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

Key Elements of a Smart Lab https://betterbuildingssolutioncenter.energy.gov/accelerators/smart-labs

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

NREL ESIF Lab, Data Center and Office HIGH BAY LABORATORIES

Performance Targets Data Center PUE 1.06, ERE 0.9 Office - 26.7 kBTU/sf/yr Lab – 30% Less than ASHRAE 90.1 - 2007 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.

Impact of Poor Exhaust Design

ANSI/ AIHA Z9.5 Standard Prescriptive Based Design Min. 10 ft (3.3 m) Stack Height Min. 3000 fpm (15 m/s) Extract Velocity

Section 5.4.6 Exhaust Stack Discharge Prescriptive Based Design ANSI Z9.5 Section 5.4.6 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.

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.

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...

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.

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

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

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

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

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

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

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

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

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

Case Study NREL ESIF

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

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

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

Case Study LEF-1, -2, -3

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

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 HP @ 30,000 cfm)

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 HP @ 30,000 cfm)

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

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

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

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

Questions. Otto Van Geet Otto. vangeet@nrel Questions? Otto Van Geet Otto.vangeet@nrel.gov Brad Cochran bcochran@cppwind.com For More Smart Labs Information Contact Rachel Shepherd FEMP, Smart Labs Sector Lead rachel.shepherd@ee.doe.gov