NIH Design Requirements Manual 2012 1 Section 6.2

1 Section 6.2 Supply Air-Handling and Exhaust Systems 2 3 6.2.0. General 4 5 6.2.1 Supply and Exhaust Air-Handling Capacity 6 For laboratories and animal research facilities, supply air handlers and exhaust fans shall be 7 sized to provide 20% future requirement above design conditions to allow for changes in 8 research and future growth. The requirement will apply to both for new or renovation projects 9 The 20% shall apply to fans, motors, dampers, cooling coils, heating coils, humidifiers and 10 filters. 11 12 For administrative and general use facilities, supply air handlers, return and exhaust fans shall 13 be sized to provide at no more than 10% above design conditions for future growth. 14 15 Throughout this document, the term “capacity” shall be understood to be the total design 16 capacity exclusive of this 20% future growth. 17 18 The 20% future requirement for administrative and general use facilities is to accommodate 19 changes in research over the service life cycle of the unit 20 21 HVAC systems serving laboratories and animal research facilities shall further comply with the 22 following: 23 1. 100% O.A. with no recirculation (single pass air). 24 Provides protection against cross-contamination of airborne contaminants. Recirculating 25 systems are not allowed due to potential for cross contamination, vapors and odors via 26 HVAC system 27 2. Supply and exhaust systems using dedicated, pressure-independent air terminal devices 28 shall be used. 29 3. Hot water reheat coils are required for the supply air terminals. 30 31 4. The four-pipe (with both reheat water valve and chilled water valve) active chilled beams 32 terminal units shall be used in the laboratory spaces as an alternative to VAV-reheat 33 systems Primary air flow will be introduced to the chilled beam via pressure 34 independent air terminal. Chilled beams only provide sensible cooling to the space. The 35 latent load is handled by a dedicated outside air system (DOAS). The chilled beam water 36 temperature must be actively maintained above room air dew point to prevent 37 condensation. Adequate number of chilled beams should be installed to avoid high 38 flows. Chilled beams are impractical in cooling intensive rooms or in labs with high fume 39 hood density. They also cannot be used in the spaces with high latent loads or where 40 humidity control is critical.

41 Chilled beams (which decouple the air and cooling requirements) can significantly 42 reduce the size of the air system when cooling loads drive the design air flow rates. 43 Chilled beams adjust the flow of chilled water and hot water to match the changing loads 44 and eliminate reheat energy and minimize outside air conditioning. 45 5. Make-up and exhaust air system capacity shall account for a minimum of one 1.2m (4 46 ft.) wide vertical sash fume hood (18” sash height) in every other laboratory module. 47 6. Central systems may be supplemented by fan coil units, chilled beams, radiant panels, 48 etc. (not allowed in tissue culture rooms and BSL-3 facilities). 49 Fan coil units are not allowed in tissue culture rooms due to the presence of the 50 condensate drain pans. 51 7. Unitary direct expansion HVAC equipment prohibited in laboratory and animal research 52 facilities except where chilled water is not available in close proximity or where process 53 requirements dictate the use of DX cooling (in lieu of chilled water) for precision 54 temperature control. The A&E shall provide a detailed justification wherever DX 55 equipment is proposed. 56 57 6.2.2 System Redundancy 58 Multiple parallel supply air-handling units and exhaust fans shall be provided to operate 59 simultaneously to meet full load conditions. Air handling units (AHU) shall be designed to 60 provide N+1 reliability and maintain 100% capacity in the event of a lead component failure. 61 Each AHU system and its related components shall be capable of total isolation by the use 62 of isolation dampers located upstream and downstream of each air-handling unit. 63 Laboratory air handling systems and exhaust fans must operate continuously. N+1 redundancy 64 provides inherent reliability to the system. N+1 fans housed within the single AHU cabinet 65 cannot be interpreted as providing full redundancy requirements 66 67 6.2.3 Air Distribution Systems 68 1. Ductwork may be single-wall or double-wall construction and may be round, flat oval, or 69 rectangular in shape. 70 2. Duct lining is not permitted for use in air handling equipment and duct systems. 71 Duct lining is not permitted due to the possibility of releasing insulation fibers into the 72 airstream. Also, any moisture in the system could harbor growth within the ductwork. 73 3. Flexible ductwork may be used for branch duct connections in low-pressure supply and 74 air transfer duct systems. Flexible duct runs shall be limited to 1.8 m (6 ft.). Flexible 75 ducts shall have a UL-rated velocity of at least 20.3 m/s (4,000 fpm) and a maximum UL- 76 rated pressure of 2.5 kPa (10 in. w.g.) positive. Flexible ducts shall be factory insulated 77 and comply with the latest NFPA Standards 90A and 90B. Flexible duct connections 78 shall be made using stainless steel draw bands and manufacturer-approved tape. 79 4. Ductwork systems shall be designed, fabricated and installed in accordance with 80 ASHRAE and SMACNA standards. 81 5. Refer to Exhibit X6-2-A for a list acceptable air velocities to be used in the design and 82 sizing of different HVAC components. Refer to exhibit X6-2-B for a table showing the 83 minimum ductwork construction to be used in NIH facilities. 84 6. Construction documents shall require the sheet metal contractor conduct pressure tests 85 of the installed ductwork to quantify the leakage rate of the installed systems. Duct 86 leakage tests shall be conducted in accordance with SMACNA standards. Ductwork 87 shall be fabricated and installed to meet the sealing and leakage requirements in the 88 following table: Duct Seal and Leakage Classes Duct Pressure Classification (Rated Static Pressure) 500 Pa (2 in. w.g.) 750 Pa (3 in. w.g.) 1000 Pa (4 in. w.g.) and below and up NIH Design Requirements Manual 2012 3 Section 6.2

