILL The church of St Torney’s in North Hill, Cornwall, is a Grade I-listed church believed to be over 600 years old, the chancel dating from the 14th century, with the remainder built during the 15th and 16th centuries. The chancel is constructed of rubble stone and the aisles of ashlar granite blocks. The church contains an interesting range of monuments, memorials and stained glass with some diverse, fine and significant examples. A major programme of conservation work was underway during the study period, including extensive repair to roofs stonework and internal replastering. One of the tallest towers in Cornwall, St Torney’s sits 161 m above sea level between Bodmin Moore and Dartmoor. The ground drops away steeply to the south and west down to the River Lynher, leaving the building extremely exposed to the prevailing weather. There are mature trees within the churchyard, with large yews close to 1 See UKCP18 Guidance: Representative Concentration Pathways
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