PART 0 DESIGN STANDARDS 0.01 GENERAL DESIGN GUIDELINES A. Assume that buildings will be enlarged and modified in the future. 1. Make provisions for future interconnections, upgrading, and expansion of mechanical systems. 2. During design, provide at least one layout showing future mechanical system expansion possibilities. B. DPS is extremely conscious of maintenance costs. C. Designs for plumbing shall not locate any plumbing in exterior walls. D. DPS looks with concern on new and untried materials and equipment. We are opposed to experimentation on our projects. However, we look forward to preliminary evaluation of innovative designs. E. For aesthetic reasons, locate or appropriately enclose large and unsightly exterior installations to be hidden from public view. 1. Building elevation drawings must show mechanical installations, including installations projecting above parapet walls. 2. If due consideration of aesthetics is not observed, the Owner will require redesign until an acceptable aesthetic design is achieved. 3. Historic landmark structures require design coordination with the Denver Landmark Commission. F. For security reasons, include enclosures and barriers to protect exterior and rooftop mechanical equipment from vandalism and unauthorized intrusion. G. Major air handling equipment shall be installed in mechanical rooms accessible from the building interior. 1. Rooftop air-handling units are prohibited. 2. Refer to standard Section 05500 for guidelines on ship s ladder access. H. Equipment air intake locations 1. As high off the ground as possible to avoid vehicle exhaust and other biological contamination. 2. As far away as possible from plumbing vents, kitchen exhaust vents, fume hood exhaust, and similar ventilating and exhaust units. I. Design sufficient facilities and clearances for orderly arrangements, concealment, and optimal maintenance of equipment, piping, and conduit. Give special consideration to ceiling spaces. J. Provide sufficient and safe access for maintenance of mechanical systems. 1. Sufficient access implies the capability to replace major components with minor impact to the building. 2. Clearly indicate sizes and locations of ceiling and wall access panels. K. Provide curbed floor areas for storage of on-site water-treatment chemicals, following watertreatment consultant s recommendations. L. When renovating or retrofitting mechanical systems or spaces, review the need to remove asbestoscontaining materials including, but not limited to, insulation. M. Abandoned piping shall be removed in it s entirety from existing walls or other locations. Existing valve to be removed when new replacement valve is installed. 1. Contractor to remove all flushometers and faucets from demolished/removed plumbing fixtures and return to DPS. N. Controls: Coordinate controls standards with the DPS Project Manager and the DPS Controls Application Engineer. 15010 Page 1 of 7
O. Design temperatures for heating and air conditioning systems 1. Winter: 78 degrees F temperature difference between inside and outside conditions (-10 degrees F outside air temperature, 68 degrees F inside air temperature) 2. Summer: ASHRAE Summer 1% but 87 F db and 61 F wb outside conditions if air intake is above a roof, and 95 /59 for systems with high make-up air intake. 76 F db, 63 F wb inside conditions. 3. Consult with the DPS Project Manager for temperature and humidity requirements for special areas such as computer rooms, etc. P. Fan coil units and radiation will be required in specific areas to facilitate shut-down of major air handling units. Where necessary, the controls on these units shall be coordinated with the controls on the air handling units. Q. All air conditioning systems shall have air economizer cycles. Systems which have economizer cycles shall be capable of running the cooling equipment independent of the economizer cycle controls. Furthermore, the economizer control shall not revert to the minimum outside air damper position for cooling season unless mechanical cooling is available. 1. In order to take advantage of economizer cooling to the highest temperature possible, return air (RA) should be minimized. Therefore, RA dampers should be specified to be of outdoor sealing quality. R. Air conditioning, heating, ventilating and exhaust systems shall be matched to the maximum required performance. 1. The use of variable volume supply and exhaust air systems is encouraged to compensate for diversities in loads and to reduce equipment sizes. 2. Space supply air outlets should be aspirating-type to prevent "dumping" of air into occupied spaces. S. Interior spaces requiring cooling the year around should be handled independently from perimeter areas requiring heating during the winter and cooling during summer. 1. Interior cooling only areas should be supplied from a variable volume cooling system utilizing an air economizer cycle. 