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Table of Contents About Thermo King
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The latest advances in climate control technology
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By Steve D. Johnson, Sr.
Ensuring durability
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By Steve D. Johnson, Sr.
Eco-friendliness is a priority for HVAC
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By Steve D. Johnson, Sr.
Preventative maintenance
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By Steve D. Johnson, Sr.
Zero-emission buses, all-electric HVAC specifications and passenger comfort
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By Steve D. Johnson, Sr.
All-electric HVAC changes maintenance practices
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By Steve D. Johnson
APTA showcases the future for electric vehicles – but there are plenty of opportunities in the present
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By Steve D. Johnson, Sr.
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THERMO KING Thermo King is the world leader in transport temperature control systems for trucks, trailers, buses, rail cars and shipboard containers. Thermo King also manufactures auxiliary power units, which dramatically reduce engine idling. All Thermo King products are backed by a nationwide dealer network, which provides expert factorytrained service and a complete line of genuine and competitive parts. THERMO KING HISTORY It all started on a hot summer day in 1938 and a customer’s need to keep a load of fresh chickens cold while transporting them to market. Joe Numero accepted the challenge, and with the engineering genius of Frederick M. Jones, the two launched Thermo King and began the age of modern transport refrigeration. Ever since that day, Thermo King has been developing customer-focused innovations that deliver efficiency, reliability and safety across the planet. That commitment to innovation continues, helping to grow businesses and improve lives now and into the future. PRODUCT PERFORMANCE Long-term value for your business When your transportation equipment meets the demands of service with reliability and efficiency, it contributes to your profitability. With 75 years in the industry, Thermo King equipment has repeatedly proven its dependability, and our products retain their value longer than any others in the industry.
Built-in savings Better design means a lower cost of ownership. Tough construction, proven reliability and efficiency help you save money on service and maintenance costs. Our sustainable designs pay off with reduced energy consumption, including built-in technology to modulate the engine and maintain temperature. Quality testing in our labs improves product performance, which means fewer breakdowns. With our longer maintenance cycles, you’ll save time and money. Expert service and support When you need support, you’ll get assistance from providers who are trained and certified to specifically service our products. And with the largest service network in North America providing assistance 24 hours a day, you have the support you need anytime, anywhere. Through Thermo Gard™ Service and Maintenance Solutions, you can choose the service program that best fits your business needs. Take advantage of repair authorization options, centralized billing, extended warranty options, and service at any of our over 200 factory-authorized service centers nationwide.
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The latest advances in climate control technology By Steve D. Johnson, Sr. What are the latest advances in climate control technology? It sounds like a relatively easy question to answer, right? When the question was asked of me recently, however, my thoughts went immediately to “what’s trending in the transit bus industry?” Ask any transit professional today and most will mention “energy efficiency and sustainability” in one context or another. So what does that mean and how is it related to HVAC technology? Consider this statement: “I want to become more environmentally conscious by reducing my carbon footprint and I am looking for new technologies that help me achieve this, including but not limited to: components and systems that reduce engine emissions and improve MPG, alternative fuels, and electrification of buses and all accessories. I want the per mile cost to operate the bus to go from $0.98 cents to less than $0.30 cents. ” Here are some recent advances in climate control technologies that support “energy efficiency and sustainability”. • Controls: Mechanical controls are now microprocessor based with J1939 communications capability. Advanced microprocessor technology can be used for energy management and conservation. • Motors: Permanent magnet and field wound are now ECDC brushless with variable speed control for energy conservation. • Heating Controls: On/Off solenoids are now motorized valves with PWM control providing energy conservation during the reheat mode. • Capacity Control: Mechanical EPR valves are now unloading compressors and electronic capacity control. The energy used by parasitic loads is reduced. • Unit Weight: Units weigh 200 to 300 pounds less. Weight matters. An empty bus gets better fuel mileage than a loaded bus. • Compressors: More efficient piston type and high efficiency screw compressors provide faster pull down capability. Make no mistake about it, everything on this list contributed to improvements in efficiency. But is it enough? Given the fact that the HVAC system is the single largest load on the bus, and a better understanding of what’s trending, it’s clear that current and future climate control technologies are driven by the need for greater efficiency. The trend with the greatest impact is electrification. The trend towards HVAC electrification has been around for some time but has taken on new momentum recently as users realize the value proposition through field trials and testing. Did you know that you can have an all-electric HVAC system on a conventional diesel or CNG powered bus? This technology is available from transit HVAC suppliers and can be considered as one of the latest advancements. 4
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The one-piece all-electric Athenia AMII E-800 from Thermo King is a hermetically sealed rooftop unit for hybrid bus, trolley bus and alternator-powered applications.