Duct Seal and Leakage Classes NIH Required Seal Class A A A NIH Required Sealing Joints, Seams and Joints Seams and Joints Seams and All Wall All Wall All Wall Penetrations Penetrations Penetrations NIH Required Leakage Class (1) 6 6 6 - Rectangular Metal NIH Required Leakage Class (1) 3 3 3 - Round Metal 89 (1) See latest edition of SMACNA “HVAC Air Duct Leakage Test Manual”, for 90 maximum allowable leakage for the each leakage class. 91 7. All ductwork penetrating room wall (Above the ceiling) and all diffuser/register/grille 92 penetrating hard ceilings shall be sealed. See Exhibit X4-2-A “Joint Sealant and 93 Caulking” table. 94 8. Flexible ductwork shall not be used for exhaust and return system because it is easier 95 for the ductwork to collapse under negative pressure. 96 9. Proper positioning of diffusers and grilles is vital for providing good distribution in the 97 space. 98 99 Pressure testing of ductwork avoids unwanted leaks into surrounding areas, requiring 100 more airflow from fans, avoids increased energy cost to operate the system, and avoids 101 operating system at full capacity with no reserve capacity. 102 Poor positioning of diffusers and grilles can result in either dead zones or zones with 103 unwanted air turbulence. 104 105 106 6.2.4 Outdoor Air Intakes and Exhaust Air Discharge 107 1. Outdoor air intakes shall be at least 12 m (40 ft.) away from any of the exhaust 108 contaminants sources (all types of exhaust fans including animal room exhaust and lab 109 exhaust, vehicle exhaust, loading docks, automobiles entrances, drive ways, passenger 110 drop-offs, cooling towers, boiler or incinerator stacks, emergency generators exhaust, 111 vacuum pumps exhaust, steam relief vents or other hot vents, plumbing vents, vents 112 from steam condensate pumps units, kitchen hoods, refrigerant relief vents, 113 mechanical/electrical room ventilation systems, etc.) regardless of discharging upward, 114 horizontally or deflected downward. Other factors such as wind direction, wind velocity, 115 stack effect, system size, height of building(s), snow drift and security concerns shall be 116 evaluated, and location of intakes and outlets adjusted accordantly. 117 2. The bottom of all outdoor air intakes shall be located as high as practical, but not less 118 than 3.6 m (12 ft.) above ground level and any adjacent building or site element within a 119 horizontal distance of 4 m (13 ft.) from the air intake. 120 3. Construction documents shall include the design of lab exhaust stack height and 121 discharge air velocity characteristics to overcome the building cavity boundary and avoid 122 re-entrainment of exhaust. Stacks shall be shown as part of the architectural design and 123 the design rationale shall be described in the early design reports. In general, exhaust 124 stacks shall be designed to meet the following requirements: 125 a. Discharge shall be a minimum of 3 m (10 ft.) above the roofline and any roof 126 element within a horizontal distance of a 4 m (13 ft.) radius 127 b. Upward velocity shall be a minimum of 15 m/s (3,000 fpm) at the point of 128 discharge. Reentry calculations may dictate higher discharge velocities. 129 c. Safety concerns shall always take precedence over aesthetics. 130 d. Manifolded exhaust fans shall have separate exhaust stacks for each fan to 131 avoid positively pressuring through a non-operating exhaust fan 132  Exception: Where 2 fans are required to operate simultaneously at 50% 133 capacity, common discharge stack is permitted to minimize discharge 134 pressure loss through each stack and reduce noise, while maintaining the 135 minimum 3000 FPM stack velocity. Motorized discharge dampers are 136 required in suction and discharge of each fan. 137 4. See Appendix E.2 “Calculating Minimum Separation Distance between Intakes and 138 Exhausts” for a computational analysis in evaluating building external air flows as 139 influenced by new and existing obstacles. 140 141 6.2.5 Air-Handling Units 142 The Basis of Design report shall define the type and quality of air-handling equipment proposed 143 for use in NIH facilities. In addition, the report shall provide justification for the equipment 144 selection. 145 146 6.2.5.1. Air-Handling Systems for Administrative and General Use Facilities 147 Air-handling systems for administrative, office, conference, and other general use facilities 148 frequently employ variable air volume with terminal zone- or room-heating units. These systems 149 are a recirculating type with ventilation rates designed to meet the latest ASHRAE Standards 62 150 and 90.1 or IMC. Air-side dry-bulb economizers provide free cooling when ambient conditions 151 permit. 152 153 Air-handling systems for administrative buildings are best kept simple and zoned consistent with 154 building use and occupancy schedules. Large conference or assembly areas with intermittent 155 use should not be connected to units that supply routine office space. Air-handling systems 156 found in these buildings may have the following features: 157  Single supply and return fans without redundant components. 158  Night setback and morning warm-up control modes 159  Mixing plenums with minimum and maximum outdoor air dampers to accommodate 160 minimum ventilation and economizer operations 161  30 percent efficient pre-filters and 60 percent efficient after-filters 162  Preheat coils required to support morning warm-up functions 163  Draw through chilled water coils 164  Central AHU humidifiers only 165  750-1000 Pa pressure duct distribution to terminal control devices 166  Fully ducted return air system with building pressure-controlled relief devices. 167  Units shall be factory packaged and commercial-grade. 168  Casing shall be double wall construction for all sections of the entire unit with a minimum 169 of 50 mm (2” in.) thick insulated panel for indoor units. 170  Outdoor units shall be a minimum of 80 mm (3 in.) thick insulated panels. Outdoor units 171 shall have the exterior panels painted to pass a 1000 hour salt spray per ASTM B-117. 172  Stainless steel drain pans shall be provided under cooling coil 173  Design cooling coil velocity shall not exceed 500 FPM NIH Design Requirements Manual 2012 5 Section 6.2

