Brown University Revised August 3, 2012 Facilities Design & Construction Standards SECTION HVAC DESIGN CRITERIA

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1 SECTION HVAC DESIGN CRITERIA PART 1 - GENERAL 1.1 BACKGROUND A. The Central Heating Plant (CHP) provides heat from October to May for approximately 100 buildings on the main campus, totaling 4.5 million square feet of space. It delivers high-temperature hot water (HTHW) through a network of underground piping, at a maximum temperature of 350 degrees F. This is typically converted at the individual building, or building hub, to medium-temperature hot water (MTHW) at a maximum temperature of 180 F. In some cases, it is converted to low pressure steam (LPS) for buildings requiring steam for heating, process or humidification uses. In limited applications, it is converted to medium-pressure steam (MPS) for process uses. Flow diagrams of this system can be obtained upon request to Brown FM Engineering. B. The Central Heat Plant is shut down during summer months. If hot water is required for reheat, domestic or process needs, a separate local stand-by heating source shall be provided. C. Brown University also has four district chilled water systems which serve primarily the Science, Biomedical Research, and Academic buildings on campus. Three of these systems operate year-round, with limited free-cooling chilled water capacity in the winter. Winter time chilled water use should be limited to equipment and systems that cannot utilize local winter air-side free cooling. Whenever possible, it is expected that new buildings will be connected into district systems, rather than have stand-alone chiller plants. 1.2 RELATED SECTIONS: 1. Section Design Guidelines for Energy and Environment 2. Section Electric Rebate Program 3. Section Gas Rebate Program 4. Section Building Systems Identification and Labeling 5. Section Duct Insulation 6. Section Piping Insulation 7. Section Pipes and Tubes 8. Section Valves 9. Section Air Handling Units 10. Section Building Automation Systems 11. Section Campus Central Metering System Design Criteria of 11 HVAC Design Criteria

2 1.3 REFERENCE STANDARDS: A. The standards below shall be considered part of the requirements of this Section (Utilize latest adopted editions): 1. Rhode Island adopted International Energy Conservation Code (IECC) 2. ASHRAE 15 Safety Code for Mechanical Refrigeration 3. ASHRAE 34 Designation and Safety Classification of Refrigerants 4. ASHRAE Ventilation for Acceptable Indoor Air Quality 5. ASHRAE 90.1 Energy Standard for Buildings Except Low Rise Residential Buildings 1.4 DESIGN SUBMITTAL REQUIREMENTS: A. All Heating, Ventilation and Air Conditioning (HVAC) designs shall include the following: 1. By first submittal or Schematic Design (or proposal for design/build projects), whichever is earlier: a. Design narrative / design intent with brief description of each system. Include a flow diagram, if relevant or requested by Brown FM. 2. By second submittal, or Design Development phase, whichever is earlier: a. Basis of design including design conditions; complete thermal, acoustic, and energy design criteria; b. Description of the systems (capacities, etc.); c. BAS sequences of operation; d. Energy model for larger projects and for projects seeking LEED certification, or for projects requiring comparison of HVAC system options. The latter shall be furnished at the request of the Project Manager. 3. By third submittal, final review set, or construction documents, whichever is earlier: a. Testing requirements and criteria for acceptance; b. Requirement for submittal of operation manuals and maintenance manuals; c. Requirement for submittal of record drawings and control documents d. Testing, training, and other handover requirements. 1.5 GENERAL DESIGN REQUIREMENTS: A. Energy Conservation: For all new and major renovation projects and for equipment selection refer to Brown Standards, Section 01301C Design Guidelines for Energy and the Environment. Note that the HVAC system design shall be a minimum of 25% better than current code, up to 50% better than code. B. System design and equipment selection should be determined by minimum life cycle cost including first, operating and maintenance costs of 11 HVAC Design Criteria

