Loading...
HomeMy WebLinkAboutAgenda Statement 1987/01/06 Item 15 COUNCIL AGENDA STATEMENT Item 15 Meeting Date 1/6/87 ITEM TITLE: Resolution I ., Appropriating $121 ,000 from unappropriated General Fund Surplus to complete the upgrading of the Police Department Air Conditioning system as part of the Crime Lab Construction Project. SUBMITTED BY: Director of Public Works/Cit Engineer p1/1/Director of Public Safetyt�J V� REVIEWED BY: City Manager (4/5ths Vote: Yes X No ) The mechanical consultants working on the plans for the Police Crime Lab and Communications Center project identified a serious deficiency in the building' s air conditioning system. Those deficiencies will become critical when the new Communications Center and other first floor remodeling is completed unless the deficiencies are corrected. Apparently, the air conditioning system at the Police Department, which was built approximately 17 years ago, was not designed to accommodate full usage of the building as now proposed to be occupied. A study to determine the best method of upgrading the air conditioning system has been completed. RECOMMENDATION: That the City Council adopt Resolution appropriating $121 ,000 from unappropriated General Fund Reserves to Capital Improvement Project No. RS61 , Public Safety Communication Center. BOARDS/COMMISSIONS RECOMMENDATION: Not applicable. DISCUSSION: City staff worked with a mechanical engineer to review the existing Police Department air conditioning system and to make recommendations for necessary upgrades to eliminate the deficiencies. The Engineer' s report evaluated the system for potential operating cost savings and operational corrections. The existing air conditioning system, consisting of terminal reheat in the first floor and multizone in the basement, was compared to two alternatives involving system modifications. Alternative No. 1 is the existing system. Alternative No. 2 is conversion of the first floor to a fan powered variable air volume system, with no changes to the basement system. Alternative No. 3 includes the variable air volume modification, addition of a one hundred percent outside air economy cycle for both floors and a backup system for the computer and communications equipment. A fourth alternative involving the addition of cogeneration equipment was evaluated. There is a potential for up to four buildings at the site to be served by a cogeneration facility. Page 2, Item 15 Meeting Date 1/6/87 Following is a summary of economic data on each alternative: Alternative Installed Cost Life Cycle Cost Payback Period 1 0 $1 ,347,582 2 3 $155,165,000 1 ,297,784 4 1 ,287,409 5 4 495,560 1 ,105,879 5 The life cycle cost analysis includes the annual utility and maintenance costs over a six year life cycle. The payback period is the amount of time required to payback the initial installation costs through energy savings. Two benefits in addition to operational cost savings and improved comfort level will be achieved with Alternative No. 3. The use of an outside air economy cycle will reduce the maximum air conditioning load to a level which will allow the existing chiller equipment to accommodate the new load generated by the proposed expansion. Secondly, in the event of a chiller failure most of the building will be able to operate with little or no discomfort until repairs are completed. The backup systems will provide protection for the more critical computer and Communications operations. It is recommended that Alternative No. 3 be implemented as part of the Facility Expansion. If the Expansion Project scope were to include Alternative No. 3, the cost impact and inconvenience to the Police staff will be minimized. Implementation of Alternative No. 3 will also eliminate the existing temperature control problems which exist in the Police facility. If this Alternative is completed in conjunction with the first floor and basement expansion projects, it will minimize the first cost financial impact and inconvenience to Police personnel during construction. Outside air intakes for the economy cycle would be incorporated into the first floor expansion project construction, offsetting the need for additional holes in the existing roof structure. Once the economy cycle is operational , chiller capacity will be available for the entire expansion project. A site cogeneration facility could have as low as a five year payback. First cost of the facility will be affected greatly by S.D.G.&E. requirements. The cogeneration facility could be added to the system at any time with no adverse effect on the Police Facility Expansion. It is recommended that this be considered as a separate project at greater depth and evaluated on its own merits. FISCAL IMPACT: The total additional cost of the recommended installation is $165,000. The current budget includes $41 ,983 for the Data Processing air condition system and $2,054 for the rehabilitation of the Police Department air conditioning system which can be used for this project. The additional amount necessary is approximately $121 ,000. That amount should be appropriated from the unappropriated General Fund reserves to account number 600-6000 RS61 . WPC 0020S Item 15 ATTACHMENT HVAC SYSTEM DESCRIPTIONS TERMINAL REHEAT SYSTEM The first floor of the Police Facility is served by a terminal reheat system. Air handling units with chilled water coils supply cold air to all spaces. Each zone is served by a reheat coil controlled by a zone thermostat. All air from each air handler is cooled sufficiently to satisfy the hottest zone and then reheated at each individual zone to satisfy all the other zones. This system is very energy inefficient and hard to control . In some cases the demand for cooling is as high in winter as summer. An unreasonable load is placed on the system chiller and its support equipment. MULTIZONE SYSTEM The basement of the Police Facility is served by a multizone system. Hot and cold air are mixed at the air handler for delivery to each zone. Chilled water is supplied by a reciprocating chiller and hot water is supplied by a boiler. The heated and chilled water is used to heat and cool air which is mixed in different proportions at the air handler to provide air at the correct temperature for each zone. The chiller and boiler units are always maintained full on. This system is more efficient than a terminal reheat system. FAN POWERED VARIABLE AIR VOLUME SYSTEM This system utilizes a fan powered variable air volume device (VAV box) to control individual zones. The VAV box restricts the flow of cold air from the air handler as necessary to satisfy the temperature requirements of the zone. A small fan within the VAV box mixes the required cold air and return plenum air to maintain a constant volume of air to the space. The need for heated air is drastically reduced because heat is picked up from the room itself. This constant air flow eliminates previous complaints arising from the perception by users of a decrease in air movement associated with a decrease in cooling requirement. The Outside Economy Cycle will modulate return air and outside air to minimize the system cooling requirements. Because of the facility's 24-hours-a-day operation, there is a high percentage of total hours in which no cooling other than outside air will be required. WPC 0021S