Building Mechanical Systems
**CAM 415; Form Mechanical Checklist (MECH-CHK), Form Complex Mechanical Checklist (MECH-COMP)**
1401 Scope: This section covers the determination of requirements, system and component performance, control requirements and duct construction.
1402 Mechanical Ventilation: The minimum requirements for ventilation shall comply with the Washington State Ventilation and Indoor Air Quality Code (WAC 51-13)
Seattle Mechanical Code. **CAM
406**
SECTION 1410 - GENERAL REQUIREMENTS
The building mechanical system shall comply with Sections 1411 through 1415, Sections 1440 through 1442 and Sections 1450 through 1454, and with one of the following paths:
- Simple Systems (Packaged Unitary Equipment) Sections 1420 through 1424
- Complex Systems Sections 1430 through 1438.
- Systems Analysis. See Section 1141.4.
Figure 14A - Mechanical Systems Compliance Paths
1411 HVAC Equipment Performance Requirements
1411.1 General: Equipment shall have a minimum performance at the specified rating conditions not less than the values shown in Tables 14-1A through 14-1G. If a nationally recognized certification program exists for a product covered in Tables 14-1A through 14-1G, and it includes provisions for verification and challenge of equipment efficiency ratings, then the product shall be listed in the certification program.
| If equipment is subject to an ARI Standard, it shall be listed in the ARI certification program. |
EXCEPTION: Water-cooled centrifugal water-chilling packages that are not designed for operation at ARI Standard 550/590 test conditions of 44ºF leaving chilled water temperature and 85ºF entering condenser water temperature with 3 gpm/ton condenser water flow shall have a minimum NPLV rating as shown in Tables 14-1K, L, and M. The table values are only applicable over the following full load design ranges:
| Leaving Chiller Water Temp.: | 40 to 48ºF |
| Entering Condenser Water Temp.: | 75 to 85ºF |
| Condenser Water Temp. Rise: | 5 to 15ºF |
| Glycol percent: | 0% |
Chillers designed to operate outside of these ranges shall have a code compliant selection at the nearest table operating point based on an all-water system. Non-standard Part Load Value (NPLV) is defined as single number part-load efficiency figure of merit for chillers references to conditions other than IPLV conditions. Design condenser water flow rate shall not be less than 2.5 gpm/ton.
Equipment not listed in Tables 14-1A to 14-1G is allowed to be used.
Gas-fired and oil-fired forced air furnaces with input ratings 225,000 Btu/h (65 kW) and all unit heaters shall also have an intermittent ignition or interrupted device (IID), and have either mechanical draft (including power venting) or a flue damper. A vent damper is an acceptable alternative to a flue damper for furnaces where combustion air is drawn from the conditioned space. All furnaces with input ratings >225,000 Btu/h (65 kW), including electric furnaces, that are not located within the conditioned space shall have jack losses not exceeding 0.75% of the input rating.
Electric furnaces over 15 kW shall have a minimum of two stages of control for heating.
Cooling towers serving chilled water systems with airside economizer complying with Section 1433 without using the exceptions shall be selected to be able to maintain a return condenser water temperature to the tower of 86ºF or less at peak design conditions.
Hydronic heat pump and other cooling and refrigeration equipment (e.g. icemakers, walk-in coolers) shall not use domestic water only one time before dumping it to waste (no single pass water cooling systems are allowed). The only exceptions are: medical and dental equipment; equipment using less than 1 gpm; replacement of existing icemakers; or use of single pass cooling during power outages and other emergencies.
1411.2 Rating Conditions: Cooling equipment shall be rated at ARI test conditions and procedures when available. **Website ARI** Where no applicable procedures exist, data shall be furnished by the equipment manufacturer.
| If equipment is rated in accordance with an ARI Standard, it shall be rated at Standard (not "design") ARI Rating Conditions. |
1411.3 Combination Space and Service Water Heating: For combination space and service water heaters with a principal function of providing space heat, the Combined Annual Efficiency (CAE) may be calculated by using ASHRAE Standard 124-1991. **Website ASHRAE** Storage water heaters used in combination space heat and water heat applications shall have either an Energy Factor (EF) or a Combined Annual Efficiency (CAE) of not less than the following:
| Energy Factor (EF) | Combined Annual Efficiency (CAE) | |
| < 50 gallon storage | 0.58 | 0.71 |
| 50 to 70 gallon storage | 0.57 | 0.71 |
| > 70 gallon storage | 0.55 | 0.70 |
1411.4 Packaged and Split System Electric Heating and Cooling Equipment: Packaged and split system electric equipment providing both heating and cooling with a total cooling capacity greater than 20,000 Btu/h shall be a heat pump.
EXCEPTION: Unstaffed equipment shelters or cabinets used solely for personal wireless service facilities.
1411.5 Heating Systems in Unenclosed Spaces: Where heating is provided to unenclosed spaces, only radiant systems shall be used unless otherwise approved by the building official. The heating system shall be controlled by an occupancy sensor. An unenclosed space is one that is not substantially surrounded by solid surfaces such as walls, floors, roofs, and openable devices such as doors and operable windows. Warehouses and repair garages are considered enclosed spaces.
1412.1 Temperature Controls: Each system shall be provided with at least one temperature control device. Each zone shall be controlled by individual thermostatic controls responding to temperature within the zone. At a minimum, each floor of a building shall be considered as a separate zone.
1412.2 Deadband Controls: When used to control both comfort heating and cooling, zone thermostatic controls shall be capable of a deadband of at least 5ºF within which the supply of heating and cooling energy to the zone is shut off or reduced to a minimum.
EXCEPTIONS:
- Special occupancy, special usage or code requirements where deadband controls are not appropriate.
- Thermostats that require manual changeover between heating and cooling modes.
1412.3 Humidity Controls: If a system is equipped with a means for adding moisture, a humidistat shall be provided.
1412.4 Setback and Shut-Off: HVAC systems shall be equipped with automatic controls capable of accomplishing a reduction of energy use through control setback or equipment shutdown during periods of non-use or alternate use of the spaces served by the system. The automatic controls shall:
- have a minimum seven-day clock and be capable of being set for seven different day types per week, **CAM 404**
- be capable of retaining programming and time setting during loss of power for a period of at least ten hours, and
- include an accessible manual override, or equivalent function (e.g. telephone interface), that allows temporary operation of the system for up to two hours.