3 C. The following HVAC system design issues should be reviewed and addressed in the course of project development, per ASHRAE Standard 90.1: 1. Load Calculations: Determine heating and cooling system design loads for the purpose of sizing systems and equipment. 2. Evaluate Exhaust Air Energy Recovery Systems: Evaluate system benefits and incorporate as applicable for individual fan systems whether or not require by Energy Conservation Codes. When implemented, include bypass or control the heat recovery system to permit air-side economizer operation. 3. Evaluate Demand control ventilation (DCV) Controls for High-Occupancy Areas: Evaluate for spaces larger than 1,000 ft² and with a design occupancy for ventilation of greater than 40 people per 1000 ft² of floor area and served by systems with one or more of the following: an air-side economizer, automatic modulating control of the outdoor air damper or a design outdoor airflow greater than 3,000 CFM. 4. Evaluate capability to shut down air handlers and exhaust systems in unoccupied areas of the building: Investigate proposed space use and programming; where cost-effective, serve different space use areas and different occupancy schedule areas from separate air systems. D. Generally, spaces should not be humidified. Exceptions include Animal Care facilities, select Research facilities and selected library spaces, which are to be humidified in accordance with project specific design guidelines. E. Rebates: Actively seek out products which can qualify for rebates under National Grid s programs and complete rebate applications as required under Brown Standards, Sections and F. Outdoor equipment locations are not allowed except for cooling towers and exhaust fans, since weather impacts serviceability. Exceptions may be allowed, but only upon written permission of the project manager. G. Air handlers, fan-coil units and other terminal units shall not be provided with manufacturer-furnished controls. All controls shall be furnished by the Building Automation System (BAS) manufacturer. H. Boilers shall be selected so that individual units are rated at less than 30 BHP input. Exceptions shall be approved in advance by Brown FM Engineering. If larger boilers are necessary, those 30 BHP (1,000,000 Btuh input) and above, as well as all chillers rated over 100 tons, shall be fully integrated into the campus BAS for remote supervisory monitoring and alarming, per City of Providence Ordinances. I. Standby Power: Most new or renovated buildings will require the BAS and heating pumps be on the Standby Power system, where it is installed within a facility. Prior to commencing design, coordinate this need with Brown FM Operations & Engineering staff of 11 HVAC Design Criteria

4 J. METERING: 1. Thermal (BTU) metering for monitoring of building energy consumption where buildings are served from the campus Central Heat plant (for heating) or district chilled water plant may be required on a project. Metering requirements are found within Brown Design Standards, Division 26. Prior to initiating the project design phase, coordinate with the Brown FM Engineering to determine where meters are required. 2. Large cooling towers shall have water meters on both makeup and blowdown streams. These meter outputs shall be tied into the BAS for recording monthly use. 1.6 DETAILED DESIGN REQUIREMENTS: A. A detailed HVAC control sequence of operations and BAS points list shall be included in the plans and specifications. B. Apply good Engineering practices for the design of air handlers, ductwork, and piping systems so as to create a quiet system appropriate for the specific project. Sound and vibration criteria should be defined early in the project and documented in the Design Intent and developed with the Basis of Design. C. Plans for all HVAC equipment shall indicate required service clearances, tube pulls, shaft pulls, and other clearances per manufacturer s requirements and drawings as crosshatched areas on drawings. D. Design shall include plan for removal of all equipment. Plans shall indicate sizes of major pieces of equipment and clearly marked paths of removal and egress for this equipment from point of installed equipment-to-equipment loading area exterior to building. Entire egress path shall be coordinated for removal of equipment. Egress paths of equipment through removable louvers or rooftop ventilation louvers are acceptable provided they are crane accessible. Coordinate with structural to add lifting beams as required to move or replace heavy equipment. E. Components requiring regular maintenance per manufacturer s recommendations or Brown University standards shall not require portable ladders, lifts, or other devices for service access, except for VAV boxes and dampers located above ceilings. 1.7 MECHANICAL ROOM DESIGN REQUIREMENTS: A. All major mechanical equipment should be located within Mechanical Rooms. Generally, rooftop units are not acceptable; exceptions require approval from FM Operations & Engineering. B. Mechanical rooms shall be large enough to encourage proper servicing of equipment, include access for replacement of all mechanical equipment, and provide for required spare parts storage. Mechanical Rooms shall be accessible by a standard stair or elevator. Ship s ladders and steep stairs are NOT acceptable. Doors shall be a minimum of 36 inches wide. Adjoining pieces of equipment shall be separated by a of 11 HVAC Design Criteria

