The First Facility Management Blog

This article comes from the California Energy Commission’s PIER program. For more articles from this free resource, click here.

The ductwork that distributes conditioned air throughout many large commercial buildings is often leaky, letting air out through cracks and gaps and increasing the energy consumption of supply- and return-air fans. Efforts to address this problem have been hampered by the lack of an accurate way to measure the leakage. In addition, sound methods for comparing the efficiencies of thermal distribution alternatives, such as air versus water or central versus distributed systems, have not been available.

To address the problem of duct leakage in large commercial buildings, researchers have now developed effective ways to measure leakage and have defined a metric—“HVAC transport efficiency”—that can be used to compare the relative performance of various types of thermal distribution systems. In addition, researchers have adapted Aeroseal, an effective residential duct-sealing system, for use in sealing leaks in large commercial facilities.

Features and Benefits
Three key activities can help to quantify and cut energy losses due to duct leakage.
Measuring leakage. Researchers tested two duct leakage diagnostics and found that one reliably measured duct leakage airflows. Monitoring airflows entering and exiting the duct system provides an accurate measurement of leakage and is much easier to accomplish and more accurate than trying to infer duct leakage rates from pressurization tests. The major challenge in using this approach is being able to measure airflows exiting the multiple supply grilles that are found in a commercial building’s air distribution system. Researchers have now identified a system that is able to measure output airflows through 100 ventilation grilles in less than two hours.
Applying a new metric. To enable the industry to set standards for tighter distribution systems, researchers defined a new metric for distribution system efficiency. HVAC transport efficiency indicates the overall efficiency of the thermal distribution system in a large commercial building. It’s defined as the ratio between the energy used to transport heating and cooling media and ventilation air throughout the building, and the total thermal energy delivered to the various zones in the building. Transport energy includes all energy consumption by distribution fans, ventilation fans, and/or distribution pumps (excluding domestic hot water pumps). The thermal energy delivered is the sum of all zone loads. This ratio can be calculated both over the course of the year and under design conditions. It’s useful for comparing the relative performance of various types of thermal distribution systems (air versus hydronic or distributed versus central systems) and for setting a baseline performance standard for all such systems.
Sealing leaks. To seal leaky ducts in large commercial buildings, researchers modified a technology called Aeroseal, which has been used successfully in small commercial and residential buildings. The system features an adhesive aerosol spray that diffuses throughout the duct system, gradually building up into flexible seals at holes, cracks, and other areas of leakage. To enable the use of Aeroseal in large, complex ductwork systems, the researchers had to develop a new atomizer capable of delivering an increased flow of aerosol sealant into the ducts. In addition, when used in larger commercial buildings, the system requires multiple injection points for the sealant, in contrast to the single-location method used for homes or small commercial facilities.

Reducing duct leakage can have a significant impact on energy consumption and electricity demand. The researchers found that buildings with 15% duct leakage must use 25% to 35% more fan power to distribute air than if there were no leakage. In California, eliminating duct leakage airflows in half of all existing large commercial buildings could save about 560 to 1,100 gigawatt-hours annually (about $60 to $110 million per year, or the equivalent consumption of about 83,000 to 170,000 typical California houses) and about 100 to 200 megawatts in peak demand.

Applications
The enhanced Aeroseal technology can be used in new and existing large commercial buildings—those with over 50,000 square feet of floor area and a complex air-distribution system that features a large trunk duct with many smaller ducts connected to it.

The 2005 California Title 24 compliance process for all new large commercial buildings requires calculation of the HVAC transport efficiency metric developed in this research as part of the alternative calculation methods. Title 24 previously had no provisions for crediting energy-efficient duct systems in these buildings.

PIER is sponsoring a demonstration of the Aeroseal technology offered by Carrier Commercial Services in buildings on the University of California campus. That testing, which is scheduled to be completed by the end of 2005, will help determine what types of commercial distribution systems Aeroseal is best suited for and whether the technology is cost-effective.
Because problems associated with duct leakage in large commercial buildings have not been well-understood until now, mainstream building energy simulation programs such as EnergyPlus and DOE-2.2 have not included duct leakage models. PIER is funding work to incorporate models for leakage in large duct systems in both the EnergyPlus and DOE-2.2 building simulation tools.

About PIER:
This project was conducted by the California Energy Commission’s Public Interest Energy Research (PIER) program. PIER supports public-interest energy research and development that helps improve the quality of life in California by bringing environmentally safe, affordable, and reliable energy services and products to the marketplace.

Collaborators:
The organizations involved in this project include the Lawrence Berkeley National Laboratory, the U.S. Department of Energy, and Carrier Commercial Services.

Contacts:
Carrier Commercial Services, Mark Modera, mark.modera@carrier.utc.com
California Energy Commission, Martha Brook, mbrook@energy.state.ca.us, 916-654-4086
California Energy Commission, Norman Bourassa, njbouras@energy.state.ca.us, 916-654-4581.

Stephen P. Ashkin, president of Bloomington, IN-based The Ashkin Group – and a Green cleaning expert – applauded outgoing New Jersey Governor Richard J. Codey’s executive order mandating the purchasing of environmentally friendly cleaning products by all state agencies. Commenting on Executive Order No. 76, Ashkin called the move part of a growing trend for state agencies to implement green cleaning programs.

