HVAC System Design and Installation Procedures

8/18/2019 HVAC System Design and Installation Procedures

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Procedures For HVAC System Design and Installation

The goal for a Heating, Ventilation and Air Conditioning (HVAC) system is to provide proper air flow, heating,and cooling to each room. This page sets out key criteria that descrie a !uality system, and key design andinstallation considerations that should e met to achieve this goal. The pages following contain more detailed

information on design, farication, installation, and performance testing.

Criteria for a Quality HVAC System

An HVAC system should"

#. $e properly si%ed to provide correct air flow, and meet room&y&room calculated heating and coolingloads.

'. $e installed so that the static air pressure drop across the handler is within manufacturer and designspecifications to have the capacity to meet the calculated loads.

. Have sealed supply ductwork that will provide proper air flow.. $e installed with a return system si%ed to provide correct return air flow.*. Have sealed return ductwork that will provide proper air flow to the fan, and avoid air entering the

HVAC system from polluted %ones (e.g., fumes from autos and stored chemicals, and atticparticulates).+. Have alanced air flows etween supply and return systems to maintain neutral pressure in the home.. -inimi%e duct air temperature gain or loss etween the air handler and room registers, and etween

return registers and the air handler.. $e properly charged with refrigerant./. Have proper urner operation and proper draft.

Procedures to Design and Install an Air Distribution System

The following steps should e followed in the design and installation of the HVAC system to ensure efficiency

and comfort (for details, see Appendi0 #)"

#. 1etermine room&y&room loads and air&flows using ACCA -anual 2 calculation procedures (orsustantially e!uivalent).

'. 3ayout duct system on floor plan, accounting for the direction of 4oists, roof hips, fire&walls, and otherpotential ostructions. 1etermine register locations and types, duct lengths, and connections re!uiredto produce layout given construction constraints.

. 5i%e duct system according to ACCA -anual 1 calculation procedures (or sustantially e!uivalent).. 5i%e HVAC e!uipment to sensile load using ACCA -anual 5 procedures (or sustantially e!uivalent).*. 6nstall e!uipment and ducts according to design specifications, using installation re!uirements and

procedures from the 7niform -echanical Code, the Air 1iffusion Council, 5-AC8A, California9esidential :nergy :fficiency 5tandards, and manufacturers; specifications (Title ')< 7sing theseprocedures and those in Appendi0 A, the duct system should e sustantially air tight.

+. Charge the system appropriately, and verify charge with the evaporator superheat method or

sucooling method (or sustantially e!uivalent).. Check for proper furnace urner operation and fire&o0 drafting.. Test the system to ensure that it performs properly y determining (#) that the system is properly si%ed,

(') it does not leak sustantially, and has either (a) proper air handler fan flow, and proper plenumstatic pressures, or () proper room and return air flows, and proper plenum static pressures.(=rocedures are detailed in Appendi0 A.)


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APPENDIX A

Recommended Details for an HVAC System: Materials, Fabrication,

Design, Installation, and Performance Testing

MINIMUM MATERIALS SPECIFICATIONS

The following are minimum materials specifications recommended to achieve a sustantially tight installationthat will last"

All Materials

• 5hall have a minimum performance temperature ratings per 73## (ducts), 73##A (closure systems

for rigid ducts), 73##$ (closure systems for fle0ile ducts) and>or 73 ##$- (mastic)<

• 5hall have a flame spread rating of no more than '* and a ma0imum smoke developed rating of *?

(A5T- : )

Factory-Fabricated Duct Systems

• All factory&faricated duct systems shall include 73 ## listed ducts with approved closure systems

including collars, connections and splices<

• All pressure&sensitive and heat&activated tapes used in the manufacture of rigid fierglass ducts shall

e 73 ##A listed<

• All pressure&sensitive tapes and mastics used in the manufacture of fle0ile ducts shall e 73 ##$

(tape) or 73 ##$- (mastic) listed.

Field-Fabricated Duct Systems

•

1ucts"

o @actory&made ducts for field&faricated duct systems shall e 73 ## listed.

• -astic sealants and mesh"

o 5ealants shall e 73 ##$- listed, non&to0ic, and water resistant<

o 5ealants for interior applications shall pass A5T- tests C # (e0trudaility after aging) and 1

''?' (slump test on vertical surfaces)<o 5ealants and meshes shall e rated for e0terior use<

o 5ealants for e0terior applications shall pass A5T- tests C #, C ' (artificial weathering

test), and 1 ''?'.

• =ressure&sensitive tapes"

o =ressure sensitive tape shall e that recommended y and meet the re!uirements of the

fle0duct manufacturer<o

Tape used for duct oard shall e 73 ##A listed and so indicated with a 73 ##A mark oraluminum&acked utyl adhesive tape (#* mil. minimum).

• 1rawands"

o 5hall e either stainless&steel worm&drive hose clamps or uv&resistant nylon duct ties<

o 5hall have a minimum performance temperature rating of #+* degrees @ahrenheit

(continuous, per 73 ##A&type test) and a minimum tensile strength rating of *? pounds<o 5hall e tightened as recommended y the manufacturer with an ad4ustale tensioning tool.


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DESIGN, FABRICATION AND INSTALLATION

The following are design, farication and installation guidelines, that, if carefully followed, will provide a ductinstallation that is sustantially airtight"

General Issues

• 1ucts, plenums, and fittings should e constructed of galvani%ed metal, duct oard, or fle0ile duct.

$uilding cavities may not e used as a duct or plenum without a sealed duct oard or metal liner.

• The air handler o0 should e air&tight<

• Air filters should e easily accessile for replacement, and evaporator coils should e easily accessile

for cleaning<

• 1ucts should e configured and supported so as to prevent use of e0cess material, prevent dislocation

or damage, and prevent constriction of ducts elow their rated diameter<

• @le0ile duct ends should not e made across sharp corners or have incidental contact with metal

fi0tures, pipes, or conduits that can compress or damage the ductwork<

• 5heet metal collars and sleeves should e eaded to hold drawands.

DESIGN HVAC SYSTEMLoads and CFM Calculation

• ACCA -anual 2 3oad Calculation or e!uivalent re!uired<

• Calculate heat loss and heat gain for each room<

• Total room loads to determine system re!uirements.

Lay Out Air Distribution System

• 3ay out duct system on floor plan and determine register positions and duct paths to optimi%e room air

circulation and minimi%e duct length<

• 1uct paths must account for locations and directions of 4oists, roof hips, fire walls, and other potential

ostructions<

• 1uct paths must e planned to avoid sharp turns of fle0duct that will kink the duct.

