ADVANCED HEATING TECHNOLOGY APPLYING VRF IN COLD CLIMATES

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1 ADVANCED HEATING TECHNOLOGY APPLYING VRF IN COLD CLIMATES Presented by: LEARNING OBJECTIVES Upon completion of this course the student will be able to: 1. Identify how VRF heat pumps differ from traditional HVAC systems. 2. Describe what advanced heating technology is and how the technology works in VRF systems. 3. Describe the main benefits of using VRF heat pumps with advanced heating technology. 4. Identify how VRF systems contribute to the energy efficiency goals of buildings. CONTINUING EDUCATION AIA CREDIT: 1 HSW/LU AIA COURSE NUMBER: AROCT Use the learning objectives above to focus your study as you read this article. To earn credit and obtain a certificate of completion, visit and complete the quiz for free as you read this article. If you are new to Hanley Wood University, create a free learner account; returning users log in as usual. Ceiling-recessed indoor units offer a sleek method of air distribution in separate zones of a building s interior space. By Parker A. Grant, PhD VARIABLE REFRIGERANT FLOW (VRF) HEAT PUMPS: AN IDEAL HVAC SYSTEM Variable Refrigerant Flow (VRF) has been used throughout the world since the 1980s. In many countries, it is the most-used HVAC technology: for example in Japan VRF represents approximately 90 percent of installed systems within commercial buildings, Europe approximately 81 percent, and China approximately 86 percent. Architects have favored VRF systems for many reasons, among them longer line lengths for more flexible design and the ability to mix and match indoor unit styles. VRF for commercial applications was introduced to the U.S. market in Since then, there have been major improvements in heating capabilities, space savings, and ease of retrofitting into buildings that were never designed to have air conditioning. Furthermore, advances have been made in the performance of the inverterdriven compressor, including improved energy efficiencies and reduced operational noise. With so much to offer, it s no surprise that much of the world has taken to VRF. You can turn to VRF heat pumps for a multitude of reasons. From optimizing a building s exterior and interior space planning, to meeting the energy efficiency needs of your clients and comfort control demands of end users, VRF has the features that let your designs shine. VRF achieves such success by dividing a building s interior into zones, each of which can be conditioned separately. For VRF with heat recovery, one room can even be cooled while another is simultaneously heated. In this case the exact required capacity is distributed to each indoor unit via a branch circuit controller. The result is superior personal comfort for occupants.

2 Design Challenges of Traditional HVAC Systems Comfort trumps everything, but there are multiple kinds of occupant comfort to consider: feeling, seeing and hearing. A building must feel, look and sound good in order for occupants to enjoy their environment. Most people recognize that no one wants to be in a building that s uncomfortable. It doesn t matter how beautiful or innovative the building is; if people don t want to be in it, it s ultimately not a successful project. This is a difficult truth for designers in a world of tantalizing projects and details. When it comes to commercial buildings, architects face two main challenges when incorporating HVAC systems that bolster occupant comfort. The first is space. HVAC systems have traditionally been quite large, with outdoor units requiring ample square footage on rooftops or grounds and indoor units and ductwork consuming plenty of space in ceilings and plenums. This is bad news in a business focused on usable square footage. Ultimately an HVAC system should maximize an area, enabling you to create more useable space for your clients. The other main challenge in designing an HVAC system for comfort is acoustics. You should avoid using a system that your client or your client s tenants will complain about. Loud outdoor units, noisy indoor units, and a vibrating structure are all problematic and best avoided. You can turn these design challenges into an opportunity, but it all starts with knowing your options. Armed with this knowledge, you can influence your clients, improve project performance, and make a significant difference to the end user. As a result, your client may be able to increase rental rates and deliver more useable square footage to building owners. The Best Option: VRF Systems VRF is an HVAC system that makes the most of square footage, acoustics, and budget while offering energy-efficient technology that provides outstanding comfort. Compared to conventional HVAC systems such as Variable Air Volume, Packaged Rooftop Units, Water-Source Heat Pumps, 4-Pipe Fan Coils, Packaged Terminal Air Conditioners, and Split Systems VRF is highly favorable in every category: Comfort Total Installed Cost Efficiency Maintenance Architectural Impact In addition, with as much as 40 percent of a building s operating costs tied to HVAC and other mechanical systems, it s important to minimize operating costs while achieving goals such as reliable performance, a modern aesthetic, and personalized