Should Unconditioned Makeup Air Be Insulated In An Unconditioned Plenum

2012 IECC Mechanical Requirements

Demonstrating Compliance

Indicate equipment efficiencies, arrangement controls, outdoor-air ventilation rates, duct insulation levels, duct sealing, and water-heating components that comply on your projection plans.

Complete and sign the Mechanical Compliance Document, generated using the View/Impress Report or Salvage Study option under the File menu.

Heating and Cooling Loads

Pattern heating and cooling loads for the building must be determined using procedures described in ASHRAE/ACCA Standard 183. Loads to account for edifice envelope, lighting, ventilation, and occupancy loads. Heating and cooling loads to be adjusted to account for load reductions achieved when energy recovery systems are used in accordance with ASHRAE HVAC Systems and Equipment Handbook. Approved equivalent ciphering procedures may also be used.

All equipment and systems must be sized to exist no greater than needed to encounter calculated loads. A unmarried piece of equipment providing both heating and cooling must satisfy this provision for one role with the capacity for the other function as pocket-size equally possible, within available equipment options.

EXCEPTIONS:

The equipment and/or system capacity may exist greater than calculated loads for standby purposes. Standby equipment must be controlled to be automatically off when the primary equipment and/or organization is operating.

Multiple units of the same equipment type whose combined capacities exceed the calculated load are allowed if they are provided with controls to sequence operation of each unit of measurement equally the load increases or decreases.

System Controls

Each heating or cooling arrangement serving a unmarried zone must have its own temperature control device.

Thermostats controlling both heating and cooling must either be a solid-state thermostat or capable of a 5 deg. F deadband, or range of temperature where no heating or cooling is available.

EXCEPTION:

Deadband capability is not required if the thermostat requires manual changeover between heating and cooling and does not take automatic changeover adequacy.

The system or zone control must be a programmable thermostat or other automatic command meeting the following criteria:

Capable of automatically setting back or shutting downwardly systems during unoccupied hours for seven different day schedules

Have an attainable 2-hr occupant override

Have a bombardment back-up capable of maintaining programmed settings for at least 10 hours if ability is lost.

Automated kickoff controls capable of automatically adjusting the daily starting time time must be provided for each HVAC system.

EXCEPTIONS:

A setback or shutoff control is non required on thermostats controlling systems serving areas that operate continuously.

A setback or shutoff command is not required on systems with a total energy need of 2kW (half dozen,826 Btu/h) or less.

Heat pumps with supplementary electric-resistance estrus shall have controls that, except during defrost, prevent supplemental heat functioning when the heat pump can encounter the heating load.

Each humidification system must have its own humidity control device.

Outdoor-Air Ventilation

The arrangement must supply outside ventilation air every bit required past Chapter iv of the International Mechanical Code. If the ventilation system is designed to supply outdoor air quantities exceeding minimum required levels, the system must be capable of reducing outdoor-air flow to the minimum required levels.

Outdoor-air supply systems with design air flow rates greater than 3,000 cubic feet per minute of outdoor air and all exhaust systems must accept dampers that automatically shut while the equipment is non operating.

Individual fan systems exceeding the values in Table C403.two.vi must accept an energy recovery system with at to the lowest degree a 50% recovery effectiveness.

EXCEPTIONS :

Where prohibited by the International Mechanical Code

Laboratory smoke hood systems that include at to the lowest degree one of these features:

VAV hood exhaust and room supply systems capable of reducing exhaust and makeup air volume to 50% or less of blueprint values

Direct makeup (auxiliary) air supply equal to at to the lowest degree 75% of the exhaust rate, heated no warmer than ii ° F below room set indicate, cooled to no cooler than 3 ° F higher up room set point, no humidification added, and no simultaneous heating and cooling used for dehumidification control

System serving spaces that are non cooled and heated to <60°F

Where > sixty% of the outdoor heating energy is provided from site-recovered or site solar energy

Heating energy recovery systems in Climate Zones 1 and 2

Cooling free energy systems in Climate Zones 3C, 4C, 5B, 5C, 6B, 7 and 8

Systems requiring dehumidification that employ serial-style energy recovery coils wrapped around the cooling scroll

Where largest source of wearied air at a single location at the building exterior is less than 75% of design outdoor air flow charge per unit

Systems expected to operate less than 20 hours per calendar week at the outdoor air per centum covered by Tabular array C403.2.half-dozen

If an air economizer is also required, heat recovery must be bypassed or controlled to permit air economizer operation.

Duct Construction and Insulation

Ductwork must be synthetic and erected in accordance with the International Mechanical Code.

Supply and return air ducts for conditioned air located in unconditioned spaces (spaces neither heated nor cooled) must exist insulated with a minimum of R-6. Unconditioned spaces include attics, crawl spaces, unheated basements and unheated garages.

Supply and return air ducts and plenums must be insulated to a minimum of R-8 when located outside the edifice envelope .

When ducts are located in outside components (eastward.g., floors or roofs), minimum R-eight insulation is required only between the duct and the building exterior.