EXCEPTIONS:
- Systems serving areas which require continuous operation at the same temperature setpoint.
- Equipment with full load demands of 2 kW (6,826 Btu/h) or less may be controlled by readily accessible manual off-hour controls.
- Systems controlled by an occupant sensor that is capable of shutting the system off when no occupant is sensed for a period of up to 30 minutes.
- Systems controlled solely by a manually-operated timer capable of operating the system for no more than two hours.
1412.4.1 Dampers: Outside air intakes, exhaust outlets and relief outlets serving conditioned spaces shall be equipped with motorized dampers which close automatically when the system is off or upon power failure. Stair shaft and elevator shaft smoke relief openings shall be equipped with normally open (fails open upon loss of power) dampers. These dampers shall remain closed until activated by the fire alarm system or other approved smoke detection system.
EXCEPTIONS:
- Systems serving areas which require continuous operation.
- Combustion air intakes.
- Gravity (non-motorized) dampers are acceptable in systems with a design outdoor air intake or exhaust capacity of 300 cfm or less
buildings less than 3 stories in height. Gravity (non-motorized dampers are acceptable in exhaust and relief outlets in the first story and levels below the first story of buildings three or more stories in height.Reserved- Type 1 grease hoods exhaust.
Dampers installed to comply with this section, including dampers integral to HVAC equipment, shall have a maximum leakage rate when tested in accordance with AMCA Standard 500 of:
- Motorized dampers: 10 cfm/ft2 of damper area at 1.0 in. w.g.
- Non-motorized dampers: 20 cfm/ft2 of damper area at 1.0 in. w.g., except that for non-motorized dampers smaller than 24 inches in either dimension: 40 cfm/ft2 of damper area at 1.0 in. w.g.
Dampers used as a component of packaged HVAC equipment shall comply with the damper leakage requirements, unless it is the lowest leakage available as a factory option. Drawings shall indicate compliance with this section.
1412.4.2 Optimum Start Controls: Heating and cooling systems with design supply air capacities exceeding 10,000 cfm shall have optimum start controls. Optimum start controls shall be designed to automatically adjust the start time of an HVAC system each day to bring the space to desired occupied temperature levels immediately before scheduled occupancy. The control algorithm shall, as a minimum, be a function of the difference between space temperature and occupied setpoint and the amount of time prior to scheduled occupancy.
1412.5 Heat Pump Controls: Unitary air cooled heat pumps shall include microprocessor controls that minimize supplemental heat usage during start-up, set-up and defrost conditions. These controls shall anticipate need for heat and use compression heating as the first stage of heat. Controls shall indicate when supplemental heating is being used through visual means (e.g., LED indicators).
1412.6 Combustion Heating Equipment Controls: Combustion heating equipment with a capacity over 225,000 Btu/h shall have modulating
modulated or staged combustion control. Boilers shall have proportionately-modulated or staged combustion control to control both the fuel and the air.
EXCEPTIONS:
- Boilers under 1,000,000 Btu/h input capacity.
- Radiant Heaters.
- Systems with multiple boilers which are sequentially staged.
Boilers shall comply with the reset requirements in Section 1432.2.
1412.7 Balancing: Each air supply outlet or air or water terminal device shall have a means for balancing, including but not limited to, dampers, temperature and pressure test connections and balancing valves.
1412.8Ventilation Controls for High-Occupancy Areas.Demand control ventilation (DCV) is required for spaces that are larger than 500 ft2, have a design occupancy for ventilation of greater than 40 people for 1000 ft2 of floor area, and are 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 3000 cfm.
EXCEPTIONS:
- Systems with energy recovery complying with Section 1436.
- Multiple-zone systems without direct-digital control of individual zones communicating with a central control panel.
- Systems with a design outdoor airflow less than 1200 cfm.
- Spaces where the supply airflow rate minus any makeup or outgoing transfer air requirement is less than 1200 cfm.
1413.1 Operation: Air economizers shall be capable of automatically modulating outside and return air dampers to provide 100% of the design supply air as outside air to reduce or eliminate the need for mechanical cooling. Air economizers shall be used for RS-29 analysis base case for all systems without exceptions in Sections 1413, 1423, or 1433. Water economizers, when allowed by Section 1132.2 exception 1 or Section 1433 exception 9, shall be capable of providing the total concurrent cooling load served by the connected terminal equipment lacking airside economizer, at outside air temperatures of 45ºF dry-bulb/40ºF wet-bulb and below. For this calculation, all factors including solar and internal load shall be the same as those used for peak load calculations, except for the outside temperatures.
EXCEPTION:
Water economizers using air-cooled heat rejection equipment may use a 35ºF dry-bulb outside air temperature for this calculation. This exception is limited to a maximum of 20 tons per building.
| Note that this requirement will result in a larger cooling tower. |
1413.2 Documentation: Water economizer plans submitted for approval shall include the following information:
- Maximum outside air conditions for which economizer is sized to provide full cooling.
- Design cooling load to be provided by economizer at this outside air condition.
- Heat rejection and terminal equipment performance data including model number, flow rate, capacity, entering and leaving temperature in full economizer cooling mode.
1413.3 Integrated Operation - Building Heating Energy: The HVAC system and its controls shall allow economizer operation when mechanical cooling is required simultaneously. Air and water economizers shall be capable of providing partial cooling even when additional mechanical cooling is required to meet the remainder of the cooling load.
EXCEPTIONS: 1. Individual, direct expansion units that have a rated capacity less than 65,000 Btu/h and use nonintegrated economizer controls that preclude simultaneous operation of the economizer and mechanical cooling.
2. Water-cooled water chillers with waterside economizer.
1413.4 Humidification: If an air economizer is required on a cooling system for which humidification equipment is to be provided to maintain minimum indoor humidity levels, then the humidifier shall be of the adiabatic type (direct evaporative media or fog atomization type).
EXCEPTION: 1. Health care facilities where WAC 246-320-525 allows only steam injection humidifiers in ductwork downstream of final filters.
2. Systems with water economizer
3. 100% outside air systems with no provisions for air recirculation to the central supply fan.
4. Nonadiabatic humidifiers cumulatively serving no more than 10% of a building's air economizer capacity as measured in cfm. This refers to the system cfm serving rooms with stand alone or duct mounted humidifiers.
