MODULE 5 - Tradeline, Inc. · 5 HVAC FUNDAMENTALS OF MODERN LAB DESIGN . Module 5 Concepts – Other Devices (Non Containment) Module 5 PG36 . Other Devices – Canopy Hoods • Not

5 HVAC FUNDAMENTALS OF MODERN LAB DESIGN

MODULE 5 HVAC FUNDAMENTALS OF MODERN LABORATORY DESIGN


Module 5 PG1


Module 5 PG2

MODULE 5 GOAL Provide a fundamental understanding of Laboratory Heating, Ventilating and Air

Conditioning Concepts and Systems


Module 6 Outline

• Issues

• Drivers

• Concepts

• Systems

Module 5 PG3


Module 5 Issues

Some of the most common concerns of laboratory facility users are relative to the HVAC system, including:

• “It’s too hot and humid in my lab!”

• “It’s too cold and dry in my lab!”

• “It’s like a tornado in my lab!”

Module 5 PG4


Module 5 Drivers

• Laboratory Equipment Heat Generation • Air Change Rates • Containment Equipment • Occupant Gowning Requirements • Type of Laboratory and Science

Module 5 PG5


Module 5 Drivers – Laboratory Equipment Heat Generation

Heat Generation Information • Heat is expressed in BTU/Hour • 1 Watt = 3.414 BTU/Hour • Sensible Heat: Energy Required to

Change Temperature • Latent Heat: Energy Required to Remove Moisture • One Ton of Air Conditioning: 12,000

BTU/Hour or 3,515 Watts • 135 cfm of outside air equals 1 ton

of cooling (Kansas City weather) Module 5 PG6



Module 5 PG7

Loads for Bench Mounted Equipment (low density)

Item Bench L.F. Btuh Optical Microscope 2 222 Analytical balance 2 24 Computer & Monitor 4 461 Rotary Evaporator 3 253 Total 11 960 Btuh Per Linear Foot 87 Watts per linear foot 26 Sources: ASHRAE 2001 Fundamentals Handbook Labconco Catalog Revco Freezer Data Sheets NOTE: This is heat release, not equipment nameplate

electrical data



Module 5 PG8

Loads for Bench Mounted Equipment (high density)

Item Bench L.F. Btuh Optical Microscope 2 222 Small Centrifuge 3 304 Thermal Cycler 2 795 Fluorescent Microscope 2 700 Flame Photometer 2 365 Rotary Evaporator 3 253 Total 14 2639 Btuh Per Linear Foot 189 Watts per linear foot 55 Sources: ASHRAE 2001 Fundamentals Handbook Labconco Catalog Revco Freezer Data Sheets



Module 5 PG9

Loads for Floor Mounted Equipment (high density)

Item Floor L.F. Btuh Ultra Low Freezer 4 3618 Large Centrifuge 4 4014 Large Incubator 4 4556 Refrigerator 3 1672 Total 15 13860 Btuh Per Linear Foot 924 Watts per linear foot 271

Sources: ASHRAE 2001 Fundamentals Handbook Labconco Catalog Revco Freezer Data Sheets



Module 5 PG10

Two Module Lab Example (484 SF): • 16 feet of space allocated for floor

mounted equipment • 48 feet of bench space • Assume half the bench is full – 24’ of

equipment Heat Generated using moderate density: • Bench: 138 btuh/ft X 24’ = 3312 btuh • Floor: 662 btuh/ft X 16’ = 10,592 btuh • Total: *13,904 btuh More than 1 ton of A/C • Using 100% outside air in Kansas City:

57,300 btuh (4.75 tons) *There is no diversity in this number



Module 5 PG11

When figuring equipment heat gain: • Use published or measured heat release

information, not electrical nameplate • Apply diversity carefully based on

expected lab use • Consider sub-metering loads in similar

buildings prior to planning a new lab • The answer is not “10 watts/sq.ft.”


Module 5 Drivers – Air Change Rates

Module 5 PG12

• 1 Air Change per Hour – The Amount of Air in Cubic Feet per Minute (CFM) it Takes to Completely Replace the Air in a Laboratory once in One Hour • CFM = (Floor Area x Ceiling Height x Air

Change Rate)/60 • 135 CFM per One Ton of Cooling • Standards and Guidelines Vary from 4 to

12 AC/hr


Module 5 Drivers – Air Change Rates

Module 5 PG13

• 2 Module Laboratory (22’ x 22’); 484 SF • CFM Requirement for varying ceiling heights and air change rates MORE IS NOT NECESSARILY BETTER Airflow in CFM at Given Air Change Rate

