William Atkinson 2015-07-22 17:39:53
There has been a lot going on in recent years related to advancements in commercial HVAC, including variable refrigerant flow (VRF), chilled beams, energy recovery, and ultraviolet (UV) light. Some of the systems that are new to the US have been used successfully in Europe for decades, and others are brand new technologies still making their way into the sectors that can benefit most from them. Variable Refrigerant Flow “The demand for efficient heating and cooling options has catapulted the growth of VRF systems in the United States,” says Brendan Casey, commercial product manager for Fujitsu General America. “The benefits of energy savings, flexible installation, ease of installation, advanced controls, and superior comfort for occupants make VRF an ideal choice for most commercial applications.” VRF allows for single source equipment by using refrigerant as the medium for heating and cooling, along with a single outdoor condensing unit to condition the refrigerant, which is circulated within the building to multiple fan coil units. The refrigerant is getting super heated and super cooled, depending on the control settings in the various spaces, cycling from hot gas and cooled liquid as it goes through refrigeration cycle stages. According to Casey, VRF systems provide the most efficient HVAC option for most buildings. By using inverter-driven compressors, the outdoor unit only runs as fast as necessary to meet the needs of a space. “No longer do compressors need to cycle on and off, wasting energy and reducing the life of the system,” he says. A VRF system also provides the option of installing the outdoor unit indoors. By mounting the unit in a weatherproof mechanical room, the outdoor unit can be located closer to the conditioned space. This reduces the piping required and gives each tenant more control over the system on the floor. “This is a very popular option for large buildings in metropolitan areas where ground or roof space might not be available,” says Casey. VRF systems can also connect local controls, central controls, and remote access to an entire VRF system, up to 1,600 indoor units controlled by a single controller located in a building management office. VRF systems also provide the benefit of being scalable. “If a building plans to convert to VRF, it is not necessary to install all 1,600 indoor units at the same time,” says Casey. A building going through a conversion can add units or floors as each new tenant is added. Individual refrigerant circuits can be added and brought online with the central controller as they are installed. Another manufacturer offering VRF technology is Lennox Industries. “Our VRF system has one outdoor unit that can consist of multiple modules, connected to multiple types of indoor units through a single refrigerant piping network,” says Chris Drury, vice president of sales VRF. “Each indoor unit, or zone, is controlled by its user.” The system constantly varies the amount of refrigerant flowing to each indoor unit to match the internal load requirement by allowing the compressors to work only at the needed capacity in order to meet that load. This ends up consuming less energy than “on/off” systems. Even if the VRF run time is longer, a VRF system is usually operating at a capacity of less than 100%. VRF offers a number of benefits over conventional HVAC systems, according to Drury. Among these are: • Superior zoning- Individual users can control temperatures in their own areas, providing cooling or heating when and where it is required. Each indoor unit controls its own environment by sensing the temperature of the return air and controlling the electronic expansion valve accordingly. • Energy efficiency- A VRF system only uses the energy required to meet load requirements, making it extremely energy efficient. Depending on the application, usually comfort cooling and heating, most VRF systems operate at part load 60 to 80% of the time. • Adaptable to application- VRF systems are modular, or scalable, in system capacity. Multiple modules can be added to meet design load capacities. Modular versatility, varying capacities for outdoor units, and multiple types of indoor coils (both ducted and non-ducted) make the VRF system a solution that meets a wide variety of applications. • Quiet performance- VRF outdoor unit sound ratings are comparable to indoor units of other HVAC systems. “Many VRF indoor units are so quiet that it is difficult to even tell they are operating,” says Drury. The Lennox VRF line of products provides a number of benefits to commercial building facility managers, such as: • A variety of local controllers allow for user control of zones, but with limitations. “That is, centralized controllers allow facility managers to set up schedules, remotely control indoor units, and create appropriate restrictions to user control of local controllers,” says Drury. • There are significantly fewer maintenance points compared to chillers. Quarterly maintenance on a VRF system consists of cleaning indoor unit filters, keeping the indoor and outdoor heat exchangers clean, and checking condensate pumps and drains for leakage and blockages. Four-pipe heating and cooling systems, on the other hand, require water treatment, cooling tower maintenance, water circulating pumps maintenance, central heating plant maintenance, and a number of motorized valves and control items that require regular servicing. • Modularized