Second Stakeholder Meeting for Variable Exhaust Flow Control

Transcription

1 Second Stakeholder Meeting for Variable Exhaust Flow Control March 7, 2017 Jared Landsman

2 Agenda 1. Background 2. Proposed Code Changes 3. Technical and Market Barriers 4. Compliance and Enforcement 5. Cost-Effectiveness and Energy Impacts 6. Next Steps 2

3 1. Background 3

4 System Description: Conventional Stack Exhaust Releases lab exhaust at height above air intakes at low discharge velocity Requires tall exhaust stack Source: Greenheck Fan Corp. 4

5 System Description: Induction Exhaust Fans Entrains outdoor air, combined with lab exhaust, to achieve larger momentum higher effective plume height Allows for shorter exhaust stack exhaust stack not visible from line of sight more aesthetically pleasing Provides equivalent level of safety as conventional stack Source: Greenheck Fan Corp. 5

6 System Description: Induction Exhaust Fans Effective plume height (h e ) dependent on: Stack height (h s ) Mass flow rate Exit velocity (V) Windband diameter (d) Wind speed (U) h e = 3Vd U + h s ASHRAE Laboratory Design Guide Equation 9-2 Source: Greenheck Fan Corp. 6

7 System Description: Induction Exhaust Fans Concentric nozzle Uniform velocity profile Low turbulence within plume Bifurcated nozzle Widely varying velocity profile High turbulence within plume Cannot achieve plume rise of conventional system Bifurcated nozzle velocity profile, Concentric nozzle velocity profile Testing the Applicability of Briggs Equations to Lab Exhaust Fans 7

8 System Description: Induction Exhaust Fans Induction exhaust fans require higher fan power than conventional stack exhaust Laboratories for the 21 st Century: Best Practices 8

9 System Description: Rooftop Anemometers Effective plume height highly dependent on wind speed Low wind speed higher effective plume height Rooftop anemometer control of exhaust fan allows for: Lower fan energy consumption during low wind speed events Source: Safely Cut Your Laboratory Energy Usage in Half, Labs21 9

10 System Description: Rooftop Anemometers Effective plume height highly dependent on wind speed High wind speed lower effective plume height Rooftop anemometer control of exhaust fan allows for: Safer air quality during high wind speed events Source: Safely Cut Your Laboratory Energy Usage in Half, Labs21 10

11 System Description: Chemical Monitor Monitoring chemical concentrations inside exhaust stack can: Allow for reduced fan speed when chemical concentration is below health limit Ramp up fan speed for safer air quality when chemical concentration is above health limit Source: Saving Energy in Lab Exhaust Systems, ASHRAE Journal 11

12 System Description: Staging Exhaust Fans System operates with fewer fans at minimum building demand conditions and adds fans as needed to match demand Fewer fans running exit velocity for safe dilution needed from less fans reduced flow Source: Saving Energy in Lab Exhaust Systems, ASHRAE Journal 12

13 Relevant Code History Existing requirements in Title 24, Part 6 Prescriptive requirement for all laboratory exhaust systems with minimum ventilation rates of 10 air changes per hour (ACH) or lower to be designed for variable volume control (added 2013 Cycle) Source: Safely Cut Your Laboratory Energy Usage in Half, Labs21 13

14 Relevant Code History Other Relevant Code Requirements ANSI Z9.5: Laboratory Ventilation Minimum 10 feet above roof line Minimum exhaust discharge velocity of 3,000 fpm NFPA 45: Standard on Fire Protection for Laboratories Using Chemicals Height and velocity sufficient to prevent re-entry of chemicals Minimum 10 feet above highest point on roof Source: ANSI Z9.5, NFPA 45 14

15 Relevant Code History Other Relevant Code Requirements ASHRAE Fundamentals Chapter 24: Airflow Around Buildings ASHRAE HVAC Applications Chapter 45: Building Air Intake and Exhaust Design ASHRAE Laboratory Design Guide Chapter 9: Exhaust Stack Design Industrial Ventilation: A Manual of Recommended Practice for Design Section 5.12 Discharge Stacks University of California Lab Safety Design Manual Source: ASHRAE Handbooks 15

16 Typical Practices Design for constant ASHRAE design wind speed toward inlets Run fans at high speed even during favorable wind conditions and low contaminant conditions 16

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18 2. Proposed Code Changes 18

19 Proposed Code Change Proposed measure will impact the selection and implementation of laboratory exhaust systems Anticipated change to prescriptive code Comply with ANSI Z9.5 requirements for exhaust Limit power consumption for process discharge exhaust fans If prescriptive fan power limit cannot be met, comply with at least one of the following pathways towards compliance Control fan by rooftop anemometer Control fan by contaminant sensor Stage multiple exhaust fans 19

20 Why Are We Proposing This Code Change Lab and process facility exhaust power demand currently unregulated No existing baseline for lab and process facility exhaust power Achieve significant energy savings Align with model codes Provide builders with flexible means of compliance 20

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22 3. Technical and Market Barriers 23

23 Technical and Market Barriers All exhaust fans must be capable of wind speed or contaminant concentration control Most fans on the market already equipped Addition of variable frequency drive is cheap 24

