| Capital Projects Home Page |
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| Division Division 15 Mechanical |
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| 15-1 | Basic Mechanical Requirements |
| A. | Codes and Standards |
| 1. | All mechanical systems shall be designed to meet: |
| a. | California Code of Regulation Title 24 (Fire and Life Safety, and Energy Efficiency Requirements) and Title 8 (Occupational Health and Safety requirements). |
| b. | American Society of Heating, Refrigeration and Air-Conditioning Engineers Standard 62 - Ventialtion for Acceptable Indoor Air Quality. (ASHRAE Standard 62). |
| c. | American Society of Heating, Refrigeration and Air-Conditioning Engineers Standard 55 - Thermal Environmental Conditions for Human Occupancy, which establishes acceptable temperature, relative humidity and air movement rates for occupied spaces. (ASHRAE Standard 55). |
| B. | Overview |
| 1. | Occupant comfort and healthful indoor air quality shall be the prime considerations in any proposed design. In addition, the designer must also satisfy requirements for future expansion, provide ease of maintenance, and minimize life-cycle cost. Because of the longevity of University buildings and the great expense of modifying or replacing existing mechanical systems, the designer shall strive to ensure that the proposed systems are capable of meeting the longterm needs of the building in which they are installed. |
| 2. | The heating and ventilating system of a building is critically related to its size, shape and occupancy and it is important that proposed type or types of systems be presented during the preliminary planning stage. Carefully select building orientation, materials, and systems for control of heat gain and loss in the building . During schematic design, evaluate the life-cycle cost of several design alternatives. Design the control system to provide optimal operation of the entire system. |
| 3. | It is important that the architect retain a mechanical engineer early enough to permit his participation in the building study and design to avoid later changes that could affect the structure, or that would require modifications of the system to fit the structure. |
| 4. | The architect shall coordinate with the mechanical and electrical consultants and Capital Projects (CP) on the selection of the type of systems. |
| C. | Mechanical System Diagrams |
| 1. | Include a single line, no scale, diagram of each mechanical system, including supply and exhaust air, fume hood exhaust, hot water heating, steam, chilled water and cooling water on the mechanical plans of all buildings. Show equipment names, sizes, flow rates, dampers, valves, and direction of flow arrows. Show normal postion for each valve, either normally open (NO) or normally closed (NC). |
| 2. | Include riser diagrams of supply and exhaust duct systems. Show equipment names, sizes, cubic feet per minute, velocities, fire dampers and volume control devices (dampers, splitters, etc.) Individual room outlets need not be shown. |
| 3. | Include a riser diagram of hot water heating system show pipe sizes, gallons per minute, balancing devices and direction of flow arrows. |
| 4. | Indicate size and design quantities on these diagrams for each branch connection to a riser and for the riser at that point. |
| 5. | Indicate the basis for sizing pipes or ducts below the title of each diagram. |
| D. | Redundancy |
| 1. | Redundancy shall be provided for the following HVAC system components. |
| a. | Heating Hot Water Heat Exchangers - provide two heat exchangers, each capable of handling 50% of the system capacity. Each heat exchanger shall have two steam control valves. |
| b. | Heating Hot Water Pumps - provide two pumps, each capable of handling 100% of the system capacity. |
| c. | Chilled Water Pumps - provide two pumps, each capable of handling 100% of the system capacity. |
| d. | Tower Water Pumps - provide two pumps, each capable of handling 100% of the system capacity. |
| E. | Criteria for Determining HVAC Loads |
| 1. | The following outside air and indoor space temperatures shall be used to determine HVAC loads for spaces where occupant comfort is the sole consideration for the thermal environmental conditions: |
| Season | Outside Air Tempature | Space Tempature |
| Summer | 85oF db, 64oF wb | 74oF |
| Winter | 34oF | 72oF |
| 2. | Allowance for load safety factor shall not exceed 10%. |
| 3. | The maximum allowance for pickup loads is as follows: |
| Building Operating Schedule | Heating Pickup Load, Maximum | Cooling Pickup Load, Maximum |
| less than 24 hours/day | 25% | 0% |
| 24 hours/day | 15% | 0% |
| 4. | An allowance for future loads may be permitted. Consult with Capital Projects (CP) when future additional loads are likely to occur. |
| F. | Air Requirements |
| 1. | Determine minimum outside air required according to Title 24 Energy Efficiency Standards or ASHRAE Standard 62 whichever applies. The minimum design quantity of outside air shall be that determined according to the standards plus an additional 20%. |
| 2. | In determining heating and ventilating supply air quantities, consider all the following factors that may affect the quantity and use the largest resulting quantity. |
| a. | Air required by law or code, or campus health and safety requirements. |
| b. | Air required to heat or cool the space or control humidity. |
| c. | Make up air required for non-recirculated spaces, fume hoods, kitchen hoods, or other special exhausts. |
| d. | Air required for combustion in fuel burning equipment. |
| e. | Air required for smoke removal in areas where smoking is permitted. |