174  All unit sections shall have access doors to permit inspection and service of all 175 components. 176  Units shall have offset coil pipe headers to allow individual coils to slide out of unit 177 casings. 178  Units shall be fully tested at the factory before shipping. Testing shall verify capacity and 179 leakage rate. Unit casings shall be pressure rated for the total system design operating 180 pressure plus 25%. 181 182 183 6.2.5.2. Air-Handling Systems for Laboratory and Animal Research Facilities 184 185 The design requirements for air handling systems for laboratories and animal research facilities 186 are described in Section 6.1 and in other areas of this section. The following requirements apply 187 to all air-handling units to be used in NIH laboratory and animal research facilities: 188 1. Casings shall be double wall construction for all sections of the entire air-handling unit. 189 Wall construction shall provide a minimum of R-17 insulation Exterior and interior wall 190 panel shall be solid G90 galvanized steel or aluminum. All exterior and interior wall r 191 panels shall be 1.316mm (18 gauge) solid G90 galvanized steel minimum, or 0.05 inch 192 thick Aluminum minimum. Cooling coil and humidifier sections shall be constructed of 193 stainless steel interior panels for galvanized units. Unit roof and floor gauge (or 194 thickness) shall be one gauge (or thickness) higher than wall to handle weight of 195 personal. Unit floor shall be a minimum of 4.7 mm (3/16 in.) aluminum plate with 196 diamond tread, all welded construction. Panel construction shall allow the replacement 197 of individual panel sections without disturbing adjacent panels. 198 2. Outdoor units shall be double wall construction with minimum of R-19 insulation. 199 Outdoor units shall have the exterior panels painted with a minimum of a three step paint 200 process to pass a 1000 hour salt spray per ASTM B-117. 201 3. Units shall be custom factory fabricated and custom field erected. Units shall be 202 preassembled and fully tested at the factory before shipping. Units can be shipped as 203 one piece if possible, or in as few sections as possible to limit the number of field – 204 casing joints. 205 4. Unit casings shall be pressure rated at maximum operating pressure +50% or 10” w.g., 206 whichever is less. After installation at the field, these units shall be field-tested. 207 5. Field erected AHUs are generally large in capacity and are designed for installation in 208 existing buildings where access is restricted, or designed for new buildings where the 209 construction phasing does not permit the installation of large factory-packaged or 210 fabricated sections 211 6. Casing construction shall include full thermal breaks between exterior panels and interior 212 panels. 213 7. Casing construction shall be water and air tight. The fully assembled unit shall have a 214 maximum air leakage rate of 0.5% of the supply air volume at the prescribed test 215 pressure indicated in Item 4 above. The unit deflection shall be L/240 at the prescribed 216 test pressure. All factory and field penetrations shall be completely sealed and shall not 217 reduce the leakage rating of the casing. This includes all casing penetrations within the 218 unit and between unit’s components. All penetrations for components such as electrical 219 lighting, controls, etc. shall be sleeved and caulked to prevent leakage and condensation 220 damage. This shall also apply to heat recovery units. 221 8. Access doors shall be provided on both sides of each equipment section. Doors shall be 222 man sized and a minimum of 600 mm (24 in.) wide. Each door shall be provided with a 223 vision panel no less than 300 mm (12 in.) by 300 mm (12 in.). Door swing shall help 224 seal the access door with the unit’s internal air pressure. 225 9. Lights shall be waterproof, marine type, and provided in all sections of the unit, which 226 are more than 1.4 m (54 in.) high. Lights shall be controlled from a single pilot switch 227 located adjacent to one of the access doors. 228 10. Air filters may consist of cartridge-type elements; roll filters are not acceptable. The 229 design face velocity shall not exceed 2.5 m/s (500 fpm) nor shall manufacturers’ 230 standard nominal ratings be exceeded. The preferred filter face section dimensions are 231 600 mm (24 in.) x 600 mm (24 in.). Pre-filters shall be utilized. All filter banks shall have 232 intermediate supports to prevent bank deflection at maximum design pressure 233 differentials. Minimum 30% efficient filters shall be installed upstream of any heat 234 recovery device. 235 11. A manual magnehelic pressure gauge shall be provided, on the unit’s exterior, at each 236 filter section. One gauge shall be provided for each filter bank. BAS shall also monitor 237 the differential pressure cross the filter. 238 12. Air handler coil tubing shall be of nominal 0.035 inch copper tubes with aluminum fins of 239 at least 0.0095 inch thickness. Cooling coils shall be no more than 8 rows deep and 12 240 fins/inch to enhance cleaning and heat transfer. Galvanized coil frame and casings shall 241 be provided for heating coils and stainless steel frame and casings for cooling coils. The 242 use of Turbulators is not acceptable. 243 13. Cooling coil’s air face velocity shall be sized for a nominal air face velocity not to exceed 244 2.0 m/s (400 fpm) for the present design conditions and 2.5 m/s (480 fpm) for the future 245 growth capacity. 