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MPJohnson * Controls HVAC and Controls Replacement Roof Top Unit Replacement: The five (5) roof top DX cooling units at City Hall are 12 years old and are nearing the end of their recommended service life. Over the last several years, service calls have been placed because the compressors have been tripping out (shutting off) and there are holes in the condensers which reduce the efficiency of the system. The ASHRAE standard for light commercial roof top units shows a life expectancy of 12 -15 years. While evaluating the existing units several options were investigated. Many of the current issues with the units are based on low air flow and high cooling capacity. Some of these issues can be resolved by combining units for proper air flow with capacity. Combining units No. 2 & 5 (Multipurpose Room and Police Station) will provide better control and reliability for the building. Four (4) new DX units will be installed on the roof in the same location as the existing units. New ductwork will be installed on the roof as required for proper installation Control Replacement: City Hall has an old pneumatic control system with an independent electronic system for the roof top units. During the analysis, it was determined savings could be achieved by equipment scheduling for better control of the building. The building automation system would utilize the building's Ethernet LAN system to centralize and network building control, allowing facility personnel to monitor the buildings remotely. For more information on the controls see section `Building Automation System Control Enhancements" Boiler Plant Replacement: The existing hot water boilers at the City Hall are inefficient to operate and are reaching the end of their useful life. The current boilers are small, modular atmospheric combustion units installed with six independent boilers that fire in series to provide adequate heat to the system. Because of the way these boilers are installed and designed, maintenance is an issue for the middle boilers —many of the repairs require the removal of at least one boiler. Additionally, these boilers can only be "on" or "off'. The staging of the boilers provides some flexibility of heat supply for the system, but are not able to provide cooler water to the system. As the outdoor air temperature increases, there is less of a demand needed for heating the water. The current boilers do not allow sufficient staging during these warmer times. a result, additional energy is used during the warmer portions of the heating season. As Four new high - efficiency boilers will be installed and tied into the existing heating hydronic system. These new boilers will be vented directly to the outside for combustion air, and provide the appropriate water temperature that is needed for the spaces. The boilers will come with internal controls that optimize efficiencies based on the outdoor air temperature. The new boilers will run in unison to generate the water temperature required by the space. As a system, the boilers will be able savings. to have a high turn down to minimum output and step up to the maximum output resulting in energy Page 12 City of St. Anthony Village W Performance Contract Analysis NOT TO BE REPRODUCED OR DISTRIBUTED HOUT JOHNSON CONTROLS' PERMISSION