On average, Americans spend over 90 percent of their time indoors where concentrations of some pollutants can be two to five times higher than typical outdoor concentrations, according to the U.S. Environmental Protection Agency (EPA). In fact, the EPA ranks indoor air quality (IAQ) as a top-five environmental risk to public health while the Occupational Safety and Health Administration (OSHA) reports that approximately 1.4 million buildings in the U.S. have indoor air problems. There is also a growing awareness of the importance of IAQ among both HVAC industry and non-industry professionals. The following case studies highlight several ways in which IAQ products have been implemented to help various commercial buildings meet air quality, energy-efficiency, and comfort goals.
Originally designed to support an occupancy level of 850 people, the ArcBestSM corporate headquarters, located in Fort Smith, Arkansas, grew to 1,085 employees plus visitors. Ten percent of the people work at night, requiring 24/7 air conditioning. The increase in occupancy drove a need to introduce more outside air to maintain air quality. The outside air had to be conditioned, which increased electrical energy costs. In addition, the extra outside air caused draftiness on cold winter days, and, during the summer, the extra air flow through the air handlers resulted in some parts of the building getting too cool.
The 190,000-square-foot building has five floors of office space separated into two wings with two staircases connecting all building floors. The solution was to install 10 enVerid Systems HLR® (HVAC Load Reduction) 1000E modules — two installed on each of the five floors, one per wing — to scrub air of contaminants and reduce the amount of outside air ventilation required.
“I previously got calls from people that were cold during the summer, which was a direct result of having to introduce so much chilled air into the building to meet the appropriate CO2 levels,” said Richard Rieske, director of corporate facilities, ArcBest. “Likewise, they felt drafts during the winter due to all the outside air that was being used to ventilate the building. When the HLR modules are running, our people are more comfortable.”
An enVerid team surveyed the building’s mechanical layout, conducted an IAQ assessment, and identified potential locations for integrating the HLR systems. The number of HLR modules needed, and the resulting outside air reduction, were calculated according to ASHRAE Standard 62.1 Indoor Air Quality Procedure (IAQP) for a typical office building.
The site survey assessed the spaces that are cooled and heated, including stairways and closeted spaces, and documented the existing hydronic systems; power meters; and all demand controlled ventilation (DCV), variable air volume (VAV), and air handling unit (AHU) interactions in the building, including dampers, sensors, and exhaust systems. The survey measured and planned for the installation of the HLR modules, ensuring they would fit and could be easily moved into position. In this phase, the team also checked for wireless connectivity options and suggested connection points to the building management system (BMS).
Lastly, the team took snapshot baseline measurements of CO2, energy use, and other air quality indicators. This information was shared with the facilities management team.
Each wing is served by a dedicated AHU. Building return air is an open-plenum, suspended-ceiling type, and air is ducted to line diffusers. Building pressurization is regulated on each floor by return air mounted exhaust fans.
At the start of the project, the building’s central plant on the ground floor had two 375-ton packaged, hermetic, centrifugal, liquid, single-speed chillers. On warm days, the second chiller was required. Now, with the enVerid HLR modules, they typically only need a single chiller as the peak HVAC cooling capacity has been reduced by about 273 ton, which corresponds to a 36 percent decrease in total HVAC load. All outside air intake for the HVAC system is DCV-dependent, controlled by space CO2 sensors. The outside air damper is actuated based on an averaged CO2 value on a per floor section basis. Each floor has about 10 CO2 sensors strategically distributed. CO2 sensors residing in the eastern section on each floor were averaged separately from those in the western section. The CO2 set point is observed by the BMS to actuate outside air damper position. The building also features a Carrier iVu® Building Automation System (BAS) running BACnet over master slave token passing (MSTP), which can optionally be integrated with enVerid’s HLR BACnet to control the outside air damper.
“Running a second chiller significantly increased our energy utility costs,” noted Tom Daigle, manager of building systems, ArcBest. “By using the enVerid HLR modules, we are not conditioning as much outside air, and we are projected to save $63,709 annually.”
