Overview of Dynamic Control of Lab ACH s

Transcription

1 A Comprehensive Review of the Indoor Environmental Quality and Energy Impacts of Dynamically Varying Air Change Rates at Multiple Laboratory Facilities

2 Overview of Dynamic Control of Lab ACH s Background Review former Labs21 sessions 2005 The concept 2006 HSPH lab case study 2007 Installed site analysis Overview of site aspects Analyzed data: ~ 4M sensed values, 250K hours: TVOC s, Particles, CO2, Dewpoint Dynamic ACH rate performance review Case studies showing energy savings

3 2005: The Controversy Around Air Change Rates Minimum air changes still fixed at 6-12 / ACH Far majority of time lab air is clean However, there many times when more air is better Dilute vapors from a spill when lab is occupied or unocc. Dilute vapors or particles caused by poor practices Working outside the hood, improper storage No localized exhaust for instruments Improper bedding changing The human factor There is no one ventilation rate that is right all the time!

4 Lab Application: Dynamic Control of Lab ACH Lab Multi-parameter DCV: Dynamic control of min. ACH Now all three factors affecting lab airflow can be varied Significantly cuts energy & first cost, while enhancing safety Constant Ventilation rate (cfm) VAV VAV Significant energy waste VAV 6-12 ACH ACH* 2-4 ACH 6-8 ACH* *vivariums Hoods Thermal Load ACH / Dilution Requirement

5 Lab/Vivarium Demand Controlled Ventilation Vary min ACH rate by sensing room IEQ If room air is clean, maintain low dilution airflow When contaminants detected, Increase airflow Set min dilution level at 4 or even 2 ACH One option is run at 4 ACH occupied & 2 ACH unocc. Set max dilution to ACH for safest purge Typically set max ACH to max capacity of valves Critical piece: Sensing of IEQ parameters: Lab TVOC s, particles, RH, CO, & CO2 New cost effective sensing approach required