comfort control. Because of this, VRF is the option that can bring flexibility to your building designs. Design Flexibility with VRF Systems VRF systems allow flexibility within your design since there is little to no ductwork involved. By reducing the plenum size, you can raise your ceiling heights leading to more stunning designs. The benefits are fourfold: A more spacious, modern feel Lower construction costs due to the possibility of designing shorter buildings More natural light and better indoor environment due to bigger windows The option to develop additional leaseable space VRF enables you to reclaim usable square footage such as space that would otherwise go to mechanical rooms. This can also take the form of minimized wall penetrations, where two small pipes connect the outdoor unit(s) to the indoor units, thereby reducing installation costs and impact. VRF s smaller footprint also means a lighter weight. In some cases, VRF systems can be 30 percent lighter than chilled-water systems. The implications are profound: ultimately, lower construction costs because installations of lighter systems require less structural support, reducing the amount of physical materials and labor required. You can even transport the outdoor units in a service elevator, potentially eliminating the need to rent cranes. In addition, the exterior of a building is often reserved for the outdoor components of an HVAC system. VRF s modular and compact design reduces the size of the outdoor units versus traditional HVAC systems. This enables flexible design since outdoor units can be spread around a property or located together, placed inside or outside, such as in a mechanical room or in an alleyway. A 4-way ceiling-recessed cassette can be used to provide a more spacious feel. With many indoor unit styles and the ability to mix and match ductless and ducted options, you can design to your vision. Some of these indoor unit choices include: Wall-Mounted Low Profile Ceiling-Concealed Ducted High Static Ducted Multi-Position Ducted Floor-Standing 1-Way Ceiling-Recessed Cassette 4-Way Ceiling-Recessed Cassette While VRF is in many cases an ideal HVAC option, heating in cold climates has historically presented challenges. Heat pumps have been troublesome in extreme cold climates. Below 17 degrees Fahrenheit, an auxiliary heat source, such as a gas-fired boiler, was needed to adequately heat a building. In many places throughout the country electricity was a much more accessible and affordable fuel than gas. The result was a technological gap the need for heat pumps that could operate in even the coldest weather. Today, those heat pumps exist. VRF heat pumps with advanced heating technology were developed to address these very issues, and heat pumps can now offer impressive performance in even the coldest climates with no need for auxiliary heat. With advanced heating technology, your design flexibility increases. This saves end users energy, money, and maintenance headaches, which is excellent news for the building professionals who get called in every winter to solve cold-climate heating problems. ADVANCED HEATING TECHNOLOGY: WHAT IS IT AND HOW DOES IT WORK? There is currently no industry-wide definition of advanced heating technology since it is

3 Add a highly responsive VRF system with advanced heating technology to any building project, in any climate. relatively new to the United States and only some VRF manufacturers offer it. Among those who do, a general definition of the technology is the ability to provide full rated heating capacity at zero degrees Fahrenheit (or below depending on the manufacturer) and offering substantial heating capacity at minus 13 degrees Fahrenheit. Heating in Cold Climates Historically, heating in cold climates has put industry professionals to the test. When it comes to heating indoor spaces from office buildings to schools to health and wellness facilities the challenge is to not just achieve the required heating, but to do it effectively and efficiently. Many heating systems don t perform as the temperature drops, causing end users to rely on auxiliary heat, and often on fossil fuels. These are both things an energyand money-conscious market is looking to move away from. An advanced heating technology system helps eliminate the need for additional fossil fuel burning or inefficient electric heating systems. That s better for the planet and your bottom line. Proven residential and commercial success with advanced heating technology has now extended to areas of the country where historically heat pumps just couldn t be applied. How It Works As the outdoor temperature drops below freezing, traditional heat pumps face decreased performance as the flow of refrigerant circulating through the system drops. In turn, this reduces the amount of heat generated. Advanced heating technology solves this problem with the addition of a flash injection circuit. This is accomplished by injecting a portion of the refrigerant into the compressor at a lower temperature than normal, reducing the temperature inside the compression chamber and enabling the compressor to run faster. With the compressor running at higher speeds than normal, the system can maintain its heating capacity despite colder outdoor temperatures. This process is typically used in units over 24,000 Btu/h of capacity, and kicks in when the ambient temperature drops below 25 degrees Fahrenheit. Here is a further breakdown of how the process works: 1. Outdoor unit in heating mode sends superheated gas to the indoor unit. 2. Gas becomes liquid/vapor mix inside the indoor unit and migrates to the separator. 