single-module systems make it easy to shut down a portion of the system for service without affecting the operation of the remainder of the system. “Multiple-module systems provide redundancy, so that, if even one module goes down, the remaining modules can continue to operate,” says Drury. Mitsubishi Electric Cooling & Heating is another company offering VRF technology. The company recently unveiled its new line of Hyper-Heating Inverter (H2i) ductless and VRF zoning systems. “Mitsubishi Electric is the pioneer of ductless and VRF zoning technology in the US, and the first to develop low-ambient heating capabilities,” says Robert Byrd, a company spokesperson. “The H2i technology revolutionizes the heat pump by optimizing energy usage and delivering heat at very low outdoor ambient temperatures.” The technology is ideal for various commercial applications, in that it helps facilities accommodate various load requirements for separate rooms or buildings, saving energy and maintaining valuable square footage. According to Byrd, there are four major benefits of H2i technology: • Energy savings- Because H2i technology recovers heat energy that would otherwise be wasted, energy usage is kept at a minimum. In addition, while traditional systems continually turn on and off to meet a desired temperature, the inverter-driven compressor quickly adjusts and maintains speed, reducing energy usage and increasing utility bill savings. • High performance- A flash process cools the compressor, allowing the zoning system to heat rooms at lower outdoor temperatures without overheating. The process provides optimal heating performance at low temperatures. “In fact, systems can operate effectively, even in outside temperatures at minus 13 degrees Fahrenheit,” he says. • Low life cycle costs- The highly efficient hyper-heating systems help decrease the overall equipment tonnage of projects. This means lower initial costs; the smaller outdoor system footprint and ability to be installed more quickly allows for reduced installation costs. The technology also eliminates the need for supplemental heat sources in many cases, such as fossil fuel burning or inefficient electric systems. • Reduced maintenance costs- “Hyper-heating technology offers year-round efficiency for optimal occupant comfort, which translates to fewer complaints and system adjustments,” says Byrd. Schools Choose VRF With Controls One satisfied Mitsubishi customer is the Screven Elementary School in Sylvania, GA, a 143,000-square-foot facility built in 1989. While the facility was partially renovated in 2002, a dated and inefficient HVAC system remained. After the pipes of the original water-source heat pump deteriorated, William Bland, superintendent of the Screven County School System, says, “There was no question about the need for a renovation of the HVAC system at the elementary school.” While the initial plan was to repair the old system, research showed that not only would the cost be substantial, but also there would be no increase in energy efficiency. As a result, the school elected to purchase and install a VRF zoning system from Mitsubishi Electric. “It was the energy efficiency that grabbed our attention,” says Mike Dixon, maintenance director at the elementary school. “We were also interested in the ability of the units to maintain the temperature within one or two degrees, and the quiet operation.” The installation took less than 12 weeks and took place over the summer when school was not in session. The VRF system allows Preston Dees, director of school safety and energy management for the Screven County School System, to monitor and control the cooling and heating in each classroom. “We have had an aggressive energy management system in place for five years, and we are documenting substantial savings with the system from previous years of record,” says Bland. In fact, average annual savings are $16,225, representing an average energy savings of 25%. Mitsubishi offers an additional way to help HVAC systems manage energy, called the Diamond Controls Solutions. According to Byrd, one of the best ways to manage energy, particularly that used by HVAC systems, is with an automated controls solution, which can control numerous systems through a single interface. Mitsubishi’s Diamond Controls Solutions pairs building automation controls with comprehensive customer service. Since HVAC is the largest significant feature that commercial controls systems manage, Mitsubishi’s new DC-600E Integration Controller system centers around the facility’s HVAC system. However, it can also manage the following: access control, air compressors, ancillary heating, boilers, chillers, centralized water plants, domestic hot water, energy recovery, generator monitoring, humidifiers, occupancy sensors, photovoltaic panels, pumping systems, refrigeration monitoring, sprinklers, thermostats, ventilation, and more. The system also provides efficiency gains. VRF zoning systems consistently perform at 25 percent higher efficiency than traditional systems. Managing VRF through Diamond Controls Solutions provides an additional level of efficiency, because the systems come with built-in sensors, and the controls use the standard cooling and heating building controls best practices. As a result of its efficiency, facilities can use Mitsubishi’s VRF and Diamond Controls Solutions in combination to help meet or even exceed US Green Building Council’s LEED requirements, as