246 14. Maximum size for individual coils shall be 3.0 m (10 ft.) long by 0.91 m (3 ft.) high. If 247 larger coils are required then multiple coils shall be provided. 248 15. Multiple coils shall be valved separately so that, if any individual coil fails, it can be 249 isolated and drained while the remaining coils stay in operation. Coils shall be installed 250 to allow the removal of individual coils without disturbing pipe headers or anything else 251 that would prevent the remaining coils from operating. Coils shall be removable without 252 major rigging. 253 16. Integral face by-pass dampers steam coils are preferred over standard coils with 254 separate by-pass dampers. 255 17. Return header for multiple-stacked coils shall be piped in a reverse return configuration 256 to assist with the balancing of the water flow. Strainers shall be provided on the feed line 257 for each coil bank. Control and balancing valves shall be installed on the return line. 258 Each coil shall be provided with a balancing valve with integral memory stop. 259 Combination balancing, shutoff, and flow meter devices are not acceptable. 260 18. Each AHU section shall be provided with drains that permit the internal wash down of 261 the unit in the event of a coil failure. 262 19. Drain pans shall be provided for each cooling coil. Intermediate stainless steel drain 263 pans shall be provided for each coil bank, which is more than one coil high. Drain pans 264 shall extend a minimum of 12-in downstream of the cooling coils. The drain pan shall be 265 stainless steel with a positive slope to a bottom drain connection. Pan drains shall be 266 properly trapped. Static pressure conditions accounting for dirty filter(s) at fully loaded 267 (100%) condition shall be used to calculate the trap height. 268 20. Moisture eliminators may be considered where carryover presents a problem. However, 269 eliminators shall not impede service access for cleaning of the coil face surface. NIH Design Requirements Manual 2012 7 Section 6.2

270 21. Fans may be vane-axial, airfoil centrifugal (single or double width), or plenum as justified 271 by life-cycle cost analysis. All fans shall be of a minimum construction class II as per the 272 Air Movement and Control Association (AMCA). Fans shall be totally isolated from the 273 unit by the use of inertia bases and spring isolation. Fan volume control shall be 274 achieved by using VFDs on centrifugal and plenum fans. Fans shall be arranged in the 275 draw-through position. Blow-through configurations are not allowed. 276 22. Direct drive small plug fans (commonly called “fan wall”) arranged is an array may be 277 used to replace a traditional single large fan where there are space constraints. Each fan 278 shall be provided with isolation damper so air does not the short circuit through the non- 279 working fan. Direct fans motors operating with VFD’s shall not operate at higher than 280 90Hz frequency and motor size shall be based on the operating frequency. Units 281 operating with direct drive fans should be carefully selected so the operating speed 282 during VFD bypass mode does not exceed the maximum allowed fan rpm. 283 23. Fans shall be vibration isolated from the remaining parts of the unit and the connecting 284 ductwork system. 285 24. Fan shafts shall be solid and precision ground and polished. 286 25. Fan bearings shall be selected for minimum average life of L10 200,000 hours 287 26. When space limitations dictate that fans be placed in close proximity of heating or 288 cooling coils, the distance between the fan inlet and the coil shall be a minimum of a 289 wheel diameter for single width fans and 1.5 wheel diameter for double width fans. 290 27. Sound attenuators may be necessary to meet the room sound criteria for the room 291 served by the AHU. When feasible, they shall be integrated as a part of the AHU. 292 Sound attenuators shall be pack-less type. The silencer rating shall be certified in 293 accordance with ASTM E-477. 294 28. Control dampers shall be low leakage opposite blade for modulation control and parallel 295 blade for open-closed operation or for mixing. Ultra-low leakage, industrial-quality 296 isolation dampers shall be installed at the discharge of manifolded systems. Sufficient 297 space should be provided to remove and install actuators without the need for removal 298 of dampers or other equipment. 299 29. Fan airflow measurement in or near the fan inlet should not impede airflow 300 30. Unit louvers are typically used for outdoor air intakes. Louver shall be AMCA rated and 301 selected for low-pressure drop with less than 0.003 kg/m2 (0.001 lb. /ft2) penetration at 302 3.8 m/s (750 fpm) free-area velocity. Louvers shall be drainable and be constructed of 303 anodized aluminum or stainless steel with 304 SS hardware and bird screen. 304 31. Heat recovery may be considered as demonstrated by the life cycle analysis. The 305 heating and cooling coils shall be designed and sized to function at full load without the 306 energy recovery system. Units with heat recovery systems shall be designed such that 307 devices could be out of commission without any interruption to AHU system operation. 308 32. Contract documents shall fully detail the size, dimensions, and specific component 309 configuration of each factory-fabricated air-handling unit, including: all components, 310 capacity of all components, all controls components, all sequences of operation, access 311 areas, access doors, casing openings, service clearances, and overall dimensions. 312 Layouts shall include sections to define the overall height and vertical location of duct 313 connections, dampers, louvers. 314 33. The NIH Project Officer shall determine if NIH representative will witness the factory- 315 testing for the mission critical AHUs. 316 317 Air handling unit requirements are predicated upon AHUs having a service life much longer than 318 traditional commercial units. 