Size Air Distribution System

• ACCA -anual 1 1uct 1esign or e!uivalent re!uired<

• Calculate correct cfm for each room and total for uilding for oth supply and return<

• 5i%e ducts according to -anual 2 loads, -anual 1 air flows, and final layout on plans<

• Choose registers to optimi%e air distriution and duct static pressure<

• 5i%e and locate returns to optimi%e air flow per -anual 1<

• @or return&filter grills, calculate minimum return filter area per -anual 1.

Select System


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• ACCA -anual 5 9esidential :!uipment 5election or e!uivalent re!uired. ACCA, #*#* #+th 5t., 8,

ashington, 1C '??+, ('?')&/?<

• @rom -anual 2 loads and -anual 1 cfm, determine appropriate e!uipment

• :!uipment should e si%ed to sensile loads<

• :!uipment sensile capacity should not e more than #*B larger than the total sensile design load

(as specified in -anual 5).

FABRICATE AND INSTALL AN AIRTIGHT DUCT SYSTEMAll Duct Types

• All 4oints and seams of duct systems and their components should e sealed with mastic, mastic and

emedded mesh, or pressure&sensitive tape approved for use y the duct manufacturer and meeting73## specifications (approved tape)< this includes around 4unctions of collars to distriution o0es andplenums<

• All sealants should e used in strict accordance with manufacturer;s installation instructions and withinsealants moisture and temperature limitations<

• All tapes used as part of duct system installation should e applied to clean, dry surfaces and sealed

with manufacturer;s recommended amount of pressure or heat. 6f oil is present, taped surfaces should eprepared with a cleaner > degreaser prior to application<

• 6t is recommended that all register o0es should e sealed to the drywall or floor with caulking or

mastic.

Flexible Ducts

• @le0ile ducts should e 4oined y a metal sleeve, collar, coupling, or coupling system. At least '

inches of the eaded sleeve, collar, or coupling must e0tend into the inner core while allowing a # inchattachment area on the sleeve, collar, or coupling for the application of tape<

• The inner core should e mechanically fastened to all fittings, preferaly using drawands installed

directly over the inner core and eaded fitting. 6f eaded sleeves and collars are not used, then the innercore should e fastened to the fitting using D screws e!ually spaced around the diameter of the duct, andinstalled to capture the wire coil of the inner liner ( screws for ducts up to #' diameter, and * screws forducts over #' diameter)<

• The inner core should e sealed to the fitting with mastic or approved tape<

• Tape used for sealing the inner core should e applied with at least # inch of tape on the duct lining, #

inch of tape on the fitting of flange, and wrapped at least three times<

• The outer sleeve (vapor arrier) should e sealed at connections with a drawand and>or three wraps

of approved tape<

• The vapor arrier should e complete. All holes, rips, and seams must e sealed with mastic or

approved tape.

Metal Ducts and lenums

• -etal&to&metal connections should e cleaned and sealed in accordance with manufacturer;s

specifications<

• Epenings greater than #>#+ inch should e sealed with mastic and mesh, or utyl adhesive tape<

• Epenings less than #>#+ inch should e sealed with mastic or 73#A listed tape


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• 5pecial attention should e paid to collar connections to duct&oard and>or sheet metal< seal around

the connection with mastic<

• Connections etween collars and distriution o0es should e sealed with mastic or approved tape<

• At least three e!ually&spaced D screws should e used to mechanically fasten round ducts ( screws

for ducts up to #' diameter, and * screws for ducts over #' diameter)<

• Crimp 4oints should have a contact lap of at least #>' inches<

• 5!uare or rectangular ducts should e mechanically fastened with at least one screw per side.

Duct !oard

• 1uct oard connections should e sealed with adhesive, mastic, or 73 ##A listed pressure&sensitive

or heat&activated tape in accordance with manufacturer;s specifications.

Duct Support

• 5upports should e installed per manufacturer;s specifications or per 7-C re!uirements<

• 5upports for fle0ile ducts should e spaced at no more than foot intervals<

• @le0ile ducts should e supported y strapping having a minimum width of #>' inches at all contactpoints with the duct<

• 5upports should not constrict the inner liner of the duct<

• @le0ile ducts should have ma0imum of #>' inch sag per foot etween supports<

• @le0ile ducts may rest on ceiling 4oists or truss supports as long as they lie flat and are supported at

no more that foot intervals.

!oots

• After mechanically attaching the register oot to floor, wall, or ceiling, all openings etween the oot

and floor, wall, or ceiling should e sealed with caulk or mastic.

Seal Air "andler

• Epenings greater than #>#+ inch should e sealed with mastic and mesh, or utyl adhesive tape<

• Epenings less than #>#+ inch should e sealed with mastic or 73 ##A listed tape<

• 7nsealed access doors should e sealed with 73 ##A listed tape.

CHECK REFRIGERANT CHARGE

• @or systems with fi0ed metering devices use evaporator superheat method"

o 6ndoor coil airflow must e greater than *? cfm>ton<

o 9efrigerant system evacuation must e complete (all non&condensales must e removed

from the system<o 6n hot, dry climates e cautious to e within range of superheat charging chart or use a

different method.

• @or systems with thermostatic e0pansion valves use the sucooling method.


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CHECK COMBUSTION PERFORMANCE

• Check each chamer for correct flame<

• Check for proper drafting.

TEST SYSTEM PERFORMANCET#e $ollo%in& are testin& re'uirements and procedures t#at must be $ollo%ed to ensure t#at t#e "(ACsystem #as been properly installed) T#e tests are desi&ned to determine %#et#er*

#. +oom-by-room air $lo%s are correct,'. Total supply is as desi&ned,. Total return total supply,. Ducts. plenum. and air #andler are tit,*. Static pressure is correct)

• Test the system to ensure that it performs properly, y (#) verifying HVAC e!uipment si%es installed are

those specified, (') measuring duct leakage, and measuring either () fan flow or () supply and returnflows and plenum static pressures"

#. Air conditioner sensile capacity must e no more than #*B greater than the calculatedsensile load< fan flow must e greater than *? cfm>ton< check that the correct si%e air handler isinstalled.

'. :nsure that the duct system does not leak sustantially"

#. A rough system, including oth supply and return ut without the air handler, should notleak more than ?.?Fconditioned floor area (ft') per system measured in cfm G *? =a<

'. The finished installation, including supply, return, the air handler and finished registers,must not leak more than ?.?Fconditioned floor area (ft') per system measured in cfm G*? =a<

'. -easure air handler air flow and static pressure across fan< ensure that total air handler

output is within *B of design and manufacturer specifications at a static pressure within ?.# in wgof design.