Ceiling Height 6 8 10 12

9 436 581 726 871 10 484 645 807 968 11 532 710 887 1065 12 581 774 968 1162


Module 5 Drivers – Air Change VS. Fume Hoods

Module 5 PG14

Nominal Fume Hood CFM

5' Fume Hood

6' Fume Hood

8' Fume Hood

960* 1180* 1660*

610** 750** 1060**

Airflow in CFM at Given Air Change Rate

Ceiling Height 6 8 10 12

9 436 581 726 871 10 484 645 807 968 11 532 710 887 1065 12 581 774 968 1162

* Sash full open; face velocity 100 fpm

** Sash at 18”; face velocity 100 fpm

• 2 Module Laboratory (22’ x 22’); 484 SF • CFM Requirement for varying ceiling heights and air changes


Module 5 Drivers – Containment Equipment

Module 5 PG15

Approximate Exhaust CFM for 6’ BSC • Class II Type A2 Cabinet without

canopy: 0 cfm • Class II Type A2 Cabinet with

canopy: 600 - 700 cfm • Class II Type B2 Cabinet : 1150 cfm

(requires a dedicated exhaust fan

Select the correct cabinet for the application

Cabinets that use ECM motors have

significantly lower heat gain and higher efficiency than PSC motors


Module 5 Drivers – Air Changes VS. Containment Equipment

Module 5 PG16

• *Laboratories often use 4 to 6 times more energy per sq. ft. than a typical office building

• *Nearly half of electrical energy used in a laboratory building can be attributed to ventilation

• The decision on air exchange rates and fume hood sash position affect both first cost and lifetime building energy costs

Annual electricity use in Louis Stokes Laboratory, National Institutes of Health, Bethesda, MD Courtesy of Labs 21

*Courtesy of Labs 21


Module 5 Drivers – Gowning/PPE

Module 5 PG17

Impact of Gowning/PPE in Laboratory • May require reduction in Laboratory

Design Temperature • Reducing Design Temperature from 72

deg. F to 70 deg. F results in: • A 12% increase in cooling airflow • A 12% increase in cooling capacity


Module 5 Drivers – Type of Laboratory/Type of Science

Module 5 PG18

Animal Holding Rooms • 10 to 15 Air Changes per hour



Module 5 PG19

Instrument/Computational Laboratories • High Equipment Heat Loads



Module 5 PG20

Chemistry/Analytical Laboratories • High Fume Hood Density


Module 5 PG21

MODULE 5 – BASIC CONCEPTS

Laboratory Hazards Containment

Flexibility & Redundancy


Module 5 Concepts – Laboratory Hazards

Module 5 PG22

Health Hazards • Irritants • Corrosive Substances • Allergens • Asphyxiants • Carcinogens • Reproductive Toxins • Neurotoxins Flammability Hazards Reactivity Hazards Explosive Hazards Biohazards Radioactive Hazards


Module 5 Concepts – Containment

Module 5 PG23

Primary Containment • First Level of Containment; typically

a containment device: chemical fume hood, biological safety cabinet, etc.



Module 5 PG24

Secondary Containment • Second Level of Containment:

• Laboratory Envelope • Directional Airflow • 100% Outside Air • Differential Pressure or Volumetric

Offset • Doors must be kept closed • Exhaust fans run continuously Best Practices: Use Primary and Secondary Containment to Protect Personnel from Exposure to Hazards ANSI Z9.5 requires air movement from lower hazard to higher hazard



Module 5 PG25

Primary Containment Devices - Chemical Fume Hoods • Bench Mounted Chemical Fume Hoods • Each Fume Hood uses as much energy as an entire house* * From Labs 21



Module 5 PG26

Primary Containment Devices - Chemical Fume Hoods • Floor Mounted Chemical Fume

Hoods or Ventilated Enclosures


Module 5 PG27

Primary Containment Devices - Chemical Fume Hoods • Floor Mounted Hood Location is Critical



Module 5 PG28

Primary Containment Devices - Chemical Fume Hoods • Radioisotope Hood

• Stainless steel interior • Requires dedicated exhaust fan • Coved corners for decontamination • May need HEPA filters • Consult your Radiation Safety Officer



Module 5 PG29

Primary Containment Devices - Chemical Fume Hoods • Perchloric Acid Hood

• Acid resistant interior • Dedicated acid resistant ran • Acid resistant sealed ductwork • Washdown system • Treat wastewater from washdown • Do NOT manifold these hoods



Module 5 PG30

Primary Containment Devices - Chemical Fume Hoods • Variable Volume Fume Hood

• Face velocity is maintained constant as sash is raised and lowered

• Requires pressure independent control device

• Requires variable control – usually exhaust air bypass damper

• Must maintain a minimum flow when sash is fully closed (ANSI Z9.5 no longer specifies how much)



