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REGENERATION PROJECT BSEE
Efficiently heating Wembley Park: One of London’s largest community heating projects
The increasing demand for ecient and environmentally friendly building services has seen the rise in popularity of district heang networks as a means of heang new homes and buildings in the UK. One of the largest to be installed is in the Wembley Park regeneraon project, as Crispin Matson, director at Ramboll, explains…
he use of district heating in cities is far from a recent trend; indeed, in Copenhagen most residences are connected to such networks. District heating is an efficient solution, providing heating to a number of homes or buildings from a singular source. These systems ensure that the provision of heat is more environmentally-friendly, and by removing the need for individual gas boilers, with homes connected to a centralised heat source, heat is delivered more efficiently, cheaply and with lower carbon emissions.
T District heating network
As one of the UK’s largest ‘build-to- rent’ developments to date, the Wembley Park regeneration project will provide over 5,500 new homes along with commercial spaces in an 85-acre complex around Wembley Stadium. Ramboll was approached by Quintain in May 2016 to help with the design and delivery of a district heating network to serve this new development – a project which would be one of the largest district heating networks in London. The preliminary concept of the project was to offer accommodation for rent by paying a single monthly, all-inclusive payment (including all utility bills).
The outline planning permission for the development allowed for two distinct and independent district heating networks, connected to nearly 20 separate buildings. Initially, the team undertook a design review, leading to the merger of the two separate networks into one, served by a single energy centre. Located underneath the residential tower of the largest development, the energy centre contains the main heat generating equipment: gas-fired combined heat and power (CHP) plant and gas-fired boilers, and the primary distribution pumps.
Energy analysis software was used for detailed analysis of the predicted energy demand, allowing for the calculation of the optimum size of the CHP plant to work in conjunction with the optimum size of thermal stores, in order to achieve the maximum carbon savings. The CHP plants produce both heat, which is fed into
the district heating network, and electricity, which is fed back directly into the electricity grid, resulting in the desired reduction in carbon waste. The optimum size of the CHP was calculated to be two 1.5MWe gas- fired engines, and the corresponding thermal store size was calculated to be 150m3
. This was achieved by installing two 75m3 tanks, each four
metres in diameter and seven metres high. Three gas-fired boilers (rated at 9MW capacity) provide additional heating capacity for peak and standby scenarios.
Main energy centre
From the main energy centre, the pipe network of the district heating system branches out to connect into the 20 separate buildings. Located on three sides of the existing Wembley football stadium, buildings require a network route that connects them to the main energy centre to be approximately 2.5km in length. Ramboll used its in-house ‘System Rornet’ hydraulic analysis software to adapt the district heating pipework size, and to determine the size of the most economical circulation pumps. The final route of the district heating pipework threads in a complex pattern through both public and privately-owned land, and is coordinated to avoid the multitude of other existing and new utility services (including, but not limited to, power cables, telecommunications services and gas services). Ramboll was employed to produce detailed drawings of the pipework installation to enable it to be built in independent construction phases. This meant the pipework could be installed to suit the programme of when spaces would be available for access, depending on the events schedule of the stadium. It is commonplace in most new residential communal heating systems built in the UK today for district heating networks to connect into an individual building block from a secondary heat exchange substation, usually found in the basement. From there, a secondary heating distribution system feeds into heat interfaces units (HIUs), located in each separate apartment. At Wembley Park, it was decided that, given the flats were to be rented rather than sold, the HIUs were to be omitted and instead, centralised
heating and hot water systems would be installed in each building to feed the individual apartments. This had two advantages – firstly, a reduction of capital costs and secondly (and equally importantly), meaning that the overall heating system would be more energy efficient due to the lower district heating return temperatures resulting from the omission of the heat exchanger typically located within HIUs. The two separate circuits were connected by two distinct heat exchangers within each building – one for the buildings’ centralised heating circuit, and one for the centralised hot water system. Both heat exchangers are integrated into a single building substation, maximising their thermal efficiency by utilising the return water from the secondary radiator heating circuit’s heat exchanger to preheat the cold-water feed for the hot water domestic use. Hence, the return water temperature of the primary district heating network is kept at an absolute minimum and, in doing so, heat losses from the network are reduced.
Project challenges
A number of challenges have been faced throughout the project. Working within the fixed space available for the energy centre, and designing the complex pipework route had proved to be difficult, as was maximising the energy efficiency of the network and working to the phased construction programme for the development. However, by utilising software to account for these issues with detailed designs, and integrating heat exchangers in a unique manner, Ramboll was able to overcome such challenges.
uThe Wembley Park regeneraon project will provide over 5,500 new homes along with commercial spaces in an 85acre complex around Wembley Stadium
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The district heating network and energy centre are currently under construction, whilst most of the pipework has been installed. Progressing equally rapidly is the installation of the energy centre. The thermal stores were installed initially, with the other major items of equipment including the CHPs, boiler and pumps due to be installed later this year. The plan is to have the entire district heating network installed and running by late summer 2019 – adding thousands more homes into the growing UK district heating network.
www.ramboll.co.uk BUILDING SERVICES & ENVIRONMENTAL ENGINEER DECEMBER 2018 15
uThe outline planning permission for the development allowed for two disnct and independent district heang networks
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The final route of the district heang pipework threads in a complex paern through both public and privatelyowned land, and is coordinated to avoid the multude of other exisng and new ulity services.
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