Damper and Air Economizer Leakage Requirements in U.S. Energy Codes and Standards Article

AMCA inmotion magazine supplementIn the AMCA inmotion magazine supplement to the Summer ASHRAE Journal the latest damper and air economizer leakage requirements in U.S Energy Codes and Standards are discussed in detail including California title 24.

This article illustrates how controlling the movement of air both in and out of a building is critical to ensuring proper IAQ (Indoor Air Quality) with the added benefits of minimizing energy consumption, averting condensation, and generally maximizing the total comfort levels of the building’s occupants.

The maximum allowable leakage requirements in energy codes and standards for non-residential building envelopes are examined.

The codes and standards covered are as follows:

Similarities and distinctions are highlighted between the damper leakage requirements in the 2015 IECC and the 2013 version of ASHRAE 90.1.

cd50 - Low Leakage DamperDampers are shown to be a key component in controlling air intake, exhaust and leakage associated with a building. The types of dampers covered include outdoor air intake and exhaust opening dampers, including those used for economizers.

It is concluded that to ensure compliance with all three building regulations, dampers and air economizers should be purchased with Class 1 performance certification under the AMCA Certified Ratings Program. Building owners and engineers can then be assured in the knowledge that the required leakage performance will be met by the dampers they specify meeting AMCA Class 1.

To read the complete article in detail from the AMCA inmotion magazine supplement Click HERE

Low leakage dampers Class 1Applicable Low Leakage Dampers

Ruskin offers both CD50 and CD60 Class 1A dampers. The CD50 damper is an extremely low leakage damper designed for use in medium to high pressure commercial HVAC systems.  It was the first AMCA licensed low leakage damper. The CD60 offers sturdy, steel construction with an interlocking frame design, enabling it to lock together without bolts, screws, or rivets that could shake loose.

For more information about Ruskin’s complete product line, application and design support, and our state-of-the-art manufacturing capabilities, contact your local Ruskin representative nearest you or Contact Ruskin directly at (816) 761-7476.

Schools and Outside Air Measurement

School Ventilation IAQIn the past, a common method to measure ventilation was to determine the difference between return air and supply air measuring stations. This difference was the approximate amount of outside air introduced into the building.

However, if each airflow-measuring station in the supply and return air was 3-percent accurate, an error rate of 6 percent for the total system air could result.

For example, if there is 100,000-cfm supply air system with a 6-percent error rate (or 6,000 cfm) compared to the requirement of 15,000 cfm outside air, the total error of the outside air system is 40 percent. This demonstrates the driving trend toward today’s more preferred system: direct measurement of outside air. By directly measuring outside air, the system designer minimizes the error and increases the accuracy.

In the last few years, several products have come into the market that are designed to directly control the outside air introduced into a building.

One method uses two outside air-measuring stations to control the outside airflow through the unit. One station is designed for 25-percent airflow and the other sized for 75-percent flow.

The control scheme is designed to keep the pressure signal viable for control. These stations stage their operation to keep the signal pressure useable, thus maintaining ventilation rates.

Another method integrates an air-measuring station into an outdoor air intake louver. Stability and control signals are amplified in this scheme, since air is measured at the highest velocity point in the outside air system. It is important that the manufacturer test this as a package. The louver can impact the performance of the air-measuring station if it is not designed and tested as a combination.

The fan-injection method consists of a separate fan and air-measuring station and is used to control the minimum outside air introduced into the HVAC system. These types of systems require extra space to install. Also, the extra energy required to operate the injection fan must be taken into consideration. It is possible that the injection fan could overpower the system and relieve air through the outside air damper.

Measuring and controlling outside air with an integrated air measuring station/damper assembly is becoming more popular. For constant-volume applications, these are usually set up to maintain minimum ventilation; a separate, standard damper for economizer operation obtains free cooling.
Accuracy is increased in measuring and controlling the minimum outside air versus the total air because the signal (or velocity pressure) from Pitot arrays is limited to 300 to 400 fpm on the low end. (The velocity pressure at that point is only 0.01 inches wg.)

Typical commercially available transducers have limited accuracy at these low pressures. By directly measuring and maintaining minimum ventilation rates, again the error rate is minimized.

louverMeasuring Air Quality

Ruskin has the most comprehensive line of air measuring and control solutions in the industry. Products include differential pressure probes for high velocity applications, combination units that measure and maintain flow, and highly sophisticated, intelligent solutions that incorporate thermal dispersion technology with microprocessor based controls that communicate with any building automation system.

For more information about Ruskin’s complete product line, application and design support, and our state-of-the-art manufacturing capabilities, contact your local Ruskin representative nearest you or Contact Ruskin directly at (816) 761-7476.