1413.5 Economizer Heating System Impact: Any HVAC system that increases the building heating energy use during economizer operation is not allowed (e.g. single-fan/dual-duct systems and multizone systems).
EXCEPTION: Where the heating is allowed by Section 1435.
|
Note that single fan/dual-duct systems and multizone systems do not comply with this requirement. This is because economizer operation lowers the temperature of the air entering the hot deck heating coil, increasing its energy use. In order to use this type of system, a water economizer must be used, or the system must meet one of the economizer exceptions and have neither type of economizer. (Another resolution is to use a dual fan/dual-duct system where the hot deck fan supplies only return air or return air plus minimum ventilation air.)
This requirement will not affect three-deck multizone since they cannot work with an air economizer in any case (it would make the neutral deck a cold deck). An exception to the heating impact is provided for economizers on VAV systems that cause zone level heating to increase due to a reduction in supply air temperature. Reducing supply air temperatures on a cooling-VAV system will reduce fan energy (particularly if the system has a variable speed drive), offsetting the energy lost due to increased reheat energy. See the discussion diagrams of Section 6.3.1.4 of ASHRAE/IESNA Standard 90.1 in the Users Manual.**Website ASHRAE** |
1414.1 Sealing: Duct work which is designed to operate at pressures above 1/2 inch water column static pressure shall be sealed in accordance with
Standard RS-18
. Extent of sealing required is as follows:
Static pressure: 1/2 inch to 2 inches; seal transverse jointsReserved.- Static pressure:
21/2 inches to 3 inches; seal all transverse joints and longitudinal seams. Spiral lock seams in round and flat oval ductwork do not require sealing, however, other seams shall be sealed. - Static pressure: above 3 inches; seal all transverse joints, longitudinal seams and duct wall penetrations.
Duct tape and other pressure sensitive tape shall not be used as the primary sealant where ducts are designed to operate at static pressures of 1 inch W.C. or greater.
All low-pressure supply and return air systems not located entirely within the conditioned space, include the unconditioned side of enclosed stud bays or joist cavities/spaces used to transport air, shall be securely fastened and sealed. Ductwork shall be sealed using welds, gaskets, mastic, or mastic-plus-embedded-fabric tape. Enclosed stud bays or joist cavities/spaces used to transport air shall be sealed using mastic-plus-embedded-fabric tape or, when drywall is used to enclose the air system, drywall and mud tape. Duct tape is not permitted as a sealant on any ducts.
EXCEPTION: Fibrous glass duct systems installed in accordance with standard UL 181A and flexible duct systems installed in accordance with standard UL 181B may use tapes listed for those systems.
| Note that longitudinal seams are joints oriented in the direction of airflow. Transverse joints are connections of two duct section oriented perpendicular to airflow. Duct wall penetrations are openings made by any screw fastener, pipe, rod or wire. All other connections are considered transverse joints, including but not limited to spin-ins, taps and other branch connections, access door frames and jambs, duct connections to equipment. |
1414.2 Insulation: Ducts and plenums that are constructed and function as part of the building envelope, by separating interior space from exterior space, shall meet the requirements of Chapter 13. These requirements include insulation installation, moisture control, air leakage, and building envelope insulation levels. Unheated equipment rooms with combustion air louvers shall be isolated from the conditioned space by insulating interior surfaces to a minimum of R-11 and any exterior envelope surfaces per Chapter 13. Outside air ducts serving individual supply air units with less than 2,800 cfm of total supply air capacity shall be insulated to a minimum of R-7 and are not considered building envelope. Other outside air duct runs are considered building envelope until they,
- connect to the heating or cooling equipment, or
- are isolated from the exterior with an automatic shutoff damper complying with Section 1412.4.1.
Once outside air ducts meet the above listed requirements, any runs within conditioned space must comply with Table 14-5 requirements.
Other ducts and plenums shall be thermally insulated per Table 14-5.
EXCEPTIONS:
- Within the HVAC equipment.
- Exhaust air ducts not subject to condensation.
- Exposed ductwork within a zone that serves that zone.
1415.1 Insulation: Piping shall be thermally insulated in accordance with Table 14-6.
EXCEPTION: Piping installed within unitary HVAC equipment.
Cold water pipes outside the conditioned space shall be insulated in accordance with Washington State Plumbing Code (WAC 51-56).
1416 Mechanical Systems Commissioning and Completion Requirements **CAM 419; Seattle City Light; Website PECI, Website Oregon Office of Energy**
1416.1 General. Commissioning is a systematic process of verification and documentation that ensures that the selected building systems have been designed, installed and function properly, efficiently, and can be maintained in accordance with the contract documents in order to satisfy the building owner’s design intent and operational requirements. Drawing notes shall require commissioning and completion requirements in accordance with Section 1416. Drawing notes may refer to specifications for further requirements.
1416.1.1 Simple Mechanical Systems. For simple systems, as defined in Section 1421, and for warehouses and semi-heated spaces, commissioning shall include, as a minimum:
a. A Commissioning Plan,
b. Systems Testing and Balancing,
c. Controls Functional Performance Testing,
d. A Preliminary Commissioning Report,
e. Post Construction Documentation in the form of O&M and Record Drawing Review, and
f. A Final Commissioning Report.
1416.1.2 All Other Mechanical Systems. For all other mechanical systems, commissioning shall include, as a minimum:
a. A Commissioning Plan,
b. Systems Testing and Balancing,
c. Equipment Functional Performance Testing,
d. Controls Functional Performance Testing,
e. A Preliminary Commissioning Report,
f. Post Construction Documentation (all), and
g. A Final Commissioning Report.
1416.2 Commissioning Requirements
1416.2.1 General. The plans shall require tests mandated by this section be performed and the results recorded. The plans shall require preparation of preliminary and final reports of test procedures and results as described herein. At a minimum, the plans shall identify the following for each test:
a. A detailed explanation of the original design intent.
b. Equipment and systems to be tested, including the extent of tests,
c. Functions to be tested (for example calibration, economizer control, etc.),
d. Conditions under which the test shall be performed (for example winter and summer design conditions, full outside air, etc.), and
e. Measurable criteria for acceptable performance.