. 5upply and return air flow, and static pressure re!uirements" :nsure that supply and returnflows are correct, and that the static pressure across the fan is correct"

#. -easure room&y&room air flows to ensure that each register is within #*B of -anual 1design air flow, and that the entire supply is within *B of design<

'. -easure return air flow to ensure that it is within *B of the total supply air flow<. Test static pressure drop across the lower to ensure that it is within ?.# in wg of design

and manufacturer specifications.

• 1uct leakage can e determined using a pressuri%ation or depressuri%ation techni!ue< for details, see

-inneapolis 1uct $laster manual, or other commercially availale duct pressuri%ation or depressuri%ationdevices<

• 1uct leakage to unconditioned space can e determined with the house pressuri%ation or 3$3

simplified techni!ue< for details see California :nergy Commission report =??&/#&?#C8, 5ection 5i0<

• @an flow, supply flow and return flow measurements, see -inneapolis 1uct $laster T- manual (or

e!uivalent)< alternatively for supply and return flows, use a calirated flow hood. 1o not use a pitot tue, orany type of anemometer to determine these air flows<

• 5tatic pressure drop across the fan is measured using a small proe in the return plenum and in the

supply plenum.


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APPENDIX B

=9E$3:-5 6TH ACC:=T:1 =9ACT6C: 56I68J -:THE15

9elationship $etween 1uct 5ystem =erformance, ACCA 1esign =rocedures, and 6nstalled&5ystem Kuality

Background

The Air Conditioning Contractors of America (ACCA) association pulishes four manuals related to residentialheating and air conditioning that address many of the issues associated with residential duct systems. ACCA-anual 2 (3oad Calculation for 9esidential inter and 5ummer Air Conditioning, Copyright #/+) is theindustry&standard design&load calculation procedure for residences. ACCA -anual 5 (9esidential :!uipment5election, '>/') provides procedures for choosing residential heating and cooling e!uipment ased on theloads calculated with -anual 2. ACCA -anual 1 (9esidential 1uct 5ystems, Copyright #//*, 'nd =rinting)

provides design procedures for residential duct systems, focusing on how to produce the desired air delivery ateach register, as well as discussions of the magnitudes and impacts of duct&system inefficiencies. ACCA-anual T (Air 1istriution $asics for 9esidential and 5mall Commercial $uildings, 7=$*/'?-) addressesroom air motion issues, focusing on the impacts of register>grille location and diffuser performance.

Treatment of Duct Performance in ACCA Manual J

ACCA -anual 2 addresses residential duct system performance in three ways" #) it provides room&y&roomloads, which are intended to e used to calculate the energy that needs to e transported y the ducts to eachroom, ') it provides a tale of duct&loss multipliers that are used to calculate the e0tra design load associatedwith conduction losses from the ducts, and ) it provides a tale of recommended levels of duct insulation, and

states that All ducts should have their seams sealed with tape.

6n calculating the energy load impacts of ducts and room&y&room loads, -anual 2 makes two fundamentalassumptions" #) that there is no duct leakage, and ') that the load due duct conduction is independent of thelength and design of the ducts. The implication of the first assumption is that the actual load associated withduct losses is in general significantly higher than that assumed in -anual 2. The second assumption impliesthat even if the average conduction losses in the duct&loss multipliers are correct, the calculated room&y&roomloads are incorrect due to non&uniform conduction losses.

A significant ody of research performed over the past five years in California and other states that installductwork in attics and crawlspaces demonstrates that duct leakage increases space&conditioning energy usey #*&'?B on average, even in new construction. This loss needs either to e eliminated, or to e added to thelosses associated with conduction gains to otain correct loads seen y the e!uipment. @ield research has alsodemonstrated the effective increase in heating and cooling system capacity associated with improving duct

performance (-odera and 2ump, #//*). Those studies show reduced fractional on&times and increased cyclingunder the same weather conditions after duct retrofit.

A logical !uestion that arises with respect to these duct leakage losses is why -anual 2 is not resulting insignificantly undersi%ed systems ecause of the fact that it does not include these duct leakage losses. Thereasons for why this is not the case seem to stem principally from the application of -anual 2, rather than themanual itself. 6n general, -anual 2 leaves !uite a it to the discretion of the user, leaving numerousopportunities for increasing the si%e of the unit. 5ome of the common points at which safety margins seem tocreep in are"


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• The use of the worst house orientation for load calculations,

• The choice of the ne0t si%e up in the piece of heating>cooling e!uipment,

• The assumption of *?B 9H indoor conditions in most manufacturer;s capacity data, which is higher

than what is found in much of California, and which results in a lower estimated sensile capacity for apiece of e!uipment as compared to the sensile capacity the e!uipment would have at a lower indoor

humidity level,• 7sing a somewhat lower indoor design temperature,

• 7sing a higher outdoor design condition, such as #B, or utility&peak outdoor design temperature rather

than the '.*B values recommended in -anual 2.

• 7sing the ne0t&highest outdoor&temperature rating point, rather than interpolating manufacturer;s

capacity data.

• The recommendation of ?*B oversi%ing of sensile capacity in -anual 5.

To e fair, it should also e noted that there are some factors that tend to decrease the si%e of the e!uipmentchosen with the ACCA procedures, including"

•

A96 capacities are normally !uoted at ?o

@, whereas -anual 2 re!uires capacities at *o

@, which wille smaller.

6t is very difficult to !uantify e0actly how much the aove trends influence e!uipment si%ing. A contractor surveyperformed in @lorida indicated that there is a large variaility in the e!uipment&si%ing practices used ycontractors (Home :nergy #//*). 6t is safe to say that there are numerous opportunities for a contractor toincrease e!uipment si%e within the ACCA procedures so as to maintain the si%ing with which they arecomfortale. A related study of e!uipment si%ing and ACCA manuals is pulished in Home :nergy maga%ine(=roctor et al. #//*).

The assumption of constant duct&loss multipliers for all duct sections (or in other words, that duct loads scalewith room load, and not with duct design or length) is more of a design&flaw and comfort prolem, rather than

an energy&use or e!uipment&si%ing prolem. 8amely, after calculating room&y&room loads including constantduct&loss multipliers, the air flow re!uired for each room is calculated from the loads, the duct system is laidout, and the cross&sectional area of the ductwork is calculated and checked with -anual 1 ased upon theaility of the system to supply the re!uired air flow. This implies that the percentage energy loss from thelongest duct run is the same as that from the shortest run. 6t seems clear that this is not a realistic assumption,however the magnitude of the resulting disparity, ased upon field measurements, is striking. 8amely, theedroom closest to the furnace for an 9& duct system in a 5acramento attic was measured to have #'B of theduct energy lost y conduction on the way to the register. The e!uivalent losses for the master edroom at theend of the duct run were more than ?B (-odera and 2ump, #//*). The #'B loss is line with the losses thatare calculated from the -anual 2 duct loss multipliers, and the ?B loss clearly indicates that the masteredroom duct is most likely undersi%ed. 5ure enough, the homeowner commented on the improvement inmaster&edroom conditions after the retrofit. The end result of this disparity is that the entire duct&designprocess is skewed so as to provide far less than optimal distriution of heating and cooling.