2. Perimeter systems should use economizer cycles when cooling is required and minimum ventilation rates when heating is required. T. Provide filters upstream of all air handling coils, including heat-recovery coils. All coils shall have access for cleaning, including re-heat coils in, for example, VAV terminals. U. Outside air ventilation shall be per latest approved version of ASHRAE Standard 62. V. Direct evaporative cooling may be used in kitchens. Indirect evaporative cooling may be used in gymnasiums. Supply air temperature shall be controlled by the unit s DDC controller. W. Pressure gauges are required across all AHU coils and filters. X. Combustion air for boilers and gas water heaters shall be tempered. Provide 45 F minimum. Y. Elevator shaft venting: In order to minimize drafts, heat loss and elevator door "whistling", it may be necessary to install a motorized damper where only a louver may be specified for elevator shaft venting. Review with current Elevator Code for minimum requirements. Z. Energy conservation 1. The District is dedicated to the principle of conserving energy and will scrutinize proposed construction for means of reducing not only initial cost, but also long-range operating costs. Design new buildings and remodeling of existing buildings to make the most efficient use of building materials and energy sources available. The architect and engineers are required to work in close cooperation to design energy efficient buildings. 15010 Page 2 of 7
2. At minimum, comply with design standards in codified ASHRAE Standard 90, with a heat loss not to exceed 55,000 Btu/(ft2.Yr). If, in preliminary or basic submittals, it is determined that the BTU allotment or maximum allowable energy load will exceed the stated standards, a conference with the DPS Project Manager will be required to determine the course of action. Redesign of problematic portions of the facility will be required. 3. For new facilities, additions, and major remodeling projects, the design team may be directed to work with Xcel Energy and participate in Xcel s Energy Design Assistance (EDA) program. 4. In design of HVAC and electrical systems, give consideration to building use by planning for conservation of energy during summer and winter vacations and for other periods of minimum occupancy. Spaces which might require vacation schedule operation or 24 hours/day operation must be serviced by systems separate from classroom systems. 5. The capability of using alternate sources of energy is of extreme importance. 6. Where feasible, DPS intends to employ geothermal ground source heating and cooling systems for new schools and major additions. 7. Provide an updated energy budget. The budget shall show the estimated use of energy for the structure calculated on appropriate energy units per square foot per year basis. 8. Plumbing fixtures shall be water conserving type and comply with current Denver Water Department requirements. 9. Building envelope a) Maintenance, security, and utility costs indicate the need for restraint in the use of large areas of glass. If large areas of glass are required for aesthetics, give careful consideration to orientation of these areas for reduction of heat loss and heat gain. Refer to Division 8 window and glazing standards b) Operable windows sections shall be the minimum practical size. c) Also refer to standard Section 07210 for thermal resistance. i) Walls shall have R-19 or greater thermal resistance factor. ii) Roof and roof-ceiling assemblies shall have R-30 or greater thermal resistance factor. d) Infiltration should not exceed ASHRAE Guidelines (specifically <=.10 CFM/SF wall area). 10. Design air conditioning systems to conserve energy. The use of evaporative cooling systems and gas cooling systems is encouraged where feasible. Systems shall automatically adjust to the actual space load conditions to reduce energy consumption at partial space loads rather than falsely load and waste energy. a) Consider constant volume HVAC systems with variable-air-volume outdoor make-up air in order to minimize the use of re-heat coils. 11. Occupied-unoccupied programming of systems should be initiated to shut off ventilation air, exhaust air, fan system, pumps, etc., wherever possible. Where shut-down of systems cannot be accomplished during unoccupied hours, heat recovery systems should be considered. Each application should be examined independently to determine any special sources for obtaining recovery of usable energy. AA. Vibration engineering 1. Unless specifically rejected by the DPS project team during program planning, vibration analysis is required for buildings having: a) a reciprocating machine, or an air handling unit exceeding 5,000 CFM b) in buildings which may be used for other than storage c) where equipment or foot-fall vibration will affect the users 15010 Page 3 of 7