1416.2.2 Systems Balancing
1416.2.2.1 General. Construction documents shall require that all HVAC systems be balanced in accordance with generally accepted engineering standards. Air and water flow rates shall be measured and adjusted to deliver final flow rates within 10% of design rates, except variable flow distribution systems need not be balanced upstream of the controlling device (for example, VAV box or control valve). Construction documents shall require a written balance report be provided to the owner. Drawing notes may refer to specifications for further systems balancing requirements.
1416.2.2.2 Air Systems Balancing. Air systems shall be balanced in a manner to first minimize throttling losses then, for fans with system power of greater than 1 hp, fan speed shall be adjusted to meet design flow conditions.
1416.2.2.3 Hydronic System Balancing. Hydronic systems shall be proportionately balanced in a manner to first minimize throttling losses, then the pump impeller shall be trimmed or pump speed shall be adjusted to meet design flow conditions.
EXCEPTIONS:
- Pumps with pump motors of 10 hp or less.
- When throttling results in no greater than 5% of the nameplate horsepower draw above that required if the impeller were trimmed.
1416.2.3 Functional Performance Testing
1416.2.3.1 Equipment/Systems Testing. Functional Performance Testing shall demonstrate the correct installation and operation of each component, system, and system-to-system intertie relationship in accordance with approved plans and specifications. This demonstration is to prove the operation, function, and maintenance serviceability for each of the Commissioned systems. Testing shall include all modes of operation, including:
a. All modes as described in the Sequence of Operation,
b. Redundant or automatic back-up mode,
c. Performance of alarms, and
d. Mode of operation upon a loss of power and restored power.
1416.2.3.2 Controls Testing. HVAC control systems shall be tested to ensure that control devices, components, equipment and systems are calibrated, adjusted and operate in accordance with approved plans and specifications. Sequences of operation shall be functionally tested to ensure they operate in accordance with approved plans and specifications.
1416.2.4 Post Construction Commissioning
1416.2.4.1 General: Construction documents shall require post construction commissioning be provided to the building owner. Drawing notes may refer to specifications for further commissioning requirements. Post construction commissioning shall include, as a minimum, review and approval of Operation and Maintenance Materials, Record Drawings, and Systems Operational Training.
1416.2.4.2 Operation and Maintenance Materials: The O & M manual shall be in accordance with industry accepted standards and shall include, at a minimum, the following:
a. Submittal data stating equipment size and selected options for each piece of equipment requiring maintenance.
b. Operation and maintenance manuals for each piece of equipment requiring maintenance, except equipment not furnished as part of the project. Required routine maintenance actions shall be clearly identified.
c. Names and addresses of at least one service agency.
d. HVAC controls system maintenance and calibration information, including wiring diagrams, schematics, and control sequence descriptions. Desired or field determined set points shall be permanently recorded on control drawings at control devices, or, for digital control systems, in programming comments.
e. A complete written narrative of how each system and piece of equipment is intended to operate including:
i. A detailed explanation of the original design intent.
ii. The basis of design (how the design was selected to meet the design intent).
iii. A detailed explanation of how new equipment is to interface with existing equipment or systems (where applicable).
iv. Suggested control set points.
NOTE: Sequence of Operation is not acceptable as a narrative for this requirement.
1416.2.4.3 Record Drawings: Record drawings shall include as a minimum the location and performance data on each piece of equipment, general configuration of duct and pipe distribution system, including sizes, and the terminal air and water design flow rates of the actual installation.
1416.2.4.4 Systems Operational Training: The training of the appropriate maintenance staff for each equipment type and/or system shall include, as a minimum, the following:
a. System/Equipment overview (what it is, what it does and which other systems and or equipment does it interface with).
b. Review of the available O&M materials.
c. Review of the Record Drawings on the subject system/equipment.
d. Hands-on demonstration of all normal maintenance procedures, normal operating modes, and all emergency shutdown and start-up procedures.
1416.2.5 Commissioning Reports
1416.2.5.1 Preliminary Commissioning Report. A preliminary report of commissioning test procedures and results shall be completed and provided to the Owner. The preliminary commissioning report shall identify:
a. Deficiencies found during testing required by this section which have not been corrected at the time of report preparation and the anticipated date of correction.
b. Deferred tests which cannot be performed at the time of report preparation due to climatic conditions.
c. Climatic conditions required for performance of the deferred tests, and the anticipated date of each deferred test.
1416.2.5.2 Final Commissioning Report: A complete report of test procedures and results shall be prepared and filed with the owner. The Final Commissioning Report shall identify:
a. Results of all Functional Performance Tests.
b. Disposition of all deficiencies found during testing, including details of corrective measures used or proposed.
c. All Functional Performance Test procedures used during the commissioning process including measurable criteria for test acceptance, provided herein for repeatability.
EXCEPTION: Deferred tests which cannot be performed at the time of report preparation due to climatic conditions.
1416.3 Acceptance Requirements
1416.3.1 Acceptance: Buildings or portions thereof, required by this code to comply with this section, shall not be issued a final certificate of occupancy until such time that the building official determines that the preliminary commissioning report required by Section 1416.2.5.1 has been completed.
SECTION 1420 - SIMPLE SYSTEMS (Packaged Unitary Equipment)
**CAM
415; Form
Mechanical Checklist (MECH-CHK)**
1421 System Type: To qualify as a simple system, systems shall be one of the following:
- Air cooled, constant volume packaged equipment, which provide heating, cooling or both, and require only external connection to duct work and energy services with cooling capacity of 135,000 Btu/h or less.
- Air cooled, constant volume split systems, which provide heating, cooling or both, with cooling capacity of 84,000 Btu/h or less.
- Heating only systems which have a capacity of less than 5,000 cfm or which have a minimum outside air supply of less than 70% of the total air circulation.
All other systems shall comply with Sections 1430 through 1439.
1422 Controls: In addition to the control requirements in Section 1412, where separate heating and cooling equipment serve the same temperature zone, thermostats shall be interlocked to prevent simultaneous heating and cooling. Systems which provide heating and cooling simultaneously to a zone are prohibited.
1423 Economizers: Economizers meeting the requirements of Section 1413 shall be installed on:
- cooling units installed outdoors or in a mechanical room adjacent to outdoors having a total cooling capacity greater than 20,000 Btu/h including those serving computer server rooms, electronic equipment, radio equipment, and telephone switchgear; and
other cooling units with a total cooling capacity greater than 54,000 Btu/h, including those serving computer server rooms, electronic equipment, radio equipment, and telephone switchgear.