6 10) CO2 (%) CO2 (ppm ) ( F) CO (ppm) Ozone (ppm) A New Approach: Multiplexed Sensing Routes multiplexed air samples to central sensors Integrated into BMS for monitoring & control Includes web based data collection & analysis Sensor Suite Web Analysis Executive Summary Area Summary - Accounting cubicles Building Data Summary Historical Summary Test Area Highlights Headquarters - Building Overview Test Dates Start Dates Hours Tested 12/16/2001 6:53:00 AM 22:28 The following table presents the reader with a very high-level view of the building perfo rmance in three performance categories. Any review suggested at this level refers to further reading within this report. A complete listing of individual area and sensor ratings can be found in the Results Summary immediately following this section. Within guidelines or recommended levels Review Review Improvement No action required suggested possible suggested Accounting cubicles Lara office M arketing Comfort and Ventilation - Assessment Comfort and Ventilation Air Cleanliness Building Pollutants CO2 Temperature Relative Particles (PM Humidity This category applies to those parameters normally associated with comfort, but are not necessarily health related. Temperature, relative humidity and carbon dioxide are included. Carbon dioxide in this case is used as an indicator of ventilation in the building since the primary source is occupants, and is not normally considered a pollutant. Summary CO2 Temperature (ppm) ( F) Relative Humidity CFM (Outdoor Air PP) A verage Values Extreme Values N/A Typical/Comfort < > 15 R ecommended < > 15 Within guidelines - no action Within guidelines - improvement possible Outside guidelines - Review Outside guidelines - Review required suggested The data gathered by the Optima system during the building s occupied hours is summarized below. The average values are shown for each area tested (please note that the carbon dioxide reported value is not the average), and are compared to typical values seen in similar buildings to those recommended by industry guidelines and standards. Values outside these guidelines are highlighted and are further explained in each area analysis section. Data collected during unoccupied hours is also screened by the expert system and is noted where appropriate on the individual area sections of the rep ort. Average Values - Occupied Hours Particles (PM 2.5) TVOC CO Radon Ozone Comfort and Ventilation Air Cleanliness Building Pollutants Comfort and Ventilation - This category applies to those parameters normally associated with discomfort, but are not necessarily health related. Temperature, relative humidity and carbon dioxide are included. Carbon dioxide in this case is used as an indicator of ventilation in the building since the primary source is occupants, and is not normally considered a pollutant. Air Cleanliness This category includes those parameters to which standards do not necessarily apply, but which may still be the source of occupant complaints within the building. These parameters include particles and Total Volatile Organic Compounds (TVOC). In this case, values in the building are scored against values typically associated with occupant discomfort based on documented case studies. Building Pollutants - This category includes those parameters classified as potential pollutants within buildings, and are scored against regulatory standards. They include carbon monoxide, radon and ozone. Most are typically found at low levels in most buildings. When moderate to high levels are found, simple cost-effective solutions are typically available to bring levels within guidelines. Comfort and Ventilation Air Cleanliness Building Pollutants Temperature Relative CFM (Outdoor PM 10 PM 2.5 TVOC Radon Humidity (%) Air PP) (µg/m3) (µg/m3) (index) (pci/l) Accounting cubicles Lara office M arketing Typical/Com fort < > 15 < 40 < 20 < 10 < 3 < 2 < 0.1 Recommended < > 15 < 40 < 20 < 35 < 9 < 4 < 0.1 Under the conditions of this test, and based on carbon dioxide levels, the amount of outdoor air to this area meets or exceeds the currently accepted guideline and no action is required. During this testing period, the area temperature was outside of Typical/Comfort guidelines as well as being outside of recommended guidelines and should be reviewed. (Percentage of time outside of recommended guidelines = 8%; Median of values outside recommended guidelines is 67.14). Operations Assessment o The control system (thermostat sensor, controller, and controlled device) settings, or programmed parameters may not be optimized for accurate temperature regulation. The test area thermostat may not be set or calibrated correctly. The test area thermostat may be poorly located. During this testing period, the area relative humidity was within recommended guidelines and does not require attention. Comfort and Ventilation Ratings Outside guidelines, Outside guidelines, W ithin guidelines, Within guidelines, requires attention should be reviewed improvement possible No action required This assessment uses the temperature and ventilation measurements during both occupied and unoccupied hours to assess the potential for energy savings. Existing air quality issues are taken into account in this assessme nt. A n onsite building professional is required to determine whether an actual savings opportunity exists or is appropriate. Sav ings like ly Savings possible Good Optimum Review suggested Review suggested Performance Performance Accounting cubicles Lara office Marketing Temperature 45 Relative Humidity Recommended Actions The following recommendations are suggested to improve temperature in the area: * CO2 (C arbon Dioxide) values expressed as 90th percentile ppm during occupied hours - see Test Methods and Background Information * CFM (Outdoor Area) refers to Cubic Feet per Minute of Outdoor Air per Person as calculated using ASHR AE guidelines * CO (Carbon Monoxide) * TVOC (Total Volatile Organic Compounds) * PM 2.5 (Particu late M atter 2.5 microns an d less in size) * PM 10 (Particu late M atter 10 microns and less in size) Lab Airflow Controls Room 101 Room 102 AHU 2-1

7 Multiplexed Sensing Operation Outdoor Air Probe Room 101 Room 102 Room 103 Room Sensor Sensor Suite Server Air Data Router Vacuum Pump Connectivity Web Based User Interface

8 The Multiplexed Sensing Architecture

9 2006: Case Study: Laboratory DCV Project Harvard School of Public Health FXB Bldg Varying ACH Rate based on IEQ Monitoring 5 parameters One full floor - 20 sensing locations Subject of study by Prof. Jack Spengler For presentation at 2006 Labs21 conf.

10 Simulated Spill & Response w/ Dynamic Control 40 ml acetone trash can spill Supply DP1 RS1 111 GEX DP2 RS2 RS3 Airflow from 4 to 12.7 ACH RS4 107 GEX DP3 RS5

11 Response to Particle Source by Dynamic Control Particle source off Supply DP1 RS1 GEX DP2 RS2 111 Particle source on Airflow from 4 to 12.7 ACH RS3 RS4 107 GEX DP3 RS5

12 Normal Lab Operation: Small Release Event Real world VOC release event Due to alcohol for repair of DNA Extractor Flow was fixed at 4 ACH (no control) Would have increased flow if control active Event lasted over 3 hours

13 Normal Lab Operation w/ Dynamic Control VOC event sensed at GEX Approx. 1 hour long event ACH varies 4 to 12.7

14 Normal Lab Operation w/ Dynamic Control VOC event (1.4 PPM) sensed at GEX 20 Minute Event System Increases ACH from 4 to 8

