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.
- 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.
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.
The implementation of Department of Energy efficiency standards for clean-water pumps is another topic that will be top of mind among the engineering community in 2018. As the pump industry continues progressing toward the January 2020 compliance date, design engineers should keep abreast of updates so they can make informed decisions in the specification process.
The Hydraulic Institute (HI) has established a new designation to encourage the purchase of high-efficiency pumps called the energy rating (ER). It’s 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.
Products with the ER label are listed in a database on the HI ER Program Portal, searchable by manufacturer, model number, and rating ID listed on the hydraulic energy rating label distributed with the pump (see Figure 1).
In establishing the PEI metric to rate the performance of pumps, the DOE offered manufacturers testing methods for both constant load and variable-load equipment classes. Pumps that meet the standard are assigned a PEI value of 1 or below. PEICL applies to pumps sold without variable-speed controls; PEIVL applies to pumps sold with variable-speed controls.
Figure 2 illustrates the improvements to pump efficiency after hydraulic redesign using the DOE’s PEICL calculation.
The second testing method, PEIVL, applies to pumps sold with variable speed controls. Variable speed drives (VSDs) often are applied as an addition to existing systems to increase overall efficiencies.
By including the PEIVL method in the standard the DOE had wanted to encourage VSD use to further improve efficiency of pumping systems. When a VSD is installed properly, pumps can work more efficiently, thereby extending product life, reducing energy consumption and decreasing electrical system stress.
Just as the 80SC and redesigned e-80SC pumps calculated for PEICL realized a 6% energy savings in Figure 2, when applying a VSD to the same two pumps and calculating PEIVL, an additional 6% increase in energy savings can be achieved as illustrated in Figure 3.
Even though putting a VSD on an inefficient pump achieves the PEIVL rating-acceptable under the DOE test procedures-the non-compliant pump has not been upgraded for efficiency and would not meet the DOE’s standard for PEICL if tested on its own. This opens the door for manufacturers to avoid costly and time-consuming upgrades to their product line offering.
In order to ensure hydronic HVAC and plumbing systems are being designed from the start with the most efficient pumps, engineers should look at both PEICL and PEIVL.
It’s also important to underscore that the DOE standards for pump efficiency are just the starting point—even greater energy efficiencies can be realized if designers continue to seek smarter ways to specify pumps and stay abreast of industry advances and new technologies.
Government and industry regulations focused on reducing energy consumption in commercial buildings will continue to drive innovation of products for hydronic plumbing and heating and cooling systems.
For example, requirements within ASHRAE Standard 90.1-2013: Energy Standard for Buildings Except Low-Rise Residential Buildings are facilitating an increased use of heat exchangers in commercial buildings. As such, heat exchanger design and effectiveness are advancing to help buildings operate more efficiently through waterside economization.
To provide engineers with the information to make accurate and appropriate selections, intuitive selection programs, provide engineers with the tools to optimize designs by easily entering and comparing various system parameters for heat exchangers, such as temperature approach and pressure drop, until they find the best solutions in terms of performance, cost, and energy efficiency for a particular project.
Third-party certification is another valuable tool for engineers in the specification process. The Air-Conditioning, Heating & Refrigeration Institute’s (AHRI) Liquid to Liquid Heat Exchanger (LLHE) certification program is based on AHRI Standard 400 for gasketed plate-and-frame type heat exchangers. Certification provides assurance that the equipment will perform accurately and consistently and ensures all manufacturers are building to the same tolerances.
The desire for HVAC and plumbing systems to automatically integrate with building systems and provide instant performance diagnostics on flow, head, and energy consumption is creating a demand for pumps with embedded diagnostics and advancing sensorless control of pumps. With sensorless technology, the speed of the pump is adjusted based on control curves rather than stand-alone differential pressure sensors.
Technology and regulation, along with health and safety issues, will shape the design of commercial building systems in 2018 and beyond. Education and collaboration among engineers, architects, building owners, manufacturers, contractors, and facility managers will be the keys to designing buildings that will ensure a sustainable and safe future.
Kyle DelPiano is the Xylem AWS business development manager—commercial building services market. He has nearly 10 years of experience in the HVAC industry in a variety of sales and training roles.