Warming up to Chilled Beams
Revolutionary new pump module is a game changer for chilled beam designs.
Someday, HVAC/R and plumbing engineers will look back at 2016 as the year chilled beam hydronic design was revolutionized by the emergence of the controlled chilled beam pump module (CCBPM).
Chilled beams, which are ceiling mounted coils that receive cold or hot water from a pipe loop, have steadily gained market share for heating and cooling offices, hospitals, schools and other commercial buildings in the last decade. Conversely, chilled beam technology is a booming market in Europe due to energy efficient fan reductions of up to 50 percent versus conventional rooftop, variable air volume (VAV) and fan coil systems. However, that region of the globe is more of a hydronic market than the U.S., and engineers aren't as climatically burdened with high humidity challenges.
The CCBPM promises to exponentially accelerate future chilled beam market share gains because it eliminates the need of a secondary pipe loop associated with chilled beam designs. A CCBPM is a packaged unit complete with its own powered integrated direct digital controller, chilled and hot water connections, valves, variable-speed electronically commutated (EC) motor pumps, smart sensors and other features. For contractors, a CCBPMs plug-and-play attributes limit jobsite installation, commissioning and test/balancing errors. It can control up to 10 chilled beams in a zone, or up to five zones when less chilled beams are used per zone.
The revolutionary description for CCBPMs might appear premature, but several facts back up the claim. A CCBPM entered under the model name of NEUTON won this year’s coveted AHR Innovation Award in the Plumbing category at January’s Air Conditioning, Heating and Refrigeration Expo in Orlando.
Furthermore, literally dozens of commercial buildings are currently being specified for chilled beams because of the CCBPMs, which was only introduced in late 2015.
One of those projects is 3.0 University Place, a Philadelphia-based five-story, 160,000-square-foot sustainable building, which is scheduled for completion next year. It is the world’s first commercial office project that's Platinum Pre-certified Global Pilot 6 projects for LEED v4. The project's CCBPMs will control up to 10 chilled beams in zones throughout the building for pinpoint temperature control. The CCBPM design will cut the building’s piping costs by up to 35 percent. Their efficiencies combined with fan energy savings associated with chilled beams will garner LEED credits and save hundreds of thousands of dollars in operational savings over the HVAC system's lifecycle. The building owner was so impressed with the CCBPM concept that he requested it for the final build-out of the facility’s predecessor, the neighboring commercial office building, 2.0 University Place, which was designed with only chilled beams several years ago before CCBPMs were introduced. For the final fit-out, the CCBPMs were practically free because of the capital saved from the reduced pipe and control costs.
Eliminating secondary pipe loops
Previously, chilled beam designs in new buildings required a secondary pipe loop, chiller and boiler because the building’s primary pipe loop of 42F to 45F chilled water and 160F to 180F hot water were too extreme for chilled beam use. Additionally, the colder dew point water temperatures of primary pipe loops can potentially cause condensation in chilled beams.
Now, engineers are forgoing a secondary loop and instead using a building’s primary loop for chilled beams, thanks to CCBPM technology, which uses warmer water returning from chilled beams zones to temper supply water to chilled beams at optimal 57F and 110F cooling and heating temperatures, respectively.
Another prime CCBPM application is retrofits, especially in buildings with existing two-pipe or four-pipe loops. CCBPMs now give chilled beam methodology a very significant capital cost retrofit advantage over competing technologies, such as variable refrigerant flow (VRF), because the existing pipe loop can be reused.
For example, the Clark County Public Schools, Winchester, Kentucky, became the world’s first CCBPM user last fall when it retrofitted the 43-year-old Robert D. Campbell Junior High School to chilled beams from an antiquated two-pipe unit ventilator design. The school reused nearly all the building's existing piping, plus its chiller and boiler, to supply the 46 CCBPMs and 212 chilled beams. Choosing chilled beams versus VRF saved the school district $147,000 in labor costs. Condensation is less of a concern with CCBPM-based chilled beam designs, however the project also included several 5,000-CFM dedicated outdoor air system (DOAS). They supply ASHRAE Standard 62.1 outdoor air to the active chilled beams for condensation prevention. The DOAS also supply code-mandated outdoor air to large rooms, such as the gym, which don't use chilled beams. The chilled beam/DOAS combination also saves $33,000 in operational costs annually; offers superior temperature and humidity control; and provides a quieter learning environment, versus the existing unit ventilators. The energy savings will lower capital dollars spent on the project by $500,000, which is guaranteed by a performance contract with the Lexington, Kentucky, branch of Indianapolis-based, Performance Services Inc. (PSI), an integrated design and delivery engineering contractor that led the project.
The plug-and-play CCBPMs eliminated the guesswork previously associated with chilled beam system specification, installation, balancing and commissioning.
Unlike the former two-pipe unit ventilator system, which takes long periods to switch from cooling/heating modes, Campbell's design provides pinpoint tempered conditions within a one-degree tolerance, regardless of the season, because its control is based on outdoor dew point, not temperature. If the outdoor air (OA) dew point is less than or equal to 45F, the space latent load is satisfied by DOAS ventilation air, which is distributed through each chilled beam and controlled via its respective CCBPM. When the dew point surpasses 45F, the chiller is needed to maintain space conditions.
Most CCBPMs are mounted above each level's classroom zone's 18-inch high T-bar drop ceilings and typically control four ceiling flush-mounted chilled beams ranging from 2x2-foot to 2x8-foot sizes. Each CCBPM was centrally positioned in each zone to limit chilled beam piping circuitry and allow its front panel to swing down through a removed 2x2-foot ceiling tile for easy access.
The CCBPM blends and re-circulates its return water within its zone to convert typical 42F (cooling) and 140F (heating) primary loop supply water temperatures to optimal 58F (cooling) or 100F (heating) chilled beam discharge temperatures, respectively. This prevents cooling mode condensation and heating season heat stratification.
The CCBPM is expected to boost the number of chilled beam designs exponentially in the next few years if the current interest by specifying engineers is an indicator.
Thomas Rice is director of sales at SEMCO LLC, a Fläkt Woods Company specializing in energy recovery equipment, chilled beams, controllable chilled beam pump modules, spiral metal ductwork, and acoustical products. He has 16 years of experience in HVAC/R and has assisted, consulted, and participated in the specification and installation in dozens of CB and dedicated outdoor air system projects. Rice serves on American Society of Heating, Refrigerating, and Air-conditioning Engineers (ASHRAE) technical committees for room air distribution, air-to-air energy recovery, and desiccant dehumidification components. He can be reached at firstname.lastname@example.org