Safely Reducing Outside Air in Laboratories...ANSI Z9.5 – 2012 ACH / Dilution Rates “An air...
74
Safely Reducing Outside Air in Laboratories David Warner, PE, CEM HTS Chicago
Transcript of Safely Reducing Outside Air in Laboratories...ANSI Z9.5 – 2012 ACH / Dilution Rates “An air...
Safely Reducing Outside Air in LaboratoriesDavid Warner, PE, CEMHTS Chicago
What is a lab?
OSHA 29
“It is a workplace where relatively small quantities of hazardous chemicals are used on a non-production basis.”
- CFR 1910.1450, subpart 2, paragraph 191.1450) [4]
Primary Purpose
SAFETYComfort (Productivity)
Efficiency
Sustainability
Flexibility
other
Lab Safety
#1 Most Important Factor for Lab Safety
Primary Mechanism for Protection
• Ventilation Systems
• Typically 100% OA
• Continuous Operation
Impact of Continuous Ventilation
Lab Energy Usage ~ 3 to 8 times office
Campus Energy Usage< 20% sq. footage
> 40% energy usage
http://www1.eere.energy.gov/buildings/commercial/bba_laboratories_team.html
Why Focus on Ventilation?
Ventilation > 40% energy usage
HVAC> 65% energy usage
Drivers of Laboratory Ventilation
ThermalACH / DilutionHoods
Why Ventilation Drives Lab Energy Cost
Constant Volume Fume Hood
1000 cfm x $3/cfm/year = $3,000
Average US Home
10,000 kWh/year x $0.10 /kWh = $1,000
Why Ventilation Drives Lab Energy Cost
Constant Volume Fume Hood
One
Average US Home
Three>
Why Ventilation Drives Lab Energy Cost
Constant Volume
20 ACH3 cfm /sf
Primary Drivers of Laboratory Ventilation
Hoods Thermal Load
VAV ACH
VAV Hoods
ACH / Dilution Requirement
VAV Supply
2-4 ACH Min
To achieve goal all flow requirements need to be reduced
Min Flow
Min Load
Safely Reducing Outside Air in Laboratories
Agenda• Historical Background
• High Payoff Strategies
• Case Study
• Q & A
Oracle at Delphi
1876 - First R&D Lab in US
1899 – Classroom, Mechanical Ventilation
Lab - 1916
Lab - 1920’s
Lab - 1941
New Lab
“Typical” Lab?
The “Human Factor”
Lab Safety
Most Important Device for Lab Safety
Exposure Control Devices
Fume HoodBiological Safety Cabinet
Point Exhaust
Flammable Storage Cabinet
Expensive Storage
Step 1. Reduce Fume Hood Airflow
• Eliminate Unused Hoods
• Reduce Hood Size
Step 1. Reduce Fume Hood Airflow
Fundamental ApproachVAV Hoods (most labs)
Step 1. Reduce Fume Hood Airflow
Strategies• Reduce Design Opening
• Reduce FH Min. NEW ANSI Z9.5
• Reduce Face Velocity
• Close the Sash
• Use Diversity
Design Opening
Design Opening
e.g. 60” x 30” = 12.5 sf
12.5 sf x 100 fpm = 1250 cfm
Reduce Design Opening
e.g. 60” x 18” = 7.5 sf
7.5 sf x 100 fpm = 750 cfm
Vertical Sash Stop
Vertical Rising Sash
Reduce Design Opening
e.g. 30” x 30” = 6.25 sf
6.25 sf x 100 fpm = 625 cfm
Horizontal or Combination Sash
Left Side Open
Reduce Design Opening
Center Open
Horizontal or Combination Sash
Reduce Design OpeningHorizontal or Combination Sash
Right Side Open
Reduce Design Opening
Max Horizontal Opening
22” x 22”, 336 cfm
Low Flow Hood
Reduce FH Minimum Flow Rate
Fume Hood Min:• For VAV hoods
• Only affects hood flow for small or closed sash positions
• Independent of face velocity
• Changing min will not reduce face velocity
Old Min (250 CFM)
Reduce FH Minimum Flow Rate
Fume Hood Min:• For VAV hoods
• Only affects hood flow for small or closed sash positions
• Independent of face velocity
• Changing min will not reduce face velocity
Old Min (250 CFM)
New Min 150 ACH
Reduce FH Minimum Flow Rate
Fume Hood Min:• For VAV hoods
• Only affects hood flow for small or closed sash positions
• Independent of face velocity
• Changing min will not reduce face velocity
New Min (100 CFM)
Old Min (250 CFM)
Reduce Face Velocity
e.g. 60” x 18” = 7.5 sf
7.5 sf x 100 fpm = 750 cfm
Vertical Sash Stop
Vertical Rising Sash
Reduce Face Velocity – Design 80 fpm
e.g. 60” x 18” = 7.5 sf
7.5 sf x 80 fpm = 600 cfm
Vertical Sash Stop
Vertical Rising Sash
Reduce Face Velocity – Design 80 fpm
750 cfm
600 cfm
Savings150 cfm at Max
0 cfm at Min
Why not?
Reduce Face Velocity – Unocc . 60 fpm
Reduce Face Velocity – Unocc . 60 fpm
750 cfm
450 cfm
Savings300 cfm at Max
0 cfm at Min
Diversity Diversity Assured
Close the Sash – Automatic Closer
Close the Sash – Increase Awareness
Energy Usage “Dashboards”
Close the Sash – Increase Awareness
Close the Sash - Influence Behavior
Close the Sash – Results
Close the Sash – Does it Work?
