Ashrae Std 62 11

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62.1-2010

Dave Kahn, P.E.

Dave Kahn, P.E. Dave Kahn, P.E.

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62.1?



 _{The Industries Ventilation Standard}_{The Industries Ventilation Standard}



_{Consensus Standard}_{Consensus Standard}



_{Standard of Care}_{Standard of Care}



_{Used in NFPA 5000 Building}_{Used in NFPA 5000 Building}

Construction and Safety Code Construction and Safety Code



_{LEED Requirement}_{LEED Requirement}



 _{2009 IMC –}_{2009 IMC – Ventilation system}_{Ventilation system}

efficiency may be calculated by efficiency may be calculated by Appendix A (62.1-2004)

(4)

H

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

 _{1905 Flugge 30 cfm}_{1905 Flugge 30 cfm}



 _{1936 Yaglou 10 cfm}_{1936 Yaglou 10 cfm}



 _{1973 First Issued}_{1973 First Issued} _{office 15 cfm/p}_{office 15 cfm/p}



 _{1981 Lower Rates}_{1981 Lower Rates} _office_office _{5 cfm/p}_{5 cfm/p}



 _{1989 Higher Rates}_{1989 Higher Rates} _office_office _{20 cfm/p}_{20 cfm/p}



 _{1999 Little Change}_{1999 Little Change} _office_office _{20 cfm/p}_{20 cfm/p}



 _{2001 More}₂₀₀₁_{More Mandatory}_{Mandatory Language}_Language _{office 20 cfm/p}_{office 20 cfm/p}



 _{2004 Key Changes}_{2004 Key Changes} _{office 17 cfm/p}_{office 17 cfm/p}



 _{2007 Appendix H}_{2007 Appendix H} _{office 17 cfm/p}_{office 17 cfm/p}



(5)

Acceptable Indoor Air Quality

What Is It?

 _{Standard 62: “Air in which}

there is no known

contaminants at harmful

concentrations as determined by cognizant authorities and with which a substantial

majority (80% or more) of the people exposed do not

(6)

How Much Ventilation?



_Unknown

 _{Chamber studies}

 _{Limited to body odor (olf)}

 _{Medical evidence}

 _{No “evidence based” studies}

(7)

Chamber Body Odor Studies

Impact of ventilation rate on “ visitors”

From ASHRAE presentation by

(8)

Body Oder Studies

Cain & Leaderer

From ASHRAE presentation by

(9)

Cain & Leaderer

1983

 _{For nonsmoking occupancy, 47 combinations}

of temperature, humidity, ventilation rate and occupancy density were examined. Odor

level depended entirely on ventilation rate per person irrespective of the number of persons in the chamber.

 _{For both smoking and nonsmoking}

conditions, a combination of high

temperature (78°F) and humidity (r.h. > 70 %) exacerbated the odor problem

(10)

Recent Studies

 _{Hillsborogh County Schools}

 _{March 2011 Engineered Systems}

 ₉th _{largest district in US}  _{7.5 cfm/student}

 _{2 California Studies ongoing}

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62.1 New in 2010

 _{PM2.5 non-attainment areas require air cleaning}  _{Smoking spaces no longer covered by the}

standard

_{Air intake separation distances revised}

 _{Deletes requirements for health care spaces}  _{Revises IAQ procedure to make it more robust}  _{Most natural ventilation systems now require}

mechanical systems for when natural vent cannot be used (thermal comfort, noise, security)

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Fun Facts

 _{Means to balance the system to achieve minimum}

airflow.

 _{Design documentation to state ventilation rate and}

air distribution assumptions.

 _{Controls to enable the fan to operate whenever}

the spaces served are occupied.

 _{VAV systems with fixed OA dampers must comply}

at minimum supply airflow.