Here are the benefits of all-electric HVAC that will help drive down your cost of operation. • Saves fuel by eliminating the effect of variable engine RPM on bus load and cooling demand • Constant A/C unit capacity at all bus speeds including idle. Capacity is not dependent on engine speed. • Dramatically improved reliability because the units are hermetically sealed and tested at the factory. No field plumbing, evacuation and charging in the field is necessary. • Hermetically sealed, integrated electric compressors with variable speed control to eliminate belt-driven parasitic loads • A reduced number of maintenance items and components that can fail • No tubing or hoses needed in engine compartment to connect the HVAC unit and compressor. Potential leak points are eliminated. For the all-electric battery bus, which is gaining popularity, it is a given that you must have an all-electric HVAC system. While the same benefits are available, the all-electric bus is driving further improvements in climate control technology such as smaller and even more efficient HVAC systems. Here, efficiency is related to the range of the bus before the batteries have to be recharged. Naturally, the focus is on the HVAC system which happens to be the largest load on the battery. You can expect continuous improvement. I will close with this final thought: In its pursuit of improved efficiency, the industry must not forget the original intent of HVAC – passenger comfort. Our goal must be to provide the most efficient HVAC system possible without compromising passenger comfort. Steve D. Johnson, Sr. serves as product marketing manager, Bus HVAC, at Thermo King, Minneapolis, MN. Thermo King is a world leader in transport temperature control systems for buses. Thermo King also manufactures auxiliary power units, which dramatically reduce engine idling. All Thermo King products are backed by a nationwide dealer network. Visit www.thermoking.com for more information.
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Ensuring durability By Steve D. Johnson, Sr.
Modern HVAC units must be durable in many environments and road conditions, because any HVAC failure means pulling a vehicle off the road.
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n the early days of transit, it was not completely uncommon for an HVAC system to look as if it had fallen off the back of a bus after the vehicle hit a pothole. Let’s talk briefly about why that scenario is not likely to occur today by examining some important requirements in the transit industry that not only affect HVAC suppliers, but all suppliers. I can’t speak on the North American transit industry without commenting on its unique characteristics. It is part of the smallest public transportation system in the world. We produce between 5,000 and 7,000 buses a year. A single OEM in countries with multiple OEMS can produce as many as 12,000 buses a year. Our industry is federally funded and buses must run a minimum of 12 years or 50,000 miles. Many agencies are now keeping buses for 15 years. With these requirements in place, it becomes pretty clear as to what drives the demand for durability. The HVAC is now like the engine, transmission and brakes. A failure means the bus will not be in service that day. How do we ensure durability? It starts with design. We design for the conditions that the bus will see and the design must be robust enough to live in those conditions for 12 years. That sounds straightforward enough, but how do we know when we’ve got it right? We must rely on testing, validation and most of all collaboration. Testing: The testing regiment comes in two pieces. First, HVAC OEMs take a road profile from a bus in service. The bus is instrumented and the levels of shock and vibration that the HVAC unit would experience are recorded. This test is useful when something breaks to help understand why it broke so preventative measures can be taken. It is most useful for new designs. Next, the HVAC unit is subjected to the shock and vibration levels recorded on the road test. This can be done prior to the HVAC system being installed on a bus.
Validation: Of course, the best validation would be many hours in service without a failure. Unfortunately, we can’t afford to wait and see what breaks. The solution is accelerated testing, also known as endurance testing where the conditions are repeated nonstop 24/7 for a period of time to simulate thousands of hours or miles. For our industry, new bus designs must be tested at the Altoona test facility with HVAC units installed. There buses are subjected to accelerated testing before being approved for transit duty. Collaboration: As noted above, this is probably the most important piece of the equation that has enabled us to move from things breaking and falling off the bus prematurely to more robust designs. Collaboration drives more than the structural design. It drives all aspects of the design including, but not limited to, operating in extreme conditions, individual component design and overall life cycle cost. Collaboration starts with our transit partners who are the stewards that make sure the funding is used for the purposes intended. Transit agencies need to know what to put in the specifications and work with suppliers to test new technologies as well as perfecting existing technologies. It is this collaboration that makes North American transit one of the strongest public transit systems in the world. Steve D. Johnson, Sr. serves as product marketing manager, Bus HVAC, at Thermo King, Minneapolis, MN. Thermo King is a world leader in transport temperature control systems for buses. Thermo King also manufactures auxiliary power units, which dramatically reduce engine idling. All Thermo King products are backed by a nationwide dealer network. Visit www.thermoking.com for more information.