$41,000 per year
Diversity
Given 10 Fume Hoods in 10 LabsHow many need Max Airflow at the same
time?
If “Events are independent and random,
• Calculate using Binomial Distribution
• “Hunter’s Curve” concept
Diversity Calculation
Total # of HoodsCertainty level:
10 20 40
% of Time # of FH @ Max
97% 2 4 6
99% 3 5 7
99.9% 4 6 9
99.99% 5 7 10
Hood Airflows Combining Various Strategies
Sash Position
100 fpm 80 fpm 2 hr. Occ.w/ Setback
10 FH@ Max
12,500 10,000 6,333
10 FH @ Stop
7,500 6,000 4,420
3 @ Stop7 @ 9”
4,875 3,900 3,010
3 @ Stop7 closed
4,000 2,640 2,230
e.g. 10 Fume Hoods in 10 Labs
Hood Airflows Combining Various Strategies
Sash Position
100 fpm 80 fpm 2 hr. Occ.w/ Setback
10 FH@ Max
12,500 10,000 6,333
10 FH @ Stop
7,500 6,000 4,420
3 @ Stop7 @ 9”
4,875 3,900 3,010
3 @ Stop7 closed
4,000 2,640 2,230
Combines all Five Strategies
Step 2: Reduce Thermal Load Flow Drivers
Strategies• Right Size the Load
• Use Diversity
• Decouple Thermal from Ventilation
Thermal Load
VAV Supply
Min Load
Right Size the Load
UC Davis – LBNL Study� HPAC Article (Sept & Oct, 2005)
Measured plug loads in labs
Lighting, people ~ 1 w/sf
Step 2: Reduce Thermal Load Flow Drivers
Thermal Load
VAV Supply
Min Load
Labs 21 & UC Davis study: • Avg plug & lighting: 2.5 to 3 W/ft 2
• < 20% of labs loads > 4 W/ft 2
Typical rooms:• Daytime: Loads < 4 ACH
• Nighttime: w/ Temp Setback
can achieve 2 ACH
Diversity for HVAC Capacity
Given 40 Lab Zones,
How many need Max Cooling at the same time?
Life Sciences Lab
Low Load (blue)
Medium Load (yellow)
High Load (red)
Decouple Thermal from Ventilation
For high load labs & more efficiency: Use Hydronic Cooling
(Chilled Beam, Fan Coil Units)
Thermal Load
VAV Supply
Min Load
Step 3: Reduce ACH / Dilution Rate
How?• Occ/Unocc Control
• Active/Demand Based Control
What Rates?
Demand Based Control
ACH Requirement
2 ACH Min
ACH / Dilution Rates
ASHRAE 62.1�Labs: 0.18 cfm /sf (1.2 ACH) of fresh air
City of Chicago Code�Labs: 1.2 cfm /sf (8 ACH with 9 ft. ceiling)
�1/3 of max permissible with VAV (2.67 ACH)
Most fixed ACH values are being reduced:�NFPA 45 – 2011: Rates removed, Refers to ANSI
�ANSI Z9.5 -
ANSI Z9.5 – 2012 ACH / Dilution Rates
“An air exchange rate (air changes per hour) cannot be specified that will meet all conditions.”
“Furthermore, air changes per hour is not the appropriate concept for designing contaminant control systems.
2011 ASHRAE Handbook, Lab Chapter 16
Occ/Unocc Control
� “There should be no entry into the laboratory during unoccupied setback times”
� “…Occupied ventilation rates should be engaged possibly one hour or more in advance of occupancy to properly dilute any contaminants.”
2011 ASHRAE Handbook, Lab Chapter 16
Active/Demand Based Control
“Reducing ventilation requirements in laboratories and vivariumsbased on real time sensing of contaminants in the room environment offers opportunities for energy conservation.”
“This approach can potentially reduce lab air change rates down safely to as low as 2 air changes per hour when the lab air is ‘clean’...”
Demand Based Control
Lab air is “clean” > 98% of the time
Vary based on real time sensing
Safety?• Fixed ACH is either too high or low
• Dilution up to Max
• “Clean” set to 2 ACH at night
Daytime Airflow, 4 ACH� Rates < 4 ACH also used
� Couple with other strategies
DBC provides a safe means to achieve 2 ACH when lab air is clean
Demand Based Control
ACH Requirement
2 ACH Min
The “Human Factor”
“Our goal is to find the sweet spot where we maximize energy savings without compromising safety.”
Marc GomezAssistant Vice Chancellor
Facilities Management/Environmental Health & Safety
University of California, Irvine
Case Study – UC Irvine
Case Study – UC Irvine
Hewitt Hall: Designed in 2001
Exceeded Title 24 by 23.7%
Biomedical Research
Re-Commissioned in 2010
6 ACH fixed minimum76,905 Square Feet
Gross Hall: Designed in 2009
Exceeded Title 24 by 50.3%
Biomedical Research
Submitted: LEED Platinum
DBC: 4/2 ACH Occ/Unocc94,705 Square Feet
Both buildings similar in layout, function, & use
Airflow Savings ~ 1 cfm/sf
Lab Air Flow vs. Time For Both Bldgs
Wendell C. BraseVice Chancellor, Administrative & Business Services, UC Irvine
Chair, University of California
Climate Solutions Steering Group
“Smart Labs”
4/2 ACH
What is Possible?
Design and Benchmarking Resources
Safely Reducing Outside Air in Labs
Questions?