2. The analysis shall be done by a firm capable of performing predictive dynamic modeling of building structures based on finite-element analysis, multi-modal structural dynamics, etc. It is typically necessary to use a total system approach wherein all of the vibratory components are included. 3. Criteria for vibration amplitudes and structural center-bay stiffness a) Classroom and office areas i) Amplitude: 300 to 900 micro-inches (peak to peak) ii) Stiffness: 100 to 300 KIPS/inch 4. Bear in mind that each building is a unique combination of shape, structure, use and equipment. As such, each should be analyzed to determine what will meet its specific requirements. BB. Design calculations 1. Base calculations on methods and data from the most recent issues of the ASHRAE Handbook of Fundamentals. 2. Computer analysis, using approved programs, is acceptable. Acceptable programs include Trane, Carrier, and Elite. (Phaser is not a practical program to use for load calculations of buildings.) CC. Heating systems 1. Minimum two (2) hot water heating steel tube or copper tube boilers. a) Boilers may be forced draft; using modulating/condensing technology. Utilize highest efficiency possible. b) Boilers should be sized at: two at 65 +/-% or three at 35 to 45% of design heating load with boiler circulating pump (BCP) on each boiler. 2. The heating water pumping system shall be 100% redundant lead/lag stand-by system. If parallel pumping is used, then a stand-by pump shall be provided. 3. Heating water systems may be primary/secondary systems. The main distribution (secondary) pumps shall be redundant. Boiler circulation pumps (primary pumps) do not need to be redundant. 4. Do not design heating systems that utilize tertiary or circulation pumps located at the equipment. (Heating water systems shall be designed to utilize a glycol/water fluid to prevent freezing of the heating water). 5. Heating equipment shall be provided with control valves that fail to the open position. 6. Heating systems shall be provided with automatic glycol/water mixture feed tanks. Do not connect the heating water system to directly to the domestic make-up water system. 7. Refer to specification sections 15511 Hydronic Piping and Specialties and 15895 Control Sequence of Operation for additional heating system requirements. DD. Cooling systems 1. Chilled water type systems a) Buildings under 75 tons of total cooling load: Air cooled chillers b) Buildings over 75 tons of total cooling load: Water cooled chillers 2. Water cooled chiller systems between 75 and 300 tons: Minimum of one (1) chiller and one (1) one-cell cooling tower 3. Water cooled chiller systems over 300 tons: Minimum of two (2) chillers and two (2) one-cell cooling towers 4. Consider absorption water and gas-fired chillers, for energy conservation. 15010 Page 4 of 7
5. Chilled water pumping systems may be primary/secondary type systems. However, the distribution system shall be 100% redundant lead/lag stand-by. 6. Provide one pump per cooling tower. Redundancy is not required for cooling tower pumps. 7. Design chilled water systems to supply 45 F chilled water and return water at 55 F. 8. Provide cooling equipment with control valves that fail to the closed position. 9. Provide automatic glycol/water mixture feed tanks. Do not connect the chilled water system to directly to the domestic make-up water system. EE. Meters 1. Unless otherwise indicated by DPS, all buildings shall be metered for all utilities including electricity, gas, water, etc. 2. Meters may be connected to the IBAS for energy monitoring. Coordinate controls standards with the DPS Project Manager and the DPS Controls Application Engineer. PART 1 GENERAL 1.01 INSTALLER QUALIFICATIONS A. Plumbing and pipefitting work shall be performed under the direct supervision of licensed plumbers (5-year), with a ratio of not more than two apprentices per journeyman. 1.02 COORDINATION A. Utilities 1. In general, include utility work in Division 2 and work in Division 15 will only extend to 5 feet outside of building or structure excavation perimeter. a) Require the mechanical contractor to coordinate invert elevations and connections with the Civil team. 2. Specify the following where exceptions occur and Division 15 includes utility extensions and connections to public utilities: a) In the event that the serving utility company installs their own taps, service, meters, etc., all costs imposed by this action shall be paid for by the District. Extensions from termination points to connection with building services and systems will be the responsibility of the Division 15 Contractor. 1.03 SUBMITTALS A. Submit detailed shop drawings for fan systems having structural frame supports for the fan housing. 1. Include solid rotor shaft dimensions, wheel weight, bearing center-to-center distances, bearings, bearing support pedestals and structure, etc. 2. None of the above-cited items shall be considered as being "unavailable" or "proprietary". 3. Relevant sketches giving pertinent details are acceptable. 4. The design resonant speed of the fan system shall be a minimum of 25% above the fan operating speed, considering both wheel mass and inertia. 5. Appropriate engineering calculations must be available to support the design resonant speed value and to insure that the bearing support structure has adequate stiffness in all three directions (lateral, axial, and vertical). 6. The installed, operating fan bearing motions (inboard and outboard) shall not exceed 1.5 mils peak-to-peak in any direction when measured in the "filter out" measurement mode at any operating speed; "filter in" mode measurements are not acceptable. 7. The instrument system used must have a flat response down to 120 RPM. 8. Fan speed shall not exceed 1200 RPM. 15010 Page 5 of 7