319 320 6.2.5.3. Air-Handling Systems for Clinical Facilities 321 Air-handling units designed for clinical facilities shall be similar to air handers used in NIH 322 laboratory and animal research facilities: except these units are typically provided with return 323 fans with economizer system. The air handlers are provided with second filter bank downstream 324 of fan. Consideration should be given to ensure the final filter is not too close to the fan resulting 325 in uneven air distribution across the filter and potential wetting of the filter from upstream cooling 326 or humidifier. 327 328 329 6.2.6 Air Filtration Systems 330 1. Air filtration shall be provided to all supply air used to provide heating and air- 331 conditioning for laboratories and animal research facilities. As a minimum, supply air 332 shall pass through a pre-filter and final filter on the upstream side of heating and cooling 333 coils. Filter average efficiencies shall be MERV-8 (30%) for pre filter and MERV-14 334 (95%) for final filter, based on ASHRAE Standard 52.2, Minimum Efficiency Reporting 335 Value (MERV). HVAC air systems shall automatically adjust fan speed to compensate 336 for the additional system static pressure produced by filter loading. 337 2. Final filtration shall be provided downstream of supply air fans serving animal research 338 facilities to protect against particulate and other containments possibly generated by the 339 air handling equipment. Average efficiency of the final filters shall be MERV-14 (95%), 340 based on ASHRAE Standard 52.2, Minimum Efficiency Reporting Value. The A/E shall 341 review the project’s program requirements to establish specific filtration criteria. 342 3. Supply air for clinical facilities shall pass through a prefilters and final filters at the air 343 handling unit. Filter average efficiencies shall be MERV-8 (30%) for pre filter and MERV- 344 14-15 (95%) for final filter based on ASHRAE Standard 52.2, Minimum Efficiency 345 Reporting Value (MERV). HEPA filtration (MERV 17 and above) may be required for 346 patients vulnerable to infections. If HEPA filters are used they should be designed for 347 maximum of 300 FPM. The A&E shall consult with NIH Safety and NIH DTR prior to the 348 designing HEPA filters in the system. 349 4. Fan filter modules (FFU) are self-contained filter assembly with fan, prefilters, shallow 350 HEPA filter and speed controls. FFU’s are not recommended unless the duct system is 351 incapable of providing the pressure drop or an addition of a HEPA filter would create an 352 imbalance in the system. FFU’s are costly, require service and can generate room noise 353 when multiple units are installed in the room. 354 355 6.2.7 Humidification Systems 356 1. Winter humidification shall be provided where required to maintain space humidity 357 requirements. In the Bethesda campus steam from the central plant shall be utilized for 358 this purpose. In other NIH locations, the A/E shall verify suitability of using plant steam 359 with the Project Officer during the design stage. Written record of this verification shall 360 be included in the Basis of Design Report. 361 The chemicals such as amines introduced in steam typically remain at below exposure 362 level recommendations by OSHA, ACGIH or FDA 363 2. Humidifiers shall be steam separator type with jacketed steam injection, which do not 364 require a drain from the steam manifold. They may be located within air-handling units 365 or installed in the supply air ductwork When located in the air handling unit the 366 humidifier section shall be located upstream of the cooling coil section (which should be NIH Design Requirements Manual 2012 9 Section 6.2

367 off in summer) to ensure efficient distribution and absorption of vapor into the air stream. 368 Connections should be piped to exterior of the unit casing. Duct mounted steam 369 distribution manifold shall be installed within a fully welded stainless steel ductwork 370 section. The stainless steel section shall extend 0.6 m (2 ft.) upstream of the manifold 371 and at least 2 m (6 ft.) downstream from the manifold. The downstream length may 372 need to be extended depending on the absorption distance for the particular system 373 design. Stainless steel ductwork shall be pitched and connected to a drain. Steam 374 piping to the humidifier shall be low pressure and include a manual isolation valve for 375 equipment isolation during service. Humidifier controls shall include an automatic 376 isolation valve to remain closed during cooling mode. Humidifier controls shall also 377 include a high limit humidistat located downstream of the humidifier manifold. 378 3. Adiabatic humidifiers shall not be used for humidification in laboratories, animal facilities 379 at NIH. Adiabatic humidifiers are not allowed in clinical facilities per ASHRAE 170. 380 Steam is sterile and therefore eliminates risk of introducing viable microorganisms in the 381 air stream. Ultrasonic humidifiers shall not be used at NIH because of risk of aerosolized 382 fine particles that could deposit in the lungs. 383 4. Humidification systems shall also comply with the following: 384 a. Clean steam shall be used for humidification in special areas such as: transgenic 385 animal housing and barrier housing. Clean steam shall also be used for 386 autoclaves, sterilizers, and rack washers when required by program and/or 387 manufacturer. 388 b. The A/E shall consult with the NIH Safety and DTR to establish a list of areas 389 requiring the use of clean steam. 390 c. Clean steam shall be produced by a steam-to-steam generator by vaporizing 391 either: RO water or distilled water or deionized water. 392 d. Clean steam to steam generators may be provided with medium pressure steam 393 to reduce the size of the generators. 394 395 6.2.8 Fans 396 Variable and constant air volume centrifugal and plenum fans serving multiple zones shall be 397 equipped with variable frequency drives (VFDs) for control of volumetric flow rate and duct static 398 pressure. 