All joints, longitudinal and transverse seams and connections in ductwork must be deeply sealed using weldments; mechanical fasteners with seals or gaskets or mastics; mesh and mastic sealing systems; or tapes. Tapes and mastics used to seal ductwork must be listed and labeled in accordance with UL 181A and marked "181A-P" for pressure-sensitive tape, "181A-M" for mastic or "181A-H" for estrus-sensitive tape. Tapes and mastics used to seal flexible air ducts and flexible air connectors must comply with UL 181B and be marked "181B-FX" for force per unit area-sensitive tape or "181B-M" for mastic. Unlisted duct tape is not permitted equally a sealant on any metal ducts. All ducts, air handlers and filter boxes must be sealed, and joints and seams must comply with Section 603.nine of the International Mechanical Code.

EXCEPTION:

Continuously welded and locking-type longitudinal joints and seams on ducts operating at static pressures less than 2 in. w.g. pressure level classification.

Ducts must be connected to fans and other air distribution equipment including multi-zone terminal units using mechanical fasteners with seals, mastics or gaskets.

Each supply air outlet or diffuser and each zone last device (such equally VAV or mixing boxes) must take its ain balancing device. Acceptable balancing devices include adjustable dampers located within the ductwork, terminal devices or supply air diffuser.

All ducts and plenums operating at static pressures greater than 2 in. w.g. must be sealed.

Ducts designed to operate at static pressures in excess of 3 in. w.k. must be insulated and sealed.

Pressure classifications specific to the duct organization must be clearly indicated on the construction documents in accordance with the International Mechanical Lawmaking.

Hydronic Controls

Multiple-packaged boilers on a common distribution system must have controls to sequence their operation.

Banality plants consisting of a unmarried banality over 500,000 Btu/h must include multistaged or modulating burners

3-pipage systems, having a common return for hot and chilled water, are prohibited.

Two-pipage systems must:

Be designed to allow a deadband between changeover from one mode to the other of at least xv deg. F exterior air temperature.

H ave controls to allow operation in one style for at least 4 hours earlier irresolute over to the other mode

H ave controls that allow heating and cooling supply temperatures at the changeover bespeak to be no more than 30 deg. F apart.

H2o loop oestrus pump systems must be designed to allow a water supply temperature expressionless ring of at least xx deg. F.

In Climate Zones 3-8 if a closed-circuit cooling belfry is used, an automated tower bypass valve or lower leakage positive closure dampers must exist provided.

If an open up-circuit cooling tower is used directly in the rut pump loop, an automated valve shall exist installed to bypass all heat pump water menstruation around the tower.

If an open-circuit cooling tower is used in conjunction with a separate heat exchanger to isolate the cooling belfry from the heat pump loop, then heat loss shall be controlled by shutting down the circulation pump on the cooling tower loop.

Each hydronic heat pump on the hydronic system having a total pump system power exceeding 10 hp must take a two-position valve.

EXCEPTION:

Where a system loop temperature optimization controller is installed and can determine the most efficient operating temperature based on real time conditions of demand and capacity, deadbands of less than 20 deg. F are permitted.

Hydronic systems 300,000 Btu/h or greater must be capable of automatically resetting the supply water temperature past at to the lowest degree 25% of the pattern supply-to-render h2o temperature divergence or reduce the pump flow rates to 50% or less of the design menstruation rate.

Pipe Insulation

All pipes serving infinite conditioning systems must be insulated to the following levels (a partial table is provided):

EXCEPTIONS:

Mill-installed piping inside room fan-coils and unit ventilators tested and rated per AHRI 440 (except sampling and variation provisions of Department 6.5 don't employ) and 840.

Piping that conveys fluids that have a design operating temperature range between lx deg. F and 105 deg. F.

Piping that conveys fluids that have not been heated or cooled through the use of fossil fuels or electric power.

Strainers, command values, and balancing valves associated with pipe one in. or less bore between the control valve and HVAC whorl.

Direct cached piping that conveys fluids at lx deg. F or less.

Materials and Equipment Information

The following documentation must be supplied to the building possessor within 90 days of the date of receipt of the certificate of occupancy

Drawings with location and operation data on each piece of equipment

Operations and maintenance manuals including

Information on equipment size and options for each piece of equipment requiring maintenance

Manufacturer'due south O&M manuals with required routine maintenance actions identified

Proper name and accost of at to the lowest degree one service agency

HVAC controls system maintenance and calibration information

Information on how each system is intended to operate, including recommended setpoints

Written written report describing organization balancing activities

Final commissioning report

Air Arrangement Blueprint and Command

Each HVAC arrangement with a full fan organisation motor nameplate hp > v must meet the following:

Each organization at fan organisation blueprint conditions to not exceed allowable fan system motor nameplate hp or fan system bhp, per Tabular array C402.2.10.i(one)

EXCEPTION : The following fan systems are exempt:

Private exhaust fans with motor nameplate hp of i hp or less

Hospital, vivarium and lab systems that apply flow control devices on frazzle and/or return to maintain infinite pressure relationships necessary for occupant health and safety or environmental control tin use variable book fan power limitation

Selected fan motor to exist no larger than starting time available motor size greater than bhp. Bhp to be noted on pattern documents.

EXCEPTIONS :

Fans < 6 bhp, where first available motor larger than bhp has nameplate rating within l% of bhp, next larger nameplate motor size may exist selected

Fans 6 bhp or greater, where first available motor larger than bhp has nameplate rating within 30% of bhp, next larger nameplate motor size may exist selected

Source: https://energycode.pnl.gov/COMcheckWeb/robohelp/2012_IECC_Mechanical_Requirements1.htm

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