EXCEPTION: For Group R Occupancy, economizers meeting the requirement of Section 1413 shall be installed on single package unitary fan-cooling units having a total cooling capacity greater than 54,000Btu/h.
The total capacity of all units without economizers (i.e., those units with a total cooling capacity less than a and b above) shall not exceed 240,000 Btu/h per building, or 10% of its aggregate cooling (economizer) capacity, whichever is greater. That portion of the equipment serving Group R occupancy is not included in determining the total capacity of all units without economizers in a building.
1424 Separate Air Distribution Systems: Zones with special process temperature requirements and/or humidity requirements shall be served by separate air distribution systems from those serving zones requiring only comfort conditions.
SECTION 1430 - COMPLEX SYSTEMS
**CAM
415; Form
Mechanical Checklist (MECH-CHK), Form
Complex Mechanical Checklist (MECH-COMP)**
1431 System Type: All systems not qualifying for Sections 1420 through 1424 (Simple Systems), including field fabricated and constructed of system components, shall comply with Sections 1430 through 1438. Simple systems may also comply with Sections 1430 through 1439.
1431.1 Field-Assembled Equipment and Components: Field-assembled equipment and components from more than one manufacturer shall show compliance with this section and Section 1411 through calculations of total on-site energy input and output. The combined component efficiencies as measured per Section 1411.2, shall be in compliance with the requirements of Section 1411.1.
Total on-site energy input to the equipment shall be determined by combining the energy inputs to all components, elements and accessories such as compressors, internal circulating pumps, purge devices, viscosity control heaters and controls.
1431.2 System Sizing Limits: Heating and cooling design loads for the purpose of sizing systems shall be determined in accordance with one of the procedures described in Chapter 29 of Standard RS-1 listed in Chapter 7 or an equivalent computation procedure. For interior temperatures, 70ºF shall be used for heating and 75ºF for cooling, except where different values are specified in the Washington Administrative Code (WAC). For exterior temperatures, 24ºF shall be used for heating and 82ºF dry bulb and 66ºF for wet bulb for cooling.
Building mechanical systems for all buildings which provide space heating and/or space cooling shall be sized no greater than 150% of the design load as calculated above, except that cooling towers shall comply with the sizing requirements in Section 1411.1. No additional safety factor is allowed.
For buildings with a total equipment cooling capacity of 300 tons and above, the equipment shall comply with one of the following: (1) no one unit shall have a cooling capacity of more than 2/3 of the total installed cooling equipment capacity; (2) the equipment shall have a variable speed drive; or (3) the equipment shall have multiple compressors.
EXCEPTIONS: The following limited exemptions from the sizing limit shall be allowed, however, in all cases heating and/or cooling design load calculations shall be submitted.
- For a single piece of equipment which has both heating and cooling capability, only one function, either the heating or the cooling, need meet the requirements of this section. Capacity for the other function shall be, within available equipment options, the smallest size necessary to meet the load.
- Stand-by equipment may be installed if controls and devices are provided which allow redundant equipment to operate automatically only when the primary equipment is not operating.
- Multiple units of the same equipment type, such as multiple chillers and boilers, with combined capacities exceeding the design load, or a single unit that is capable of modulating to a part-load capacity of 50% of the load or less, may be specified to operate concurrently only if controls are provided that sequence or otherwise optimally control the operation of each unit based on load.
- Installed space heating equipment output that does not exceed 14 Btu/h per square foot of gross conditioned floor area and installed space cooling equipment output that does not exceed 23 Btu/h per square foot of gross conditioned floor area. No additional safety factor is allowed.
1432.1 Setback and Shut-Off: Systems that serve zones with different uses, as defined in Table 15-1,
- shall be served by separate systems, or
- shall include isolation devices and controls to shut-off or set back the supply of heating and cooling to each zone independently.
EXCEPTION: Isolation or separate systems are not required for zones expected to operate continuously or expected to be inoperative only when all other zones are inoperative.
1432.2 Systems Temperature Reset Controls
1432.2.1 Air Systems for Multiple Zones: Systems supplying heated or cooled air to multiple zones shall include controls which automatically reset supply air temperatures by representative building loads or by outside air temperature. Temperature shall be reset by at least 25% of the design supply-air-to-room-air temperature difference.
EXCEPTION: Where specified humidity levels are required to satisfy process needs, such as computer rooms or museums.
1432.2.2 Hydronic Systems: Systems with a design capacity of 300,000 Btu/h or greater supplying heated or mechanically refrigerated water shall include controls which automatically reset supply water temperatures by representative building loads (including return water temperature) or by outside air temperature. Temperature shall be reset by at least 25% of the design supply-to-return water temperature differences.
EXCEPTIONS: 1. Hydronic systems that use variable flow devices complying with Section 1438 to reduce pumping energy.
2. Steam boilers.
3. Systems that provide heating with 100ºF or lower supply temperature (e.g. water source heat pump loops).
To limit the heat loss from the heat rejection device (cooling tower), for hydronic heat pumps connected to a common heat pump water loop with central devices for heat rejection (e.g., cooling tower),
a. If a closed-circuit tower (fluid cooler) is used, either an automatic valve shall be installed to bypass all but a minimal flow of water around the tower (for freeze protection), or low leakage positive closure dampers shall be provided.
b. If an open-circuit tower is used directly in the heat pump loop, an automatic valve shall be installed to bypass all heat pump water flow around the tower.
c. If an open-circuit tower is used in conjunction with a separate heat exchanger to isolate the tower from the heat pump loop, then heat loss shall be controlled by shutting down the circulation pump on the cooling tower loop.
For hydronic heat pumps connected to a common heat pump water loop with central devices for heat rejection (e.g., cooling tower) and having a total pump system power exceeding 10 hp, each hydronic heat pump shall have:
a. A two-position two-way (but not three-way) valve, or
b. A variable head pressure two-way (water regulating) control valve or pump.
For the purposes of this section, pump system power is the sum of the nominal power demand (i.e., nameplate horsepower at nominal motor efficiency) of motors of all pumps that are required to operate at design conditions to supply fluid from the heating or cooling source to all heat transfer devices (e.g., coils, heat exchanger) and return it to the source. This converts the system into a variable flow system and, as such, the primary circulation pumps shall comply with the variable flow requirements in Section 1438.
