2018 HVAC, plumbing system updates

Education and collaboration will facilitate smarter building design for HVAC and plumbing systems. Technology and regulation, along with health and safety issues, will shape the design of commercial building systems in 2018 and beyond.

02/26/2018


Learning objectives 

  • Know the requirements for commercial building HVAC and plumbing systems.
  • Understand how mechanical engineers can design systems to avoid Legionnaires' disease.
  • Learn about efficiency standards for clean-water pumps.

Figure 1: The energy rating (ER) label that appears on a Bell & Gossett e-1510 4BD-4P-BP pump is similar to an Energy Star rating for appliances and is based on the pump energy index (PEI) in the DOE Energy Conservation Standards for Pumps. Courtesy: Bell & Gossett Increased emphasis on industry regulation and overall efficiency of building systems is creating the need for greater collaboration and higher-level knowledge to ensure successful project outcomes. Engineers also will be tasked with designing plumbing, and heating, and cooling systems that incorporate technically advanced components, while ensuring the comfort and safety of building occupants. Here are two things to consider in 2018 and beyond. 

Escalating the fight against Legionellosis

With the steady rise of Legionnaires' disease in the United States since 2000, the plumbing and HVAC industries are aggressively seeking product and system solutions to eradicate the often-fatal disease.

The disease is spread when contaminated water is disseminated through a water system, most often in aerosol form, spray or mist, and manifests as pneumonia in affected individuals. According to the Occupational Safety & Health Administration (OSHA), primary sources of exposure to contaminated water in commercial and industrial facilities are plumbing and HVAC systems—potable water sources such as domestic hot and cold water as well as cooling towers or fluid coolers.

More than 6,000 cases of Legionnaires' disease were reported in 2017, up nearly 15% from the previous year, according to statistics from the U.S. Centers for Disease Control and Prevention. It's difficult to distinguish Legionnaires' disease from other forms of pneumonia, so many cases are not linked to contaminated water systems—as many as 25,000 cases annually, OSHA estimates.

Because there are no medical prevention measures for Legionellosis, the name of the disease produced by Legionella bacteria, diligent maintenance of water systems is current protocol; OSHA recommends proper maintenance and periodic inspection of systems to control growth of the bacteria.

OSHA also has developed recommendations for HVAC and plumbing system designers to consider that includes locating HVAC outdoor-air intakes so that they do not draw the mist from a cooling tower, evaporative condenser, or fluid cooler into the system. For plumbing system design, dead legs should be minimized to reduce stagnation or eliminated altogether, for example.

In recognition of the seriousness of Legionnaires' disease—1 in 10 cases result in death—the 2015 release of ASHRAE Standard 188: Legionellosis: Risk Management for Building Water Systems, which establishes minimum Legionellosis risk management requirements for building water systems.

For engineers involved in the design of centralized building water systems and components, Section 8 of ASHRAE Standard 188 outlines specific guidelines to for designers to follow.

The first step is to determine if the project includes risk factors associated with Legionnaires' disease, which most often affects the elderly or those with compromised immune systems. Examples include health care facilities and senior housing facilities.

If projects include components that have the potential to release water in an aerosol form, such as domestic plumbing fixtures, cooling towers or evaporative condensers, ornamental fountains, or even ice machines, then design engineers must adhere to Section 8 of the standard.

Section 8 also requires engineers to provide detailed construction documents that include instructions for proper balancing and commissioning of all building water systems including the procedures for flushing and disinfection.

Until such time as Legionnaires' disease can be eliminated, design engineers will continue to play an important role in keeping Legionella bacteria at bay.


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