399 1. All fans on a manifold or in parallel configuration shall be identical and have identical 400 isolation dampers and volume/pressure controls. 401 2. All fans shall be constructed to meet a minimum of Class II rating. They shall be fully 402 accessible for inspection, service and routine maintenance. Fan bearings, where 403 possible, shall be serviceable from outside hazardous or contaminated exhaust 404 airstreams. Inline fans with motors or drives exposed to exhaust airstreams serving 405 laboratories and animal research facilities are not permitted. 406 3. Fans shall have a certified sound and air rating based on tests performed in accordance 407 with AMCA Bulletins 210, 211A, and 300. See AMCA Standard 99, Standard Handbook, 408 for definitions of fan terminology. The arrangement, size, class, and capacity of all fans 409 shall be scheduled on the contract drawings. 410 4. Certified fan curves including power curves as well as acoustical data shall be submitted 411 for each fan. All data shall be from factory test(s) performed in accordance with 412 applicable AMCA standards. Data shall include published sound power levels based on 413 actual factory tests on the fan sizes being furnished and shall define sound power levels 414 (PWL) (10-12 W for each of the eight frequency bands). 415 5. Fan curves shall show: volumetric flow rate of the fan as a function of total pressure, 416 brake horsepower and fan efficiency. System curves shall include estimated losses for 417 field installation conditions, system effect, and actual installed drive components. All 418 losses shall be defined on the fan curves. Data may also be submitted in tabular form, 419 but tables are not a substitute for actual performance curves. 420 6. All fans shall be statically and dynamically balanced by the manufacturer and shall be 421 provided with vibration isolation. All fans 18.6 kW (25 HP) and larger shall also be 422 dynamically balanced in the field by the manufacturer upon installation completion. All 423 fan’s parts shall be protected against corrosion prior to operation. 424 7. Belt driven fans shall be provided with drives with multiple V-belts. Belts shall be cogged 425 type and shall be constructed of endless reinforced cords of long staple cotton, nylon, 426 rayon, or other suitable textile fibers imbedded in rubber. 427 8. Variable-pitch sheaves shall be used to accommodate initial balancing and shall be 428 replaced with fixed pitch when balancing is complete. Sheaves shall be constructed of 429 cast iron or steel, bored to fit properly on the shafts, and secured with keyways of proper 430 size (no setscrews) except that for sheaves having 13 mm (1/2 in.) or smaller, bores 431 setscrews may be used. 432 9. Fans shall be furnished complete as a package with electric motors, motor drives, fan 433 bases, and inlet and outlet ductwork connections. 434 435 6.2.9 Motor and Variable Frequency Drives 436 437 438 6.2.9.1 Motors 439 Motors utilized on NIH projects shall be premium high efficiency and selected to optimize the 440 efficiency of mechanical and building systems. Motors shall always be of adequate size to drive 441 the equipment without exceeding the nameplate rating at the specified speed or at the load that 442 may be delivered by the drive. 443 1. Motors shall be rated for continuous duty at 115% of rated capacity and base 444 temperature rise on an ambient temperature of 40°C (105°F). Motors 560 W (3/4 HP) 445 and larger shall be three-phase, Class B, general-purpose, squirrel cage, open-type, 446 premium-efficiency induction motors in accordance with National Electrical 447 Manufacturers Association (NEMA) Design B standards, wound for voltage specific to 448 the project, 60 Hz AC, unless otherwise required by the design. Motors 373 W (1/2 HP) 449 shall be either single or three-phase. Motors smaller than 373 W (1/2 HP) shall be 450 single-phase, open-capacitor type in accordance with NEMA standards for 115 V, 60 Hz, 451 AC. Motors 124 W (1/6 HP) and smaller may be the split-phase type. 452 2. All motors 0.75 kW (1 HP) and larger shall have a composite power factor rating of 90% 453 to 100% when the driven equipment is operating at the design duty. Devices such as 454 capacitors, or equipment such as solid-state power factor controllers, shall be provided 455 as part of the motor or motor-driven equipment when required for power factor 456 correction. 457 3. Motors specified to be controlled by variable speed drives shall be rated for such use. 458 Per CEE Premium Efficiency Criteria, minimum efficiencies for TEFC motors shall be 459 equal or greater than those shown in the minimum efficiency table included in Exhibit 460 X6-2-C “Minimum Motor Efficiency”. Motors used on VFD’s shall be provided with Class 461 F insulation. Motors used on VFD’s shall be provided with shaft ground ring to mitigate 462 effects of bearing currents and protect bearings from premature failure. 463 464 6.2.10 Variable Frequency Drives NIH Design Requirements Manual 2012 11 Section 6.2