5 minimum of three feet. Provide space to store two changes of air filters, lubricants, etc. C. Design shall provide for clear service and maintenance access to all equipment. Service areas shall comply with Codes, manufacturer s recommendations and shall be reasonably planned for human access. D. Mechanical Rooms shall be well lit using fluorescent lamps, maintaining a minimum of 30 foot-candles. Lighting shall be switched at each exit. Power at least 25% of mechanical room lighting from standby generator power source where available. Provide 120VAC convenience outlets in mechanical rooms to provide for ready servicing of equipment. E. Provide adequate number of floor drains in mechanical rooms; drains are to be connected to the sanitary sewer system, not to storm sewer. Locate drains to avoid running of condensate drains and other similar equipment across mechanical room floors. F. Locate all floor-mounted major mechanical equipment on concrete housekeeping pads. G. Mechanical rooms located above the lowest floor shall be curbed, room floors waterproof sealed, and all floor penetrations sleeved to 2" above the floor to prevent liquid spills and leaks from traveling out of the space. H. Provide thermostatically controlled ventilation as required. I. Prime coat and finish paint all un-insulated, uncoated steel components (i.e., supports, hangers, etc.). J. Preference for mounting of air handler temperature control valves and piping system isolation and control valves is for serviceability from the floor without the use of ladders; maximum height 6'0" AFF. Where service valves are mounted 8 feet above the floor provide service platform, catwalk, or valve chain wheels and safety-trimmed chains. Do not block equipment access when locating valves. 1.8 OPERATIONS &MAINTENANCE REQUIREMENTS: A. Operating and Maintenance procedures shall be provided in Owner-approved format compatible with the requirements in Brown Standards, Section HVAC Operations & Maintenance documentation shall include: 1. Actual shop drawings of the equipment showing capacities, fan curves, etc. 2. Preventive Maintenance schedule 3. Preventive Maintenance procedures 4. Description of overall system operation, including failure modes 5. System flow diagrams of 11 HVAC Design Criteria

6 6. Baseline performance measurements for use in troubleshooting, recommissioning, engineering, and cost analyses B. All building water systems Operations & Maintenance procedures shall meet the recommendations in ASHRAE Guideline 12, latest edition, Minimizing the Risk of Legionellosis with Building Water Systems. C. Labeling and equipment identification: Refer to Section VENTILATION: A. Mechanically-provided outdoor air supply is required in all spaces served by any new or retrofit HVAC systems, whether or not operable windows exist. In some cases, such as for individual Residence Hall rooms and residences, this requirement may be waived, but only upon permission from Brown FM Operations & Engineering. B. Building space conditioning provided by supply air with VAV (Variable Air Volume) boxes is the preferred design approach for Academic, Research and Administrative buildings. If this is not feasible, fan-coils with a separate dedicated outside air system are allowed. C. Fan-coil or packaged terminal air-conditioning unit wall-caps shall not be used for fresh air supply. D. Tempered makeup air is preferred; either by employing preheat/precooling coils, heat recovery, or both. E. Any air intakes located near grade shall be located to be remote from vehicle exhausts and sited to avoid building exhaust reentry UTILITIES, HEATING: A. Connection of building heating system to Central Heating Plant High Temperature Hot Water (HTHW) heating system is required for new buildings located on the main campus, unless economic analysis proves this connection is not economically feasible. B. HTHW design criteria shall be based on 335 F supply and 235 F return temperature; Design pressure is 150 psig. C. Medium temperature hot water (MTHW 180 F max) is strongly preferred to steam or other heating systems for reliability, controllability, and to facilitate future conversion of yard steam systems to medium temperature hot water. D. Independent boilers are required to provide hot water, or any required and permissible reheat, when the Central Heat Plant is shut down or for any buildings not served by the CHP of 11 HVAC Design Criteria

