Europe's building stock is increasing in floor area by approximately 1% per annum. This represents an additional operational energy demand of over 4.5 million tonnes of oil equivalent, year on year. Of that energy requirement up to three quarters is related to space heating (or cooling), representing about half of total energy usage in Europe and North America. Ground source heat pumps, which can reduce the net consumption of energy for space heating by approximately 75%, can therefore play a significant and timely role in tackling the energy and carbon emissions challenge. Despite the urgent need to curb the increasing energy requirements of new buildings, the market for ground source heat pump systems faces a number of barriers to expansion. While some of the barriers are related to regulation, investment cost intensity remains an important factor. Consequently, research and development must focus on increasing energy efficiency and reducing capital costs. One route to reducing investment capital costs is through the combined use of building foundations for the heat exchanger component of the system, thereby avoiding the need for construction of special purpose heat exchangers such as boreholes. This has the potential to both reduce capital expenditure and deliver increased energy per drilled metre of the heat exchanger. Piles are the most common type of deep foundation. These are typically constructed by augering a hole which is infilled with concrete and steel reinforcement. Energy pile is the term used for a foundation pile which is equipped with heat transfer pipes to act as the heat exchanger part of a ground source heat pump system. Energy piles were first trialled in Austria in 1984, but thermal analysis and design methods have lagged substantially behind the practical application. Recent breakthroughs have shown the importance of the concrete part of the pile in storing thermal energy on a short term basis. This is significant because fluctuating operational energy demand means that a thermal steady state in the piles is rarely achieved. Despite this, most routine design approaches still characterise energy pile in terms of a steady state thermal resistance parameter. This means that any storage of energy in the concrete is neglected and the energy capacity of the system is routinely underestimated. Indeed, the steady state assumption has been shown to underestimate the potential energy saving available from energy piles by around 20%. This proposal outlines planned work which will develop new non-steady models for use with the thermal analysis of energy piles. The work will also include application of these models to in situ thermal response tests which are used to determine the thermal characteristics of the soil surrounding the pile. Hence the new models will contribute to both improved soil parameter selection and less conservative design approaches. This work is novel because there are currently no analytical models that appropriately simulate the transient behaviour of energy piles. By the introduction of appropriate non steady models this work will lead to improved and less conservative assessment of energy available from energy piles and hence increase their uptake in practice. This work is pressing because the alternative of using inappropriate steady state models will result in the under-prediction of ground source heat pump system performance and thereby inhibit uptake of this key renewable heat technology.

The latest report of Intergovernmental Panel on Climate Change (IPCC) 'Global warming of 1.5C' emphasises the need for 'rapid and far-reaching' actions now to curb carbon emission to limit global warming and climate change impact. Decarbonising heating is one of the actions which is going to play a key role in reducing carbon emission. The Committee on Climate Change states that insufficient progress has been made towards the low carbon heating homes target that requires immediate attention to meet our carbon budget. It is well known fact that the ground is warmer compared to air in winter and cooler in summer. Therefore our ancestors build caves and homes underground to protect them against extreme cold/hot weather. Geothermal energy pile (GEEP) basically consists of a pile foundation, heat exchanging loops and a heat pump. Heat exchanging loops are usually made of high density polyethylene pipes and carry heat exchanging fluid (water and/or ethylene glycol). Loops are attached to a reinforcement cage and installed into the concrete pile foundations of a building to extract the shallow ground energy via a heat pump to heat the building during winter. The cycle is reversed during summer when heat is collected from the building and stored in the ground. GEEP can play an important role in decarbonising heating as it utilises the sustainable ground energy available under our feet. High initial cost remains the main challenge in deploying heat pump technology. In the case of GEEP, the initial cost can be reduced, if the heat capacity of the concrete is improved and loop length can thus be decreased. This can be achieved by incorporating phase change material (PCM) in the concrete. PCM has a peculiar characteristic that it absorbs or releases large amount of energy during phase change (solid to liquid or liquid to solid). This project aims to develop an innovative solution by combining two technologies GEEP and PCM to obtain more heat energy per unit loop length which would reduce the cost of GEEP significantly. PCM has never been used with GEEP in the past, therefore obvious research questions that come to the mind are (1) how to inject PCM in concrete (2) what would be the effect of PCM on concrete strength and workability (3) how PCM would affect load capacity of GEEP as primary objective of the GEEP is to support structure (4) how much heat energy would be available (5) what would happen to the ground temperature surrounding GEEP (6) how much it would cost (7) whether it would reduce carbon footprint of concrete. We aim to answer all the above research questions by employing sustainable and environmental friendly PCM and impregnate it in light weight aggregates (LWAs) made with waste material (e.g. fly ash, slag, glass). There are three advantages of using LWAs made from waste: first LWAs will replace natural aggregate in concrete as natural aggregates are carbon intense, second LWAs are porous and light so they can absorb large amount of PCM and reduce the weight of concrete, third reuse the waste. Laboratory scale concrete GEEP will be made with PCM impregnated LWAs and tested under heating and cooling load to investigate thermal (heat transfer) and mechanical (load capacity) performance. Extensive experimental and numerical study will be carried out to design and develop novel PCM incorporated GEEP which can provide renewable ground energy for heating and cooling.