Based on sensible and latent energy calculations, the energy savings for reducing outside air by 26,640 cfm equates to $63,709 annually using a standard energy model as applied to temperature and relative humidity data downloaded hourly from 2009 to 2013 in Fort Smith, Arkansas. ArcBest was also able to conserve on cooling tower water, but a separate water meter wasn’t available, so this information was not included in the overall project savings. However, based on standard calculations, ArcBest reduced water usage by 2.175 million gallons, saving approximately $11,535.
Additionally, the HLR modules allow ArcBest to maintain IAQ. CO2 levels vary throughout the day but are maintained at levels below 1,000 ppm. Volatile organic compound (VOC) measurements included total VOC (TVOC) and a full scan of speciated (separated by species) VOCs identified by the U.S. Green Building Council (USGBC) as contaminants of concern (COC). The results demonstrate the air scrubbing effectiveness of the HLR technology.
By incorporating HLR modules and using IAQP to manage how much outside air is used for ventilation, ArcBest no longer needs to rely on its DCV system. Using IAQP, HLR modules enable reduction in outside air because it provides IAQ management for all contaminants, not just people-related contaminants. Consequently, ArcBest is using the HLR modules to control outside air dampers, thereby bypassing the DCV system. Additionally, by using the HLR and IAQP, ArcBest is now managing ventilation based on all COC, instead of just CO2.
The enVerid project team continues to work with ArcBest’s facilities management team to optimize energy, IAQ, and environmental comfort. ArcBest data is captured for the National Renewable Energy Laboratory (NREL) to provide documented consumption information to the U.S. Department of Energy (DOE).
FLORIDA’S BAYVIEW CORPORATE TOWER
When competing for premier office tenants in a high-rent market like south Florida, your building better have the best finishes and systems to stand out from the competition. That’s an ongoing challenge that motivates Bunnie Willis in her role as vice president and senior property manager for the 12-story BayView Corporate Tower in Fort Lauderdale. Built in 1973, the 412,000-square-foot Class A building houses 13 corporate tenants, including AT&T, Whole Foods, and Landmark Worldwide.
Willis routinely looks for ways to enhance the value of BayView and other Florida commercial properties she manages on behalf of New Boston Fund Inc., a multibillion-dollar private real estate investment management firm. In July 2011, during a routine evaluation of BayView Tower’s mechanical systems, Willis learned that she could provide her tenants with cleaner, healthier air by making modest upgrades to the building’s HVAC systems. One such upgrade also held the promise of saving energy, reducing maintenance costs, and extending equipment life.
A key component in the HVAC system upgrades was the addition of ultraviolet-C (UV-C) lamps. Used extensively since the 1990s to improve IAQ, and later to improve heat exchange efficiency, boost airflow, and reduce maintenance, the UV-C wavelength eliminates and further prevents microbial and organic materials buildup on HVAC cooling coils, air filters, and duct surfaces and in drain pans.
However, it is the technology’s ability to potentially slash between 10-25 percent of HVAC energy use that drives nine out of 10 UV-C installations, according to Bruce Fontaine, vice president of business development and operations, Sustainable Management Solutions. Fontaine’s team recommended the sustainable UV-C solution, product selection, and installation at BayView.
Following the recommendation to add UV-C technology to BayView’s air handling units (AHUs) Willis met with Miki Minic, the building’s chief engineer, who had successfully used UV-C lamp systems in several other buildings.
“There are many benefits of UV-C,” said Minic, who enthusiastically supported the addition of a UV-C energy install. “Most important is the improvement to indoor air quality levels, so tenants enjoy cleaner, healthier air. Absenteeism due to the spread of unsafe microorganisms via HVAC systems is almost eliminated. Moreover, equipment life is improved, downtime and preventive maintenance expenses like cleaning the coils, drain pans, and the purchase of coil and drain treatments, etc., is significantly reduced.”
