Case Studies Show How Green Technology Helps Commercial Buildings
When Going Green Is Just Good Business
Commercial buildings are going green — and it’s not just new construction. Across the commercial market, demand for energy-efficient materials remains high as manufacturers work to develop products and processes that reduce a building’s overall energy consumption and stack up against stringent performance criteria.
Following are four examples — a kosher wine shipping center, a chiller plant in a marine research lab, a community pool, and a 10th-floor medical office retrofit — that illustrate just how creative high-efficiency products can be when it comes to unique solutions for everyday issues.
DODGING THE DRAFT
Royal Wine’s distribution center responded to employee wintertime requests for a warmer shipping area and received a bonus when six new air curtains significantly reduced operational energy costs.
Royal Wine, a global kosher winemaker, imports and produces more than 60 brands of wine, manufactures the Kedem fruit juice brand, and operates Herzog Wine Cellars with vineyards in Oxnard, California. During the winter, its distribution center in Bayonne, New Jersey, was losing thousands of dollars a year because of open shipping doors. Subfreezing temperatures near the open doors required workers to wear heavy clothing, which hampered their productivity, and caused cold air drafts regardless of portable truck and dock seals, according to Abraham Wechter, plant engineer.
Employees wanted a warmer shipping area. In response, Royal Wine decided to install air curtains on six shipping doorways.
The curtains were purchased from Berner International LLC, a U.S. manufacturer of air door/air curtain equipment. Berner is a member of the U.S. Green Building Council (USGBC), Green Building Alliance (GBA), Air Movement & Control Association (AMCA), and ASHRAE.
Royal Wine’s solution for the 8-by-10-foot roll-up door openings came in the form of six Berner Industrial Direct Drive model IDC-12 air curtains with indirect gas-fired heat. Each air curtain incorporates three ½-hp, single-speed, dual-shaft motors that drive blower wheel assemblies delivering 4,443 cfm. The resulting laminar air stream returns 70 to 80 percent of indoor energy back into the space while blocking drafts from outdoors.
Each air curtain has one 200-MBtuh indirect gas-fired unit heater, delivering a 32°F temperature rise to the air stream. Berner’s custom metal shop also attached a 14-gauge aluminized steel duct plenum transition to the air curtain inlet. Thus, the unit heater discharges heat toward the plenum, and each air curtain draws it through for uniform distribution. The heat option supplements Royal Wine’s existing unit heaters and high volume/low speed (HVLS) fans, which aid in pushing static heat down from the ceiling. The shipping area now remains at 70°, regardless of the outdoor temperature or how long the doors are open.
Each air curtain’s control package includes a factory-mounted and -wired UL listed motor control panel, complete with a rotary non-fused disconnect switch, time delay relay, a 24 V transformer, and a remote-mounted combination switch and thermostat. When the overhead roll-up doors are raised, the air curtains are activated through a 24 V floor-mounted magnetic reed switch.
Royal Wine plans to keep the air curtains activated year-round, as the plant uses several 20-ton rooftop HVAC units to maintain optimum temperatures for wine and juice storage. In addition to stable temperatures, summertime door protection will aid sanitation by keeping out dust and flying insects.
The air curtains, duct transition, and gas unit heaters were suspended from the 25-foot-high ceiling with threaded rod. Stabilization bars were used to maintain distance away from the wall, so the downward air stream isn’t obstructed by the roll-up door mechanism canister, and the air curtains were field-adjusted, so the air stream meets the floor just outside the threshold.
Consequently, employees now work in a warm, comfortable environment. Plus, per Berner’s calculations, each door reaps an annual energy savings of $3,500. Multiplying those savings by six doors totals an estimated savings of $21,000 per year.
THE CHILLER EFFECT
By using ASHRAE Standard 90.1-2013 as a baseline, a marine research lab at the University of North Carolina Wilmington (UNCW) reduced energy consumption at its chilled water plant by nearly 40 percent.
Located just 100 yards from the Atlantic Intercoastal Waterway and 500 yards from the Atlantic Ocean itself, UNCW takes marine science seriously. UNCW CREST Research Park includes three world-class marine laboratories, including the MARBIONC Building — a new 69,000-square-foot interdisciplinary research facility for marine biotechnology. A LEED Silver facility, the MARBIONC Building leases labs to commercial enterprises that require reliable, energy-efficient 24/7/365 cooling. That’s why Steve Sharpe, energy manager for UNCW, selected Smardt chillers using Danfoss Turbocor® compressors to handle humidity that ranges from Amazon-rainforest highs to Seattle lows.
“Summers can get pretty swampy on the North Carolina coast,” said Sharpe. “But it’s a mid-Atlantic region, so we experience climate variations throughout the year. Consequently, we decided to build a chiller plant that could take advantage of that wide range of operating conditions and still run reliably. If we lose cooling, we can lose research — which is very bad. Smardt centrifugal chillers with Danfoss Turbocor magnetic-bearing variable-speed compressors could handle that range of conditions with 100 percent reliability.”