Since the turn of the century there has been a reduction in UK energy independence. While this trend has recently started to reverse, there is still a pressing need to further increase energy independence, as well as continue reduction in total consumption, and work towards becoming a carbon free energy nation. The Climate Change Act 2008 mandates the UK government to reduce carbon dioxide emissions by at least 80% (based on 1990 levels) by 2050. In total, domestic, commercial and industrial heat provision in the UK accounts for around one third of all greenhouse gas emissions and 40% of energy consumption. Hence tackling heating (and cooling) for all buildings is essential for addressing the energy problem. One energy efficiency solution which must play a future role in both demand reduction and decarbonisation is ground thermal energy storage. Such systems typically comprise some form of ground heat exchanger connected to a heat pump and a low temperature building heating delivery system (and/or higher temperature cooling delivery system). Traditional schemes use special purpose drilled boreholes as the ground heat exchanger, but since the 1980's building foundations developed as ground heat exchanger have also been used. Foundation ground heat exchangers are now becoming more common place, but there remains significant opportunities to use other underground structures for heat transfer and storage, thus contributing to the delivery of sustainable heating and cooling for overlying buildings. Retaining walls, tunnels and water/waste water pipes can all potentially be used as so called energy geostructures, where they exchange and store heat as well as performing their original structural function. However, despite a number of trials, most of these energy geostructures are a long way from routine adoption. Rigorous assessment of both their energy potential and how they are constructed is lacking. There are no routine design guides or standards and where schemes have been, or are being developed, they usually involve expensive and complicated analyses typically conducted in collaboration with a university partner. There are challenges in terms of energy assessment and further barriers to adoption in the requirement for adjacent consumers of the supplied energy. There is also a need for a heat/cool distribution network to reach the consumers which may not be currently in place. This proposal will tackle the challenges relating to routine implementation of energy geostructures, including design, construction and heat/cool delivery. This will encourage future adoption and help the development of the UK ground energy market.

Energy Management of existing non-domestic buildings is wrought with many challenges, a number of which arguably exist due to the diversity found amongst individual buildings and amongst the humans who occupy them. Buildings are inherently unique systems making it difficult to generalize technology solutions for any individual property. Instead, to make robust investment decisions for the energy-efficient upkeep of a particular building requires some degree of tailored engineering and economic analysis. To understand why this is the case, one need only to consider the chain of questions one would likely need to address for decision-making in an arbitrary building. For instance, we might ask: what is the age of the building and the equipment currently installed in it? Does the heating system need to be replaced? If yes, is the current system a boiler, and if so, how efficiently does it perform? Would the building benefit from a new boiler or an electric heat pump? Would it benefit from replacing the heating distribution pipes? Do the cost / benefits of any of these technologies depend on government tariffs and subsidies? What is the risk faced if any available subsidies are cut in the future? How robust is either technology to the future price of natural gas and electricity? Would that risk be worth taking? Is it too expensive to even start thinking about the options and associated risks? How would a facility manager visualise the options available and possible spreads of benefits and risks for all these aspects? This project aims to respond to these challenges. Indeed, in order to make sound decisions on future building operation and technology investment, evidence shows that one needs adequate information on a number of engineering, economics, and social science matters pertaining to each individual project. To obtain this information has so-far been viewed as a costly exercise, and has contributed to the general perception that undertaking deep cuts to building energy consumption (achieving more than 15% in energy savings per investment) is an economically risky affair. This proposal is the first to develop and recommend an altogether new approach to performing building audits, energy simulation, uncertainty analysis, data visualization, and finally investment decision-making. It will lead to a marked reduction in the cost of acquiring information for robust retrofit and facility management decisions. The direct outputs of this project will be a series of software tools for three distinct but related purposes: (i) collecting building data on relevant uncertainty parameters (i.e., "what do we know now?"); (ii) propagating and quantifying uncertainty using building simulation models, measurements obtained from key monitored building sites, and cutting-edge statistical approaches (i.e., Bayesian analysis); and (iii) the display and interpretation of uncertainty. During the course of the project, workshops will be organised to lay out the current (uncertain) knowledge that has been, until now, largely undocumented in the buildings sector and inaccessible to the energy research community. This includes gaining understanding on the most common faults observed in managing conventional energy systems, and how spatial layouts in building evolve. The graphical presentation of risk information and understanding users' perception of uncertainty and risk will be key elements of these workshops and the research programme. Our software tools, user guidance, and numerical runs of test cases will be made available, as the web-based B-bem portal, via the University of Cambridge web site.