There is another assumption within -anual 2 that is likely to result in inaccurate estimates of room&y&roomloads. 8amely, it is assumed that the infiltration load is split etween rooms ased on the estimated relativee0ternal leakage area of that room. The prolem with this assumption is that it ignores the fact that a significantfraction of residential air infiltration is driven y the stack effect. The implication of ignoring the stack effect intwo&story houses is that in general the upstairs flows will e oversi%ed for heating, resulting in unnecessarystratification and discomfort in the winter. This upstairs&duct oversi%ing should actually help reduce stratificationin the summer.


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6n addition, it is also worth noting that the duct loss multipliers for an attic and a crawlspace are the same,which is clearly inconsistent with intuition and field e0periments. The result is that cooling e!uipment with atticductwork is likely to e relatively undersi%ed as compared to cooling e!uipment with crawlspace ductwork.

Treatment of Duct Performance in ACCA Manual D

As noted aove, the principal function of -anual 1 is to assure that a given duct layout delivers the appropriateair flows to each room, ased upon the room&y&room loads calculated with -anual 2. Thus, if the total loadseen y the duct run to a given room is not correct, the si%e of the ductwork leading to that %one will not ecorrect, resulting in poorly designed system (i.e., one that does not provide uniform heating or cooling, andwhich is difficult or impossile to alance).

There is however a disconnect within -anual 1. 8amely, -anual 1 contains an entire, fairly complete sectionon duct&system energy efficiency, however this section is not connected to the load calculation proceduresused to si%e the e!uipment and ductwork.

Treatment of Duct Performance in ACCA Manual T

As noted aove, -anual T focuses on the room&air motion aspects of air distriution systems. The way that thisrelates to duct performance and !uality HVAC installations is through the performance of the diffusers. 6nparticular, if a diffuser is designed to provide a given throw at a specific air flow rate, that throw will e reduced(potentially significantly) y supply&duct leakage or y flow restrictions within the ductwork (e.g., fle0duct that isnot fully e0tended, that is ent at hangers, or that is ent at too sharp of a radius).

Recommended Strategy for California

$ased upon the discussion aove, a two&phase strategy for improving the !uality of HVAC installations isrecommended. The first phase of the strategy simply addresses the issue of duct leakage, focusing on theinteraction etween duct leakage and e!uipment si%ing with -anual 2 and -anual 5. The second phaseaddresses the !uality of the design, focusing on a methodology for accurately laying out and si%ing ductwork soas to provide etter occupant comfort.

The essence of the =hase&6 strategy is to develop a modification to -anual 2 duct loss>gain multipliers thattakes into account duct leakage losses, and to comine this with an appropriate training course designed tohelp contractors take some of the oversi%ing trends out of their -anual&2 calculations.

The essence of the =hase&66 strategy is to address the duct&design prolems in the comination of -anual 2and -anual 1. This can e accomplished y inserting an overall duct&loss calculation procedure for eachregister in the house into the process. This may re!uire some iteration etween the duct&si%ing procedure andthe duct&loss calculation procedure, however one or two iterations will most likely e ade!uate, and the final

design will not only provide etter comfort, ut should ultimately result in etter energy efficiency. This overallduct&loss calculation procedure should most&likely e ased on the simplified procedure developed y =almiter(#//*) that is likely to e adopted into the proposed A5H9A: 5tandard #*'=. This procedure should e usedseparately for heating and cooling operation.


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HVAC SYSTEMS

Heating, Ventilation and Air-Conditioning(HVAC) Systems

Indoor Air Quality Design Tools for Schools

• Preliminary Design Phases

• Controlling Pollutants and Sources

• Heating, Ventilation, and Air-Conditioning (HVAC)

•

Moisture Control• Construction

• Commissioning

• Renovation and Reair

• !erations and Maintenance

• Porta"le Classrooms

#he main uroses o$ a Heating, Ventilation, and Air-Conditioning (HVAC) system are to helmaintain good indoor air %uality through ade%uate ventilation &ith $iltration and rovide thermalcom$ort' HVAC systems are among the largest energy consumers in schools' #he choice and

http://www.epa.gov/iaq/schooldesign/predesign.htmlhttp://www.epa.gov/iaq/schooldesign/controlling.htmlhttp://www.epa.gov/iaq/schooldesign/hvac.htmlhttp://www.epa.gov/iaq/schooldesign/moisturecontrol.htmlhttp://www.epa.gov/iaq/schooldesign/construction.htmlhttp://www.epa.gov/iaq/schooldesign/commissioning.htmlhttp://www.epa.gov/iaq/schooldesign/renovation.htmlhttp://www.epa.gov/iaq/schooldesign/o&m.htmlhttp://www.epa.gov/iaq/schooldesign/portables.htmlhttp://www.epa.gov/iaq/schooldesign/predesign.htmlhttp://www.epa.gov/iaq/schooldesign/controlling.htmlhttp://www.epa.gov/iaq/schooldesign/hvac.htmlhttp://www.epa.gov/iaq/schooldesign/moisturecontrol.htmlhttp://www.epa.gov/iaq/schooldesign/construction.htmlhttp://www.epa.gov/iaq/schooldesign/commissioning.htmlhttp://www.epa.gov/iaq/schooldesign/renovation.htmlhttp://www.epa.gov/iaq/schooldesign/o&m.htmlhttp://www.epa.gov/iaq/schooldesign/portables.html


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design o$ the HVAC system can also a$$ect many other high er$ormance goals, including &aterconsumtion (&ater cooled air conditioning e%uiment) and acoustics (See Acoustics)'

#he $ollo&ing actions detail ho& engineers can design a %uality system that is cost-cometitive&ith traditional ventilation designs, &hile success$ully roviding an aroriate %uantity and%uality o$ outdoor air, lo&er energy costs, and easier maintenance'