3. Heat exchanger pulls remaining heat from liquid/vapor mix; mix becomes subcooled liquid. 4. Outdoor unit pulls heat from outside air to get liquid into gaseous form. In order for this to happen, the refrigerant must be colder than the air outside, making a freeze protection circuit necessary. For example, if the temperature outside is minus 10 degrees Fahrenheit, the refrigerant must be colder. 5. Flash injection circuit cools down compressor. 6. In the freeze protection circuit, a hot gas loop eliminates ice buildup. The result of this technology is impressive heating capacity 100 percent at 0 degrees Fahrenheit and 85 percent at minus 13 degrees Fahrenheit, for example. In the case of VRF with heat recovery and advanced heating technology, simultaneous cooling and heating is generally available down to minus 4 degrees Fahrenheit (instead of the 14 degrees Fahrenheit associated with most manufacturers standard version of VRF). Having the ability to cool and heat at the same time during negative ambient temperatures is necessary in applications such as office buildings that need to serve both workers sitting all day (requiring heating) and occupants using gym facilities (requiring cooling) even as the temperature drops. Between minus 4 degrees Fahrenheit and minus 25 degrees Fahrenheit outdoor ambient temperatures, a VRF system with heat recovery and advanced heating technology will operate in heating mode only. The advanced heating technology process uses a flash injection circuit to help the system maintain a high heating capacity despite colder outdoor temperatures.

4 A Closer Look at the Defrost Cycle None of this, of course, would be possible without a defrost cycle. For VRF with advanced heating technology, defrost cycles help to: Stop the indoor unit fan motor, preventing cold air from being distributed into the conditioned space ( cold blow ). Stop the outdoor unit fan, allowing the outdoor condenser coil to increase in temperature to more efficiently eliminate ice build-up. Operate the compressor frequency at a high speed, increasing the discharge gas temperature. A VRF system with advanced heating technology looks at three variables to determine when a defrost cycle should be initiated: outdoor ambient air temperature, cumulative compressor operating time, and outdoor refrigerant pipe temperature. The cycle auto-terminates either when the maximum defrost time is reached or when the outdoor refrigerant piping temperature has reached or exceeded a pre-set level for a pre-set amount of time (e.g., 50 degrees Fahrenheit for two minutes). End users will find that defrost cycles occur more often when it s warmer out, for example 32 degrees Fahrenheit and snowing, than during periods of extreme cold with a lack of moisture in the air. Regardless of the temperature, end users likely won t notice the defrost cycle taking place at all. If the system stops heating during a defrost cycle, heat will only be absent for a few minutes. Some manufacturers also offer a technology that creates heating capacity even during a defrost cycle. This happens by defrosting one section of the condenser coil at a time. The resultant operation shows a marked increase in heating capacity during defrost (from 0 percent to up to 60 percent depending on the outside temperature), as well as a small increase in overall heating capacity. This technology takes different forms depending on the manufacturer. Some use hot gas defrost, others reverse defrost and others use a hybrid. With some manufacturers, a hybrid of hot gas and reverse defrost can take place in a single module, making the technology applicable to smaller projects. While the use of hot gas defrost does increase the frequency of defrost cycles and make cold blow possible, it is still widely sought after for its impressive increase in heating capacity. QUIZ 1. Compared to conventional HVAC systems, in which of the following categories do VRF systems excel? a. Comfort b. Total installed cost c. Efficiency d. Maintenance e. Architectural impact f. All of the above 2. percent of a building s operating costs are tied to HVAC and other mechanical systems. a. 10 b. 40 c. 60 d True or False: VRF enables designers to reclaim usable square footage within a building such as spaces that otherwise would go to mechanical rooms. 4. VRF systems can be percent lighter than chilled-water systems. a. 10 b. 20 c. 30 d True or False: Advanced heating technology is typically used in units over 24,000 Btu/h of capacity, and kicks in when the ambient temperature drops below 25 degrees Fahrenheit. 6. What is the heating capacity with advanced heating technology? a. 100 percent at 0 degrees Fahrenheit b. 85 percent at minus 13 degrees Fahrenheit c. 10 percent at 0 degrees Fahrenheit d. 100 percent at minus 13 degrees Fahrenheit e. Both A and B 7. True or False: In the case of VRF with heat recovery and advanced heating technology, simultaneous cooling and heating operation is generally available down to 14 degrees Fahrenheit. 