well as meet Energy Star requirements. The technology also provides cost savings. The building’s facilities manager or engineer can use the controls to modify heating and cooling, as well as the other systems that are connected—all around the facility’s optimal schedule. The manager can also schedule setbacks based on weather forecasts. In addition, the system can check the ambient temperature conditions and adjust itself automatically, such as turning down the temperature during an unseasonably warm winter day. Costs can also be reduced via utility rebates. For example, the Diamond Controls Solutions can adjust usage based on signals from a utility via a Demand-Response program. Liberty Memorial Central Middle School in Lawrence, Kansas has also been pleased with what Mitsubishi had to offer. The school had an aging four-pipe HVAC system in need of replacement, and chose a VRF zoning system from Mitsubishi Electric, but also wanted controls that would provide efficient management. “Diamond Controls Solutions offered a great solution, giving the school full access to the VRF system, as well as full integration into existing mechanical equipment,” says Ed Lange, a sales engineer with Morgan & Associates (Shawnee, KS). “Mitsubishi’s Professional Solutions Group worked closely with our field techs to ensure a seamless project. When most of the equipment and control devices were installed, the PSG sent a team of four individuals for a week to begin the commissioning process.” The school district is so satisfied with the solution that it is extending it to include five of its other schools. Each school will be outfitted with Diamond Controls Solutions, and all six schools’ controls will be connected to a web server application for central monitoring. Chilled Beams Another innovative HVAC technology is chilled beams, which work by convection. The beams, suspended from the ceiling, chill the air around them. The cool air is dense and thus falls to the floor, and warmer air rises up. Overall, there is a passive, constant flow of cooling air. There are active versions of the technology, too, which push air toward the units. “We are the first US manufacturer of chilled beams,” says Tom Rice, director of sales for SEMCO. “We manufacture the beams as flexible as possible for ease of design and contractor installation.” The company’s newest related product is called the Neuton pump module, which is coupled with chilled beams. “You can have a central plant that is creating 45-degree [Fahrenheit] water, and feeding that to all of the air handling units,” says Rice. “With chilled beams, you need 58-degree [Fahrenheit] water. So, you can create a blend loop, which blends the 45-degree water to where it becomes 58-degree water, and this is fed out to the chilled beams. This is called a tertiary loop." The Neuton creates a tertiary loop at the zone level, rather than at the full-building level. So, if one zone has a problem, such as the rising humidity, the pump module addresses that one zone, as opposed to the central tertiary loop, which would affect all of the zones. “This zone approach provides a lot of energy savings,” says Rice. “In addition, the pump system controls allow the facility to save on first-cost from the piping perspective, from the electrical perspective, and from the control perspective.” Energy Recovery Besides chilled beam technology, SEMCO also offers energy recovery technology for HVAC systems. Its new Unitary Wheel Cassette (UWC) Series, an aluminum energy recovery dessicant wheel, is designed as the HVAC industry's first drop-in replacement for plastic/polymer dessicant wheels in most unitary energy recovery ventilator (ERV) brands. The wheel features a fast-acting and corrosion-resistant dessicant that is applied to a sturdy but lightweight all-aluminum wheel substrate. The honeycomb matrix’s opening design produces maximum air-to-air heat transfer, but generates up to 50% less HVAC system static pressure than polymer film wheels. It also has a longer life cycle and less periodic maintenance requirements than polymer wheels. “The marketplace is filled with inexpensive plastic wheels that have a very short lifespan—one to three years,” says Rice. Since the units could last 15 years, it required a lot of time and money to continually replace the wheels. “In addition, plastic is not a good conductor of energy. So, our goal was to develop an aluminum drop-in replacement wheel that could replace these short lifespan wheels that no longer worked. Aluminum, of course, is a good heat transfer device.” It is important to consider recovery energy ratio (RER) when purchasing replacement wheels. The RER takes into account the efficiency and static pressure of a dessicant wheel replacement. Not calculating the RER can result in thousands of dollars of lost energy savings over the course of the wheel’s life cycle. “The RER on our wheels, in some cases, is double what our competitors’ wheels produce, because ours use much less energy to recover exhaust energy,” says Rice. UV Light A progressive new technology incorporating UV light in HVAC systems comes from Fresh-Aire UV, a division of Triatomic Environmental. One of its products is the Commercial Series APCO Rack System, which is a non-ozone air purification system for HVAC units in commercial, industrial and institutional facilities. It is designed for hospitals, offices, schools, hotels, and other commercial buildings that require reduction of