Sharpe aimed to build the chilled water plant to exceed ASHRAE Standard 90.1-2013, Energy Standard for Buildings Except Low-Rise Residential Buildings, which requires selecting chillers optimized for part-load conditions as gauged by the Integrated Part Load Value (IPLV) metric. IPLV measures chiller efficiency over a range of operating conditions — precisely the situation Sharpe was facing.
“Our climate extremes are 97.5°F dry bulb and 88.3° wet bulb temperatures,” Sharpe explained. “The MARBIONC Building uses nearly 100 percent outside air. So, when you have high wet bulb temperatures, you have to wring the moisture out of the outside air being supplied inside. Outdoors, the high humidity hampers evaporation, making it tough for cooling towers to reject heat into the atmosphere.”
Fortunately, less than 150 hours a year occur at the highest dry bulb and wet bulb temperatures — creating potential to save energy during lower operating conditions. Based on ASHRAE recommendations at that time, the most efficient type of plant was determined to be a single, primary-flow, fully variable-volume chiller plant. To take maximum advantage of the 8,610 hours operating below full load, Sharpe selected two 750-ton Smardt WA240 water-cooled variable-speed chillers. Each chiller uses five Danfoss Turbocor TT400 oil-free magnetic-bearing centrifugal compressors, each with a nomical rating of 150 tons.
“The key is to use multiple compressors that can throttle back or ‘turn down’ capacity to match the reduced load,” Sharpe said — for example, when outdoor conditions are cooler, or on weekends, when the building has fewer occupants. When entering condenser water temperatures (ECWT) can be lowered, the compressor work and energy use decreases. For example, every 1° drop in ECWT below the full-load design point can increase chiller efficiency by 1 to 2 percent.
Often, when load decreases, so does a factor called “lift:” the difference between refrigerant pressure in the condenser and refrigerant pressure in the evaporator. It’s affected by both weather and the cooling load of the chiller. Through constant system monitoring, the Turbocor compressor modulates refrigerant flow and impeller speed to counteract conditions that could create surge or choke. Turbocor also mandates that a stop/check valve be installed to prevent reverse gas flow, which could cause an internal mechanical issue.
Along with a variable-speed, variable-flow chiller, the system also uses a Tower Tech forced-updraft, counter-flow cooling tower. In this case, one 100-hp Danfoss VLT FC 102 drive was used to operate 10 10-hp direct-drive fan motors. The drive slows fan motor RPMs and cuts electricity consumption exponentially. For example, reducing speed by 20 percent results in nearly 50 percent energy savings.
To optimize all the variables of the chiller plant, Sharpe used a Central Plant Energy Control System (CPECS) from Kiltech, a Smardt company. The system runs on a model-based analysis method that analyzes the chiller plant’s actual load and outside air conditions, uses equipment models to predict the most efficient operating point, then controls the plant to meet this operating point. At the same time, it runs a model ASHRAE 90.1 plant and compares the two to determine the savings realized over the ASHRAE 90.1 baseline.
The CPECS report from August 2016 to 2017 shows the plant ran 6,687 hours using 1.1 million kWh, for an average annual plant efficiency of 0.576 kW per ton. A baseline ASHRAE Standard 90.1 plant modeled on those same hours would have had an efficiency of 1.034 kW per ton, costing an additional $67,855.
With a conventional chiller plant design, those numbers would never be possible, Sharpe noted.
“It’s smarter to use chillers that can handle temperature reset and not work as hard,” he said. “If you have a plant that can unload efficiently, run at those part-load conditions, and take advantage of cooler outside conditions, the savings cascade hour by hour, day by day. We’re saving a lot of money, with a payback well under five years, with less maintenance and 100 percent uptime — all while shrinking our facility’s carbon footprint.”
YES, YOU DO WANT A GREEN POOL
The retrofit of the 45-year-old Donald Richards Community Pool HVAC system was by no means a conventional drop-in replacement. Instead, officials opted for an upgrade that reduced refrigerants and chloramines, recovered heat, and added efficient serviceability when it reopened in 2016.
It was the third HVAC retrofit for the 250,000-gallon, high school-level competition pool in the town of Cape Elizabeth, Maine — a pool named for a long-time Cape Elizabeth High School swim coach who holds a record of 903 wins, making him one of the most successful coaches in the state.
The existing 30-ton direct expansion (DX) dehumidifier dated from 1996 and the two-circuit, four-stage model had surpassed its life span. The primary compressor was inoperable, and the secondary compressor/circuit couldn’t maintain levels, so space temperatures were a steamy 85°F. Space/water temperature differentials fluctuated as much as 10°, relative humidity (RH) averaged 75 to 85 percent, and the dehumidifier had degraded to where it was costing $30,000 annually to maintain.