1433 Economizers: Air Economizers meeting the requirements of Section 1413 shall be provided on all new systems, including those serving computer rooms, electronic equipment, radio equipment, telephone switchgear.
EXCEPTIONS:
- Qualifying small equipment: This exception shall not be used for unitary cooling equipment installed outdoors or in a mechanical room adjacent to the outdoors. This exception is allowed to be used for other cooling units and split systems with a total cooling capacity rated in accordance with 1411.2 of less than 33,000 Btu/h (hereafter referred to as qualifying small systems) provided that these are
Highhigh-efficiency coolingunitsequipment with SEER and EER values more than10%15% higher than minimum efficiencies listed in Tables 14-1A, 14-1B and 14-1D, in the appropriate size category, using the same test procedures. The total capacity of all systems qualifying small equipment without economizers shall not exceed480,00072,000 Btu/h per building, or20%5% of its air economizer capacity, whichever is greater. That portion of the equipment serving Group R Occupancy is not included in determining the total capacity of all units without economizers in a building. Redundant units are not counted in the capacity limitations. This exception shall not be used for RS-29 analysis ((nor include unitary cooling equipment installed outdoors nor in a mechanical room adjacent to outdoors)).
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Note: Exception 1 is only applicable to HVAC equipment that complies with Section 1411.1 and is regulated in Tables 14-1A, 14-1B and 14-1D. - Section 1411.1 requires that “If a nationally recognized certification program exists for a product covered in Tables 14-1A through 14-1G, and it includes provisions for verification and challenge of equipment efficiency ratings, then the product shall be listed in the certification program.” As the ARI program does satisfy those criteria, products subject to the ARI standards must be listed in the ARI Certification Program. - In Tables 14-1A, 14-1B, and 14-1D, virtually all of the equipment efficiency ratings are required to be determined in accordance with an ARI standard. Energy Code compliance is determined at standard conditions (not at project specific conditions). Compliance should be verifiable through the ARI directory at www.aridirectory.org. It is not acceptable for a manufacturer to submit their own calculations for ARI standards. - Consequently, to use Exception 1 to Section 1433, a product must both: be within the scope of the specified ARI standard and be included in the ARI certification program. Certain equipment used in computer server rooms is not within the scope of the standards listed in Tables 14-1A, 14-1B, and 14-1D and is not eligible for certification. Therefore, such equipment does not qualify to use Exception 1 to Section 1433 (though it may qualify to use another exception). |
- Chilled water terminal units connected to systems with chilled water generation equipment with
COP andIPLV or NPLV values more than 10% higher than minimum efficiencies listed in Table 14-1C, 14-1K, 14-1L or 14-1M, in the appropriate size category, using the same test procedures. The total capacity of all systems without economizers shall not exceed480,00072,000 Btu/h per building, or20%5% of its air economizer capacity, whichever is greater. That portion of the equipment serving Group R Occupancy is not included in determining the total capacity of all units without economizers in a building. This exception shall not be used for RS-29 analysis. Water-cooled refrigeration equipment provided with a water economizer meeting the requirements of Section 1413. Water economizer capacity per building shall not exceed 500 tons. This exception shall not be used for RS-29 analysis.Reserved- Systems for which at least 75% of the annual energy used for mechanical cooling is provided from site-recovery or site-solar energy source.
- Systems where special outside air filtration and treatment, for the reduction and treatment of unusual outdoor contaminants, makes an air economizer infeasible.
- Systems with dehumidification that affect other systems
(such as dehumidification and supermarket refrigeration systems)so as to increase the overall building energy consumption. New humidification equipment shall comply with Section 1413.4.
- Systems complying with all of the following criteria:
- Consist of multiple water source heat pumps with a total cooling capacity for each water-source heat pump of less than 54,000 Btu/h that are connected to a common water loop;
- Have a minimum of 60% air economizer complying with Section 1413 that is ducted in a fully enclosed path directly to every heat pump unit in each zone, except that ducts may terminate within 12 inches of the intake to an HVAC unit provided that they are physically fastened so that the outside air duct is directed into the unit intake;
- Have water source heat pumps with an EER at least 15% higher for cooling and, for units serving perimeter zones with heating loads (e.g. zones with exterior walls, roofs, or floors), a COP at least 15% higher for heating than that specified in Section 1411;
- Where provided with a dedicated boiler or furnace for that building, have a central boiler or furnace efficiency of:
-
- 90% minimum for units up to 199,000 Btu/h; and
- 85% minimum for units above 199,000 Btu/h input; and
- Provide heat recovery with a minimum 50% heat recovery effectiveness as defined in Section 1436 to preheat the outside air supply.
- For Group R Occupancy, cooling units installed outdoors or in a mechanical room adjacent to outdoors with a total cooling capacity less than 20,000 Btu/h and other cooling units with a total cooling capacity less than 54,000 Btu/h.
- Equipment used to cool any dedicated server room, electronic equipment room or telecom switch room provided that they completely comply with option a or option b or option c or option d in the table below. This exception shall not be used for RS 29 analysis.
| Equipment Type |
Higher Equipment Efficiency | Part-load Control | Economizer | |||
| Option a | Table 14-1A and Table 14-1B a |
+ 15% b | Required over 85,000 Btu/h c | None required | ||
| Option b | Table 14-1A and Table 14-1B a |
+ 5% d | Required over 85,000 Btu/h c | Waterside economizer e | ||
| Option c | Table 14-1K Table 14-1L and Table 14-1M f |
+ 5%/10% g | Required for all chillers h | Waterside economizer e | ||
| Option d | ASHRAE Standard 127 i |
+ 0% j | Required over 85,000 Btu/h c | Waterside economizer e | ||
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1434 Separate Air Distribution Systems: Zones with special process temperature requirements and/or humidity requirements shall be served by separate air distribution systems from those serving zones requiring only comfort conditions; or shall include supplementary control provisions so that the primary systems may be specifically controlled for comfort purposes only.
EXCEPTIONS: Zones requiring only comfort heating or comfort cooling that are served by a system primarily used for process temperature and humidity control provided that:
- The total supply air to those comfort zones is no more than 25% of the total system supply air, or
- The total conditioned floor area of the zones is less than 1,000 ft2.