 _{MERV 6 filters upstream of all coils or other}

(13)

Two paths to compliance

 _{Ventilation Rate Procedure}  _{Most commonly used method}

 _{Lookup table (simple) or Appendix A (complex)}  _{Need zone air distribution effectiveness}

 _{LEED requires this method}  _{Indoor Air Quality Procedure}

 _{Design to maintain specific contaminant levels}  _{Mass Balance Analysis}

 _{Methods used in similar buildings}

 _{Validation by contaminant monitoring}

Single duct systems such as VAV

reheat

Multiple paths: Fan powered VAV and

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Classroom Example

Single zone 2010

 _{High School classroom 35’x35’ 30 people}

 _V_bz _{= R}_p_P_z _{+ R}_a_A_z _V_bz _{= Breathing Zone OA}  _{10 cfm /person 10 * 30 = 300 cfm}

 _{0.12 cfm/ft}2 _{0.12 * 35 * 35 = 147 cfm}

 _{300 + 147 = 447 cfm}

 _{Zone outdoor airflow V}_oz _=V_bz_/E_z

(18)

Short-Term Conditions

 _{Peak occupancy of short duration}

 _{Ventilation interrupted for a short period of}

time

 _{T = 3V/ V}_bz

 _{V = Volume of ventilation zone}  _{+ Zone outdoor air flow}

(19)

Example Private Office

 _{230 Sq Ft, 9 ft ceiling Work station and 2}

guest chairs



T= 3V/ V_bz = 9*230*9/(3*5 +230 *0.06) = 3.6 hrs

_{Assume guests present 1/3 of time}

(20)

Multiple-Zone Recirculating

Systems

 _{For each zone:}

 _V

bz = RpPz + Ra Az Just like previous example  _V_oz _=V_bz_/E_z _{Just like previous example}

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Multiple-Zone Recirculating

Systems

 _{Primary outdoor air fraction Zp}  _Z

pz = Voz/Vpz (For each zone)  _V_oz _{- zone outdoor airflow}

 _V_pz _{- minimum zone primary airflow}

(22)

Uncorrected Outdoor

Air Intake



_V

ou

= D

Σall zones

R

p

P

z

+

Σall zones

R

a

A

z

 V

ou - uncorrected outdoor air intake

 D - occupant diversity = P

s/ Σall zones Pz

 P_s -total population of area served

by the system

 P_z - largest number of people

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Outdoor Air Intake

 _V

ot = Vou/Ev  _V

ot - design outdoor air intake flow  _V_ou _{- uncorrected outdoor air intake}

 _E_v _{- ventilation efficiency from Table 6-3}

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DYNAMIC RESET

 _{VRP procedure gives the peak rate based on}

worst case assumptions (design)

 _{Reset based on}

 _{Occupancy: time of day}

 _{Occupancy sensors}

 _{Carbon dioxide}

_{Air distribution efficiency}

 _{Multiple space equation solved}

dynamically

(29)

Dynamic Reset

_{Air Distribution Efficiency}

 _{If min OA determined in heating mode, OA can be} reduced during cooling due to a higher Ez

 _{Solve equations in appendix A dynamically based on} zone and system flows to reset zone minimums and outdoor airflow.

 _{OA economizer reset of VAV Box minimum}

 _{Don’t drop below the area outdoor air rate R}_a_.

(30)

Demand Controlled Ventilation

 _CO 2.

 _{Time averaging to reduce zone population is not} allowed

 _{Constant Volume with no air flow measurement}

_{At CO}

2 max, damper positioned to admit Vot design

occupancy

_{At ambient CO}

2 levels set minimum to admit required

air quantity with no occupants Vat  _{Linear reset between CO}

(31)

Demand Controlled Ventilation

 _CO

2 sensor location:

 _{In the breathing zone}

 _{Typically adjacent to the temp sensor}

 _44” AFF

 _{Return air sensing doesn’t work}  _{Sensor type}

 _Infrared

(32)

Constant Volume W/O air flow

measurement

 _{Calculate Vot at design occupancy rate}

 _{Calculate Vot with no occupants call it Vat}  _{Reset min OA damper position from Vat to}

Vot as CO2 varies from 400 (ambient) to 800 (calculated or arbitrary setpoint)

 _{Damper positions set in conjunction with}

(33)

Constant volume with air

flow measurement

 _{Solve equations A-H dynamically to reset the}

required min OA qty

 _{Can’t reduce the number of occupants using}

time averaging

 _{Can reset zone effectiveness based on}

(34)

Multiple Zone Systems

_{ASHRAE Research 1547TRP is working on it}

(35)

Learning More

 _{Read the standard}

 _{2010 Handbook is available}