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Roseville Skating Center and City Hall Feasibility Study September 23, 2007 The GHX system can be designed to accommodate the immediate requirements of the Ice Arena 1 Banquet Hall facility itself, or to allow for future expansion for connections to other buildings such as the City Hall 1 Public Safety Building, Maintenance Garage, Fire Hall and the refrigeration system in the Speed Skating Oval. The size of the GHX needed for the Cc� Arena ! Banquet Hall facility is estimated to require a capacity of "60 to 80 tons". The capacity of a GHX is influenced by a number of factors, including: * GHX configuration (horizontal trenches or vertical boreholes) • Spacing of the boreholes or trenches * Soil conditions (moisture, type of soil or rock formations) * Depth of burial of the GHX * Available land area The energy balance of the building{s} connected to the GHX, however, has the most significant impact on the size and cost of the GHX. For example, if all of the thermal energy from a refrigeration system can be used immediately, whenever it is available, thermal storage (in a GHX) is unnecessary. If there is a lag time between when the energy is available, if only a portion of the energy can be used, or more energy is needed than is immediately available, a GHX provides the thermal storage to accommodatethe diverse building loads. The peak heating and cooling loads that reach the GHX also impact the size of the GHX. In the Banquet Hall area of this building, the peak cooling loads occur only a few times a week when the building is heavily occupied at the same time the solar gains hit the west facing glass in the banquet rooms. The existing roof mounted heating and cooling equipment has a peak cooling capacity of approximately65 tons (780,000 Btulhr), based on the nameplates of the equipment. The heating load of the banquet halls, office area and the locker room areas of this type of building is typically ranges from 12 to 15 Btulhr per square foot. If we assume a heat loss of 15 Btulhr per square foot, the heat loss of the 30,000 square foot area has a peak heat loss of approximately450,000 Btulhr. This is considerablyless than the peak cooling load. It is possible to design a heat pump system to accommodate the peak heating load of 450,000 Btulhr. The equipment will only provide approximately450,000 Btulhr of cooling capacity, and will not provide enough cooling capacity during peak use. However, since the peak cooling requirements only occur intermittently, the refrigeration equipment used to maintain the ice in the ice arena can also be used to build ice in an ice storage tank located outside the building. The ice in the storage tanks can be built at off-peak times (typically night time), when the ice arena is not in use. The ice is then used to provide the additional cooling capacity required in the banquet hall. Making use of the same equipment to provide ice in the arena, as well as ice to provide cooling in the banquet hall reduces the total amount of cooling equipment needed in the facility. Instead of installing heat pumps that provide 720,000 Btulhr of cooling capacity, the capacity required in this scenario is reduced to 450,000 Btulhr... a reduction of 330,000 Btulhr (27.5 tons) Geo-Xergy Systems Page 24 of 33