1435 Simultaneous Heating and Cooling: Systems which provide heating and cooling simultaneously to a zone are prohibited. Zone thermostatic and humidistatic controls shall be capable of operating in sequence the supply of heating and cooling energy to the zone. Such controls shall prevent:
- Reheating for temperature control.
- Recooling for temperature control.
- Mixing or simultaneous supply of air that has been previously mechanically heated and air that has been previously cooled, either by economizer systems or by mechanical refrigeration.
- Other simultaneous operation of heating and cooling systems to the same zone.
- Reheating for humidity control.
EXCEPTIONS:
- Zones for which the volume of air that is reheated, recooled, or mixed is no greater than the larger of the following:
- The volume of air required to meet the ventilation requirements of the
Washington State Ventilation and Indoor Air Quality CodeSeattle Mechanical Code for the zone.- 0.4 cfm/ft2 of the zone conditioned floor area (before reheating), provided that the temperature of the primary system air is, by design or through reset controls, 0-12ºF below the design space heating temperature when outside air temperatures are below 60ºF for reheat systems and the cold deck of mixing systems and 0-12ºF above design space temperature when outside air temperatures are above 60ºF for recooling systems and the hot deck of mixing systems. For multiple zone systems, each zone need not comply with this exception provided the average of all zones served by the system that have both heating and cooling ability comply.
- 300cfm. This exception is for zones whose peak flow rate totals no more than 10% of the total fan system flow rate.
- Any higher rate that can be demonstrated, to the satisfaction of the building official, to reduce overall system annual energy usage by offsetting reheat/recool energy losses through a reduction in outdoor air intake in accordance with the multiple space requirements defined in ASHRAE Standard 62.
- Zones where special pressurization relationships, cross-contamination requirements, or code-required minimum circulation rates are such that variable air volume systems are impractical.
- Zones where at least 75% of the energy for reheating or for providing warm air in mixing systems is provided from a site-recovered (including condenser heat) or site- solar energy source.
- Zones where specific humidity levels are required to satisfy process needs, such as computer rooms, museums, surgical suites, and buildings with refrigeration systems, such as supermarkets, refrigerated warehouses and ice arenas.
1436.1 Fan Systems: Fan systems which have both
- have both (1) a capacity of 5,000 cfm or greater
andor serve a space with a design heating or cooling load exceeding 150 Btu/h-ft2 andwhich have(2) a minimum outside air supply of 70% or greater of the total air circulation, or - have both (1) a capacity of 10,000 cfm or greater and (2) a minimum outside air supply of 50% or greater of the total air circulation, or
- have both (1) a capacity of 20,000 cfm or greater and (2) a minimum outside air supply of 30% or greater of the total air circulation,
shall have a heat recovery system with at least 50% recovery effectiveness. Fifty percent heat recovery effectiveness shall mean an increase in the outside air supply temperature at design heating conditions of one half the difference between the outdoor design air temperature and 65ºF F (44.5°F in Seattle). Provision shall be made to bypass or control the heat recovery system to permit air economizer operation as required by Section 1433. Heat recovery energy may be provided from any site-recovered or site-solar source.
EXCEPTIONS: These exceptions only apply to the particular exhaust subsystems. The remaining cfm of the main supply system is subject to the heat recovery requirements.
- Laboratory systems equipped with both variable air volume supply and variable air volume or two-speed exhaust fume hoods, provided that an instruction label is placed on the face of the hood that matches Exhibit 14-1.
Exhibit 14-1
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INSTRUCTIONS TO OPERATOR |
- Systems serving spaces heated to less than 60ºF.
- Systems which can be shown to use as much energy with the addition of heat recovery equipment as without it.
- Systems exhausting toxic, flammable, paint exhaust or corrosive fumes making the installation of heat recovery equipment impractical.
- Type I commercial kitchen hoods.
1436.2 Condensate Systems: On-site steam heating systems shall have condensate water recovery. On-site includes a system that is located within or adjacent to one or more buildings within the boundary of a contiguous area or campus under one ownership and which serves one or more of those buildings.
Other buildings with steam heating systems which do not have condensate water recovery shall have condensate heat recovery.
1436.3 Heat Recovery for Service Water Heating: Condenser heat recovery systems shall be installed for heating or preheating of service hot water provided all of the following are true:
a. The facility operates 24 hours a day.
b. The total installed heat rejection capacity of the water-cooled systems exceeds 6,000,000 Btu/h of heat rejection.
c. The capacity of service water heating equipment exceeds 1,000,000 Btu/h.
The required heat recovery system shall have the capacity to provide the smaller of:
a. 60% of the peak heat rejection load at design conditions, or
b. preheat of the peak service hot water draw to 85ºF, or
c. 50% of the service water heating load.
EXCEPTIONS:
1. Facilities that employ condenser heat recovery for space heating with a heat recovery design exceeding 30% of the peak water-cooled condenser load at design conditions.
2. Facilities that provide 60% of their service water heating from site solar or site recovered energy or from other sources.
1437 Electric Motor Efficiency: Design A & B squirrel-cage, T-frame induction permanently wired polyphase motors of 1 hp or more having synchronous speeds of 3,600, 1,800 and 1,200 rpm shall have a nominal full-load motor efficiency no less than the corresponding values for energy efficient motors provided in Table 14-4.
EXCEPTIONS:
- Motors used in systems designed to use more than one speed of a multi-speed motor.
- Motors used as a component of the equipment meeting the minimum equipment efficiency requirements of Section 1411 and Tables 14-1A through 14-1G provided that the motor input is included when determining the equipment efficiency.
- Motors that are an integral part of specialized process equipment.
- Where the motor is integral to a listed piece of equipment for which no complying motor has been approved.
Fan motors less than 1 hp in series terminal units shall
a. be electronically-commutated motors, or
b. have a minimum motor efficiency of 65% when rated in accordance with NEMA Standard MG-1 at full load rating conditions.
1438
Variable Flow Systems and
System Criteria for All Fans and Pumps: For fans and pumps 7.5 hp and greater than 10 horsepower, where the application involves variable flow, and water source heat pump loops subject to the requirements of Section 1432.2.2, there shall be
- variable frequency drives or
- other controls and devices that will result in fan and pump motor demand of no more than 30% of design wattage at 50% of design air volume for fans when static pressure set point equals 1/3 the total design static pressure, and 50% of design water flow for pumps, based on manufacturer's certified test data. Variable inlet vanes, throttling valves (dampers), scroll dampers or bypass circuits shall not be allowed.
| At the time this code was adopted, very few technologies could be shown to meet the criteria in option b. |
EXCEPTIONS: Variable speed devices are not required for motors 7.5 hp and greater that serve:
- Fans or pumps in packaged equipment where variable speed devices are not available as a factory option from the equipment manufacturer.
