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Technology and Connectivity Enhance HVAC Efficiency

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Credit: iStock/RapidEye; composite: Deja Hsu
Building owners and operators are adopting “smart” and non-traditional HVAC technologies that not only continue to meet occupancy comfort needs, but provide operation and efficiency benefits. They’re also seeking systems that put more control at their fingertips, industry experts say.

To meet that market demand, Carrier focuses on three primary areas where technology is improving the efficiency of HVAC systems overall through improvements in system components, notes Chris Opie, Carrier’s director of North America commercial marketing.

One area is improved compressors. “In our DX rooftop units, the consolidation of multiple compressors into one refrigeration circuit—known as tandem compressors—can allow for unique compressor staging with a simple design, resulting in increased efficiency and comfort.”

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Carrier chillers are designed to use direct-drive, variable-speed screw compressors with no mechanical unloaders to maximize compressor efficiency, “the biggest energy-consuming component of the chiller,” says Opie. “Removing the mechanical unloaders creates a system that is more energy-efficient.”

A second area: the application of variable-frequency drives (VFDs) into more products “is providing significant efficiency improvements,” says Opie.

“VFDs on indoor fan motors have helped improve Seasonal Energy Efficiency Ratio and Integrated Energy Efficiency Ratio (IEER) for rooftop and air handling products,” he says. “VFDs reduce condenser fan power consumption.”

In 2014, Carrier introduced Greenspeed Intelligence on condenser fans. It also is available on some of the company’s water- and air-cooled chillers.

The use of refrigerant circuits with multiple stages of capacity and the combination of varying indoor cubic feet per minute using VFDs greatly increases IEER, notes Opie.

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Credit: Fujitsu
To heat and cool the historic Rithet Building in Victoria, BC, custom-fabricated air handlers with high-static fan coils were connected to existing duct work.

The adoption of “smart” technology is a third area in which Carrier is improving HVAC system efficiency, notes Opie.

“The adaptation of existing technology from other industries—such as ‘self-learning’ controls—is helping to make equipment smarter and more efficient,” he adds.

Carrier provides an option to add “secure and reliable wireless communications” to equipment with product-integrated controls, Opie notes.

“This feature provides the ability to remotely monitor and analyze a multitude of unique data points from the equipment,” he says. “The data is transmitted in near real-time to a secure cloud platform providing a broad suite of services that include advanced notification via alerts and alarms, predictive diagnostics and insights on equipment performance, short-term and long-term performance trending, benchmarking, and recommendations for suggested proactive interventions to improve energy efficiency and reduce maintenance costs.”

Tim Sykes, co-founder of Capital City Refrigeration, checks connections and refrigerant change on a Fujitsu Airstage VRF system.

Carrier recently added AT&T wireless connectivity on commercial HVAC equipment with Carrier SMART Service, a remote connectivity and advanced analytics solution.

“This new offering uses the AT&T network to help collect and analyze chiller operating performance to deliver pre-emptive service solutions,” he says. “The data collected through AT&T IoT technology can reveal operating trends and provide a more complete understanding of the health of the chiller.”

Depending on the results, Carrier SMART Service can then provide recommendations for service, repairs, or system modifications.

“This collaboration will provide facility managers the capability to make more informed maintenance decisions so that service and repairs are only performed when needed—often before an issue arises,” says Opie.

Opie indicates Carrier engineers continue to focus on product innovation to identify ways to improve existing designs in fans, compressors, motors, and new control methodologies to deliver a higher level of unit efficiency.

Carrier also has designed smart controls to simplify troubleshooting, provide a user-friendly interface, and optimize unit operation while simultaneously reducing the barriers to adoption and presenting a clear return on investment (ROI), notes Opie.

For example, Carrier AquaEdge water-cooled chillers operate through a network of sensors that provide data on hundreds of operating characteristics.

“With the option to add wireless communications, this data can be continually streamed to Carrier’s secure cloud database,” he says. “Carrier SMART Service then leverages the cloud to provide an entirely new level of equipment connectivity solutions including remote diagnostics, long-term performance trending, benchmarking, decision analytics, and advanced notifications.”

Using those insights, Carrier SMART Service “can help drive increased reliability, reduced energy and maintenance expenses, and diminished resource consumption,” adds Opie. “We also are focused on reducing the overall size of equipment to reduce materials and impact on the environment, while requiring less physical space in or on a building.”

As these systems take up less space, that means freeing up space for other commercial needs and in some cases, enabling facility owners to increase revenues.