Contents

• Codes and Standards

• Potential $or atural Ventilation and !era"le indo&s

• Selection o$ HVAC *%uiment

o *nergy Recovery Ventilation

• +ocation o$ !utdoor Air ntaes and *.haust

• !utdoor Air /uantity

• Air 0iltration

o 0ilter *$$iciencyo Pressure Dro

o Monitoring Pressure

o Air Cleaning $or 1aseous Contaminants

• Ventilation Controls

o Volume Monitoring and Control

• Moisture and Humidity Control

• Air Distri"ution

o #yes o$ Air Distri"ution

• *.haust Air

• Designing $or *$$icient !erations and Maintenance

• Commissioning

• Re$erences and Resources

Codes and Standards

#he national consensus standard $or outside air ventilation is ASHRA* Standard 23'4-355,Ventilation $or Acceta"le ndoor Air /uality (availa"le online via &&&'ashrae'org

) and its u"lished Addenda' #his standard is o$ten incororated into state and

local "uilding codes, and seci$ies the amounts o$ outside air that must "e rovided "y natural ormechanical ventilation systems to various areas o$ the school, including classrooms,gymnasiums, itchens and other secial use areas'

Many state codes also specify minimum energy efficiency requirements, ventilation controls, pipeand duct insulation and sealing, and system sizing, among other factors. In addition, some states

and localities have established ventilation and/or other indoor air quality related requirements

that must also be followed.

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• Design in accordance with ASHRAE standards Design systems to rovide outdoor air

ventilation in accord &ith ASHRA* Standard 23'4-3556 (availa"le at &&&'ashrae'org) and thermal com$ort in accord &ith ASHRA* Standard 7784993 (&ith

4997 Addenda) #hermal *nvironmental Conditions $or Human !ccuancy

•

Ensure familiarity with, and adherence to, all state and local building codes andstandards

#o o$ age

!otential for "atural #entilation and $%erable &indows

n some arts o$ the country, &here temerature and humidity levels ermit, natural ventilationthrough oera"le &indo&s can "e an e$$ective and energy-e$$icient &ay to sulement HVACsystems to rovide outside air ventilation, cooling, and thermal com$ort &hen conditions ermit(e'g', temerature, humidity, outdoor air ollution levels, reciitation)' indo&s that oen andclose can enhance occuants: sense o$ &ell-"eing and $eeling o$ control over their environment'#hey can also rovide sulemental e.haust ventilation during renovation activities that mayintroduce ollutants into the sace'

Ho&ever, sealed "uildings &ith aroriately designed and oerated HVAC systems can o$ten rovide "etter indoor air %uality than a "uilding &ith oera"le &indo&s' ;ncontrolled ventilation&ith outdoor air can allo& outdoor air contaminants to "yass $ilters, otentially disrut the "alance o$ the mechanical ventilation e%uiment, and ermit the introduction o$ e.cess moisturei$ access is not controlled'

Strategies using natural ventilation include &ind driven cross-ventilation and stac ventilationthat emloys the di$$erence in air densities to rovide air movement across a sace'


13/24

n most arts o$ the country, climatic conditions re%uire that outdoor air must "e heated andcooled to rovide acceta"le thermal com$ort $or "uilding occuants, re%uiring the addition o$HVAC systems' #he selection o$ e%uiment $or heating, cooling and ventilating the school "uilding is a comle. design decision that must "alance a great many $actors, including heatingand cooling needs, energy e$$iciency, humidity control, otential $or natural ventilation,

adherence to codes and standards, outdoor air %uantity and %uality, indoor air %uality, and cost'

• &here feasible, use central H#AC air handling units *AH+s that ser'e multi%le

rooms in lieu of unit 'entilators or indi'idual heat %um%s

Although there are many di$$erent tyes o$ air handling units, $or general A/imlications in schools, air handling units can "e divided into t&o grous unit ventilatorsand individual heat um units that serve a single room &ithout ducts? and central airhandling units that serve several rooms via duct &or' ;nit ventilators and heat umshave the advantage o$ reduced $loor sace re%uirements, and they do not recirculate air "et&een rooms' Ho&ever, it is more di$$icult to assure roer maintenance o$ multile

units over time, and they resent additional oortunities $or moisture ro"lems throughthe &all enetration and $rom drain an and discharge ro"lems' Central air handlingunits have a num"er o$ advantages as comared to unit ventilators and heat umsserving individual rooms' #hey are

o /uieter, and there$ore more liely to "e turned on or le$t on "y teachers and sta$$?

o +ess dra$ty due to multile sulies and a return that is a&ay $rom occuants?

o


14/24

Double-slo%ed drain %an and drain tra% de%th

o Dou"le-sloed drain an - A dou"le-sloed an revents &ater $rom standing and

stagnating in the an'o on-corroding drain an - Made $rom stainless steel or lastic' Prevents corrosion

that &ould cause &ater to lea inside the AH;'o *asy access doors - All access doors are hinged and use %uic release latches that

do not re%uire tools to oen' *asy access to $ilters, drain ans, and cooling coils isimerative'

o Dou"le &all ca"inet - #he inner &all rotects the insulation $rom moisture and

mechanical damage, increases sound damening, and is easier to clean'o #ightly sealed ca"inet - Small yet continuous air leas in and out o$ the AH;

ca"inet can a$$ect A/ and energy' #he greatest ressure di$$erentials drivingleas occur at the AH;'

o Dou"le &all doors &ith gasets - Dou"le &all doors rovide "etter thermal and

acoustic insulation, and &ill remain $latter, allo&ing a "etter seal against door

$rame gasetso Minimum 3 inch thic $ilter slots - 0or "etter rotection o$ the indoor

environment, as &ell as the e%uiment and ducts, the $ilters slots should "e a"le toaccommodate 3 in' or thicer $ilters'

o *.tended sur$ace area $ilter "an - #o reduce the $re%uency o$ $ilter maintenance

and the cost o$ $an energy, the "an is designed to allo& more $ilter area, such asthe dee V aroach or "ags'

o Air $ilter assem"lies (racs B housings) designed $or minimum leaage - #he

$ilter "an should have gasets and sealants at all oints &here air could easily "yass the air $ilters, such as "et&een the $ilter rac and the access door' ;se roerly gaseted manu$acturer sulied $ilter rac sacers'

o Air $ilter monitor - A di$$erential ressure gauge to indicate the static ressuredro across the $ilter "an' #his $eature could easily "e installed as an otion inthe $ield'

o Corrosion resistant damers B lins - All mo'ing %arts such as %i'ot %ins,

dam%er actuators, and lin.ages are able to withstand weather and moisture-

induced corrosion for the full life of the system

Energy Reco'ery #entilation

Consider s%ecifying energy reco'ery 'entilation e)ui%ment

ndoor air can "e 3 to 7 times more olluted than outdoor air? there$ore, most HVAC systemdesigners understand that increased amounts o$ outdoor air suly is generally "etter $or A/'et there are concerns over the imlications that this added amount o$ outdoor air suly has onthe $irst cost and oerating cost o$ the HVAC system, as &ell as moisture control $or the school(too &et or too dry)' As a result, school designers o$ten try to reduce the amount o$ outdoor aire%ual to 8 or even "elo& -- 47 cu"ic $eet er minute (c$m) o$ outside air er erson, theminimum $or school classrooms, as esta"lished "y the American Society o$ Heating,Re$rigerating and Air -conditioning *ngineers (ASHRA*) &&&'ashrae'org ' n

