Owned and operated by the registered charity Our Wilton Trust, the Veterans Hub project serves as part of a unique campus to support military veterans. Sited at the former Erskine Barracks in Wilton, Wiltshire, the hub provides a total of 44 high quality and contemporary studio, one-, and two-bedroom flats in addition to training and social enterprise opportunities.
A well designed and reliable heating and hot water system is paramount to care and accommodation buildings, where the comfort and wellbeing of residents can require year-round energy demands and a reliable source of hot water. Our Wilton’s Veterans Hub, like most care and residential applications, exhibits a continuous electrical demand alongside a significant, but varied, hot water and heating usage pattern. To meet this demand, the most effective design was that of a Combined Heat and Power (CHP), or cogeneration, preheat domestic hot water system.
CHP is the simultaneous production of thermal and electrical energy from a single source of fuel, and is an effective method of significantly increasing the energy efficiency of a building. Producing electricity by connecting an engine to a generator at the point of consumption can achieve similar levels of generation efficiency to that of a conventional power plant, while also eliminating the energy losses associated with transmitting power over long distances. The waste heat produced in the process is additionally recovered through a series of heat exchangers and used towards the thermal energy demands of the building, ensuring that minimal fuel energy is lost as exhaust. Sizing a CHP unit to meet the thermal energy requirements – knowing that there will always be an electrical demand to make use of the produced power – allows the machine to maximise its contribution to a building’s overall efficiency.
Our Wilton turned to Adveco Ltd., specialists in advanced heating and hot water systems, which supplied a TOTEM T20 m-CHP cogeneration system. The Adveco T20 CHP serves as the central part of a domestic hot water system designed by Contractors Design Partner (CDP), and brings high-efficiency renewable technology to the accommodation building. The use of CHP allows the building to meet strict building standards, increasing energy efficiency while lowering harmful emissions in an environmentally friendly answer to the building’s year-round domestic hot water requirements.
The system design features the 20kWe, 42kWTh TOTEM micro-cogenerator operating by heating an Adveco MSS 3000 litre thermal storage tank, which in turn feeds an A.O. Smith IT 1000 litre pre-heat vessel and two further IT 1000 DHW indirect calorifiers.
A correctly sized thermal store allows the CHP to run for extended periods of time while it heats up – all the while providing low carbon power to the building – ready to cover periods of peak usage. This arrangement allows the CHP to supply the full domestic hot water requirement for the building. A 140 kW A.O. Smith Upsilon boiler cascade has additionally been installed to serve as a top-up energy source for periods of excess or off-peak demand while the thermal store is recharging. The use of supplementary boilers additionally increases the overall reliability of the system by adding further heating redundancy.
The CHP, boilers, thermal storage tank and indirect water heaters supplied by Adveco alongside ancillaries, safety, and flue components create a bespoke and practical DHW system that prioritises low-carbon heat generation in a high-efficiency arrangement. The use of renewables leads to an estimated annual carbon saving in excess of 9,000 kg CO2.
The Adveco TOTEM CHP is the first in a new generation of micro-cogenerators, featuring market-leading efficiencies and the lowest NOX and CO2 emissions available from any CHP within its class. Designed and built in Italy by Totem-Energy s.r.l., the TOTEM is the result of 40 years of continuous research and development, and features components purpose-built for operation on natural gas. A 1.4-litre Fiat Fire engine, sourced directly from Fiat Chrysler Automobiles – the developers of the original TOTEM in 1978 – and an ECU supplied and tuned by automotive experts Magneti Marelli allow the TOTEM to achieve unparalleled cogeneration quality and reliability. With NOX emissions at <12 mg/kWh, the TOTEM remains one of the few CHP appliances on the market that is still eligible for full points under the revised POL02 category of the 2018 BREEAM New Construction Scheme, even when installed in high pollution urban areas.
In addition to its market-leading efficiencies, the TOTEM CHP offers improved reliability through features such as a self-change oil system to reduce its maintenance demand and extend engine lifetime. The TOTEM has also been designed as a fully serviceable appliance that can be repaired and overhauled on-site with minimal effort to ensure operation is resumed promptly.
The Totem T20 CHP gives Our Wilton a single, reliable system to both meet the demands of the varied accommodations and provide the versatility to meet future demands for hot water and power across this unique project.
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