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are accounted for. It will also reduce their carbon footprint by more than 91 tonnes annually, equivalent to taking 20 cars off the road each year. Hotchkiss School, Lakeville Founded in 1891, the Hotchkiss School in Lakeville, Connecticut, attracts students from across the US and 34 other countries. In 2002, Hotchkiss opened the Forrest E Mars Jr Athletic Center, with multipurpose playing surfaces, elevated indoor exercise track, Olympic Rink, NHL Rink, 10-lane swimming pool and separate diving pool, hardwood basketball court, wrestling room, eight international squash courts, indoor tennis courts, fitness centre, locker rooms and shower facilities. When it was built, the centre (known as the MAC) was heated by two large boilers fuelled by heating oil. Since 2012, when the school’s biomass facility came online, the oil boilers were used only from mid-April to mid-October and for peak-load winter back-up. In addition, conditions inside the athletic facility are carefully controlled to ensure a comfortable environment for occupants. This climate conditioning was achieved via use of an electric chiller. However, since this cooling load existed simultaneously with the heating demand from the pool and showers, the MAC presented a great opportunity to apply the Ilios GHP. By simultaneously heating and cooling, the water-source heat pump would replace the operation of both the heating oil-fuelled boiler and electric chiller. In 2014, school alumni Roger Liddell of Clear Harbor Asset Management persuaded the school that a gas heat pump would save the MAC thousands of dollars a year by significantly offsetting the operation of the existing heating and cooling systems.

There is an inherent cleanliness to using propane, a gaseous rather than a liquid fuel… as far as Tecogen has been able to determine, it has the world’s cleanest exhaust

In order to persuade the school to adopt the suggested technology, the project was funded as a cooperative venture. Liddell brought the various parties together, and contributed significantly toward the purchase of the heat pump. Hotchkiss paid to install it, and to hook the machine into the school’s energy management system. Manufacturer Tecogen contributed an Ilios heat pump fitted with its Ultera emissions-cleaning equipment and the Propane Education & Research Council supplied some generous funding, because the engine may be used to demonstrate the superiority of propane fuel. “There is an inherent cleanliness to using propane, a gaseous rather than a liquid fuel,” Liddell says. “More importantly, the engineering of this system is so advanced that, as far as Tecogen has been able to determine, it has the world’s cleanest exhaust. The carbon

monoxide and nitrogen oxide exhaust levels are so low that the California Air Resources Board rates Tecogen equipment as having zero emissions.” Tecogen and Liddell estimate that Hotchkiss will save 113 tonnes of carbon dioxide emissions per year. The school estimates that the MAC boilers had been using about $35,000 worth of oil per year compared to approximately $10,000 in annual fuel expense for the propane-fired heat pump. Although the benefits of gas heat pumps over electric heat pumps are proven, a barrier to adoption has been that the capital costs are slightly higher than for an electric heat pump. While the extra expense is quickly recouped from the savings, higher capital costs can still be difficult to get cleared at board level. However, this can be overcome through On-Site Utility solutions whereby the equipment provider sells the energy produced from an on-site energy system to an individual property School’s annual as an alternative to saving from using the outright sale of energy equipment. propane-fired On-Site Utility heat pump solution customers only pay for the energy produced by the system and receive a guaranteed discount rate on the price of the energy. All system capital, installation, operating expenses and support are covered by the provider, removing all equipment risk from the customer. This On-Site Utility model has already proven successful in boosting adoption of CHP in the UK. If more heat pump customers are persuaded to adopt a similar approach, entire communities may eventually benefit from cheaper and more environmentally friendly sourced heating and cooling. te


The Ilios GHP at Hotchkiss School

June/July 2016


The Energyst  

June/July 2016 - The UK's energy magazine for business