Fujitsu’s entire product line is based on a multi-split type of Variable Refrigerant Flow (VRF) system.

It differs from a traditional system which typically entails one large unit providing heat or cooling for an entire floor or building, notes Brendan Casey, New York City sales engineer for Fujitsu.

For example, when the temperatures dip in a city, a boiler in a building’s basement that works from steam or hot water may be activated to provide heat throughout the entire building, notes Casey.

Fujitsu’s VRF systems can be split up into different zones or individual units for certain areas as needed. For example, “if you only need a little bit of heat in one area, it is able to operate at a variable speed—a slower speed—and provide only what is needed and by doing that, it avoids the expense of overheating or overcooling a space that’s not being used,” notes Casey.

The company’s Airstage system is designed for the commercial sector to provide the benefits of energy efficiency, flexible design, ease of installation, and optimal reliability while offering comfort and convenience.

The energy efficiency benefits focus on technology that enables energy savings, a room temperature set point limitation, a peak cut operation, an economy operation, and an auto-off timer.

Power consumption is reduced by using a compact DC fan motor, designed for high performance.

High efficiency is achieved by using a sine wave DC inverter control, a large capacity DC twin rotary compressor—improving refrigerant intake and compression efficiency—and the use of a four-face heat exchanger that increases effective surface area.

A low-noise Computational Fluid Dynamics fan is designed for high performance.

High heat exchange efficiency is achieved by using an internal projection shape double pipe construction. In multiple outdoor unit installations, the front intake is designed to improve air flow into the heat exchanger.

The room temperature set point limitation enables a minimum and maximum temperature range to be set to provide energy savings while accommodating occupants’ comfort.

Peak cut operation is designed to reduce peak demand charges, setting a maximum value (a maximum average power) for the entire air conditioning system during specified peak periods with consumption monitored using a field-installed power meter.

During a peak cut condition, the heating or cooling delivered to each indoor unit is adjusted by shifting indoor set temperature, applying a forced-off function to specified units, or by stopping the entire system.

The economy operation is set by remote controller, with the temperature setting offset automatically over a certain time period. The remote controller is equipped with an “off” timer function that automatically stops operation when a fixed time has elapsed from the start of operation designed to prevent energy waste.

Credit: Carrier Corp.
A Carrier DX rooftop unit with tandem compressors

Casey points out that in some office settings, occupants are notified that the air conditioning system may be shut off on a holiday, for example.

“They’re not going to run an entire building system on a holiday weekend,” he says. “They basically just shut it down and the building gets hot.”

In contrast, a building with a VRF system enables a person to go into the office and meet with a client, turning on the air conditioning just in their office or in the conference room and have a meeting without comfort problems, he adds.

“If the building has a chiller and a cooling tower, you have to turn on a lot of large pumps and fans just to cool one room whereas by being modular and having individual controls, you have the ability to control that,” says Casey. “People want more control.”

Credit: Fujitsu
Technicians install Fujitsu Airstage VRF units atop Tabco Towers, a 22-story HUD building in Maryland.

Casey says the system can easily be encompassed in a building retrofit without the need to disturb an existing building system.

“If someone wanted to convert their building over to the technology and they have an oil-fired steam system in place, they could switch over one floor at a time over a few years,” he says. “When a tenant leaves, they can retrofit their floor while not removing the existing system until the entire building is switched over so they wouldn’t need to rip out the old system and put in a new system. They can have a huge increase in building efficiency.”

The ROI is immediate in facilities that rent out space, he adds.

“The minute you put this in, you’re going to be able to collect higher rent,” says Casey. “Tenants who are in place aren’t going to want to leave. There’s going to be more rentable floor space. It’s going to be a more comfortable building.”

Casey says that a commercial end-user recently told him that if a tenant takes 3 months to decide to move into his building in New York City, the loss of rent in that time frame exceeds the cost of installing the system.

Additionally, “if someone has a system that makes a lot of noise during meetings, a tenant may indicate they want a site that is more professional,” notes Casey. “In a market as competitive as this, the benefit is immediate.”

The system works with any fuel being used in a facility, says Casey.

“In an oil-fire steam building that converts to natural gas, there is still combustion on site, still CO2, and now the building owner is completely dependent on the price of natural gas, which right now is cheap, but it’s unpredictable,” he says. “You can’t run a natural gas system on any other fuel.

“If you have a building running off of electricity and something happens that spikes the price of natural gas, my guess is they realize that fraction causes severe greenhouse effect and then they stop doing it, but whatever it is that might cause natural gas prices to spike doesn’t matter.”