7 1.11 UTILITIES, COOLING: A. Chilled water is strongly preferred to direct expansion systems from both an energy standpoint and to facilitate future interconnection of district chilled water systems. B. Brown University s district chilled water design standard is variable primary-only configuration. Any connection to, or expansion of, this system shall conform to this design scheme. C. Design supply temperature is 42 F and return is 54 F. During winter, in waterside economizer mode, design supply temperature is 50 F. D. Alternative chilled water system designs within the building, such as chilled beams are acceptable in certain cases upon approval HYDRONIC SYSTEMS, BUILDINGS: A. Four- pipe systems are required in all buildings requiring both heating and cooling, unless approval is given by Brown FM Operations & Engineering. B. Where modifications are made to existing buildings already served by two-pipe systems, two pipe changeover design will be considered. C. Where heating-only fan-coil systems are installed, chilled water condensate drain piping shall be installed, along with chilled water piping rough-ins where possible or, as a minimum, fan coil piping insulation shall be adequate for a dual-temperature application. D. Closed systems and portions of open systems running through buildings shall be pressure tested before lagging. Pressure tests shall be witnessed by Brown University personnel and documented by the contractor. E. If connecting to existing changeover or constant-volume systems, provide 2-way injection valves on the primary side and modulate these valves to maintain secondary side HW or CHW temperature setpoint. F. All base-mounted pumps, 5 hp and greater, shall be laser-aligned after they are installed. G. Preheat coils on large air handlers shall be provided with freeze pumps to protect against freezing and temperature stratification. H. Closed Loop Hydronic Systems: 1. Expansion tanks shall be diaphragm type, and the pre-charge pressure shall be specified to suit the system of 11 HVAC Design Criteria

8 2. Air elimination shall be installed in each heating system at the point of lowest air solubility and vented to atmosphere. 3. A chemical pot feeder shall be installed across the hot water pump. 4. Pressure gages at pumps shall be glycerine-filled INSULATION: A. Lace-up blankets shall be used on components requiring service. B. Any nameplates on heat exchangers or other equipment requiring insulation shall be removed and riveted or screwed to the nearest adjacent permanent, suitable, and accessible frame. C. Foam pipe insulation is not permitted except where approved in writing by Brown Project Manager; when permitted, foam requires an aluminum jacket on exposed and outdoor runs CONTROL VALVES A. Refer to Section Building Automation Systems, for requirements WATER TREATMENT: A. All HVAC water subsystems, closed or open, shall be drained, flushed, and equipped with treatment systems. B. Treatment systems shall include complete, fully functional chemical injection and control systems. C. Water treatment procedures and equipment shall be coordinated and specified based on Brown University s current contracted Chemical Treatment vendor. Chemicals and chemical feed equipment shall also be provided by this same vendor. D. All building water systems including cooling tower installations and treatment systems shall meet the recommendations in ASHRAE Guideline 12, latest edition, Minimizing the Risk of Legionellosis with Building Water Systems REFRIGERANTS: A. CFC refrigerants and refrigerant types HCFC-123 and HCFC-22 are not allowed. B. Refrigerant HFC-134a is preferred for larger chillers. C. Conform to ASHRAE Standards 15 and 34 when designing both central plant and smaller DX refrigerant systems of 11 HVAC Design Criteria

9 D. Variable-refrigerant volume (VRF) systems, may only be consider in certain applications, where approved in advance by FM Operations & Engineering. If approved, maximum allowable refrigerant concentration from a system leak in an occupiable shall not exceed 50 % of the maximum allowable levels under the ASHRAE guidelines. Also, avoid routing of refrigerant piping through any occupied areas where there is no mechanical ventilation FILTRATION: A. Air filters less than MERV 7 are not permitted except as prefilters where approved, unless on existing equipment where airflow restrictions cannot be avoided with an upgraded filter and would adversely impact equipment operation. B. Provide Magnahelic pressure drop indicators at filter racks of 4,000 cubic feet per minute and over, or for air handlers in research or other critical spaces. Provide DP pressure sensors on racks, connected to building BAS to permit remote monitoring and alarm of filter differential pressure SOUND, VIBRATION AND SEISMIC CONTROL: A. Acoustical sub-consulting services by a Brown-approved firm shall be utilized on all projects with critical user requirements such as testing, research, teaching, or performance. This shall also include outdoor-located mechanical equipment which may have an impact on the surrounding community in order to verify that local noise criteria ordinance is met. B. These services shall include developing space requirements, testing actual performance indoors, and reviewing property line impacts of any outdoor equipment. NC levels only are not adequate; RC levels shall also be used. C. Sound and vibration criteria shall be defined early in the project and documented in the Basis of Design. Equipment and systems requiring isolation or attenuation to satisfy ASHRAE, or the User s own, noise and vibration requirements shall be identified and appropriate design measures shall be implemented AIR DISPERSION: A. All projects that may involve air re-entrainment or excessive concentrations of fume exhaust at nearby air intakes or buildings shall utilize a Brown-approved firm to perform an air dispersion analysis HEAT RECOVERY: A. Even where reheat is allowed by code, enthalpy exchange energy recovery, and other dehumidification methods, are required to minimize fuel-fired or electric reheat costs. B. For Wet Labs and Vivaria, sensible-only heat recovery shall be implemented in order to prevent airstream cross-contamination of 11 HVAC Design Criteria

