1. Implementing Wind Responsive VAV Exhaust Systems at NREL's ESIF Building: A Four-Year Follow-Up
Otto VanGeet, PE, NREL
Brad Cochran, CPP
I2SL -August 29, 2017

2. Key Elements of a Smart Lab

3. Smart Labs Ventilation System – Flow & Energy
Max
Energy
Exhaust
Supply
Average
Min
Courtesy of ECT

4. NREL ESIF Lab, Data Center and Office
HIGH BAY LABORATORIES

5. Performance Targets
Data Center PUE 1.06, ERE 0.9
Office kBTU/sf/yr
Lab – 30% Less than ASHRAE
Actual – low flow  CFH set to 100 FPM vs NREL standard of lowest FPM that provides containment using ASHRAE 110 tests
Ventilation rates occupied/unoccupied of 6 ACH/4 ACH (1/ 0.66 CFM/ sq. ft.) per NREL standards BUT construction did not install occupancy sensors – Need to install push button overrides to bring room out of scheduled unoccupied mode.
Wind responsive exhaust controls installed, programed but not operational – Now operational.

6. Impact of Poor Exhaust Design

7. ANSI/ AIHA Z9.5 Standard Prescriptive Based Design Min. 10 ft (3.3 m)
Stack Height
Min fpm (15 m/s) Extract Velocity

8. Section 5.4.6 Exhaust Stack Discharge
Prescriptive Based Design
ANSI Z9.5
Section Exhaust Stack Discharge
Exhaust stack discharge velocity shall be at least 3000 fpm (15.2 m/s) is required unless it can be demonstrated that a specific design meets the dilution criteria necessary to reduce the concentration of hazardous materials in the exhaust to safe levels at all potential receptors.

9. Appendix 3 Selecting Laboratory Stack Design
Prescriptive Based Design
ANSI Z9.5
Appendix 3 Selecting Laboratory Stack Design
Necessary measures must be taken to protect the laboratory building and adjacent buildings from reingestion of toxic laboratory chemical hood exhaust back into a building air supply system.

10. Appendix 3 Selecting Laboratory Stack Design
Prescriptive Based Design
ANSI Z9.5
Appendix 3 Selecting Laboratory Stack Design
Necessary measures must be taken to protect the laboratory building and adjacent buildings from reingestion of toxic laboratory chemical hood exhaust back into a building air supply system. The 10 ft (3.05 m) minimum stack height called for in the body of this standard is primarily intended to protect maintenance workers from direct contamination from the top of the stack. However, the minimum height of 10 ft is not enough by itself to guarantee that harmful contaminants would not be reingested...

11. Appendix 3 Selecting Laboratory Stack Design
Prescriptive Based Design
ANSI Z9.5
Appendix 3 Selecting Laboratory Stack Design
... Similarly, a minimum 3000 fpm (15.3 m/s) exit velocity is specified in the body of this standard, but this exit velocity does not guarantee that reingestion will not occur.

12. If Exit Velocity isn’t the metric to use then what is?
Prescriptive Based Design
If Exit Velocity isn’t the metric to use then what is?
Exit Velocity
Volume Flow Rate
Wind Speed
Stack Orientation
Building Configuration
Relative Height of Building
Location of Intakes
Presence of Penthouses or other Roof Top Obstructions
Chemical Utilization
Plume Momentum

13. Performance Based Design
“SAFE AND
ENERGY EFFICIENT”
Optimum balance between energy & air quality.
Low flow and low energy,
under-designed specifications.
Adverse Air Quality
High flow and high energy.
Typical manufacturer specifications.
Wasted Energy Potential

14. Physical Dispersion Methods
Performance Based Design
Dispersion Modeling – Wind Tunnel
Physical Dispersion Methods
You Are Here

15. Energy Efficient Design
Energy vs. Air Quality
Traditional Constant Volume System Max Load
Energy Efficient Design
15K cfm
% Open
1K cfm
14K cfm
Δ P

16. Energy Efficient Design
Energy vs. Air Quality
Traditional Constant Volume System Min Load
Energy Efficient Design
15K cfm
7K cfm
8K cfm
% Open
Δ P

17. Energy Efficient Design
Energy vs. Air Quality
Energy Efficient Design
Simple Turndown VAV Max Load
14K cfm
0.0 cfm
14K cfm
Fan Speed
% Open
Δ P
10K cfm
~15% - 20% Energy Savings