If an energy provider stops generating electricity with natural gas and switches to wind or another renewable, “whatever fuel it is, they can run a VRF system because it creates electricity which is used to drive the system,” points out Casey.

Thermal stratification occurs when cooler, denser air sinks and warmer and thinner air rises, creating layers of air with a gradient of temperatures, notes Christian B. Avedon, director of sales and marketing for Airius.

“In buildings with high ceilings, the temperature differential from floor to ceiling can reach extremes,” he adds. “With overhead ducts, the air at the ceiling may be too hot for comfort while the air at floor level remains too cold.”

The hot air high above the floor level does little good for the building occupants during the cold months, notes Avedon, adding that conversely, in the summer, the layered air can create stagnant pockets of chill while other areas remain too warm.

Avedon points out that in “rooms with lots of space, it’s notoriously difficult to control the temperature. Hot air obviously rises, leaving those in the rafters toasty while those on the ground warm their hands.”

Ductwork and traditional air distribution systems can be costly and limited in moving air around, says Avedon.

“Many HVAC systems in large commercial and public buildings rely on brute force to create a comfortable atmosphere at floor level,” he adds. “Operational budgets must fund a considerable amount of waste. Due to the phenomenon of stratified air, keeping a consistently warm or evenly cool building environment requires an enormous amount of energy during the extremes of winter or summer.

Noting that “effective destratification can chop costs while creating a unified, pleasant indoor temperature fit for human habitation,” Avedon points out that “without an effective way to redistribute the warmer ceiling air to the floor, the heating system must produce enough hot air to fill the entire space such that the lowest level of the strata receives sufficient heat for comfort.”

In cooling situations, more air must be chilled to overcome sultry zones, he says, adding that “one of the first casualties of human discomfort is productivity.”

In addition to the costs of lost worker output, operational budgets are negatively impacted in other ways, notes Avedon:

  • High energy expenses to heat or cool more air than necessary
  • Shorter HVAC lifespans from excessive run time
  • Shorter lighting lifespans “as they cannot dissipate heat,” he notes. “The solution lies in forcing a direct, non-turbulent air flow from ceiling to floor. This straight column of air gently pushes the upper air to the floor, which then washes horizontally. A customized grid of Airius fans eliminates the problems of stratified air.”

Destratification fans work in concert to make the room one temperature—a balanced temperature experience regardless of where a person is in the space, says Avedon.

“Whether warm air or cooled air is being delivered, a series of destratification fans will work together to continuously mix and redistribute conditioned air throughout a space,” he says. “Branch ductwork can be eliminated and in certain cases, all duct work can be eliminated.”

Avedon points out that some of the benefits of destratification include: up to 35% lower heating, 30% lower cooling costs, more comfort at the human level, increased worker focus and productivity, increased HVAC and lighting system longevity, and a smaller carbon footprint.

“With Airius fans in place, the natural but expensive issues of stratified air in conditioned spaces can be conquered,” he adds. “Once de-stratified, indoor spaces remain pleasant, workers keep focus, and operational/maintenance costs drop, while nature receives a break, too.”

HVAC ductwork is minimized with Airius, says Avedon.

“The trends are undoubtedly clear: more buildings are minimizing ductwork in high-bay spaces to a much more efficient solution,” he adds. “From retail spaces to industrial facilities, those in the building trades are discovering the possibilities of ductless HVAC.”

The reduction in material cost and labor can have a significant impact on the overall project cost, Avedon adds.

Case in point: when Colorado University at Boulder opened up an indoor practice facility in 2016 of 68,000 square feet of space and 90 feet from ceiling to floor, “they needed a cost-effective design that would keep athletes comfortable,” says Avedon. “With two main supply ducts mounted at the eaves along with 24 Airius Designer Series 125 fans mounted at ceiling level, designers were able to ensure the entire space is conditioned and fully mixed.”

In increasing HVAC air distribution effectiveness, Avedon points out that according to ASHRAE 62.1, spaces with high supply and high return vents are required to introduce 20 percent more fresh air than other supply and return configurations.

“By using a series of Airius fans between the supply and return vents, some applications can minimize the waste of conditioned air by circulating air down to the breathing zone of 150 fpm air jet and reduce short circuiting,” he says.

“By doing so, the fresh air intake can be reduced by 20 percent without having a negative impact on indoor air quality. Note that by definition in ASHRAE 62.1, the ‘ceiling’ includes any point above the breathing zone. So even in spaces that have returns at a lower position but still above the breathing zone, this strategy could apply.” BE_bug_web

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