465 Variable Frequency Drives (VFD) to be used in NIH facilities shall include consideration to the 466 following: 467 1. Harmonic distortion on both the supply and motor side of the VFD. 468 2. Equipment de-rating due to harmonic distortion produced by VFDs. 469 3. Audible noise caused by high-frequency (several kHz) components in the current 470 and voltage. 471 472 6.2.10.1 The design of system utilizing VFDs shall incorporate the following provisions 473 1. An independent and dedicated VFD shall be provided for each prime motor and 474 each standby motor in equipment requiring the use of VFDs. 475 2. Equipment motors shall be matched to the drive so that low speeds can be 476 achieved. 477 3. VFDs shall have a manual bypass independent of the drive. For motors 37.3 kW 478 (50HP) and larger, a reduced voltage starter shall be provided in the by-pass 479 circuit. Motors shall operate at full speed while in the bypass position whenever 480 the speed drive is de-energized and/or open for service. 481 4. VFDs shall be located in environments that are within manufacturer’s 482 specifications. 483 5. VFDs that serve fans shall be able to maintain operation during short power 484 fluctuations. That is the VFD shall be able to maintain the operation of the motor 485 during short interruptions of the building electrical power system without the need 486 to shut down the equipment and without damaging the motor. 487 6. 18 pulse VFDs shall be provided for all motors 56 kW (75 HP) and above. 488 7. 6 or 12 pulse VFDs shall be provided for all motors less than 56 kW (75 HP. 489 8. VFDs shall be provided with integral passive or active harmonic filters, phase 490 multiplication devices and any other components required to mitigate harmonic 491 voltage total distortion (THD) to 5%, current THD to 5% at any load level, and no 492 individual harmonic greater than 3% distortion. 493 9. Compliance measurement shall be based on actual THD measurement at the 494 VFD circuit breaker terminals during full load VFD operation. Designs which 495 employ shunt tuned filters shall be designed to prevent the importation of outside 496 harmonics, which could cause system resonance or filter failure. Calculations 497 supporting the design, including a system harmonic flow analysis, shall be 498 provided as part of the submittal process for shunt tuned filters. Any filter 499 designs, which cause voltage rise at the VFD terminals, shall include 500 documentation in compliance with the total system voltage variation of plus or 501 minus 10%. Documentation of Power Quality compliance shall be part of the 502 commissioning required by the VFD supplier. 503 10. Actual job site measurement testing shall be conducted at full load condition and 504 a copy of the report shall be included in the operation and maintenance manuals. 505 Harmonic measuring equipment utilized for certification shall carry a current 506 calibration certificate. The final test report shall be reviewed for compliance by a 507 manufacturer’s certified representative. Text and graphical data shall be 508 supplied showing voltage and current waveforms, THD and individual harmonic 509 spectrum analysis in compliance with the above standards. 510 11. VFD locations shall be as close as practical to motor to minimize motor circuit 511 conductor length issues. VFD incoming power wiring, wiring from VFD to motor, 512 and motor control wiring shall be installed in separate, dedicated conduits. 513 514 6.2.10.2 Additional Variable Frequency Drive Information 515 Refer to Appendix E.4 “Harmonic Control in Electric Power Systems” for additional 516 information regarding harmonic distortion concerns. Refer to Appendix E.6 “Selecting 517 and Specify Variable Frequency Drives for HVAC Systems” for additional information 518 regarding variable frequency drives concerns. 519 520 Refer to section 10 “Electrical” for additional requirements. 521 522 6.2.11 Emergency Electrical Power Generators 523 Emergency electrical power generators shall comply with the following requirements: 524 1. Engine exhaust system shall not create excessive back pressure on the 525 engine and shall not be connected to any other exhaust system serving other 526 equipment. Engine exhaust back pressure should be calculated before exhaust 527 system layout is finalized 528 Soot, corrosive condensate, and high exhaust-gas temperatures will damage idle 529 equipment served by a common exhaust system. Excessive exhaust back 530 reduces engine power and engine life 531 2. Engine exhaust piping shall comply with the following: 532 a. Refer to Exhibit X6-3-A for requirements of the engine exhaust pipes. 533 b. Exhaust pipes shall be freestanding, not supported by the engine or 534 muffler. 535 c. Exhaust pipes shall use vibration-proof flexible connector. 536 d. Exhaust pipes and mufflers shall be guarded to prevent contact with 537 personnel, and avoid personnel injuries and burns. 538 e. Exhaust pipes shall be routed to avoid fire detection devices and 539 automatic sprinkler heads. 540 f. Exhaust pipes shall be vented to the atmosphere away from building 541 doors, windows, and ventilation intake vents. It is recommended that exhaust 542 system be carried up as high as practical to maximize dispersal. Dispersion 543 analysis may be required to determine effect of exhaust fumes at various 544 intakes. 545 g. Insulated thimble pipe fittings shall be used at the point where the 546 exhaust pipe penetrates the exterior wall or roof. A hinged rain cap or 547 fabricated rain shield shall be provided on the vertical discharge. 548 h. Horizontal exhaust pipes shall be pitched downward and away from the 549 generator set. At the end of the horizontal run, a condensate drain trap with 550 hose connection shall be provided. A drain valve shall be provided at the 551 bottom of each vertical section of the exhaust piping. 552 i. Locate muffler as close to the engine to reduce corrosion due to 553 condensation 554 j. Expansion joints shall be provided in long straight tums of pipe and where 555 exhaust changes direction 556 557 6.2.11.1 Emergency Generator Room Ventilation 558 11.1. The space where the emergency generator is located shall include a 559 ventilation system to remove heat and fumes dissipated by the engine, electrical 560 generator, accessories, and other equipment located in the room. A maximum 561 11°C (20°F) room temperature rise above ambient shall be utilized in designing 562 the ventilation air system. The maximum room temperature shall be determined NIH Design Requirements Manual 2012 13 Section 6.2

