THE GROUND SOURCE HEAT PUMP ASSOCIATION The National Energy Centre - PDF document

THE GROUND SOURCE HEAT PUMP ASSOCIATION The National Energy Centre • Davy Avenue • Knowlhill • Milton Keynes • MK5 8NG Tel: 01908 354545 • e-mail: info@gshp.org.uk • Fax: 01908 665577 Website: www.gshp.org.uk 09:00 Welcome Address Duncan Nicholson 09:05 Desk study stage and site investigation and response testing Chair: Duncan Nicholson Recorder: Brian Stringer Regulation of GSHP systems Jenny Thomas In common with other forms of renewable energy, the Environment Agency wishes to encourage the sustainable use of GSHP systems. We are therefore looking to simplify regulation and require the minimum information from applicants. To achieve this, we are looking to publish good practice guidance. We do not regulate closed loop systems. Open loop systems require a groundwater investigation consent, followed by an abstraction licence, and a discharge consent. There is currently limited information available on the temperature of aquifers and in practice how they respond to changes. This, together with simple tools to enable rapid assessment of applications, covers our main research needs. Borehole Heat Exchanger Model Development Miaomiao He Common approaches to the simulation of Borehole Heat Exchangers (BHEs) assume heat transfer in circulating fluid and grout to be in a quasi steady state and ignore fluctuations in fluid temperature due to transport of the fluid through the loop. However, the dynamic responses of circulating fluid and BHEs have important implications for systems design under some circumstances. In this research project a dynamic three dimensional numerical model has been developed by applying the finite volume method to simulate the fluid transport and transient conduction in and around the BHE. The model is being used to study short time scale dynamic behaviour, the effect on peak performance, control system interaction and develop improved simplified models. Mitigation potential of horizontal ground coupled heat pumps for current and future climatic conditions: UK environmental modelling and experimental studies Anne Verhoef A NERC research project started in May 2009 to calculate the mitigation potential of horizontal GCHPs. The team consists of soil physicists, climate modellers, building and energy technologists, groundwater modellers and GCHP installers, from Reading and Nottingham University, BGS, CEH-Wallingford and EarthEnergy Ltd. The combined effect of environment dynamics and GCHP technical properties on long-term GCHP performance will be assessed using simulation modelling, by combining the UK Met Office land surface model, which provides key variables such as land surface temperature and soil moisture content, with equations describing the interaction between GCHP heat exchangers and the surrounding soil Registered in England No. 1372316 VAT No. 354 3365 56

09:55 Open Systems Chair: David Whitaker Recorder: Huw Williams Development of Finite Element thermal groundwater models Huw Williams The presentation will cover the thermal groundwater finite element modelling (in FEFLOW) undertaken to date by LoopMaster (Europe) to investigate the suitability of each system in the dual porosity Chalk Aquifer of the London Basin. A brief discussion of modelling techniques will be given, including a review of the initial results which have lead to LoopMaster offering support for a post graduate Thesis to further develop these preliminary findings. Sustainability assessments of GSHP Systems Martin Preene The Presentation will briefly present work Golder Associates has recently completed in Ontaria, Canada reviewing best practice on the assessment and subsequent regulation of environmental impacts from GSHP systems 10:35 Closed loop borehole and horizontal systems Chair: Robin Curtis Recorder: Nic Wincott Spiral Probes as alternative to Horizontal Collector Ralf Winterling Either probes or horizontal collector are the standard application for ground source solutions in the residential market. Probes require on average a 100 m bore hole, which could be problematic in certain ground conditions or restricted by planning, e.g. in areas of ground water usage. Whereas horizontal collectors require a sizable ground space which is most often not available on the average new build plot size. To address these topics a spiral collector has been developed, requiring only a 5 m deep bore hole and significantly less ground space. The presentation will provide an overview of the spiral probe development, the design parameter and installation technique as well as monitored performance figures of a test field installation Building Simulation Nick Kelly The Energy Systems Research Unit (ESRU) has considerable experience in the development and use of building simulation tools. These offer a useful mathematical test bed for the design and performance analysis of a range of microgeneration technologies such as ground source heat pumps (GSHP) when integrated into buildings. This presentation will highlight the capabilities of building simulation with regards to analysing low carbon energy systems such as GSHPs and will highlight areas of potential research and development in modelling tools. 11:25 Coffee Break

11:40 Case history performance Chair: Robin Curtis Recorder: Peter Smith Replacing oil fired boilers by GSHP pumps in existing school buildings in Reading Rayner Mayer There are a number of schools in Reading which are currently heated by oil fired boilers. When these come to the end of their working life, the question for both the schools and the Borough Council is whether to bypass gas heating and to consider using renewable heating systems like GSHP. The first school which is being considered is A and B blocks of Prospect College. One of the key issues is how to anticipate future needs when building schools for the future funding will be used to refurbish or rebuild these blocks. Keble College energy piles Natasha Kefford In 2006 Arup led a DTI Partners in Innovation (PII) project into the ground storage of building energy. Part of this work highlighted the lack of case histories detailing the performance of ground energy systems in England. To improve upon the lack of published data, an agreement was reached between Arup and SEEDA (South East England Development Agency) to undertake energy pile monitoring at the Sloane Robinson Building, Keble College, Oxford. This presentation summarises the findings from the first monitoring report. 12:20 Lunch 13:00 Swedish Perspective on GSHP Research Goran Hellstrom 13:10 Geothermal Piles – Codes of Practice Chair: Tony Amis Recorder: John Patch Knightsbridge Palace Hotel Tony Amis The proposal is to undertake a conductivity trial of a loop installed within a diaphragm wall panel at Knightsbridge palace Hotel before excavation and then again once excavation is completed to ascertain the effects on overall conductivity values by the removal of soil from one face. NHBC - Energy piles for houses Duncan Nicholson NHBC guide on piling has been written. It includes a section on energy pile for houses. This considers the code for Sustainable Homes future requirements for zero carbon emissions. In addition specification for energy piles are discussed. Geotechnical Design of Heat Exchanger Piles Herve Peron There is currently a lack of established calculation method for the geotechnical design of heat exchanger piles, although the technology is experiencing a fast expansion. Instead of quantifying the effects of temperature changes on the static behaviour of heat exchanger piles, the common geotechnical practice is to apply a large overall security factor. This is done in order to be on the side of safety with respect to thermal effects. The few existing in situ experiments show that applying a thermal load induces a significant change in the stress-strain state of a pile. This talk presents a geotechnical numerical design method, based on the load transfer approach, which assesses the main effects of temperature changes on pile behaviour. The method is validated on the basis of two in situ measurements of the loads and deformations experienced by heat exchanger test piles. The occurrence of critical design situations is further discussed. Some conclusions are formulated on concrete failure and the full mobilization of the pile shaft friction and base resistance during the operation of the heat exchange system.