- Fans or pumps that are required to operate only for emergency fire-life-safety events (e.g. stairwell pressurization fans, elevator pressurization fans, fire pumps, etc.).
Static pressure sensors used to control variable air volume fans shall be placed in a position such that the controller set point is no greater than 1/3 the total design fan static pressure.
For systems with direct digital control of individual zone boxes reporting to the central control panel, there shall be static pressure reset controls and the static pressure set point shall be reset based on the zone requiring the most pressure; i.e., the set point is reset lower until one zone damper is nearly wide open.
1438.1 Cooling Towers: All cooling towers with a total fan motor horsepower 7.5 hp and greater than 10 hp shall be equipped with variable speed drive or with a pony motor of a rated hp no greater than 1/3 of the hp of the primary motor. For pony motors, the cooling tower control shall provide two-stage operation of fans and shall bring on the pony motor to operate without the primary motor while meeting the condenser water setpoint.
1439.1 Kitchen Hoods. Individual kitchen exhaust hoods larger than 5000 cfm shall be provided with make-up air sized so that at least 50% of exhaust air volume be (a) unheated or heated to no more than 60ºF and (b) uncooled or cooled air without the use of mechanical cooling.
EXCEPTIONS: 1. Where hoods are used to exhaust ventilation air which would otherwise exfiltrate or be exhausted by other fan systems.
2. Certified grease extractor hoods that require a face velocity no greater than 60 fpm.
1439.2 Fume Hoods. Each fume hood in buildings with fume hood systems having a total exhaust rate greater than 15,000 cfm shall include at least one of the following features:
- Variable air volume hood exhaust and room supply systems capable of reducing exhaust and make-up air volume by 50% or less of design values.
- Direct make-up (auxiliary) air supply equal to at least 75% of the exhaust rate, heated no warmer than 2ºF below room set point, cooled to no cooler than 3ºF above room set point, no humidification added, and no simultaneous heating and cooling used for dehumidification control.
- Heat recovery systems to precondition make-up air in accordance with Section 1436, without using any exception.
- Constant volume fume hood designed and installed to operate at less than 50 fpm face velocity.
SECTION 1440 - SERVICE WATER HEATING: Service water heating equipment shall comply with the applicable efficiencies in Table 14-1A through 14-1M.
Effective January 1, 2004, commercial clothes washers installed in Seattle shall have a minimum modified energy factor (MEF) of 1.26. The MEF definition and test procedure set forth at 10 C.F.R. Part 430 (Energy Conservation Program for Consumer Products), as amended, is incorporated into this section by reference. Commercial clothes washers are defined as all clothes washers
a. installed for use on a fee basis, e.g. coin- or card-operated;
b. not covered by federal residential clothes washer efficiency standards; and
c. having a capacity of 20 lbs. or less.
1441 Water Heater Installation: Electric water heaters in unconditioned spaces or on concrete floors shall be placed on an incompressible, insulated surface with a minimum thermal resistance of R-10.
1442 Shut Off Controls: Systems designed to maintain usage temperatures in hot water pipes, such as circulating hot water systems or heat traced pipes shall be equipped with automatic time switches or other controls to turn off the system during periods of non-use.
1443 Pipe Insulation: Piping shall be thermally insulated in accordance with Section 1415.1.
1451 General: The requirements in this section apply to "general and limited use pools" as defined in the Washington Water Recreation Facilities Regulations (WAC 246-260).
1452 Pool Water Heaters:
Pool water heaters using electric resistance heating as the primary source of heat are prohibited for pools over 2,000 gallons. Heat pump pool heaters shall have a minimum COP of 4.0 determined in accordance with ASHRAE Standard 146, Method of Testing for Rating Pool Heaters. Other pool heating equipment shall comply with the applicable efficiencies in Tables 14-1A through 14-1G
14-1M.
1453 Controls: All pool heaters shall be equipped with a readily accessible ON/OFF switch to allow shutting off the operation of the heater without adjusting the thermostat setting. Controls shall be provided to allow the water temperature to be regulated from the maximum design temperature down to 65ºF.
1454 Pool Covers: Heated pools shall be equipped with a vapor retardant pool cover on or at the water surface. Pools heated to more than 90ºF shall have pool cover with a minimum insulation value of R-12, and the sides and bottom of the pool shall also have a minimum insulation value of R-12.
LINKS TO CHAPTER 14 TABLES
TABLE 14-1A - Unitary Air Conditioners and Condensing Units, Electrically Operated, Minimum Efficiency Requirements
TABLE 14-1B - Unitary and Applied Heat Pumps, Electrically Operated, Minimum Efficiency Requirements
TABLE 14-1C - Water Chilling Packages, Minimum Efficiency Requirements
TABLE 14-1D - Packaged Terminal Air Conditioners, Packaged Terminal Heat Pumps, Room Air Conditioners, and Room Air Conditioner Heat Pumps, Electrically Operated, Minimum Efficiency Requirements
TABLE 14-1E - Warm Air Furnaces and Combination Warm Air Furnaces/Air-Conditioning Units, Warm Air Duct Furnaces and Unit Heaters, Minimum Efficiency Requirements
TABLE 14-1F - Boilers, Gas- and Oil-Fired, Minimum Efficiency Requirements
TABLE 14-1G - Performance Requirements for Heat Rejection Equipment
TABLE 14-1H, 14-1I, and 14-1J - Reserved.
TABLE 14-1K - IPLV/NPLV for Water Cooled Chillers < 150 Tons
TABLE 14-1L - IPLV/NPLV for Water Cooled Chillers > 150 Tons, < 300 Tons
TABLE 14-1M - IPLV/NPLV for Water Cooled Chillers > 300 Tons
TABLE 14-2 - RESERVED
TABLE 14-3 - RESERVED
TABLE 14-4 - Energy Efficient Electric Motors Minimum Nominal Full-Load Efficiency
TABLE 14-5 - Duct Insulation
TABLE 14-6 - Minimum Pipe Insulation (inches)