8. What are the three variables used to determine when the defrost cycle should be initiated with a VRF system with advanced heating technology? a. Outdoor ambient air temperature b. Number of pipes in the boiler c. Cumulative compressor operating time d. Outdoor refrigerant piping temperature 9. True or False: VRF systems have the ability to treat hot and cold spots via zoning and simultaneous cooling and heating to ensure comfort for all. 10. True or False: VRF consistently performs at 25 percent higher efficiency than conventional systems. ÄThis article continues on Go online to read the rest of the article and complete the corresponding quiz for credit. SPONSOR INFORMATION Mitsubishi Electric US, Inc. Cooling & Heating Division (Mitsubishi Electric) is headquartered in Suwanee, Georgia. Mitsubishi Electric is a leading marketer of Zoned Comfort Solutions and Variable Refrigerant Flow (VRF) air-conditioning and heating technology in North America, Latin America, the Caribbean and Bermuda. In 1982, Mitsubishi Electric introduced its state-of-the-art, ductless air conditioners and heat pumps in North America and later expanded its product line with VRF zoning heat pump systems using INVERTER technology to offer simultaneous cooling and heating capabilities. The division also offers compressors and a full line of air-conditioning accessories.

5 BENEFITS OF VRF HEAT PUMPS USING ADVANCED HEATING TECHNOLOGY Now that advanced heating technology makes VRF an appealing choice in even the coldest climates, let s explore the main benefits of using VRF systems. Precise Temperature Control The outdoor unit's inverter-driven compressor varies its motor rotation speed, which allows the system to precisely meet each zone s conditioning requirements while reducing overall power consumption. In a VRF system, the inverter-driven compressor seamlessly adjusts speeds to reduce fluctuations of the set point temperature in partial-load conditions. In contrast, a traditional fixed-speed compressor cannot effectively handle partial-load conditions, resulting in poor set point temperature satisfaction. VRF systems are capable of providing simultaneous cooling and heating in separate zones to ensure everyone s comfort. Quiet Operation VRF operates at whisper-quiet levels. This is no exaggeration: Whispers come in at 35 decibels; VRF indoor units have a lower decibel rating for some brands, between 19 and 34 decibels. Reduced Costs The cost over a VRF system s lifetime represents ample savings versus conventional HVAC systems all while enjoying benefits like comfort and sustainability. It is true that VRF s initial equipment cost can be higher than traditional HVAC systems. In a cold climate application, the first cost can increase further due to factors like a higher electrical requirement or the need for coldweather accessories. However, VRF s installation cost is often lower than that of conventional systems, such as a four-pipe boiler/chiller setup with a building management system (BMS). With VRF, fewer materials are needed, less labor is demanded, and less structural work to the building is required. In addition, some control systems come standard and users can add advanced monitoring and control for a fraction of the cost of a BMS. Operation represents another venue of cost savings with VRF. As efficiencies increase, operational costs decrease because less energy is required to operate the system. Thanks to VRF s inverter-driven compressor, users can expect to see a savings of up to 25 percent on utility bills throughout the year. More Space There is more awe factor because of more useable space within a building. All of the space saved with VRF s smaller footprint means more room to include value-added amenities for your occupants. Picture being able to offer higher ceilings, smaller or no mechanical rooms, more rooftop space and more garden space, among many other options. System Controls From simple remote controls to whole building controllers that tie in multiple automated systems, VRF systems work on management platforms that are user-friendly and highly effective. Facility managers can access and operate systems from any place, at any time of day or night. Current controller options empower owners and managers to maximize the system s capabilities from adjusting set points to enjoying the convenience of energy allocation. Advanced Controls VRF with advanced heating technology offers a variety of advanced control options that Elimination of Hot and Cold Spots Just because a building is located in a cold climate doesn t mean that every occupant requires the same temperature. Maybe one side of an office building gets ample sunlight and actually needs cooling during the winter. Perhaps a health clinic or school with areas for both active and inactive occupants needs a mix of temperatures. In these situations, VRF s ability to treat hot and cold spots via zoning and simultaneous cooling and heating ensures everyone s comfort. With VRF indoor units at 30 decibels or lower, architects can avoid the problematic application of conventional, noisy indoor HVAC units.