“The executive order requires the State of New Jersey to figure out what is Green,” said Ashkin. “Obviously, we would like it to be consistent with the work that has already been done on the issue so that it does not create barriers for our industry or add unnecessary costs for public agencies.”

Executive Order No. 76, effective immediately, allows for the exhaustion of existing cleaning inventories and provides for the training of cleaning staff.

It directs the New Jersey departments of Treasury, Health, Senior Services, and Environmental Protection to establish guidelines to implement the program; the Department of Treasury will provide the governor and legislature with a report assessing the program within one year.

The order states that, “All state departments, authorities, and instrumentalities with purchasing responsibility shall procure and use cleaning products having properties that minimize potential impacts to human health and the environment, consistent with maintaining the effectiveness of these products for the protection of the public health and safety.”

“It also encourages county, municipal governments, and school districts not expressly subject to the requirements of the order to review their purchasing and use of cleaning products,” says Ashkin. “This is very significant and reflects the apparently unstoppable trend toward healthier, green cleaning.”

This Web exclusive comes from Leslie North, PE and Jack Black (pictured below)

Electromagnetic Interference, or EMI, has been a subject of considerable discussion, regulation, and public concern for years. While the effect of EMI can be as insignificant as a buzz on the car radio when driving underneath a power line, it can also be catastrophic, such as when interfering with the proper functioning of a life support monitor in a healthcare facility or compromising the operational integrity of sensitive safety equipment.

While many of the most frightening EMI-related events tend to occur in medical or scientific research environments, the potential for EMI-related problems exists across the spectrum of commercial, institutional and industrial facilities. In these environments, EMI can cause significant problems with computers, industrial process controls, security systems, electronic test equipment, intercoms, climate control systems, cyclotrons and even electro-explosive devices, to name just a few examples.

Consequently, minimizing the potential for EMI-based events has become increasingly important in the design and fit-up of many facilities, even in situations where EMI-based problems aren’t likely to cause injury or death. Downtime, production errors, communications failures and invalid test results represent just a few of the potential problems facility design & management teams need to prevent.

Fluorescent Lighting as a Source of EMI
One piece of equipment common to almost all non-residential facilities with the potential of creating unwanted EMI-based events is the ubiquitous—yet often overlooked—fluorescent lighting fixture.

Back when magnetic ballasts were the norm, design of EMI-sensitive spaces called for lensed fluorescent troffers with an EMI filter on the line side of the 60 Hz ballast and an RFI grid lens covering the lamp chamber. Although often compromised by ineffective manufacturing processes, this remedy was effective enough for most applications.

Electronic Ballasts: Changing the Rules
With the advent of high frequency electronic ballasts, however, these traditional “fixes” no longer sufficed. Electronic ballasts operate at significantly higher frequencies than their 60-cycle magnetic predecessors, effectively turning the fluorescent lamp’s arc into a an emitter of radio frequencies high enough to defeat the mitigating potential of both the EMI filters and the RFI grid lenses used with magnetic ballast fixtures.

Concerned facilities teams often avoided the problem simply by specifying old-style magnetic ballasts; doing so in this age of high-energy costs and mandated energy conservation, however, is no longer realistic. Today, the considerably more energy-efficient electronic ballasts are all but required in many states in order to meet lighting power density or overall facility energy consumption regulations, while magnetic ballasts aren’t even available for many of the newer fluorescent lamps.

Fortunately, approaches to emissions control have now been developed for electronic ballast-equipped fixtures, though the fixture’s design and construction quality remain crucial since high frequencies can exit the fixture through even the smallest hole or gap.

Proactive Instead of Reactive
Despite the expanding presence of EMI-sensitive equipment in a variety of facility types, the need for proactive, the value of prevention-based design is often underestimated, with responses to concerns about lighting and EMI often being: “I’m not aware of lighting causing EMI problems on my last job, so I don’t need to worry about this one either.”

Identifying the source of an EMI event after it’s occurred, however, can be extremely difficult due to the number of confounding variables that can come into play, from the quantity and type of potentially offending devices and issues of their electromagnetic compatibility with other devices—to changes in atmospheric conditions, unstable electrical loads, voltage spikes and other power system irregularities. As a result, identifying lighting as the problem after the fact may be highly problematic.

Clearly, the most effective means of eliminating light fixtures as an EMI source is by ensuring they perform as they should in the first place. Fortunately, there are now fixtures effective at trapping EMI-producing electrical energy within the fixture itself. The question that remains is how to be sure the fixtures you choose will perform as needed.

A Patchwork of Standards
As is the case with many critical product types, a performance specification based on an appropriate standard is the safest approach.

The European Community (EC) has instituted stringent requirements for electrical or electronic devices that could generate harmful electromagnetic interference. The EC standards include specific requirements for emissions—both conducted and radiated—plus immunity standards requiring that these same devices function normally in the presence of electromagnetic interference. Though we might expect equally clear and comprehensive standards for lighting and EMI here in the U.S., identifying the appropriate ones can be confusing.