“It was a Catch-22 situation,” said Greg Marles, the city’s former director of facilities and transportation, who conceived the retrofit design. “The dehumidifier’s shortcomings prevented me from maintaining RH set points, and because the RH was high, the resultant higher space temperature increased evaporation rates that the dehumidifier couldn’t handle.”
On top of that, the city had added an inflatable obstacle course that increased water evaporation by 10 percent. And the pool had high rates of chloramines, formed when chlorine molecules chemically bond with contaminants and form a heavy gas along the water surface.
The $800,000 renovation included pool surface cleaning/painting, facility LED lighting, pool support pumps, filters, and UV water disinfection systems. However, the brunt of the retrofit’s payback came from the project’s new NP-030 Protocol dehumidifier, manufactured by Seresco USA.
In retrofitting the 14,000-square-foot facility, Marles aimed to maximize equipment life cycles where the previous equipment fell short. Unlike the previous dehumidifier, which suffered premature component degradation, the Protocol includes coils and a double-wall insulated encasement with an anti-corrosion coating to keep components and electronics out of the humid, chemical-laden airstream. Plus, the unit has dozens of sensors and transducers that report more than 60 real-time parameters to its onboard CommandCenter, which can be accessed remotely via PC or smartphone. This way, inefficiencies can be addressed immediately, rather than during a semi-annual checkup after hundreds or thousands of dollars’ worth of energy — and taxpayer dollars — would have been lost.
The retrofit design also saves costs by decreasing the city’s reliance on refrigerants that could potentially leak and cause environmental damage and expensive repairs. For example, the Protocol dehumidifier uses 75 percent less refrigerant than the unit it replaced. Instead, heat rejection operates via glycol piped to dry coolers. Glycol is a fraction of refrigerant costs, uses PVC pipe instead of expensive copper pipe, is environmentally friendly, and doesn’t require EPA-certified service technicians, all of which helped cut installation costs.
Other design features included three new condensing boilers to isolate the 10,000-gallon spa’s heating and two new condensing boilers to back up the dehumidifier’s heat recovery pool water heating. The natatorium is now maintained at 83° and 81° space and water temperatures, respectively, to minimize evaporation and supply air comfort. The city also designed a tie-in of the adjacent high school’s two existing high-speed, oil-fired space heating boilers via a heat exchanger, since the boilers typically use only two-thirds of their 6 million-Btu capacity during the winter. Six new Pulsar pool water pumps, manufactured by Pulsafeeder Engineered Products, were outfitted with variable frequency drives that are controlled by the BMS to efficiently control flow rates according to usage.
The city’s pool retrofit fit its green mission. Careful planning helped reach sustainability goals and reformed the 45-year-old pool into a state-of-the-art facility.
A 10TH-FLOOR RETROFIT
A three-in-one HVAC solution from Ruskin allowed a medical office building in California to improve ventilation while providing money-saving operating efficiencies.
Retrofitting a commercial HVAC system to accommodate an existing building can be challenging, especially when the building and the original system were not designed to meet current codes and design requirements that impact IAQ and energy efficiency. A large medical office building in California presented an even bigger challenge: In addition to a system that used two large air handlers housed in two separate rooms on the building’s roof, a permanent pipe ran diagonally behind the building louvers in both rooms. The pipe could not be moved because it was part of the system designed to support the building in the event of an earthquake. However, it interfered with the installation of actuators on the jackshaft of the damper.
The task at hand was replacing the components of the building’s large, built-up air-handling system, including the outside air louvers — and finding a solution that both compensated for the 18-gague sheet metal wall separating the two rooms and provided a work-around for the pipe. For this project, Rachel Larimore, sales application engineer at Ruskin, recommended the Ruskin IAQ350XL, specifically designed to save space in tight mechanical rooms and air-handling units. The three-in-one product features a Class A wind-driven rain louver, Class 1A-rated low-leakage damper, and an air-measuring station in a common sleeve.
Installing dampers and air-measuring stations was another goal for the project, to meet new building codes and standards that dictate how much fresh air a building must bring inside, and to help the HVAC system operate with improved energy efficiency.
“Prior to this project, the building featured plain louvers, with no dampers or air-measuring stations, which meant there was no ability to modulate or control airflow,” said Larimore. “The louvers just covered a large hole in the exterior of the building, providing protection from rain while letting in a constant flow of air.”
Ruskin provided 14 sections of the IAQ350XL to cover the 336-by-118-inch opening. They’re located on the roof, approximately 10 stories above the ground, and those in charge of the building’s HVAC system can monitor all 14 sections simultaneously and control them individually.
Units were fabricated in sections small enough to transport to the roof via elevator, eliminating the cost of renting a crane.
Today, the units allow the building to meet the standards and codes that dictate fresh air intake while providing money-saving operating efficiencies and accommodating space limitations, resulting in a system that maintains proper ventilation and meets energy efficiency goals.
Publication date: 9/24/2018