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15/24

many arts o$ the country these concerns can easily "e addressed "y alication o$ "asicengineering rinciles and o$$-the-shel$ HVAC e%uiment'

0irst cost, energy costs, and moisture control do not have to "e at odds &ith good A/' *nergyrecovery ventilation e%uiment can mae the negative imlications o$ 47 c$m er erson o$outdoor air "ehave lie 7 c$m, &hile retaining the A/ advantage o$ 47 c$m' #his aroach has "een roven in many schools in various regions east o$ the Rocies, &here advanced HVACsystems cost roughly the same as conventional systems, yet rovide signi$icant oerating costsavings and A/ advantages'

*PA has develoed the School Advanced Ventilation *ngineering So$t&are (SAV*S) acage asa tool to hel school designers assess the otential $inancial ay"ac and indoor humidity control "ene$its o$ *nergy Recovery Ventilation (*RV) systems' See also

• !vervie& o$ *RV Systems

• 0inancial Asects o$ *RV Systems

#o o$ age

/ocation of $utdoor Air Inta.es and E0haust

Slo%ed Inta.e !lenum and Accessible Inta.e Screen

• !ro%er location of outdoor air inta.es can minimi1e the bloc.age of airflow and

inta.e of contaminated air

#he "ottom o$ air intaes should "e at least inches a"ove hori=ontal sur$aces (generallythe ground or the roo$) to revent "locage $rom leaves or sno&' n northern locations,

more searation may "e needed due to greater sno& deths or dri$ting sno&'

• Inta.es should not be %laced within 23 feet of any %otential sources of air

contaminants, including sewer 'ents, e0haust air from the school, loading doc.s, bus

loading areas, garbage rece%tacles, boiler or generator e0hausts, and mist from

cooling towers

$ the source is large or contains strong contaminants, or i$ there is a dominant &ind

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direction in the area, the minimum searation distance may need to "e increased' Airadmittance valves, an ine.ensive and code-aroved one-&ay air valve, can "e added tose&er vents to eliminate the otential $or release o$ gases into the surrounding air'

• 4rilles %rotecting air inta.es should be bird- and rodent-%roofed to %re'ent

%erching, roosting, and nesting

aste $rom "irds and other ests (e'g', rats) can disrut roer oeration o$ the HVACsystem, romote micro"ial gro&th and cause human disease' #he use o$ outdoor airintae grilles &ith vertical louvers, as oosed to hori=ontal louvers, &ill reduce the otential $or roosting'

• Inta.e Screens must be accessible for ins%ection and cleaning

n e.isting schools, an insu$$icient amount o$ ventilation air is o$ten the result o$ cloggedintae screens that are inaccessi"le $or insection and cleaning' Screens hidden "y anintae grille should "e designed &ith a grille that is easily oened, such as a hinged grille&ith t&o %uic-release latches, or in the &orst case, a grille &ith $our one-%uarter turn

$asteners' All screens should "e easily remova"le $or cleaning'• Consider adding a section of slo%ed inta.e %lenum that causes moisture to flow to

the outside or to a drain if inta.e grilles are not designed to com%letely eliminate the

inta.e of rain or snow

#o o$ age

$utdoor Air Quantity

Classrooms and other school saces must "e ventilated to remove odors and other ollutants' #henational consensus standard $or outside air ventilation is ASHRA* Standard 23'4-3554 -availa"le at &&&'ashrae'org

$ outside air is rovided through a mechanical system, then at least 47 cu"ic $eet er minute(c$m) o$ outside air must "e rovided $or each occuant' A tyical classroom &ith >5 eolere%uires a minimum o$ 47 . >5 or E75 c$m o$ outside air'

n saces &here the num"er o$ occuants is highly varia"le such as gyms, auditoriums andmultiurose saces, demand controlled ventilation (DCV) systems can "e used to vary the%uantity o$ outside air ventilation in these saces in resonse to the num"er o$ occuants' !netechni%ue $or doing this is to install car"on dio.ide (C!3) sensors that measure concentrationsand vary the volume o$ outside air accordingly' $ an auditorium $ills u $or school assem"ly,then C!3 concentrations &ill increase, a signal &ill "e rovided to the HVAC system and outside

air volumes &ill "e increased accordingly' hen the saces served "y an air handler have highlyvaria"le occuancy, this tye o$ control can "oth save energy and hel control moisture (andmold) "y reducing the %uantity o$ humid outside air &hen it is not needed $or ventilation' C! 3 and other sensors must "e eriodically cali"rated and maintained'

#o o$ age

Air 5iltration

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17/24

n addition to Fatmosheric dust,F air"orne articulates can include ollen, mold ($ungal) sores,animal dander, insect roteins, esticides, lead, and in$ectious "acteria and viruses' Designerscan integrate $eatures into the ventilation system that &ill rovide "ene$its $or the schooloccuants as &ell as the e$$iciency and longevity o$ the HVAC system' n addition, these $eaturescan reduce the need $or e.ensive cleaning o$ the duct &or and air handling units'

5ilter Efficiency

• Air filters should ha'e a dust-s%ot rating between 637 and 897 or a :inimum

Efficiency Rating #alue *:ER# of between 8 and ;6

#he higher the rating, the "etter the rotection $or the e%uiment and the occuants' t has "een estimated that a >5G increase in static ressure across a coil results in a 355 er45,555 c$m o$ air movement (at 6 cents er IH)' #his does not include the added costo$ cleaning dirty heating or cooling oils, drain ans, or air ducts' Designers shouldconsider seci$ying a lo& e$$iciency (J45G) re-$ilter ustream o$ the main $ilters' #he re-$ilters are generally easy and ine.ensive to change, and &ill cature a signi$icant

amount o$ the articulate mass in the air there"y e.tending the use$ul li$e o$ the moree.ensive main $ilters' See ASHRA* Standard 73'3-4999 Method o$ #esting 1eneralVentilation Air Cleaning Devices $or Removal *$$iciency "y Particle Si=e availa"le at&&&'ashrae'org