Module 5 PG31

Labconco

Lawrence Berkeley Labs

Primary Containment Devices - Chemical Fume Hoods • “High Performance” Fume Hood

• Hood provides containment at lower face velocity

• Each manufacturer uses a different design

• Apply with caution • “Low Flow does not necessarily

equate to “High Performance” • More sensitive to cross drafts



Module 5 PG32

Primary Containment Devices - Chemical Fume Hoods • “Ductless” Fume Hood

• Uses activated carbon and/or HEPA filters

• Use only in tightly controlled conditions

• NFPA 45 allows only for nuisance vapors & dusts



Module 5 PG33

Primary Containment Devices – Biological Safety Cabinets • Personnel protection • Environmental protection • Can provide product protection • Not a chemical fume hood!!!! • Used for biological/microbiological

work



Module 5 PG34

Biological Safety Cabinets (BSC’s) • Class I: Ventilated cabinet for personnel

and environmental protection. No product protection

• Class II: Ventilated cabinet for personnel, product, and environmental protection. Type A1, A2, B1, and B2

• Class III: Totally enclosed ventilated cabinet of leak-tight construction. Operations conducted through attached rubber gloves. Sometimes called glove boxes.

Select the correct cabinet for the application


Module 5 Concepts – Other Devices (Non Containment)

Module 5 PG35

Other Devices – Not Chemical Fume Hoods • Canopy Hoods • Snorkels • Slot Hoods



Module 5 PG36

Other Devices – Canopy Hoods • Not appropriate for fumes • Hot applications only (ovens,

GC/MS, non-hazardous hot tanks, glassware washing,

cage washing, etc.) • Must have mass of hot moving air

to contain



Module 5 PG37

Other Devices – Snorkel Hoods • Bench top activities that require

exhaust • Ideal containment device for

dissections • Good for bench top soldering, etc.


Module 5 Concepts – Flexibility and Redundancy

Module 5 PG38

Three truths for the Laboratory HVAC Designer • What’s happening in the laboratory tomorrow will be

different than what’s happening today • Fume hood density nearly always increases over time • The amount of heat generating equipment will increase

over time


Module 5 Concepts – Flexibility and Redundancy

Module 5 PG39

Plan for flexibility and future growth • Allow extra space in the mechanical room to add equipment

(chiller, boiler, air handler, exhaust fans) • Allow for additional shaft and ceiling space • Size ducts and pipe for spare capacity (inexpensive if done

initially)


Module 5 PG40

MODULE 5 – SYSTEMS

HVAC


Module 5 Systems – HVAC

Module 5 PG41

Laboratory HVAC • Look at three different criteria and

choose worst case: • Cooling load (primarily heat

generating equipment) • Minimum air change rate • Exhaust requirement

• Consider supplemental cooling for high density loads (freezer rooms, etc.)



Module 5 PG42

Laboratory HVAC Design Considerations

• “The effect of room air challenge is significant and of the same order of magnitude as the effect of face velocity”

• “Consequently, improper design of replacement air supply can have a disastrous effect on the efficiency of a laboratory hood.”

ASHRAE RP-70, Caplan and Knutson, 1977



Module 5 PG43

Laboratory HVAC Design Considerations

• “Supply air distribution shall be designed to keep air jet velocities less than half, preferably less than one-third of the capture velocity or the face velocity of the laboratory chemical hoods at their face opening.”

ANSI/AIHA Z9.5-2003, section 5.2.2



Module 5 PG44

Laboratory Exhaust Systems • Fan discharge design must minimize risk of

re-entrainment • Stack/Intake separation • Stack height • Stack effective height/momentum • Stack discharge velocity must be 3,000

fpm, minimum



Module 5 PG45

Laboratory Exhaust Systems • Heat Recovery

• Air to air plate heat exchanger • Run around loop • Molecular sieve enthalpy wheel



Module 5 PG46

Laboratory Exhaust Systems • ANSI/ASHRAE/IESNA 90.1 – 2010

• Prescriptive path requires some combination of VAV and/or heat recovery for most lab HVAC systems

• Alternative is Energy Cost Budget Method



Module 5 PG47

Laboratory Exhaust Systems • ANSI/ASHRAE 62.1 – 2010

• January, 2011 interpretation precludes using any technology for laboratory fume hood or chemical storage room exhaust heat recovery that results in any amount of cross contamination

• This appears to disallow the use of total energy recovery wheels

• Addendum K is out for public review



Module 5 PG48

COURTESY OF LABS 21



Module 5 PG49

How Much Mechanical Space? • Between 8 and 20% of

gross building square footage • 8% for simpler

academic buildings • 20% for complex labs

or buildings with animal areas

• Vivariums or BSL containment labs may require 50% of the gross building area for mechanical space



Module 5 PG50

Applicable Standards and Guidelines

Documents

MODULE 5 - Tradeline, Inc. · 5 HVAC FUNDAMENTALS OF MODERN LAB DESIGN . Module 5 Concepts – Other Devices (Non Containment) Module 5 PG36 . Other Devices – Canopy Hoods • Not