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INTRODUCTIONThe practicalities of groundwater reinjection have long been investigated for water resources purposes, as part of aquifer storage and recovery projects (Driscoll, 1986, Harris, 2005, Martin 2013. More recently, analysis of the fate of surplus heat introduced to aquifers with water from cooling systems has become a pressing issue, as the number of systems using the subsurface as a lowcarbon heat sink increase (e.g. Younger 2007;2014). This paper examines two years of operational data from the first large system of this type exploiting the Quaternary valley-train sand-and-gravel aquifer associated with the River Thames. Given that similar aquifers are widespread, not only in the UK but worldwide, the findings of this investigation offer valuable insights for designers and managers of such systems elsewhere, particularly in other large cities. SITE DESCRIPTIONThe site is housed within the former Bankside Power Station, built in two stages between 1947 and 1963. A former oil-fired power station, Bankside closed its doors in 1981, although the EDF Energy owned substation at the back of the building continued to operate. In 2006, half of the sub-station building was released back to the art gallery that now occupies the former power station, and the newly available space makes up part of the footprint of an expansion. The other half of the site continues to be used as the major electrical substation serving much of South London and waste heat from water cooled transformers provides 65-96% of the overall heat demand within the new development at the site. Whilst waste heat is utilized to provide most of the heating requirement approximately 11% of the buildings entire energy demand comes from cooling, even after a number of passive cooling systems were developed.Groundwater in the shallow alluvial aquifer underlying the site provides the sole source of cooling for the new development at the site and was developed between 2008 and 2010. Starting in 2012 the performance of this large open loop groundwater cooling system has been monitored closely over its first two years of operation. This has allowed closer examination of two operational aspects which are of critical importance to the efficient running and longevity of the installed system, namely the stability of the recharge and induced changes in the temperature of the groundwater in response to sustained heat rejection.In an initial nine month trial period, approximately 131,300 m 3 of groundwater was abstracted and recharged and approximately 1.3 GWh of heat was rejected to the subsurface, which verges on a proposed typical year of operation. Monitoring described in this paper has enabled closer examination of the resilience of the installed system in terms of recharge and heat rejection.A detailed description of the development of the cooling system at the site, including an assessment of the geological and hydrogeological setting, the installed borehole infrastructure, and the results of early commissioning tests and analysis, is given in Birks et al...

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Many building services consultancies use commercial software to predict which surfaces of a building are in direct sunlight and which are in shade at any given time in the year. Such an approach can yield very satisfuctory results and a large number of 'pretty pictures'. However, it does not lend itself to an understanding of what the basic physical principles are behind such a calculation. Such an analysis is particularly useful in calculating the solar gain for the large glazed geometrical shapes particularly beloved of architects. This paper is an attempt to explain these principles and to enable simple spreadsheet calculations to be carried out. The work described was carried out as part of the environmental analysis and design of the Great Glasshouse at the National Botanic Garden of Wales, Llanarthne, Carmarthenshirew. List of symbols i Unit vector parallel to the x-axis (east) i Unit vector parallel to they-(north) k Unit vector parallel to the z-axis (vertical) n Unit vector normal to a surface I~ Unit vector defined by the position of the sun in the sky G The Cartesian equation of a geometrical shape