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Eco-friendliness is a priority for HVAC By Steve D. Johnson, Sr. There is little doubt that when the term “eco-friendliness” is used, practically everyone can grasp the meaning because of the emphasis on being green and protecting the environment. It is also generally understood that the HVAC system has the potential to negatively affect the environment because of the refrigerant gases inside. But before we get into the potentially harmful effects of refrigerant gases, let’s dig deeper into the broader interpretation of eco-friendliness and being green. For a product to claim that it is eco-friendly, the manufacturer of that product must have a “cradle to grave” strategy that clearly indicates that thought and effort have been applied towards creating specific rules intended to reduce the overall environmental impact. For example, every manufacturer knows what percent of their product is recyclable because it was considered during the design phase. The higher the recyclable content, the more eco-friendly the product is. The recyclable content is generally high for HVAC systems because of the common use of aluminum, brass, steel and copper. While that is a good thing, being eco-friendly goes beyond the materials in the unit. The chemicals used in the manufacturing of the product are also important. Why? Although some chemicals may be legal to use, it is the disposal of those chemicals and the potential effect on human health that drives manufacturers to use the most eco-friendly processes available. When you replace solvents and hazardous chemicals with biodegradable solutions, you can claim that your processes are eco-friendly and you are thinking green.
The manufacture of an eco-friendly HVAC product requires some special considerations. The systems designed for our comfort contain gases that can be harmful. The stage was set in 1987 with the signing of the Montreal Protocol which eventually led to legislation that phased out certain gases like R12 and R22. The issue then was ozone depletion. No ozone depleting gases are currently being used in bus air conditioning. The issue now is global warming and the stage is being set for the next transition with the EPA working on the final rule for acceptable gases. The implications for HVAC manufacturers have not changed since 1987. To be eco-friendly, the HVAC system must be designed for containment number one, and efficiency number two. Containment simply means that the design should be such that the amount of refrigerant leaking into the atmosphere is kept to the lowest level possible. HVAC manufactures have consciously reduced the number of fittings and other potential leak areas over the years. Containment also means that the user should repair any refrigerant leak immediately and observe all of the rules around recovery and recycling to further reduce the amount of refrigerant escaping to the atmosphere. As you can see, the responsibility for an eco-friendly outcome is shared. So, how does the efficiency of the HVAC system play into the eco-friendly and green scenario? Maybe more than one might suspect. Let’s start with the fact that the HVAC system is the largest single load on the bus. The power taken from the engine, or battery in the case of all-electric, to provide enough cooling for the bus can vary widely depending on the configuration of the HVAC system. An eco-friendly HVAC system is one that is designed to reduce and manage energy consumption. This measure of efficiency manifests itself with improved fuel economy for engines and longer ranges for the battery bus. While the engine itself must be efficient and comply with emission standards, any load reduction contributes to even lower emissions. Weight matters as well. As is commonly noted, an empty bus gets better MPG than a fully loaded bus. HVAC systems weigh 200 to 300 pounds less than they did 15 years ago. All HVAC manufacturers have a set of “Green Technologies” in their portfolio. Improving efficiency in the pursuit of bringing increased value to the end user is not new for HVAC manufacturers and today, the entire Transit industry is focused on energy efficiency and sustainability. To be eco-friendly, we must think and act green. It truly is a state of mind where thought leads to execution. Steve D. Johnson, Sr. serves as product marketing manager, Bus HVAC, at Thermo King, Minneapolis, MN. Thermo King is a world leader in transport temperature control systems for buses. Thermo King also manufactures auxiliary power units, which dramatically reduce engine idling. All Thermo King products are backed by a nationwide dealer network. Visit www.thermoking.com for more information.
