Methods and Metrics for Moisture Risk Assessment- Solid Wall Insulation (MRA-SWI)

如果相当数量的实心砖墙(SMW)住宅要进行绝缘，那么评估潮湿风险的方式将必须发生范式转变。必须开发方法来清楚地证明，即使考虑到我们未来变幻莫测的气候和人们选择的居住方式，绝缘解决方案也是有效的、坚固的和对潮湿的恢复能力。这项研究将产生新的方法和指标，并有严格的科学证据支持，使SMW的潮湿风险评估能够常规进行，新的绝缘材料将被开发，更多的家庭将被绝缘。为英国现有的住房存量进行绝缘将是实现温室气体减排目标和缓解燃料贫困的关键一步。散热水平最高的是c30%(800万)安装了SMW的家庭。隔热这些墙有很大的节省燃料的潜力，但可能会导致潮湿问题。当室外下雨或室内潮湿时，水分会在SMW内积聚，随着天气变得干燥，水分会减少。这些水可以从墙面的一个面流过到另一个面，因为没有空洞来充当毛细血管破裂的角色。对墙的内表面或外表面进行隔热会改变砖石的温度、每个面上的湿润和干燥速度以及水蒸气可能凝结和积累的位置。这种水分会导致霉菌生长、间质凝结和冻融破坏。这些问题可能会造成严重的损坏，维修费用高昂，并可能影响居住者的健康。英国建筑法规(批准的文件C)和相关标准中的当前指导方针不足以评估绝缘SMW时的潮湿风险。简化的稳态水汽扩散模型是不合适的，因为当SMW暴露在降雨中时，动态的液体水汽传导是主要的水汽传输机制。对于如何使用更先进的瞬时热湿模拟软件，边界条件应该使用什么输入，以及结果如何转化为湿度风险，明显缺乏指导。基于多年实践经验和研究的直截了当的设计原则导致了相互矛盾的建议，例如，对于绝缘材料对水蒸气的渗透性应该有多大，没有明确的共识。因此，只有少数湿热专家可能会尝试对SMW的绝缘进行定量风险评估，因此被绝缘的SMW越来越少。本研究项目将解决这些问题。首先，将开发一个框架，使用先进的热湿模拟软件进行湿度风险评估。这将包括关于墙内和墙外的边界条件的指导，特别是对于风力驱动的雨水暴露。它还将确定适当的标准，以最大限度地减少墙体内水分积累、室内表面霉菌生长和外部表面冻结/融化的风险。将对许多绝缘材料进行比较，以了解哪种材料在绝缘SMW时最能降低湿气损害的风险。其次，在边界条件和材料特性存在相当大的不确定性的情况下，将使用概率建模方法来了解不同的绝缘解决方案对湿气损害的健壮性。第三，将探索湿度风险评估的新方法。“湿度安全系数”可以用来描述隔热SMW对洪水等极端事件的弹性。有可能开发一种全新的实验室测试来评估绝缘溶液。这项研究的潜在力量来自于在新的最先进的湿热试验设施中收集高质量的原始数据，以验证模型的结果。

If the significant numbers of dwellings with solid masonry walls (SMWs) are to be insulated, there will have to be a paradigm shift in the way that moisture risk is assessed. Methods must be developed to clearly demonstrate that insulation solutions are effective, robust and resilient to moisture even when considering the vagaries of our future climate and the way that people choose to live in their homes. This research will result in new methods and metrics, backed by rigorous scientific evidence, that enable moisture risk assessment of SMWs to be carried out routinely, new insulation materials to be developed and more homes to be insulated.Insulating the UKs existing housing stock will be an essential step in achieving greenhouse gas reduction targets and alleviating fuel poverty. The highest levels of heat loss occur in the c30% (8 million) homes that have SMWs. Insulating these walls offers significant potential for fuel savings but may cause moisture problems. Water accumulates within SMWs when it is raining outside or humid inside and diminishes with drier conditions. This water can pass from one face of the wall to the other as there is no cavity to act as a capillary break. Applying insulation to either the inside or outside face of the wall changes the temperature of the masonry, the rate of wetting and drying at each face and the locations where water vapour might condense and accumulate. This moisture can lead to mould growth, interstitial condensation and freeze thaw damage. These problems can cause severe damage, are expensive to repair and can affect the health of occupants.Current guidance in the UK Building Regulations (approved document C) and related standards is not adequate for assessing moisture risk when insulating SMWs. The simplified steady-state vapour diffusion model is not appropriate because dynamic liquid moisture conduction is the dominant moisture transport mechanism when SMWs are exposed to rainfall. There is a distinct lack of guidance on how to use more advanced transient heat and moisture simulation software, what inputs should be used for the boundary conditions and how the results translate into moisture risk. Straightforward design principles, based on many years of practical experience and research, have led to contradictory advice e.g. there is no clear consensus on how permeable the insulation material should be to water vapour. Thus only a small handful of hygrothermal experts might ever attempt a quantitative risk assessment for insulating SMWs and fewer SMWs are being insulated as a result.This research project will address these problems. Firstly, a framework will be developed for using advanced heat and moisture simulation software to carry out moisture risk assessment. This will include guidance on the boundary conditions to be used at the inside of the wall, and outside especially for wind driven rain exposure. It will also identify appropriate criteria to minimise risk from moisture accumulation within the wall, mould growth at the indoor surface and freeze/thaw at the outside surface. A number of insulation materials will be compared to understand which can best reduce the risk of moisture damage when insulating SMWs. Secondly, probabilistic modelling methods will be used to understand how robust different insulation solutions are to moisture damage given that there is considerable uncertainty in boundary conditions and material properties. Thirdly, new approaches to moisture risk assessment will be explored. A 'moisture safety factor' might describe how resilient an insulated SMW is to extreme events such as flooding. It may be possible to develop a completely new laboratory test for assessing insulation solutions. The underlying strength of this research comes from the collection high quality primary data, in the new state-of-the-art Hygrothermal Test Facility, for validating the results from the models.