Willis also visited similar properties in the area with HVAC UV lighting installations and looked to her peers for their input and experience with the technology.
“Following my research and meeting with other commercial property managers who had UV lighting installed, I was sold on the technology’s benefits,” she said.
With two cooling towers, three chillers, and 24 AHUs, the UV installation at the BayView Corporate Tower presented some challenges, noted Darren Ambrosi, a project manager with Sustainable Management Solutions.
“The existing AHUs were 25 years old and offered limited access to the evaporators,” said Ambrosi. “Because of the tight access, we recommended the RLM Xtreme high-output, fixtureless UV-C lamp system from UV Resources.”
Minic had experience with the RLM Xtreme system and approved the product selection. As a result of the installation flexibility of the fixtureless UV-C lamp system, the retrofits were completed in just four days with only two installers.
An independent audit documented a 47 percent increase in the building’s airflow levels following the UV-C installation. This reduced enough energy use to result in a 90-day return on investment.
“Within one month, we saw an immediate reduction in our energy costs, which has remained consistent since the installation,” Willis said. “I believe so strongly in this improvement that we are getting ready to do it at one of our other properties in Doral, Florida. We are very satisfied with the decision to install the UV lighting.”
2.0 UNIVERSITY PLACE
Philadelphia’s 98,000-square-foot 2.0 University Place is proof that office buildings featuring high-efficiency HVAC systems, superior IAQ, and other sustainable features reap higher lease premiums, 100 percent occupancies, and ultimately attract real estate investment buyers.
The heart of the facility’s sustainability is its HVAC system, which features active chilled beams, dedicated outdoor air systems (DOAS), and high-efficiency boilers and chillers.
Daily energy tracking reveals the building ranks in the upper 22nd percentile of Energy Star Program facilities nationwide. Energy modeling has demonstrated the building also surpasses requirements of ASHRAE Standard 90.1 (2004), Energy Standard for Buildings, Except Low-Rise Residential Buildings, by 44 percent.
The combination of technologies results in energy savings and environmental stewardship that attracts green-minded tenants and buyers. Furthermore, occupants feel a noticeable air comfort difference mainly due to tightly controlled temperature tolerances and relative humidity (RH) levels that chilled beams and DOAS offer.
“Many of our tenants say they’ve never felt this type of air comfort or atmosphere in an office building,” said Scott Mazo, principal, University Partnership Associates (UPA), Philadelphia, which developed the property as Philadelphia’s first multiple-certified Leadership in Energy and Environmental Leadership (LEED®) Platinum buildings and one of few nationwide.
Real estate investors have also taken notice. UPA recently sold the five-story property to Swiss-based Zurich Insurance Group (ZIG) last April.
“As a buyer, they recognized not just the energy efficiency and technology features but also the commitment to sustainability, which is important to them [ZIG],” said Mazo.
Mazo led a team of designers that included the late Shraga Berenfeld, principal of the now defunct Shraga Studios Architecture, Ardmore, Pennsylvania; SPG3 Architects, Philadelphia; McHugh Engineering Associates, Ambler, Pennsylvania; Mark Ulrick Engineers Inc., Camden, New Jersey; Accord Mechanical, Norristown, Pennsylvania; and The Sheward Partnership LLC, Philadelphia.
The bulk of the HVAC system’s LEED credits and air comfort were achieved with 500 active chilled beams and their induction principle operation. Air around ceiling-mounted chilled-beam water coils continually cools and falls while warmer air rises in a continual convection of air comfort benefits with no drafts, no noise, and stable temperature tolerances of ±1°F. Chilled beams also reduce fan energy by up to 50 percent versus the large fan horsepower required in the conventional rooftop DX, ductwork, and variable air volume system the design team considered.
“The chilled beam system is a major contributor to the building’s sustainability story and ongoing energy efficiency,” said Michael Pavelsky, sustainability director, at The Sheward Partnership, which tracks and records the facility’s energy performance.
