Performance of Ground Energy Systems Installed in Foundations

英国和欧盟在减少二氧化碳排放和增加可再生能源发电方面都有具有法律约束力的目标。由于英国每年约有25%至33%的能源使用用于空间供暖，如果要实现排放和能源目标，提供可再生热能是一个至关重要的领域。在地基和其他地下结构内增加使用地面能源系统将在这两方面都是有益的，并将有资格通过即将到来的政府可再生热激励获得财政支持。然而，尽管最近地面能源系统的使用有所增加，但其性能仍有一些关键领域不确定。从长远来看，这一点尤其重要，因为多个装置将相互影响，不平衡的加热或冷却负荷将导致地面热力学状况的变化。该项目旨在通过全面测量和监测两个场地的对比地面条件，解决安装在基础上的地面能源系统的一些不确定性。这将允许测量地面对已知的加热和冷却负荷的真实的反应，并与基于分析和数值模型的预测进行比较。对比地质状况的使用将允许调查地下水对系统性能的影响，这是很少考虑和不太了解的事情。在进行实地监测的同时，还将实施一项现场和实验室测试方案，以评估与地面能源系统有关的不同规模和温度下的热行为差异。测试方案将解决与确定关键热性能的不确定性程度有关的问题，以及如何将其与系统设计中的其他不确定性（如加热/冷却负荷）进行比较。数字模型，包括对地面能源系统的现场热响应测试和操作的反分析，将能够评估系统对不同输入参数的敏感性。该模型还将有助于评价目前用于设计地面能源系统的数字和分析技术，并评估目前在现有方法中没有考虑到的关键因素（地质变化、地下水、地表边界条件、地热梯度）的重要性。总的来说，该项目的各个方面预计将提供一个重要的数据集，这将大大增加对地面能源系统性能的理解。通过解决设计输入参数、地质条件和设计方法方面的不确定性，该项目还将提供相关经验教训，供直接应用于安装在地基中的地面能源系统的设计和建造，预计最终将成为改进后的行业指导的一部分。

The UK and the European Union have legally binding targets for reducing carbon dioxide emissions and for the increasing renewable energy generation. As about 25% to 33% of the UK's annual energy usage is expended on space heating, the provision of renewable heat energy is an area of critical importance if emissions and energy targets are to be achieved. Increased use of ground energy systems within foundations and other underground structures would be beneficial in both these respects, and will be eligible for financial support through the forthcoming government Renewable Heat Incentive. However, despite a recent increase in the use of ground energy systems, there remain key areas of uncertainty about their performance. This is especially important in the long term, where multiple installations will interact with each other and where unbalanced heating or cooling loads will lead to changes in the thermodynamic regime in the ground. This project aims to address some of the uncertainties surrounding ground energy systems installed in foundations by comprehensively instrumenting and monitoring two sites in contrasting ground conditions. This will allow the real response of the ground to known heating and cooling loads to be measured, and comparisons made with predictions based on analytical and numerical models. The use of contrasting geological regimes will allow investigation of the impact of groundwater on the performance of systems, something rarely considered and not well understood. The field monitoring will be accompanied by a programme of in situ and laboratory testing to assess differences in thermal behaviour at different scales and temperatures relevant to ground energy systems. The testing programme will address questions relating to degrees of uncertainty in determining key thermal properties and how this may compare with other uncertainties in the system design, such as heating/cooling loads. Numerical modelling, including back analysis of the in situ thermal response testing and operation of the ground energy systems, will allow assessment of the sensitivity of the systems to different input parameters. The modelling will also allow evaluation of the numerical and analytical techniques currently used for the design of ground energy systems and assessment of the importance of key factors (geological variation, groundwater, surface boundary conditions, geothermal gradient) not currently accounted for in existing methods. Taken together, the various strands to the project are expected to provide an important dataset which will add substantially to the understanding of the performance of ground energy systems. By addressing uncertainties surrounding design input parameters, geological conditions and design approaches, the project will also provide relevant lessons for direct application to the design and construction of ground energy systems installed in foundations, which it is expected will ultimately form part of improved guidance for industry.