18. Energy Efficient Design
Energy vs. Air Quality
Energy Efficient Design
Simple Turndown VAV Min Load
10K cfm
2K cfm
8K cfm
Fan Speed
% Open
Δ P
~50% - 60% Energy Savings
10K cfm

19. Energy Efficient Design
Energy vs. Air Quality
Energy Efficient Design
Wind Responsive VAV Min Load High Winds
10K cfm
2K cfm
8K cfm
Wind Speed
Wind Direction
Fan Speed
% Open
Δ P
~50% - 60% Energy Savings
10K cfm

20. Energy Efficient Design
Energy vs. Air Quality
Energy Efficient Design
Wind Responsive VAV Min Load Low Winds
8K cfm
0 cfm
8K cfm
Fan Speed
% Open
Wind Speed
Wind Direction
Δ P
~70% - 80% Energy Savings
6K cfm

21. Case Study
NREL ESIF

22. Level 3 Exhaust (LEF-4,-5,-6) Level 2 Exhaust (LEF-1,-2,-3)
Case Study
Level 3 Exhaust (LEF-4,-5,-6)
15,000 cfm; 30 HP
Level 2 Exhaust (LEF-1,-2,-3)
13,000 cfm; 25 HP

23. Simple Turndown VAV Case Study LEF-1, -2, -3
Maximum concentrations met design criteria for certain wind speeds and wind directions.
Little or no turndown available – need the maximum volume flow rate under ESE wind conditions.
No Energy Savings Available w/ Simple VAV System
East Wind Direction

24. Case Study
LEF-4, -5, -6
Simple Turndown VAV
Maximum concentrations 20% less than design criteria for worst-case wind speed and wind direction.
Some Energy Savings Available w/ Simple VAV System
NW Wind Direction

25. Case Study
LEF-1, -2, -3

26. LEF-1; -2; -3 – CAV Operation
Case Study
LEF-1; -2; -3 – CAV Operation
CV Operating Point
(40 39,500 cfm)

27. LEF-1; -2; -3 – VAV Operation – 2 of 3 fans Operating (Current)
Case Study
LEF-1; -2; -3 – VAV Operation – 2 of 3 fans Operating (Current)
VAV Operating Point
(22 30,000 cfm)

28. LEF-1; -2; -3 – VAV Operation – 3 of 3 fans Operating
Case Study
LEF-1; -2; -3 – VAV Operation – 3 of 3 fans Operating
VAV Operating Point
(16 30,000 cfm)

29. Case Study Energy Savings Constant Volume 272 MW hrs/yr 555 MW hr/yr
LEF-1; -2; -3
LEF-4; -5; -6
Constant Volume
272 MW hrs/yr
555 MW hr/yr

30. Case Study Energy Savings Constant Volume 272 MW hrs/yr 555 MW hr/yr
LEF-1; -2; -3
LEF-4; -5; -6
Energy Savings
Constant Volume
272 MW hrs/yr
555 MW hr/yr
(-)
Simple Turndown VAV
217 MW hr/yr
338 MW hr/yr

31. Case Study Energy Savings Constant Volume 272 MW hrs/yr 555 MW hr/yr
LEF-1; -2; -3
LEF-4; -5; -6
Energy Savings
Constant Volume
272 MW hrs/yr
555 MW hr/yr
(-)
Simple Turndown VAV
217 MW hr/yr
338 MW hr/yr
Wind Responsive VAV
2 Fans
145 MW hrs/yr
465 MW hr/yr

32. Case Study Energy Savings Constant Volume 272 MW hrs/yr 555 MW hr/yr
LEF-1; -2; -3
LEF-4; -5; -6
Energy Savings
Constant Volume
272 MW hrs/yr
555 MW hr/yr
(-)
Simple Turndown VAV
217 MW hr/yr
338 MW hr/yr
Wind Responsive VAV
2 Fans
3 Fans
145 MW hrs/yr
92 MW hrs/yr
142 MW hr/yr
465 MW hr/yr
593 MW hr/yr

33. Questions. Otto Van Geet Otto. vangeet@nrel
Questions? Otto Van Geet Brad Cochran For More Smart Labs Information Contact Rachel Shepherd FEMP, Smart Labs Sector Lead