6 Building owners have repeatedly demonstrated a preference for VRF systems. It is not hard to understand why because of the space gained from these systems. bolster operational savings and personalized comfort. On a small scale, several types of zone controllers are available to provide personalized temperature control. On a large scale, centralized controllers can monitor, schedule and control multiple indoor units through a Web browser interface. Multiple central controllers can be networked together with integrated centralized control software and systems can even be tied to a building management system. With controls built into the equipment and easily expanded on, this means more effective operation and further cost savings for your clients. Increased Energy Efficiency VRF consistently performs at 25 percent higher efficiency than conventional systems. Such efficiencies are a big help in achieving certification through Leadership in Energy & Environmental Design (LEED ) and other green rating programs. As an example, applying VRF can earn up to 28 points across two LEED categories (Energy and Atmosphere and Indoor Environment) advancing a project further down the track toward certification. Expandability VRF s modular nature enables phased projects. There is virtually no limit to how large a VRF system can be. This helps owners better budget and know what to expect. Additionally, VRF s lack of heavy infrastructure as compared to chiller plants, boiler systems and cooling towers, among other conventional HVAC system components, means there is simply more room within the building. Ease of Design and Specification VRF manufacturers offer design professionals an arsenal of tools to make design and VRF system controllers manage fan speeds and airflow directions for multiple indoor units. specification easy and successful. For example, some manufacturers offer a design tool with an interface that helps users determine the cooling and heating output of selected equipment for project-specific locations. The program has error indicators and built-in safeguards against exceeding limitations; this assures that line lengths, maximum connected capacities, component selections and control schemes, among other design selections, are within system requirements. These tools generally output AutoCAD drawings (or similar format) and custom-built REVIT models. Ease for the Facility Manager Since VRF with advanced heating technology can serve as a building s sole heating source throughout the year, facility managers can enjoy the simplicity of having just one cooling and heating system. Reducing the number of required systems has profound effects saving building owners upfront and installation costs, freeing up space where additional systems previously would have been required and reducing maintenance needs and complexities for the facilities management staff. Longer Operational Life Building owners benefit from having properly sized equipment, which ultimately results in a longer operational life. Traditional equipment is often oversized to meet heating needs during periods of extreme cold. This is problematic because oversizing degrades equipment life by running the compressors at full speed for long periods of time. VRF with advanced heating technology protects the compressors through an enhanced refrigerant circuit to avoid this degradation. The importance of this benefit cannot be overstated; protecting the outdoor unit in extreme cold climates is a huge step forward, and will ensure the equipment s long life and continuous operation. Adding Up the Benefits Even for geographical locations where gas is incredibly inexpensive, VRF with advanced heating technology is a worthwhile option because of its personalized comfort control, flexible design and installation, and the ability to right-size equipment (which results in more operational life out of a system). Further, as more projects incorporate solar panels and alternate energy generation methods, using an HVAC system powered by electricity becomes a way to reduce the project s carbon footprint. Opting for a singular cooling and heating system also means eliminating the need to purchase a central air-conditioning system in addition to a boiler, for example. Over a product s life cycle, these benefits add up ultimately making the case that VRF with advanced heating technology is a superior choice to other HVAC options currently available. Some manufacturers have developed efficiency evaluation tools that demonstrate the advantages, simulating the life cycle cost and other calculations for old and new buildings. For example, one simulation can compare the life-cycle cost of VRF with advanced heating technology to conventional water source heat pump (WSHP) and variable air volume (VAV) systems. Another simulation can compare the Energy Use Intensity of VRF with advanced heating technology to WSHP, VAV and packaged terminal air conditioners. In both simulations, VRF with advanced heating technology far outperforms the other technologies. Advanced heating technology is a critical component when a project calls for VRF and occupant comfort is essential. When working on multifamily buildings, you must think about the residents year-round needs, just as those working in hospice care must consider patient comfort. From small to large buildings, from residences to commercial uses, the application benefits for VRF (and ductless heat pumps) with advanced heating technology are numerous. Let s now take a look at a case study of how VRF with advanced heating technology was applied in a cold climate application.