9. Design resonant speed is that speed which corresponds to the natural frequency of the springmass system consisting of the rotating components, bearing lubrication and housing, and supporting pedestal (supporting floor, foundation, etc., considered to be infinitely rigid). 1.04 OPERATION AND MAINTENANCE INFORMATION A. Include the following information, in addition to operation and maintenance information required by Division 1 standards and other Division 15 standards. B. Alphabetical list of all system components including the name, address, and 24-hour phone number of the company responsible for servicing each item during the warranty period. C. Operating instructions for complete mechanical system, including emergency procedures for fire or failure of major equipment and procedures for normal starting/operating/shutdown and long-term shutdown. D. Maintenance instructions including valves, valve tags and other identified equipment lists, proper lubricants and lubricating instructions, and necessary cleaning/replacing/adjusting schedules for each piece of equipment. E. Manufacturer's data on each piece of equipment, including: a) Installation instructions b) Drawings and specifications (reviewed and accepted shop drawings) c) Parts lists d) Complete wiring and temperature control diagrams (reviewed and accepted shop drawings) F. In addition to the "Operation and Maintenance Manual", and keyed to it, equipment shall be identified and tagged as specified in Section 15190 - Mechanical Identification including the following: 1. Identify starters, disconnect switches, and manually operated controls, except integral equipment switches with permanently applied, legible markers corresponding to operating instructions in the "Operation and Maintenance Manual". 2. Tag manual operating valves with 1-1/2" diameter brass tags attached with chains. Tags shall be sequence numbered with legible metal stamps. 3. Provide a typed tag list or schedule mounted under glass in the Equipment Room stating number, location, and function of each tagged item. Insert a copy of tag list in each "Operation and Maintenance Manual." PART 2 PRODUCTS A. Equipment selection criteria 1. A combination of mechanical and indirect evaporative cooling is preferred. Stainless steel sumps, hardware and housings are required for their sections. Consider indirect evaporative cooling with "mechanical air-chilling coil" to complement the indirect evaporative cooling coil. 2. Consider ice storage systems in the design of air conditioning systems where gas chillers are not utilized. 3. Fans for operation above 6" total static pressure are prohibited without approval of the DPS Project Manager. 4. Compressors for electrically-driven chillers and refrigeration units, of over 100 ton capacity, shall have electrical power consumption not to exceed a maximum kw/ton between 30 percent and 90 percent of chiller capacity. Maximum kw/ton will be determined by the Owner on a project-byproject basis. a) Refer to ASHRAE 90 for minimum Energy Efficiency Ratios (EER) allowable for other compressors. 5. Absorption water and gas fired chillers should be considered. 15010 Page 6 of 7
6. Water-cooled or evaporative condensers are acceptable depending upon job requirements and necessities. Water-type cooling towers are preferred, to conserve energy, and shall generally be considered on systems 80 tons and larger. On units below 80 tons, an economic evaluation, including cost of maintenance should be made to determine if the condensing unit will be air cooled or water cooled. Cooling tower fan motor loads shall not exceed 0.06 H.P. /ton of chiller capacity. Reduced condenser water temperatures should be utilized when possible to reduce the chiller electrical consumption. 7. Air-cooled condensers shall be capable of operating at 95 F ambient temperature with 30 F temperature difference between air entering and leaving the condenser. Air-cooled condensers on roofs shall be capable of operating at 105 F ambient temperature. 8. Small water-cooled DX units, which utilize tap water for condensing, after which the water is disposed of in the drain, will not be permitted. 9. Variable-speed controllers (VSC) are generally acceptable. Specify an electrical by-pass switch with appropriate safeties (e.g., duct static pressure limit switch) and return air bypass from the supply to allow use of the equipment if the VSC fails. Also refer to Section 15170 - Motors, Starters, and Drives. PART 3 EXECUTION 3.01 OWNER INSTRUCTION A. Schedule instructional meetings for DPS maintenance personnel on the proper operation and maintenance of all mechanical systems, using the "Operation and Maintenance Manual" as a guide. END OF SECTION 15010 15010 Page 7 of 7