15 Actual TVOC Data: 35 Days of 2 Lab Zones FXB Lab TVOC GEX Levels Over Threshold % Time Over Threshold 1.40% 1.20% 1.00% 0.80% 0.60% 0.40% 0.20% 0.00% Potential Control Setpoint Range Threshold TVOC Values in PPM at 4 ACH Data represents about 1,675 hours of lab operation

16 2007: Lab IEQ Performance Monitoring Study Largest known study done to date 7 different sites selected 2 NE, 1 MW, 2 SC, 1 SW, 1 Cn. 4 Univ, 1 corporate, 1 gov, 1 hosp 85 Different lab areas observed Largest site: 28 areas, Smallest site: 2 areas Research: Life sciences, bio, physical chem, etc Almost all low density labs w/ dynamic control Some animal facility areas ~ 200 more lab areas of dynamic control in construction & were not part of this study

17 Lab IEQ Performance Monitoring Study Covers about 250,000 lab operating hours Data taken primarily from January to August 07 Approximately 4 million sensor values recorded Lab TVOC s: Measured with PID type TVOC sensor Particles: laser based particle counter -.3 to 2.5 u. Values shown are differential measurements vs. Supply air Should be room generated, not from supply/oa CO2: Measured with lab grade NDIR sensor Dewpoint: Lab grade infrared spectrometer

18 Average of TVOC Data for All Sites: 250K Hrs Using LEED flush-out of 0.18 PPM: Energy saved 99.3%

19 Average of TVOC Data for All Sites: 250K Hrs On average each lab has 4 events (1 hour) each week that need a higher ACH control action

20 TVOC Percentile Values by Lab Area: Lab areas vary but all have significant savings Some low value labs probably not heavily used University labs in summer?

21 Differential Particle Levels For All Sites On average each lab has 1 particle event (15 min) per week Using LEED flush-out of 1.6M PCF: Energy saved 99.8%

22 Particle Percentile Values by Lab Area: Reasonable variation again in lab areas At 90 th percentile level lab: ~2 particle events per wk

23 Average CO2 Levels For all Sites On average each lab has 2 CO2 events (30 min) per week People, dry ice & use of CO2 for euthanasia ups levels At 1000 PPM (500 to 600 Diff. PPM): Energy Saved 99.7%

24 Example of Data for One Vivarium for One Week This point alone represents about 4 hours of time in one week! CO2 probably exceeded 3000 PPM since sensor maxed out

25 Average Dewpoint Levels For all Sites Lab Dewpoint levels varied from below 40 to 70F

26 Average Dewpoint Levels For all Sites High lab dewpoint levels could create condensation on chilled beams w/o dewpoint sensing & control

27 Dewpoint Percentile Values by Lab Area: Area where accurate dewpoint sensing is critical 90 Th % lab has dewpoint over 55F for 5% or 8 hours/wk!

28 Dewpoint Levels For One Site for One Week This represents an average of 30 minutes for each lab High lab dewpoint levels were for week of 7/5 in Texas

29 Case Study: Texas Children s s Hospital - Houston Texas Children s Hospital Houston Retrofit Project Highlights: 2 floors of life sciences labs 28 lab areas Projected $103K annual savings based on measured airflow data 0.95 year payback Integration w/ Phoenix Controls VAV

30 Texas Children s s Hospital 7 th Floor Feigin

31 TVOC Levels Comparison by Floors

32 Worst Case Lab TVOC Levels Lab area has 4 recirculating biosafety cabinets Spray bottles of alcohol are used in prepping samples Alcohol vapors pulled out of cabinets & spread to room

33 Cumulative TVOC Levels for Worst Case 9.00% Worst Case TVOC Levels vs. Time over Threshold % Time Over Threshold 8.00% 7.00% 6.00% 5.00% 4.00% 3.00% 2.00% 1.00% Even Worst Case Lab Air is Clean ~ 93% of Time 0.00% Threshold TVOC Values in PPM in Lab Mode

34 Case Study: Arizona State University Pilot Project for ASU Biodesign Institute Large life sciences retrofit at Biodesign Bldg B One Sensor Suite, 11 lab rooms monitored

35 Biodesign B Aircuity Pilot Project

36 TVOC Performance Before & With Dynamic ACH Dynamic ACH control saved energy & reduced lab TVOCs!

37 Dynamic Lab ACH Control Summary Proven approach with many lab areas Significantly cuts energy & first costs Applicable for new & existing facilities Also provides cost effective LEED points