Office Enercase
Natural Gas HVAC Halts Escalating Costs
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City of Owen Sound Police Services Building |
Before the HVAC conversion
The building’s HVAC system consisted of an air handling unit with a
hot and cold deck, plus supplementary perimeter baseboard radiation
heating. Both the hot deck and perimeter heating were electric. The
building consumed 1,385,280 kWh and had a demand charge of 288.0 kW
in 1992-93, for an approximate cost of $80,000 and $11,000
respectively.
Located in the penthouse mechanical room, the air handling unit was a 170 kW electric heating coil and three stages of direct expansion cooling. It provided heating and cooling to the entire building via a high-pressure dual duct system.
The main supply duct from this unit included two separate dual duct systems; one serving the ground floor and the other the second floor. The supply air temperature in both the hot and cold ducts was kept constant year round. Electric baseboards provided perimeter heating, controlled by the building manager on the occupants’ demand.
Determining how to control energy costs
The City of Owen Sound explored a variety of methods to assist in controlling energy costs at this site during 1991-92. Subsequent to this initial investigation, the City determined what assistance was available via the Utilities Management Program (U.M.P.). To assist in this project, the City hired a consulting firm to conduct a feasibility study.
The study indicated that the building would benefit from a high-efficiency gas-fired hydronic system. It recommended that incremental hot water coils replace the incremental 172kW electric coils. In addition, the study suggested that implementation of a new energy management control system would achieve the best results.
The consultant’s report forecast that the conversion would cost $64,000. Concerned that the conversion required such a large capital outlay, the City asked Union Gas to revisit the project to lower costs.