24 Technical and Market Barriers Assumption that induction exhaust fans are more effective at diluting pollutants without wind speed control Will not be an issue if system is designed properly Air intake located out of reach of exhaust plume Dispersion analysis by wind consultants Potential for ensuring safer conditions for high wind speed situations 25

25 Technical and Market Barriers Hesitancy from building owners to rely on wind sensor or contaminant sensors to ensure safe discharge of pollutant exhaust Periodic calibration of the rooftop anemometer or contaminant sensor should ensure persistence of safe discharge Numerous validated products on the market 26

26 Technical and Market Barriers Necessity of dispersion modeling Employment of wind consultants can be a costly addition to project Safe conditions for building occupants cannot be met without wind analysis Safety should be placed above additional first cost 27

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28 4. Compliance and Enforcement 29

29 Compliance Process Design Phase Manufacturers ensure products are code compliant (capable of wind speed or contaminant control) Mechanical designers guarantee exhaust system is designed to code More collaboration between mechanical designers, controls engineers and wind consultants Controls engineers specify sensitivity and calibration of any sensor chosen for code compliance 30

30 Compliance Process Permit Application Phase Permit office reviews permit submittal for code compliance, issues construction permit, issues occupancy permit, and installation review Check that all equipment (variable frequency drives, sensors, etc.) specified correctly 31

31 Compliance Process Construction Phase Installers select and install exhaust system For some pathways to compliance, install rooftop anemometer or exhaust stack contaminant sensors Increased collaboration between installation teams 32

32 Compliance Process Inspection Phase Inspectors conduct inspection of exhaust system to ensure all equipment installed properly Confirm that all sensors are installed properly New certificate of installation form Inspectors conduct acceptance test of exhaust system to ensure all equipment operating as required New acceptance test requirements to certify that exhaust fans are controlled correctly and all sensors are calibrated Inspections must coordinate with all other agencies that currently conduct inspections related to lab pollution 33

33 Compliance and Enforcement Barriers Difficulty to verify effective dilution of pollutants with wind speed control or contaminant sensors Ideas are welcome! 34

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35 5. Cost-Effectiveness and Energy Impacts 36

36 Definition of Baseline and Proposed Conditions Model Assumptions Operating 9AM-5PM Exhaust airflow rate of 10 ACH 40% turndown during unoccupied hours Desired effective plume height of 20 ft Static pressure of 2.5 in Max contaminant concentration of 400 (μg/m3)/(g/s) Labs of size 1,000 sf, 2,000 sf, 5,000 sf, 10,000 sf, and 20,000 sf Fans sized for 10 mph wind speed 50% facilities containing targeted technology Baseline Conditions Fans running for assumed constant 10 mph wind speed* Proposed Conditions Compliant with proposed code change (fan speed varies according to local wind speed from rooftop anemometer) *Although many fans designed today assume constant wind speed of 10 mph, this can be unsafe and fans should be sized for ASHRAE design wind speed 37

37 Cost-Effectiveness Analysis Incremental Costs Per Lab Incremental First Cost Calibrated anemometer ($1,500) Low temperature range ($300) Cable ($250) Mounting adapter ($200) Bird screen ($250) Total Incremental First Cost ($2,500) Incremental Maintenance Costs over 15-year period of analysis Sensor Replacement ($1,500) Total Incremental Maintenance Cost ($1,500) Total Incremental Cost over 15/30-year period of analysis = $4,000 38

38 Cost-Effectiveness Analysis Incremental Cost Savings (Benefits) Energy Cost Savings over 15-year period of analysis Total Energy Cost Savings = range of $260,000 to $17,890,000 depending on climate zone Energy cost savings explained in more detail in following slides. Total Incremental Cost Savings (Benefit) over 15-year period of analysis = $88,520,000 39

39 Benefit-to-Cost Ratio Climate Zone Benefit to Cost Cost-effective in 16 Climate Zones If Benefit-to-Cost Ratio is over 1, measure is cost-effective. 40

40 Annual Energy Savings Per Square Foot Climate Zone TDV Energy Savings (TDV kbtu/ft 2 -yr) 15 Year TDV Energy Cost Savings ($2020/ft 2 ) , ,

41 Annual Energy Savings Per Square Foot Climate Zone Annual Electricity Savings (kwh/ft 2 -yr) Annual Natural Gas Savings (kwh/ft 2 -yr) Peak Electric Demand Reduction (kw/ft 2 )

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43 6. Next Steps 45

44 Next Steps Please send any additional feedback within 2 weeks to: CASE Author (see contact info at end of this presentation) Info@title24stakeholders.com Keep an eye on Title24Stakeholders.com for: Presentations from today s meeting Draft Code Change Language Notes from today s meeting Draft CASE Report (will be posted in April) 46

45 Thank you. Jared Landsman 47

46 Appendix 48

47 References Title24Stakeholders.com EnergyCodeAce.com See Reference Ace for 2016 Standards, Appendices, and Compliance Manuals California Energy Commission 2019 Standards Webpage Advanced Exhaust Dispersion Design Laboratory Standards and Guidelines Market Assessment of Energy Efficiency Opportunities in Laboratories Modeling Exhaust Dispersion for Specifying Acceptable Exhaust/Intake Designs Saving Energy in Lab Exhaust Systems Specifying Exhaust Systems That Avoid Fume Reentry and Adverse Health Effects 49