7 CASE STUDY: THE COUNTRY S FIRST CERTIFIED PASSIVE HOUSE INDEPENDENT SCHOOL The Hollis Montessori School, Hollis, New Hampshire, is the first independent school in the country to achieve Passive House certification. This certification denotes the school s extreme energy efficiency and means the facility has met rigorous energy-saving standards. The certification also hints at the thoughtful education taking place inside the classroom walls. For example, students are encouraged to interact with the facility s various energy-saving systems. Students have been particularly interested in the equipment on the walls that keeps the classrooms comfortable and the school compliant with Passive House standards. That equipment is part of an advanced heating technology system from a VRF manufacturer. Indoor units mounted to the wall of each classroom in Hollis Montessori School. Challenge Hollis Montessori faced a challenge: finding an HVAC system that could meet Passive House s stringent standards for energy efficiency. Hollis Montessori is housed in two separate sites: a brand-new building with 10,000 square feet of space and a renovated apple pie factory with 4,900 square feet of space. For both buildings design, the goal was to create the best possible environment for learning. In the case of the brand-new building, that meant Passive House certification. Jordan Goldman, Principal, ZeroEnergy Design, Boston, led the Passive House consultation and HVAC design team. Goldman explained the draw of Passive House for the new building: Everyone talks about energy efficiency and carbon footprint. You get these pieces with Passive House, but it s also about better indoor air quality, thermal comfort and natural indoor light. This is especially true for a school because there s a correlation between these three factors and student performance. The healthier the air, the healthier the student. The healthier the student, the fewer days of school they miss. The fewer days of school they miss, the better they do in school. And then oh, by the way, Passive House will save you 90 percent on your heating energy. With sights set on Passive House certification, the team s HVAC search turned to ductless heat pumps. Traditional HVAC ductwork requires significant space within a plenum space. In contrast, VRF systems often feature a ductless design because two small pipes connect the outdoor unit(s) to the indoor units. A conventional system like a boiler would have been dramatically oversized for the facility s low heating demand, which would lead to inefficient operation and increased system cost, Goldman said. Keeping the energy level down is the core of Passive House, added the team s Architect David Ely, AIA, owner, Windy Hill Associates, New Boston, New Hampshire. Ely also favored ductless heat pumps for minimal impact on the building. We didn t want ductwork; it s ugly and it takes up space. With heat pumps, all we had to do was bring in condensate lines. Frank Grossman, President, Board of Directors, Hollis Montessori, explained that having no ductwork also helped save money. We considered geothermal heat pumps, too, but air-source heat pumps were less expensive because of the ductless design and lack of drilling. Installation went very smoothly, said Grossman. Outdoor units were put on stands to maintain performance during New Hampshire s snowy winters. Indoor units were mounted to the wall of each 1,400-square-foot classroom to simplify the distribution without sacrificing any thermal comfort at all, said Goldman. Grossman explained that the school also added sub-panels throughout the building where students can find out what energy their classroom is using compared to other classrooms. Students occasionally ask for the data, which they can see on tablets. It makes them both excited and curious. They try to figure out why one classroom is using more energy than another. The upper elementary kids also do units on energy and are educated about the heat pump system. They re very interested in how, on a cold day, you can take that cold air and turn it into heat. In addition to serving as a learning tool, the HVAC system has provided reliable cooling and heating for the past two years. Grossman said, We were hesitant about heat pumps at first whether they would keep up with the northeast winter. But we were told these [VRF heat pumps with advanced heating technology] could handle cold temperatures even on negative days and still produce the right amount of heat. I ve absolutely found this to be true; the units work nicely to produce even heat. Pretty much anywhere you go in