10 1.21 LABORATORIES & RESEARCH FACILITIES: A. If a project requires Fume Hoods, Brown EH&S and Brown FM Engineering shall be consulted prior to commencing the design phase of a project to review the fume hood selection, makeup air and exhaust system design being proposed. B. Conform with NIH guidelines except for specific provisions where Brown University has verified in writing that provisions do not apply, e.g., multiple species provisions where single species space is being built. C. Vivaria shall conform to the AAALAC Guide, latest edition. D. No HVAC devices requiring scheduled preventive maintenance shall be located in or above drop ceilings in laboratory space, except fume hoods, snorkels, biosafety cabinets, tissue culture hoods, or other laboratory ventilation equipment that cannot be located adjacent to space without diminishing research functionality. E. HVAC equipment redundancy may be required at certain facilities. Redundancy and connections to emergency power shall be as directed by Brown University, and shall be included at all design submittal stages BOILERS: A. Where building heat cannot be obtained from the campus HTHW system, or if a summer boiler is required, the preferred boiler is a gas-fired condensing type. Preferred manufacturers are: A.O Smith, Camus and Harsco (tube-style) and Viessmann and Buderas (cast iron). B. Boiler Flue material of construction for condensing and near-condensing type boilers shall be AL-29C. C. Outdoor air reset of hot water supply temperature is required in all Brown facilities. If connecting to a non-condensing boiler system, provide a 4-way valve and secondary pump to permit both system reset and non-condensing boiler temperatures HEAT EXCHANGERS: A. For some buildings, two heat exchangers will be required for reliability and redundancy considerations. Determination shall be guided by Brown FM Engineering. Requirements to be coordinated with FM Operations & Engineering. B. Each heat exchanger shall have a dedicated control valve with isolation valves on each side, with a bypass globe valve provided around the control valve. C. HTHW heat exchangers shall be designed for 150 psig/400 F on the shell side and 400 psig/400 F on the tube side. Tubes shall be ¾-inch O.D., seamless, cupro of 11 HVAC Design Criteria

11 nickel. If offered as an option by the manufacturer, provide access plate or manway on shell-side for inspection purposes. D. LPS heat exchangers shall be designed for 125 psig. Head and shell shall be rated at 375 F and tubes at 300 F. E. Provide a manual-reset high limit switch on the MTHW supply side which will close HTHW or steam control valve(s) and annunciate an alarm on the BAS upon sensing water temperature above 200 F. This alarm shall be a critical alarm point. F. Process Cooling loads shall not be directly connected to the house chilled or process water systems, but shall be isolated on a separate loop by means of a plate-and-frame heat exchanger. Provide chilled water heat exchangers with supply and return isolation valves to facilitate cleaning/flushing CLEAN-STEAM GENERATORS AND HUMIDIFIERS: A. For facilities requiring steam-to-steam isolation for clean steam with 100% makeup water, the makeup water shall be pre-treated with a water softener or else reverseosmosis (RO) or deionized (DI) water shall be used. B. All steam humidifier make-up water shall be pre-treated with a water softener PREFERRED MAJOR EQUIPMENT MANUFACTURERS: A. HVAC components including packaged unitary and air handling devices: 1. Trane 2. Carrier 3. York B. Chillers: 1. Carrier 2. McQuay 3. York End of Section of 11 HVAC Design Criteria