!ressure Dro%

• Design more filter surface area into 'entilation systems

#his has t&o advantages the num"er o$ $ilter changes each year is reduced, there"yreducing the cost o$ la"or to roerly maintain the $ilters? and static ressure loss is

lo&er, &hich saves money "y reducing the amount o$ o&er needed to oerate $ans and "lo&ers' Since di$$erent $ilter media are aro.imately roortional in theire$$iciencyKressure dro ratio, the most e$$ective method $or reducing ressure dro is todesign more $ilter sur$ace area into the $ilter system' #his can "e done "y theseci$ication o$ a $ilter &ith larger amounts o$ sur$ace area, such as a leated $ilter or "ag$ilter' #he ne.t method is to increase the num"er andKor si=e o$ the $ilters in the airstream,$or e.amle, "y mounting the $ilter slots in a FVF attern, rather than a $ilter rac that issimly $lat and erendicular to the airstream'

:onitoring !ressure

• Consider installing a sim%le %ressure differential gauge across all filter ban.s

#his &ill revent school $acilities ersonnel $rom having to guess &hether the $ilter isready $or relacement' A gauge &ith a range o$ =ero to 4'5 in' &'g' can save money andthe environment "y reventing remature disosal o$ $ilters that still have use$ul li$e, andcan revent health and maintenance ro"lems caused "y overloaded $ilters that have "lo&n out' #he gauge should "e easily visi"le $rom a standing osition in an easilyaccessed location near the air handling unit'

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#o o$ age

Air Cleaning for 4aseous Contaminants

#he most e$$ective means o$ reducing e.osure o$ occuants to gases and V!Cs is to manageand control otential ollution sources' 0ilters are availa"le to remove gases and volatile organiccontaminants $rom ventilation air? ho&ever, "ecause o$ cost and maintenance re%uirements, thesesystems are not generally used in normal occuancy "uildings or schools' n secially designedHVAC systems, ermanganate o.idi=ers and activated charcoal may "e used $or gaseous removal$ilters' Some manu$acturers o$$er Fartial "yassF car"on $ilters and car"on imregnated $ilters toreduce volatile organics in the ventilation air o$ o$$ice environments' 1aseous $ilters must "eregularly maintained (relaced or regenerated) in order $or the system to continue to oeratee$$ectively' See also FResidential Air Cleaning Devices A Summary o$ Availa"le n$ormation'F

#o o$ age

#entilation Controls

Although a tyical HVAC system has many controls, the control o$ outdoor air %uantity thatenters the "uilding can have a signi$icant imact on A/, yet tyically is not art o$ standard ractice' Demand controlled ventilation is addressed as a method o$ humidity control, "ut is notother&ise discussed here "ecause its rimary use is to reduce the suly o$ outdoor air "elo& therecommended minimum $or the uroses o$ saving energy, not $or imroving A/'

$utdoor Air #olume :onitoring and Control

Sulying acceta"le %uantities o$ outdoor air to occuied saces is a critical comonent o$ goodindoor air %uality' et nearly all school ventilation systems cannot indicate &hether outdoor air is

even "eing sulied to the school, much less gauge the %uantity o$ that air' Virtually all e.istingschool ventilation systems rely uon a $i.ed damer to regulate the amount o$ outdoor air' et&ind, stac e$$ect, un"alanced suly and return $ans, and constantly changing varia"le airvolume (VAV) systems can cause signi$icant under- or over-ventilation, &hich can a$$ect A/and energy costs' Com"inations o$ these e$$ects can even cause the intae system to actuallye.haust air'

• S%ecify the addition of a measuring station that acti'ely controls the amount of

outdoor airflow by modulating the outdoor air dam%er and the return

*recirculation dam%er, if needed to o'ercome wind and stac. effects

#hese measuring stations are designed to &or in limited duct sace and &ith lo& airvelocities' #his is an easy tas, as some manu$acturers o$$er their air$lo& measuringstations in searate acages &ith damers and actuators, and others are "uilt into theAH; at the $actory'

#o o$ age

:oisture and Humidity Control

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19/24

;ncontrolled moisture indoors can cause ma@or damage to the "uilding structure, as &ell as to$urnishings and to $inish materials lie $loors, &alls, and ceilings' ;ncontrolled moisture cantrigger mold gro&th &hich not only damages the school $acility, "ut can lead to health and er$ormance ro"lems $or students and sta$$'

Primary causes o$ indoor moisture ro"lems in ne& schools include

• ;se o$ "uilding materials that &ere reeatedly or deely &etted "e$ore the "uilding &as

$ully enclosed• Poor control o$ rain and sno&, resulting in roo$ and $lashing leas

• et or dam construction cavities

• Moisture-laden outdoor air entering the "uilding

• Condensation on cool sur$aces

Controlling moisture entry into "uildings and reventing condensation are critical in rotecting "uildings $rom mold and other moisture-related ro"lems, including damage to "uildingcomonents'

0ollo& these lins $or more moisture in$ormation

•


20/24

hile there is an ongoing de"ate a"out the &isdom o$ using insulation materials in duct systemsthat might retain moisture longer, all sides agree that e.traordinary attention to reventingmoisture contamination o$ the duct &or should "e the rimary strategy $or reventing moldgro&th' See ASKASHRA* Addenda 23t and 23&, Addenda to ASKASHRA* Standard 23-3554, Ventilation $or Acceta"le ndoor Air /uality (availa"le at &&&'ashrae'org )'

As a secondary strategy, designers should consider methods o$ reducing the otential $or $uture ro"lems to occur due to un$oreseen moisture contamination "y investigating insulation roductsno& on the maret that minimi=e the otential $or moisture to enetrate the insulation material'#hese include $oil vaor retarders, tightly "onded non-&oven vaor retarders, "utt or shilaedges, and other techni%ues that have "een develoed "y insulation manu$acturers to addressconcerns a"out moisture'

• !ay s%ecial attention to %re'enting moisture from entering duct wor.

