Climate change and the greening of masonry: implications for built heritage and new build

越来越多的令人信服的证据表明，不列颠群岛的石头腐烂环境差异很大，这些气候和污染状况本身也在变化，例如，气候本身的变化，硫排放量减少和当地大气氮氧化物水平上升。因此，迫切需要审查衰变过程的变化性质，调查新的和正在发展的环境条件，推动这些变化，并确定其对砌体材料未来衰变的影响范围，以及对规范和补救策略的任何必要修改。这种需求在英国西北部最为明显。事实上，建筑用石，尤其是砂岩，已经对该地区潮湿且通常富含盐的环境产生如此不利且如此迅速的反应（Smith等人，2002年），这必然会不可避免地引起人们的担忧，即随着预计的更温暖、更潮湿且可能更长的冬季，潮湿时间的增加可能会发生什么。简而言之，为了应对不断变化的气候和污染，我们很可能不得不从根本上重新思考我们对砖石结构的腐蚀和保护的理解。石英砂岩被选择来研究这些问题，因为它们已被证明对湿度和温度制度以及污染条件的微妙变化敏感，并且是高度敏感的指标。它们还提供了有利于藻类定居的酸性，开放的质地条件。如果石雕保持潮湿的时间更长，而不是像以前那样频繁或彻底干燥，那么可以假设有许多物理和化学影响。其中包括：由于盐分（特别是流动性高的盐分）的渗透深度加深，以及生物繁殖增加，导致生物在化学和物理方面的活跃腐烂，以及建筑物的不雅观污染，修复费用昂贵。因此，本项目将以早期对砂岩腐烂过程的研究为基础，研究预测的气候变化对未来腐烂的可能影响。要做到这一点，它将集中在水分制度的变化对石英砂岩的影响。这将把联合收割机实验室模拟与环境监测和与选定的砂岩建筑物暴露条件有关的衰变模式评估结合起来，并与完整石块的取样和分析联系起来。其核心是在北方爱尔兰西部的潮湿环境中建造测试墙，并嵌入传感器系统，以监测与生物殖民有关的热和湿度状况。这将被验证对实验室调查的殖民化过程和反馈，可能会影响石头腐烂，连同调查的离子扩散与长期的“深湿”的砖石。由于该合作伙伴关系已经拥有详细的知识，并且工业合作者提供了进入正在翻新的建筑物的机会，环境监测和采样将集中在整个北方爱尔兰，并得到苏格兰和英格兰西北部砂岩结构的有限选择性采样的支持。对石头本身的所有调查的基础是国家和区域气候变化情景的统计缩小，如果要将这些设想成功地转化为适应环境变化的有意义的战略，这种新的方法在更广泛的范围内是必不可少的。

SUMMARYThere is increasingly compelling evidence that stone decay environments vary significantly across the British Isles, and that these climatic and pollution regimes are themselves changing as, for example, climate itself changes, sulphur emissions are reduced and local levels of atmospheric NOX rise. Because of this there is an urgent need to review the changing nature of decay processes, investigate the new, and developing, environmental conditions that are driving these changes and to scope their impacts on the future decay of masonry materials and any required modifications to specification and remediation strategies. Nowhere is this need more apparent than in the northwest of the UK. The fact that building stones, especially sandstones, already react so adversely and so rapidly to the moist, often salt rich environments found in this region (Smith et al. 2002), must inevitably raise fears of what could happen as a consequence of any increase in their time of wetness associated with projected warmer, wetter and possibly longer winters. In short, in response to changing climate and pollution it is likely that we will have to radically rethink our understanding of masonry decay and conservation.Quartz sandstones have been chosen to investigate these issues because they have proven to be susceptible to, and highly sensitive indicators of, subtle changes in moisture and temperature regimes, as well as pollution conditions. They also provide acid, open-textured conditions that favour algal colonisation. If stonework were to remain wetter for longer and not dry out either as frequently or as thoroughly as before, there are a number of physical and chemical effects that could be hypothesised. These include: the deeper penetration of salts (especially those of high mobility) and increased biological colonisation leading to active biological decay, both chemical and physical, as well as unsightly soiling of buildings that is expensive to remedy.This project will therefore build on earlier research into sandstone decay processes to investigate the likely impacts of predicted climate change on future decay. To do this, it will concentrate on the effects of changes in moisture regime on quartz sandstones. This will combine laboratory simulations with environmental monitoring and the assessment of decay patterns related to conditions of exposure on selected sandstone buildings, linked to sampling and analysis of complete stone blocks. Central to this is the construction of test walls in a wet environment in the west of Northern Ireland with embedded sensor systems to monitor thermal and moisture regimes linked to biological colonisation. This will be validated against laboratory investigations of the colonisation process and the feedbacks that could affect stone decay, together with investigations of ion diffusion associated with prolonged 'deep wetness' of masonry. Because of the detailed knowledge already possessed by the partnership, and the access to buildings undergoing renovation provided by the industrial collaborator, environmental monitoring and sampling will concentrate across Northern Ireland, supported by limited selective sampling of sandstone structures in Scotland and northwest England.Underpinning all investigations into stone per se, is the statistical downscaling of national and regional climate change scenarios, linked to measurements of stone condition and the factors controlling it. This novel approach is essential at a much wider scale if such scenarios are to be successfully translated into meaningful strategies for adaptation to environmental change.