While it would be convenient to simply apply EC standards to U.S. projects, the testing standards aren’t transferable because of the different voltage & frequency characteristics of European electrical systems.

Currently, the one mandatory U.S. legal standard for fluorescent luminaires comes from UL, but UL listings are limited to electrical and fire safety only. The Federal Communication Commission (FCC) issues testing standards for electromagnetic compatibility (EMC) between electronic devices, plus standards for the maximum electromagnetic emissions from certain types of electrical equipment, but the FCC’s requirements for lighting apply to RF lighting devices and ballasts only (instead of complete fixture assemblies) and don’t cover radiated emissions.

Further complicating the standards issue, the Food & Drug Administration (FDA) has the authority to require medical devices to comply with certain EMC standards that fall outside FCC authority.

Trying to understand and correctly apply different aspects of different standards from different agencies and organizations is a daunting task. It’s also hard for facilities personnel to defend the time and expense of commissioning tests to meet what boils down to a patchwork of standards, particularly when some ballast manufacturers tend to oversimplify and understate the issue by responding that their electronic ballasts “meet FCC requirements.”

Military Standard 461E
Until an American regulatory agency, professional society, or industry organization creates a comprehensive standard for electromagnetic emissions from light fixtures, the recognized standard that can be effectively applied is Military Standard (Mil Std) 461E.

461E is mandatory for certain military installations, including military hospitals, and voluntarily for other public and private applications. 461E represents a significant advance over earlier versions, such as version 461C, under which the potential for unwanted occurrences to be accidentally missed was substantially higher. Testing measurements required in accordance with Mil Std 461E are specific to both the fixtures radiated and conducted emissions, with the maximum allowable amounts of emitted energy based both on frequency range and field strength.

The most effective test procedures within 461E (when dealing with lighting fixtures) are those sections pertaining to requirements for Navy Fixed and Air Force limits for electronic devices. These limits are more stringent than those required by FCC or EC standards, as the specific tests outlined under test methods CE 102-1 (for conducted emissions) and RE 102-4 (for radiated emissions) are designed to emulate “worst case” operating conditions, making them the most appropriate and effective standards currently available. Consequently, fixtures that meet the Military Standard pose a significantly lower risk of creating unwanted EMI-based events. Further, the standards are reasonable, definable and easily defensible.

Government Certified Labs
These Mil Std procedures require specialized test equipment, such as line impedance stabilization networks, spectrum analyzers, specially tuned antennae, EMI receivers and current clamps & probes, and not all testing labs are capable of accurately performing the required tests. So, when evaluating a fixture’s test results, make sure the tests have been performed by a qualified independent laboratory accredited by the NIST and/or the US Dept. of Commerce to have both the equipment and the expertise to perform these tests with procedural exactness. Also check the application distances used in the tests, since some labs measure electromagnetic emissions from as far away as 10 meters when the appropriate distance is one-meter.

While we should be able to expect comprehensive U.S. EMI standards sometime in the future, in the meantime facilities managers can minimize the potential for costly and potentially dangerous EMI problems from fluorescent lighting by requiring that fixtures meet Military Standard 461E– an often overlooked standard that provides the best protection currently available.

The complete Mil Std 461E text can be downloaded (in PDF format) here.

Sample Specification
Looking for the correct specification language? Try the following:

Provide complete luminaire (luminaire defined as a complete lighting unit including lamps and parts required to distribute the light, position and protect lamps, and connect lamps to the power supply) meeting requirements CE-102-1 for conducted emissions and RE-102-4 for radiated emissions of Mil Std 461E for all luminaire operating parameters. Measurements to be taken one meter from source.

We also recommend that health care equipment specifiers/purchasers also require equipment to meet the CS and RS portions (as applicable) of standard 461E.

How electronic ballast-equipped fluorescent fixtures produce EMI
Unwanted electromagnetic energy, in the form of an electromagnetic field and propagated as radiated emissions, is a common phenomenon of electronic ballast-equipped fluorescent fixtures. The unwanted energy generated from the ballast can couple on to any wire or cable, light bulb, or ungrounded lighting fixture, and emit unwanted interference into the airwaves. This energy can also couple on to power lines that other devices are plugged into, causing unwanted energy to enter those devices.

An important – though often overlooked fact — is that ceiling-mounted fixtures in multi-storey buildings not only affect the space they’re lighting, but also the space immediately above the lighted area.

Jack Black is a senior member of the Institute of Electrical and Electronic Engineers (IEEE) and Chairman of the IEEE Electromagnetic Compatibility Society chapter in Chicago. He has over 18 years experience in electromagnetic compatibility and has published numerous technical articles on the subject. Black is on the staff of D.L.S. Electronic Systems, Inc., an EMC and product safety testing laboratory in Wheeling, IL.

Leslie North, PE, LC, LEED AP is a member of IALD and IESNA and serves on numerous committees including the Healthcare Lighting Committee. Founder of Aurora Lighting, an independent lighting consultancy, North has been lighting consultant for projects including the RIA Science Center for Argonne National Laboratories, O’Hare International Airport, and provides ongoing lighting design and consultation to Northwestern Memorial Hospital.