the building, it s the same temperature. This is especially nice for the teachers, who can just work. They don t have to think much about adjusting the temperature. Solution A VRF heat pump with advanced heating technology offered Passive House-worthy energy efficiency, cost savings and sustainability. The heat pumps are also keeping any humidity in check. Ely said, When a building like this gets closed up and unused with no systems running, as happens over the summers, humidity can build up. Floor boards can warp. We re mitigating that by running these units on a low setting, offering dehumidification. Outdoor units featuring cold weather accessories were placed on stands at Hollis Montessori School. This ensured continued performance after heavy snowfalls. Hollis Montessori s success resulted from lower utility bills, as well. For the Passive House-certified building, the previous year s electricity bill was $4,500. That covers HVAC, lighting, computers, hot water for hand washing, and small classroom kitchens with appliances. Goldman said, Compared to other schools, that s an 85 percent energy savings. Those savings add up quickly: It cost us about 10 percent more to put in passive design, but we expect a payback of just three years, said Grossman. Indeed, the entire Hollis Montessori design team, the teachers, the students and the surrounding community have been very supportive of the project. Energy efficiency groups have even held meetings at the school, and architects have given tours. The larger world of green building has also felt the buzz with the first certified Passive independent school in the U.S. This is not just a big accomplishment; it s an important step toward large-scale passive construction.

8 VRF CONTRIBUTIONS TO ENERGY EFFICIENCY GOALS Fixed-speed compressors in conventional HVAC systems are either running at full power or are off. In the U.S., a zone within a building exhibits part-load conditions more than 90 percent of the time. Conventional systems cannot effectively handle these part- load requirements, resulting in energy fluctuations and poor set point satisfaction. In contrast, VRF offers full-range variable capacity to deliver only the amount of conditioning required to match a zone s cooling or heating demand. Working in tandem with integrated controls and sensors that measure loads for each zone, the compressor seamlessly adjusts speeds to maintain the desired zone temperature. This function, along with a low-profile ducted or ductless design, typically increases energy efficiency about 25 percent over conventional ducted systems, partly due to the energy lost by forcing air through ductwork. As a result, VRF can help facilities meet Green Globes and LEED requirements, and achieve the highest Integrated Energy Efficiency Ratio (IEER) ratings. VRF with advanced heating technology earns impressive efficiency ratings. A typical VRF system with advanced heating technology will perform with an IEER rating of up to 16.8; VRF with heat recovery and advanced heating technology will see even higher IEER ratings up to Advanced heating technology is also available in single-zone ductless systems. In these cases, the Seasonal Energy Efficiency Ratio (SEER) gets up to a rating of 30.5 with advanced heating technology, though most units are rated in the high teens or low to-mid 20s. VRF with advanced heating technology also has an impressive Coefficient of Performance (COP). At the Air Conditioning and Refrigeration Institute s standard test temperature of 47 degrees, VRF with advanced heating technology has a COP of 3.8. At zero degrees Fahrenheit, the COP is still over 2. At minus 13 degrees Fahrenheit, the COP is about 1.4. Even at minus 25 degrees Fahrenheit, the COP of 1.25 still wins out over standard electric heat s COP of 1.0. In short, VRF with advanced heating technology contributes to energy efficiency goals because it provides more efficient performance than other heating options in extreme cold temperatures. SUMMARY For decades now, VRF has enabled architects to push the design envelope. VRF is a proven technology that still feels cutting edge. Visually, it looks modern and sleek. In terms of benefits, it s continually leading the pack thanks to the introduction of advanced heating technology. VRF lets you confidently use the highestefficiency HVAC system on the market while seeming ahead-of-the-curve. Ultimately, VRF enables you to be a leader in your field and provide an efficient solution to your clients. We hope you now have a better perspective of how to apply VRF with advanced heating technology in cold climates.