UC IrvineCentralized Demand Controlled Ventilation

The Commissioning, Lab Safety, and Energy Savings Tool

Goal: Manage Laboratory Ventilation Rate with Centralized Demand Control

Objectives: At the end of this session, you will be able to:

2. Evaluate design capabilities of a centralized demand control ventilation (CDCV) system.

3. Delineate variables and assess relative impact of a CDCV installation.

4. Specify additional features to ensure user safety and energy efficiency.

5. Resolve commissioning requirements of a CDCV system.

Laboratory Ventilation Performance: Comparing Centralized Demand Control and Zone-Occupancy Control Systems

Implementation and Testing Problems Abound

Centralized Demand Controlled Ventilation: The Commissioning, Lab Safety, and Energy Savings Tool

The intention of our testing was to determine whether occupancy based controls could be as effective at saving energy as a full CDCV system.

Changes to the HVAC system resulted in unintended excessive air flows that were difficult to troubleshoot but yielded a wealth of information, energy savings,

and the conclusion to our original question.

UC Irvine Challenging standard practice• Ventilation rate minimums are often set at a “constant rate”

24/7– This is true but they don’t have to be. If the lab experiences

varied rates of use, the ventilation system should very its delivery accordingly!

• Recommended range 4 to 12 air changes per hour minimum– Working with Environmental Health and Safety, and lab

managers, UC Irvine determines the minimum air change requirements for each lab, adjust settings and documents the requirements outside the lab entrance.

• Usually excessive during low-level process activity or non-occupancy

– CDCV, occupancy sensors, and the building EMS must work in combination to achieve the maximum energy savings and provide the highest safety and reliability possible

• System architecture allows for set back based on lab pollutant concentration and occupancy

– Indoor air quality measurements and lab activity determine the air change rate above the minimum.

System Achitecture

• Occupancy Sensor

• CDCV

• EMS (Thermostat)

• Fume Hood Sash Position Sensor

• Zone Presence Sensor

• Red button (System Override)

Lab Air Control Valves

Input Output

Centralized Demand Controlled Ventilation

CDCV is a system that:

• Monitors the indoor air quality of multiple zones through a network of structured cables and air data routers

• Analyzes the sampled air with a battery of sensors

• Provides the lab air control system with an input for increased ventilation when necessary.

1. Room sensor mounted in general exhaust duct samples a packet of air

2. Packet of air is routed to the Sensor Suite

3. Sensors measure indoor air quality

4. Information Management System determines need for increased ventilation, commands VAV controllers, and serves data to a web server.

5. System monitoring is available via a web based interface.

CDCV

Added FeaturesUC Irvine seeks to continuously update the lab air control system

with safety and energy saving features

Safety

• Red Buttons

• LDU (Lab display unit)

Energy Savings

• Occupancy sensors

Red Buttons

Red Button – In the event of a chemical spill or other event requiring increased ventilation in a lab, an emergency ventilation override button has been installed. Pressing this button will increase air change rates to maximum while maintaining negative lab pressurization. This button should not be pressed in the event of a fire!

Phoenix Controls Celeris® Display Panels

● Currently in use at Gross Hall

● Programmed to display ACH, occupancy status and ventilation offset information within lab

● Provide real time feedback to lab occupants

Occupancy Sensors

Installing occupancy sensors has provided the capability to further reduce minimum air change rates during unoccupied periods.

UC Irvine’s standard is a minimum of 4 air changes per hour occupied, 2 air changes per hour unoccupied.

Retro Commissioning

1. Heat source located near thermostat. This room will always be in maximum cooling.

2. Thermostats blocked from room air flow by equipment.

3. Diffusers covered

4. Thermostats set to extreme temperatures. (High and Low)

5. Failed Poppet valves and pneumatic valve actuators

Energy savings from each effort listed above are the result of the commissioning capabilities of the CDCV system. These indirect savings would have been difficult to discover and obtain without the clear visualization of lab performance that the system provides.

Laboratory Ventilation Performance: Comparing Centralized Demand Control and Zone-Occupancy Control Systems

Implementation and Testing Problems Abound

Centralized Demand Controlled Ventilation: The Commissioning, Lab Safety, and Energy Savings Tool

The intention of our testing was to determine whether occupancy based controls could be as effective at saving energy as a full CDCV system.

Changes to the HVAC system resulted in unintended excessive air flows that were difficult to troubleshoot but yielded a wealth of information, energy savings,

and the conclusion to our original question.

Implementation and Testing Problems Abound

Soon after installation of the occupancy sensors and over ride buttons Facilities began to receive numerous complaints from the occupants that something was wrong with the ventilation system.

Investigation in both the field and using the CDCV system revealed high supply and exhaust rates.

Diagnosis is not always simple

The building occupants call a halt to our work

• Making changes to an occupied space is always difficult.

• Combine ongoing research and the HVAC system responding with unanticipated airflows and the problems are compounded.

Calibration graph from a spectrometer in Room B321, as the graph states “Up is bad”

System Design Matters

• The override buttons were originally installed as an input to the building EMS. Pressing the button would provide maximum ventilation by sending the system into full cooling. The programming of the EMS was changed raising the full cooling CFM set point to the design maximum of the valve.

• This created a problem as the system would enter cooling mode during normal operations the occupants would be blasted with cold air. In addition the cold air would send surrounding zones into heating mode.

• The solution was to return the EMS to its original configuration and rewire the buttons to the 6N1-ISO high select boards.

• This configuration works as anticipated, providing a system override without affecting performance of other systems.

Control Diagram

Monitoring Based Commissioning

The ability to visualize IAQ, ACH, temperature, and occupancy is an invaluable tool.

With a quick glance at the graphs produced by our CDCV system, the determination is made if the system is performing as expected or if more detailed investigation is required.

Room 2213 is an example that can be repeated for all but 2 labs. There are multiple zones overlapping and fighting each other. This issue has been occurring since the building was built.

Air delivery rates in 2213 are far from balanced. The zones are totally independent.

Simultaneous heating and cooling

The re-zoned lab

Eliminated the thermostats fighting each other.

Created a balanced air delivery throughout the lab.

Before After

Before

After

Which way do your lab air control valves fail?

• Examine the room requirements and determine if loss of pneumatic pressure or voltage supplied to the valve will cause the valve to fail in an open or closed position

• Supply and Exhaust valves may be set up the same or opposite depending on lab use

Occupancy without a monitoring system is problematic

• 24 months after a commissioning of the lab air control system failed parts were found

• Occupancy controls alone will not provide the commissioning tools to visually see that the lab is operating properly

• Historical data is an invaluable tool for troubleshooting the multiple systems that now make up a lab air flow system.

What does energy savings look like?

Using the CDCV system we can see room, time, and CFM savings. UC Irvine not only uses the system as an MBCx tool but we validate our savings as well

QUESTIONS ?

Information Presented Today

• CDCV The Commissioning, Lab Safety, and Energy Savings Tool– http://

• UC Irvine’s Smart Lab Retrofit Guide– http://slidesha.re/cXtEOz

• Smart Lab Buildings Presentation– http://