Preventing moisture $rom entering duct &or is critical to reventing mold ro"lems in

all tyes o$ ducts' Moisture in ducts is usually due to enetration o$ reciitation throughinlet louvers, e.cess moisture in outdoor air, or condensation drolets $rom cooling coilsthat are not roerly drained or ducts that are not roerly sealed' ;nder certaincircumstances, &hen e.ceeding recommended ma.imum cooling coil $ace velocity, &ater drolets can escae cooling coils and "e carried into the air stream, saturating any dirt ordust do&nstream'


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n addition to signi$icant energy losses, air leaage $rom HVAC ducts and air handlingunits can cause signi$icant A/ ro"lems due to une.ected air$lo& "et&een indoors andoutdoors, and "et&een areas &ithin the school' Air leaage $rom suly or return duct&or contri"utes to the condensation o$ humid air in "uilding cavities andKor on theneigh"oring sur$aces' Air leaage can "e esecially ro"lematic $or ducts or AH;s that

are located outside the conditioned saces' #he rimary goals $or the designer are to eeall air ducts &ithin the conditioned sace, and to seci$y that the @oints and seams o$ allducts, including return ducts, are sealed using an aroriate material'

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Ty%es of Air Distribution

early all schools currently use the mi.ed-air$lo& method $or distri"ution and dilution o$ the air&ithin the occuied sace' Designers should investigate a method called vertical dislacementventilation or thermal dislacement ventilation' #his aroach success$ully uses naturalconvection $orces to reduce $an energy and care$ully li$t air contaminants u and a&ay $rom the "reathing =one'

LClic on the image to "egin the animation' Cool suly air ("lue) slo&ly $lo&s out o$ the t&oheatingKcooling registers in the corners o$ the room, and sreads across the $loor' As it is &armed "y eole ("ro&n columns reresent students) and other &armer o"@ects in the room, it risesu&ard, continuously li$ting olluted air u and a&ay $rom the occuants' t is then collected ande.hausted outdoors' #his animation re%uires indo&s Media Player or RealPlayer' Animationused courtesy o$ Dunham Associates, Minnesota, M'

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E0haust Air

/uic removal o$ concentrated air contaminants and "uilding ressuri=ation are t&o &ays thate.haust systems a$$ect A/' Secial use areas such as science la"s, vocationalKtechnical shos,ca$eterias, and indoor ools already have &ell esta"lished regulatory codes regarding ventilation&ith outdoor air and negative ressure re%uirements &ith resect to ad@acent saces' +ess &ellrecogni=ed areas in schools &here secial e.haust ventilation is desira"le are @anitor closets,coyK&or rooms and artsKcra$ts rearation areas &here o$$-gasing $rom signi$icant %uantities o$ materials or roducts may occur' #hese areas should "e maintained under negative ressurerelative to ad@acent saces'

• !ro'ide e0haust 'entilation for =anitor>s closets

$ houseeeing and maintenance sulies are roerly stored in @anitor closets, onlyenough air need "e e.hausted to lace the closet under negative ressure relative tosurrounding rooms' As long as air does not easily lea into or $rom the closet throughoenings such as lenums or utility chases, 45 C0M o$ air e.hausted $rom the room &illtyically mae it negative, and revent the "uildu o$ air ollutants'

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• !ro'ide e0haust 'entilation for co%yF or EF diameter $le.i"le duct to "econnected "et&een the coier and an e.haust $an' #his catures much o$ the heat, articles, o=one, and other ollutants and e.hausts them outdoors "e$ore they can sreadthroughout the &orroom' A small e.haust hood over a &or sur$ace, similar to a $umehood in a science la", &ould also "e hel$ul to reduce e.osure &hen adhesives, srays, aints, and solvents are "eing used in the &orroom'

• !ro'ide e0haust 'entilation for arts and crafts %re%aration areas where off-gasingfrom significant )uantities of materials or %roducts may occur

• Consider s%ecifying a differential %ressure monitor to monitor building

%ressuri1ation

A/ ro"lems are o$ten traced to imroer ressuri=ation, &hich causes une.ectedair$lo& "et&een indoors and outdoors, and "et&een areas &ithin the school' #o reduceintroduction o$ unconditioned moist air and ollutants $rom outdoors, the "uilding should "e designed to oerate "et&een =ero and 5'5> in' &'g' (5 to 6 Pa) ositive, relative tooutdoors'

• Do not o%erate e0haust systems when the H#AC system is turned off to a'oid

bringing in unconditioned moist air that may condense on cooler indoor surfaces

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Designing for Efficient $%erations and :aintenance

• Ensure that all system com%onents, including air handling units, controls, and

e0haust fans are easily accessible

#o hel ensure that roer oeration and maintenance o$ HVAC system comonents &ill "e er$ormed, it is critical that the designer maes the comonents easily accessi"le' AH;s,controls, and e.haust $ans should not re%uire a ladder, the removal o$ ceiling tiles, or cra&ling togain access' Roo$to e%uiment should "e accessi"le "y &ay o$ stairs and a $ull-si=ed door, not a$i.ed ladder and a hatch'

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• /abel H#AC system com%onents to facilitate o%erations and maintenance

+a"eling o$ HVAC comonents is an ine.ensive and e$$ective method $or heling $acilities ersonnel roerly oerate and maintain the HVAC systems' #he la"els should "e easy to read&hen standing ne.t to the e%uiment, and dura"le to match the li$e o$ the e%uiment to &hichthey are attached' At a minimum, the $ollo&ing comonents should "e la"eled in each ventilation=one o$ the school and should corresond &ith the HVAC diagrams and dra&ings' FAH;F re$ersto any air handling unit that is associated &ith outdoor air suly'

#he num"er or name o$ the AH; (e'g', AH; NN, or AH; $or est ing)#he outdoor air (!A), suly air (SA), return air (RA), and e.haust or relie$ air (*A)connections to the AH;, each &ith arro&s noting roer air$lo& direction#he access door(s) $or the air $ilters and the minimum $ilter dust-sot (or M*RV) e$$iciency(Air 0ilters, minimum ..G dust sot e$$iciency)#he $ilter ressure gauge and the recommended $ilter change ressure (0ilter Pressure, ma.

5'. in' &'g')#he access door(s) $or the condensate drain an (Drain Pan)!ther ertinent access doors such as to energy recovery ventilation &heels or lates (*nergyRecovery Ventilation ;nit)#he minimum amount o$ outdoor air $or each AH; (NNN C0M minimum during occuiedtimes)#he outdoor air damer (!A Damer), &ith secial mars noting &hen the damer is in the$ully closed (Closed), $ully oened (oen), and minimum designed osition (Min)$ a motori=ed relie$ damer is installed (*A Damer), note the same ositions as a"ove'#he access door to any outdoor air controls (!A Control(s)) such as damer ositionad@ustments, outdoor air$lo& measuring stations, resets, $uses, and s&itches)


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mem"er o$ the design team, an indeendent contractor, or a mem"er o$ the school districtsta$$?

• Collect and revie& documentation on the design intent?

• Mae sure commissioning re%uirements are included in the construction documents?

• rite a commissioning lan and use it throughout design and construction?

•

Veri$y installation and $unctional er$ormance o$ systems?• Document results and develo a commissioning reort'

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References and Resources

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Documents

HVAC System Design and Installation Procedures