MECHANICAL
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Cooling Load Summary Chart
Existing Systems
- A Central Plant supplies chilled water for cooling of all buildings, with
underground chilled water piping from the Central Plant to the respective buildings.
The site piping was installed in phases, in relation to the campus growth construction
projects, and included accommodations (i.e. pipe sizing) for additional future
building construction, primarily to the north.
- Building heating is provided by electricity, at respective air handling units.
- Buildings A and B are approximately 15 years old, and are served by multi-zone
air handling units. In general, variable air volume units are in the other new
buildings.
- According to CGCC Facilities staff, the heating and cooling supplied to existing
buildings is adequate. However, the two oldest buildings on the Pecos Campus
(A Building and B Building, both built in 1986) will be renovated in Phase 2
of this Master Plan. It would be appropriate to review the condition of the
mechanical systems of each building in its entirety at that time.
Basis for Evaluations
- The specific requirements for each building are not defined at this time.
Therefore, 300 GSF/ton is used to estimate building cooling loads, for the evaluation
of site chilled water pipe sizing.
Note: It is emphasized that ESD believes that the actual tonnage imposed on
the central plant is probably less (i.e. 400 GSF/ton).
- The proposed remodeling of areas of A Building and B Building do not impose
any additional significant load on the existing mechanical system.
Central Plant Requirements
In a separate Planning activity, the actual peak central plant-cooling load will
be confirmed by ESD, as well as an evaluation of the existing equipment and system
design. It is believed that with the addition of a new chiller and associated
equipment into the existing central plant, with up to approximately 700-800 tons
of cooling capacity, there will be sufficient campus cooling capacity for the
build-out of Phases 1 and 2 of the Master Plan. The central plant requirements
for Phases 3 and 4 will be evaluated further in the previously mentioned Planning
activity.
Site Chilled Water Piping Evaluation
The site drawings indicate 14" and 6" chilled water piping leaving
the central plant. As previously stated, the piping within the central plant
will be evaluated in a separate master planning activity. Based on a total campus
building area of approximately 568,000 GSF, the estimated peak-cooling load can
be accommodated by the existing piping mains.
Refer to the site chilled water piping drawing, which indicates new piping
to serve the proposed building construction.
Scope of Work & Related Costs
- New Buildings: Building cooling should be provided by air
handling units with chilled water-cooling coils. Variable air volume air distribution
systems should be provided for most building areas, with some areas that may
be served by constant volume systems.
- Existing Buildings: As stated in the ESD memo, in the Appendix
of this report, the multi-zone air handling units in Buildings A and B should
be considered for replacement, since they have been in operation for 15 years
and more efficient and flexible variable air volume systems are provided for
new buildings.
Cost of new air handling units, related unit controls and electrical work is
estimate at a $260,000, based on 2002 construction costs.
Note: There will be additional cost for terminal unit controls if the system
is changed to VAV, from multi-zone.
- Site Chilled Water Piping: Beyond the general construction
costs of new buildings ($255/GSF) provided by MCCCD Facilities Planning &
Development, it would be necessary to allocate additional funds for infrastructure
costs that are specific to the individual phases of the Master Plan. These chilled
water-piping costs are summarized below:
Phase I - $90,000 (includes 10" to north and portion of 6" east-west
main)
Phase II - $21,000
Phase III - $8,000
Phase IV - $40,000
View Building Estimated
Cooling Load Summary Chart