| 3. | Criteria for supply air volume for heating shall be based on the reduction of objectionable air currents in the occupied zone per ASHRAE Standard 55. The supply air temperature required to meet the space heating load should not exceed 105oF. Air required to cool a space which is not mechanically cooled shall be based on a maximum allowable temperature rise (DB) within the occupied zone of not more than 1O°F above the coincident outside air temperature. Where operable windows are present the required air volume may be provided from the combined volumes of mechanically supplied and natural ventilation. For purposes of this calculation, all heat sources, gains and losses, must be properly accounted for, with due regard to diversity and timing of intermittent loads. Where determined air change rates are excessive or exceed 20 per hour consult with Capital Projects (CP). |
| 4. | Provide mechanical ventilation for enclosed stairwells, trash rooms, elevator machinery rooms, mechanical equipment rooms and electric equipment rooms as follows: |
| a. | Supply and exhaust electrical and elevator equipment rooms with air quantities sufficient to prevent a temperature rise that would impair proper equipment operation. Filter supply air if it is not from the filtered building system. Evaluate mechanical cooling for rooms with high heat gains requiring large air volumes. |
| b. | Except for stairs designed as smokeproof enclosures per UBC requirements, design stairwell ventilation as follows: Supply air from the top of stairwell to prevent stagnation and odor buildup and to overcome the stack effect in winter. Provide one air change per hour minimum, based on total volume of the stairwell. Do not exhaust stairwell. However, pressure required to open exit doors must conform to code requirements. Provide required fire dampers in ductwork. |
| c. | Exhaust only for trash rooms, giving a negative pressure in the room to confine odors. |
| d. | Provide sufficient supply and exhaust ventilation to mechanical equipment rooms to prevent temperatures above 90°F. Use a minimum of one cubic foot per minute per square foot for cool rooms and two cubic feet per minute per square foot for hot. |
| G. | Air Conditioning and Cooling |
| 1. | Air conditioning, for occupant comfort only, will only be authorized for those spaces which qualify under the University Air-Conditioning Policy. Where conditions indicate potentially high internal or solar heat loads, discuss air conditioning, or provisions for its future addition, with Capital Projects (CP). Discuss temperature and humidity control, where required to meet laboratory or process requirements, with Planning, Design and Construction (CP) to establish clear understanding of operating limits, loads and control features required. |
| 2. | Cooling is required for all ventilation supply air to spaces for animal occupancy. Obtain temperature requirements from Capital Projects (CP). |
| 3. | Select chiller based on lowest life cycle cost. Consider absorption, vapor compression and thermal storage type systems and include costs of auxiliary equipment. For electric systems compute energy costs using actual time of use rates including demand charges and include differential cost of larger electrical system components (e.g. transformers). |
| 4. | For vapor compression type systems priority should go to systems with the lowest CFC content: HFC 134a, HCFC 123 and HCFC 22. Review preliminary selection of chiller equipment with Capital Projects (CP), as regulations change and earlier phase-out of R-22 and other refrigerants may be required. |
| H. | Recirculation |
| 1. | With the following exceptions, recirculation of HVAC system air is useful to reduce peak loads and energy requirements. During occupied periods system dampers/controls must be configured to provide at least the required minimum outside air requirements by utilizing a separate minimum outside air damper section and actuator. Controls for systems with mechanical cooling shall include an economizer sequence. |
| 2. | Exhaust ventilation for the rooms listed below or any other room with airborne hazardous materials shall not be recirculated. |
| a. | Laboratory spaces and storage rooms where hazardous materials are used or stored |
| b. | Chemical laboratories |
| c. | Noxious laboratories or rooms |
| d. | Welding or soldering areas or shop areas where hazardous materials are used or stored |
| e. | Animal areas |
| f. | Toilet rooms |
| g. | Athletic locker rooms |
| h. | Trash and garbage rooms |
| i. | Janitors closets |
| j. | Duplicating rooms using volatile solvents |
| 3. | For other occupancies, discuss air quality of recirculated supply air with Capital Projects (CP). |
| 4. | To reduce ductwork and number of exhaust fans consider grouping or stacking areas with common exhaust fans. |
| 5. | Where recirculation is used, install smoke detection equipment as required by Title 24 as applicable to the installation. When smoke is detected, dampers go to the 100% exhaust position. |
| I. | Recirculation |
| 1. | Where clean rooms are included in the building program, type, filter efficiency, cooling and ventilation air requirements shall be obtained from Planning, Design and Construction (CP). |
| 2. | Prefabricated clean rooms, modules or benches are preferred where their use will meet requirements. |
| 3. | Select equipment, air velocities, plenum and duct sizes for minimum noise generation within the work area. |
| 4. | Provide a method for introducing test media into room fan return plenum and for sampling test media density above room filters. Discuss with Planning, Design and Construction (CP). |
| 5. | Testing of room, to check compliance with specifications, will be done by the University. |
| 6. | It must be emphasized that clean rooms require special consideration and design. Drawings and specifications must cover, in detail, all points of construction, installation and sealing. |
| J. | Cold Room |
| A minimum quantity of outside air must be supplied to cold rooms to provide a safe working environment. Review at earliest design stage with Capital Projects (CP). |
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