odors and toxic vapors associated with airborne microbial and volatile organic compounds (VOC) contaminants. The APCO Rack System was the 2011 Innovation Award winner in indoor air quality (IAQ) at AHR (Air Conditioning, Heating and Refrigeration) Expo. It is the first to combine UV germicidal irradiation (UVGI) for airborne and HVAC unit internal surface disinfection, with gas-phase air purification and photo-catalytic oxidation (PCO) to capture and neutralize VOC contaminants. In specific, the APCO Rack combines three technologies: • UV-C (short-wave ultraviolet) lights sterilize airborne and surface mold, germs, viruses, and allergens found in supply air distribution and on interior HVAC surfaces. • Titanium dioxide-infused carbon cell matrix adsorbs VOCs in a gas-phase air purification process and removes them from the airstream. • PCO chemically transforms the captured VOCs into harmless water vapor and CO2 when the UV-C light shines on the titanium dioxide-infused carbon to create a photo-catalytic effect. “It also keeps air-conditioning coils, interior HVAC unit surfaces, and drain pans clean of mold and other biological growths, which increases operational efficiency, lengthens equipment life cycles, and reduces maintenance costs,” says Michael Walrath, commercial products sales manager for Fresh-Aire UV. The system efficiency he mentions that comes from keeping biofilms from accumulating leads to increased energy efficiency. The APCO Rack System installs quickly inside all brands of HVAC package and air handling units, ranging from 10 to 200 tons. It is available with Fresh-Aire UV’s proprietary tubular track installation concept, which includes brackets and mounting hardware for assembling a framework of off-the-shelf tubing. The units can be stacked or staggered to fit any coil size and configuration. “The water-resistant power supplies withstand condensation inside air handlers and all weather conditions when mounted externally on outdoor equipment,” says Walrath. Are there certain types of buildings that benefit more from UV-C technology than others? “All commercial and institutional facilities can benefit from UV-C technology, as they all can appreciate the benefits of energy savings, lower maintenance costs, longer equipment life, and improved indoor air quality,” says Walrath. “That being said, though, we spend a lot of our efforts with healthcare and educational facilities.” Benefits at a Pet Care Business A happy Fresh-Aire UV user is Spa Paw and Tail (New Berlin, WI), a 10,000-square-foot pet care facility. Animal odors are inherent challenges in any pet business. Spa Paw and Tail is now using Fresh-Aire UV’s HVAC purification technology to control odors, reduce energy bills, and prevent any potential infectious airborne animal diseases. “The sense of smell influences a customer’s first impression upon entering a pet business,” says Nina Race, president. “Bad odors give the impression that an establishment isn't clean, even though it might be spotless from a sanitation standpoint.” Race first attempted to reduce odor by introducing more outdoor air through the HVAC system, but that simply increased the cost of energy. Spa Paw and Tail arranged for a local HVAC contractor, Action Heating and Cooling, to install eight APCO air purification systems on each of four 7.5-ton rooftop HVAC systems. “Since installing the air purification equipment in our HVAC equipment, odors have been eliminated in the greeting area and gift shop,” says Race. And, as noted earlier, energy costs have decreased, and the potential for airborne infectious diseases has essentially been eliminated. Finally, the facility has seen a decrease in equipment maintenance costs. That is, the dark and moist environments inside the HVAC equipment, which were once ideal breeding grounds for microbes, are no longer so. The UV lights help to eliminate mold and subsequent dirt accumulations, which reduces coil cleaning time during semi-annual service calls. Fresh-Aire UV also offers a technology called Blue-Calc, which is a UV-C light design and analysis service using sizing software that helps facilities managers or engineers calculate the amount of UV light needed for their commercial buildings. Its web service provides calculations of both airborne and cooling coil surface microbe disinfection efficiencies from UV-C light exposure, and generates detailed color chart and graph image printouts for building owner presentations. Blue-Calc can detect inadequate coverage or insufficient microbe inactivation time in a specification conforming to the UVGI (ultraviolet germicidal irradiation) industry’s D99 criteria, a dose resulting in a minimum of 99% inactivation. It can also calculate reflectivity of a variety of duct material surfaces, such as stainless steel, galvanized steel, aluminum, and even interior insulation. A higher reflectivity equates to a higher microbe disinfection rate and the potential of cutting project costs by reducing the number of needed UV lights and their output performance. This helps cut project costs by eliminating equipment over-sizing. “Too many engineers and contractors simply rough-estimate the number of UV lamps and their placements in the HVAC unit,” says Chris Willette, president of Fresh-Aire UV. “Now they can apply an exact science for UVGI’s full benefit.” William Atkinson specializes in topics related to utilities and infrastructure.
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