Supplying the chilled beams is a four-pipe system for heating and cooling consisting of pre-insulated polypropylene (PP-R) pipe by Aquatherm, which is used in pressurized plumbing and HVAC applications. Aquatherm’s highly-efficient piping helped accumulate LEED HVAC credits as well as other pipe loop components, such as Lochinvar LLC’s 98-percent-efficient 2,000 MBH condensing boiler; Daikin Applied’s 200-ton air-cooled chiller; and four 25 hp pumps by Bell & Gossett. The four-pipe system allows simultaneous heating and cooling options during fall and spring seasonal changes, and it helps offset perimeter heat loss and solar gain.
While some chilled beam brands use factory-set airflow nozzles that require replacement or complicated pressure balance calibrations for cfm rate changes, the IQHC model features a proprietary 12-slot nozzle that’s field-adjustable with two easily-accessed, hand-operated levers for providing a unilateral, disproportional, or equal air volume from each side. Accord Mechanical and its testing and air balancing (TAB) contractor, Independent Balancing Co., Philadelphia, both received factory-assisted chilled beam training.
“The chilled beams in the external zones definitely needed different nozzle adjustments than internal zones,” said Ulrick Joseph, principal, Mark Ulrick Engineers, which specializes in mechanical, electrical, plumbing, and fire/safety building systems.
Outdoor air requirements and condensation prevention is achieved with one 20,000-cfm rooftop PVS-24 Pinnacle DOAS unit manufactured by Semco LLC. The DOAS uses its own DX condenser, so the chiller is dedicated to just the chilled beams. The DOAS controls its operation independent of the BAS by Delta Controls Inc. Each active chilled beam’s 6-inch diameter outdoor air takeoff is supplied with conditioned outdoor air to avoid condensation from the chilled water loop’s 48°F discharge. Ventilation air depends on the chilled beam’s size and ranges from 25-85 cfm, which satisfies the building’s outdoor air requirements and surpasses ASHRAE 62.1 standards for commercial buildings, according to Joseph.
“Most chilled beam manufacturers don’t make DOAS units,” said Mazo. “A manufacturer making both the active chilled beams and the outdoor air unit to supply them dehumidified air was integral for synergy and purposes of single-source responsibility.”
THE ATLANTIC CLUB
The Atlantic Club, one of the nation’s top health clubs, was faced with the decision of paying ongoing maintenance costs for an aging 15-year-old indoor pool dehumidifier at its Red Bank, New Jersey, location, or replacing it with modern HVAC technology.
The same decision confronts hundreds of health club facility managers today as new technology presents unprecedented energy savings that can offset enough equipment replacement costs to deliver a quick payback. Furthermore, new equipment provides health and environmental advantages that enhance membership.
The original dehumidifier’s maintenance was surpassing $1,000 annually, mostly from small refrigerant leak repairs. A future catastrophic leak event of losing the entire 60-pound R-22 refrigerant charge could have potentially cost more than $10,000 in refrigerant replacement and repair labor costs. More recently, the facility faced replacing the perpetually leaking remote condenser component of the rooftop split-system at an estimated cost of $10,000.
Acting on the advice from its preferred HVAC service contractor, Redbird Refrigeration LLC, Neptune, New Jersey, the 33,000-square-foot Atlantic Club chose new energy-saving technology with heat recovery and enhanced IAQ.
“The pool odors we sometimes noticed are no longer a factor, and the pool area’s air comfort is significantly improved,” said Kathy Guibord, a senior director at the Atlantic Club.
IAQ and air comfort have improved because of Redbird’s reconfiguration of the natatorium’s 6,900-cfm ventilation ductwork and installation of a new Seresco USA 14-ton NE-Series heat recovery, split-system rooftop dehumidifier and condenser. The indoor pool environment is now maintained at a 50 percent relative humidity and an energy-efficient 2° differential of 82° and 80° between space and water temperatures, respectively. Humidity and space/pool water temperature set points are maintained at a very strict ±1° tolerance.