563 on the operating limits of other equipment in the room as well as fire detection 564 specifications. 565 11.2. Air intake louvers to ventilate the generator room shall be sized to 566 accommodate the amount of combustion air needed by the engine, the amount 567 of cooling air that flows to the radiator and any other amount of air needed to 568 ventilate the room. Control air dampers on the air intake louver shall be fast 569 acting to meet code requirements. The intake damper shall be in a fail-safe 570 position. 571 11.3. Inlet and outlet should not be located on the same wall and airflow shall 572 allow to flow across the entire generator set from alternator end to radiator end. 573 11.4. Radiator discharge ducts shall be self-supporting. 574 575 576 577 6.2.11.2 Engine’s fuel oil system 578 The emergency generator shall be provided with a safe and uninterrupted source of 579 #2 fuel oil. The fuel oil system shall be engineered and installed to industry standards. 580 The advantage of sub-base tank fuel tanks is that the fuel system can be factory 581 designed and assembled however fuel capacity requirements and inability to refill and 582 access the tank may make them impractical. 583 The design of the fuel supply and storage system shall comply with the following 584 requirements when using remote fuel oil tank: 585 1. The fuel oil supply tank shall be located as close as possible to the emergency 586 generators. Emergency generator(s) fuel oil shall not be used for any other 587 purpose and shall not be shared with any other equipment. Secondary 588 containment with leak detection and alarm is required to prevent leaking fuel from 589 entering the soil or the sewer system. The fuel oil supply tank shall hold enough 590 fuel oil to run the generator(s) at full load for a minimum of 24 hours without 591 refueling. Tank-sizing calculations shall be based on the full load hourly fuel 592 consumption, (Diesel generator sets consume approximately 0.07 gallons/hour 593 per rated KW of fuel at full load) Other considerations for tank sizing shall 594 include the duration of expected power outages versus the availability of fuel 595 deliveries and the shelf life of the fuel oil. The shelf life of #2 fuel oil is 1.5 to 2 596 years. The fuel tanks must be adequately vented to prevent pressurization 597 2. The design of the fuel oil system shall specify all tank specialties such as fuel 598 level alarms, duplex pumps, filling accessories, control devices and all monitoring 599 and testing devices. 600 3. Underground fuel oil supply tanks shall be double wall fiberglass and shall be 601 provided with a leak detection and monitoring system. 602 4. Day tanks shall be as close as practical to the generator’s engine and shall be at 603 an elevation where the highest fuel level in the day tank is lower than the diesel 604 fuel injectors. Day tanks shall be vented to the outside when installed indoors. 605 Day tanks are typically sized for 2 hours of operation for the generator set at full 606 load 607 5. Underground fuel oil piping shall be double wall fiberglass and shall be provided 608 with a leak detection and monitoring system. Above ground fuel oil lines shall be 609 black steel. Compatible metal fuel oil pipes and fittings shall be used to avoid 610 electrolysis. 611 6. A flexible section, of code-approved tubing, shall be used between the engine 612 and the fuel supply line to isolate vibration from the generator’s engine. 613 7. Fuel oil supply pipes and pumps shall be sized to handle a fuel oil flow rate three 614 times greater than the full-load fuel oil consumption rate specified by the 615 generator manufacturer. In multiple day tanks applications, the main fuel oil 616 pump system shall be sized for three times the total fuel oil flow with all 617 generators at full load simultaneously. Fuel oil return pipes may be sized for 618 twice the total fuel oil flow. Engine return-fuel oil shall be piped to the fuel oil 619 supply tank. The fuel return line shall not include a shut-off device 620 8. The fuel oil supply line to each generator shall be provided with an electric 621 solenoid shutoff valve. The solenoid valve shall be connected to the engine 622 starter circuit to open the valve prior to energizing the generator. 623 9. Provisions shall be provided for manually filling the tanks should it be necessary 624 625 6.2.11.3 Generator Set Noise 626 1. The emergency generator noise levels at the property line shall follow the local county 627 noise ordinances and requirements. For properties located in Montgomery County 628 (including Bethesda, MD), the maximum allowed noise level is 55 dBA during daytime 629 and 5 5dBA during night time for residential receiving properties. 630 2 The A&E shall assess noise performance requirements early in the design cycle and 631 design appropriate sound attenuation measures based on the site conditions. 632 3 Generators sets located outdoors shall be provided with integral sound attenuators 633 enclosures. 634 4 “ Residential” or” Critical" grade silencers are typically effective in reducing exhaust 635 noise and should be evaluated as part of the noise performance assessment. 636 637 6.2.11.4 Generator Space Requirements 638 The emergency generator sets shall be provided with adequate access on both sides of the 639 engine for service, to allow removal of the largest component, for fuel and electrical 640 distribution system components. 641 642 6.2.11.5 Generator Fire Protection Requirements 643 The fire protection system must comply with the authority having jurisdiction (AHJ) which is 644 the Fire Marshal on NIH’s Bethesda’s campus. Some of the requirements include: 645 9.1. Provide adequate ventilation in the room to prevent buildup of exhaust gases 646 9.2. Provide adequate fire resistant construction for room construction 647 9.3. Provide appropriate fire detection devices 648 9.4. Provide appropriate number of fire extinguishers in the room 649 9.5. Provide manual emergency stop outside the generator to facilitate shutting down 650 the generator in the event of fire. 651 9.6. Follow AHJ’s requirement on the amount of liquid fuel stored inside the building. 652 Typical maximum allowed by code is 660 Gallons. 653