The retrofit’s fast payback derives from today’s heat recovery technology, according to Ed Sneed, sales engineer, Stillwell-Hansen Inc., an Edison, New Jersey-based HVAC manufacturer’s representative, who contributed to the retrofit’s engineering. Unlike the older technology, the NE-Series recovers heat from the exhaust air to efficiently preheat the outdoor air, which amounts to an energy savings of tens of thousands of dollars annually.
The original dehumidifier began showing corrosion problems after 10 years because its piping and components were positioned in the airstream, exposed to pool chemicals and humidity 24/7. Consequently, it suffered ongoing leaks of R-22 refrigerant, which has since skyrocketed in price, increasing 400 percent since its recent U.S. Environmental Protection Agency (EPA)-mandated phase out. The new R-410A dehumidifier’s components/piping are positioned in a sealed vestibule separated from the airstream. Furthermore, its coils and inner liners are fully anti-corrosion coated and protected by the rooftop unit’s double-insulated walls that prevent outdoor temperature expansion/contraction extremes.
Redbird Refrigeration also improved the ventilation system by relocating the natatorium’s return ductwork inlet down to deck level from its former ceiling position. The lower positioning helps draw dry, conditioned supply air toward pool occupants for air comfort and prevents air stratification.
Innovative unit replacement planning by Frank Chinnici, president, Redbird Refrigeration, saved nearly $10,000. Rather than replace the original unit’s roof curb, Chinnici ordered a custom-designed curb adaptor configured to the new dehumidifier’s ductwork configuration, which was vastly different than its predecessor. This circumvented the cost of roofing in a new curb, eliminated reconfiguring the existing downflow ductwork to fit the new dehumidifier, and minimized natatorium downtime.
Earlier in the dehumidifier’s life cycle, Redbird Refrigeration had already replaced the pool space’s two corroded in-duct electric heaters with more efficient in-duct anti-corrosion coated hot water coils, custom-manufactured by MultiTherm LLC and supplied by an existing facility boiler for space heating. The heating coil retrofit also included a 12 V modulating valve by Honeywell that steadily ramps up and eliminates overheating the pool space on start up.
The dehumidifier also provides 200 MBtuh capacity of heat recovery to efficiently heat the pool space. When the dehumidifier can’t reach set point levels, such as on extremely cold winter days, the facility’s Carrier Corp. BAS triggers the three-way modulating valve to send hot water to the pool area’s in-duct heating coil. The BAS also monitors/controls the facility’s rooftop units manufactured by Carrier.
Another Redbird Refrigeration design feature is the dehumidifier’s accompanying condenser. Chinnici chose a low-noise unit with a short profile and small footprint to comply with local zoning. The Seresco outdoor A/C heat exchanger’s quiet operation is accomplished through fan blades fashioned after the aerodynamics and contours of owl wings.
“You can’t hear the condenser operate — even when you’re standing next to it,” noted Chinnici.
The dehumidifier has an onboard CommandCenter microprocessor that reports over 60 operational parameters from dozens of factory-installed transducers to WebSentry, a proprietary browser-based software program that sends real-time data and alarms to Chinnici’s smartphone and factory servers for historical recording. Thus, any malfunction or operational inefficiency alarm is reported the day it occurs. Previously, an energy inefficiency experienced by the old dehumidifier could go unnoticed for months until semi-annual service calls.
WebSentry’s historical data recording already helped Chinnici solve a perplexing alarm. Typically, heating coils are factory installed inside the dehumidifier and a strategically-positioned supply air sensor monitors temperature. WebSentry’s recording of an intermittent space overheating suggested that repositioning the sensor downstream could better monitor temperature and, therfore, prevent overheating.
With minimal maintenance costs and thousands of dollars in annual energy savings, the retrofit payback is expected in just a few years. Meanwhile, club members have experienced an immediate improvement in the indoor comfort.
Publication date: 11/20/2017