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Preventative maintenance By Steve D. Johnson, Sr. When it comes to HVAC system performance and reliability, there is no substitute for a proactive, well planned year-round maintenance strategy that focuses on preventing – rather than fixing – problems. Performing maintenance tasks at recommended intervals helps ensure that fleet operators stay on schedule and avoid breakdowns and service disruptions. A good example of why this is more important now than ever is the dramatic drop in the number of buses transit agencies designate as spares. Who wants a $500,000 asset sitting idle just waiting to be used or undergoing a major repair that could have been handled before it became catastrophic? In some cases, everything else on the bus is working just fine when an unexpected, major failure of the HVAC system forces the asset to sit idle or be taken out of service prematurely. Ideally, if I have a 100 buses available I want 95 of them ready for service every day. Some number of buses will always be out of service for scheduled maintenance and repairs. PREVENTATIVE MAINTENANCE (PM) INTERVALS Maintenance intervals should be scheduled, focused on specific items to be checked and the results should be recorded. Operators usually perform preventive maintenance inspections and routine service on their buses based on the number of miles that have been driven. Because it is most convenient for operators to perform HVAC unit maintenance at the same intervals they use to service the bus engine and chassis, HVAC suppliers use a blended approach that considers both mileage and hours when structuring a PM schedule. For example, many transit companies change engine oil, lubricate the chassis and go through an inspection checklist at 6,000-mile intervals, adding other maintenance tasks at multiples of 6,000 miles. THE ABC’S OF PM SCHEDULING The 6,000 mile PM check can be the A inspection which comes due about every 30 days or monthly. At this inspection the technician will change or clean the air filter, do visual checks and validate proper operation of the system. The 18,000 mile check would be the B inspection which comes due about every 90 days or quarterly. The B inspection includes the A inspection plus more physical checks like adjusting the air gap on the compressor clutch. The annual or C inspection which will come due at approximately 48,000 miles is a comprehensive check of all systems and components. The C inspection includes both A and B inspections and is the ideal time to replace worn parts before they fail.
Allow the system to breathe by washing coils annually and changing the air filter monthly.
Operators often modify the ABC approach to fit their fleet profile and local operating conditions. In areas where the air conditioning season is short, agencies might use the seasonal approach. Spring is probably the best time for the Annual Inspection. Keep in mind that there are also some very specific checks that should be done each autumn in preparation for the heating season. PREVENTATIVE MAINTENANCE AND NEW TECHNOLOGY Ask any tenured technician in the automotive industry and they will tell you that preventative maintenance practices have changed dramatically. This holds true for the HVAC system as well. Complex electronic systems driven and monitored by highly advanced microprocessor controllers with diagnostic capabilities have significantly reduced the time it takes to diagnose and repair a failure. Advancements in clutch and motor technology have come with longer maintenance intervals. Additionally, the PM check for all-electric HVAC systems can be done in less than half the time needed for a conventional system because there is much less to check. PM TIP: CHANGE AIR FILTERS MONTHLY, WASH COILS ANNUALLY Clean filters and coils keep the system breathing easily. Changing or cleaning the air filter is one of the easiest PM activities you can do, yet it remains as one of the most neglected. A severely restricted air filter or coil not only affects system performance, it can contribute to unexpected system failures. Prolonged operation affects fuel economy and will shorten the life of major components like the compressor and fan motors. Steve D. Johnson, Sr. serves as product marketing manager, Bus HVAC, at Thermo King, Minneapolis, MN. Thermo King is a world leader in transport temperature control systems for buses. Thermo King also manufactures auxiliary power units, which dramatically reduce engine idling. All Thermo King products are backed by a nationwide dealer network. Visit www.thermoking.com for more information.
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Zero-emission buses, all-electric HVAC specifications and passenger comfort By Steve D. Johnson
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he subject line looks busy and is clearly about three different things. However, the three are related in ways that you might not expect. This conversation is intended to start a discussion between the stakeholders; the suppliers, the operators and the most important stakeholder, the passenger. To frame this conversation properly, and to establish the context for the rest of the article, let’s start with the passenger and work our way back. I can assure you that it will all come together by the end of this article. The passenger: The most important thing that an operator can do to get people to ride the bus, who otherwise might not use the bus, is to create a comfortable environment. Just ask any operator what they fear most and you are likely to hear, among other things, “cold bus complaints in the winter” and “hot bus complaints in the summer.” So, throughout all the years of advancements in vehicle and component efficiency, none have been made at the expense of passenger comfort. In fact, passenger comfort either drove or received benefit from most efficiency improvements. One would have to believe that the improvements have contributed to the steady increase in ridership, especially in the high-end markets.
Zero-emission buses: This is what I wrote in the last installment of this series. “It’s clear that the drive to zero emission in transit vehicles has started. So, what does this have to do with the HVAC? A lot, actually. The zero emission bus is powered by batteries and all of the electrical loads, like the all-electric HVAC, use power from the battery. As on conventional buses, the HVAC is the largest single load on the engine. Now, the load is on the battery and affects how far the bus can go on a single charge. I think that you can easily understand that 8
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reducing the load allows the bus range to improve.” Operators have determined that they need a range of 100-150 miles to ensure that routes can be completed on a single charge. In the effort to extend range various proposals have come forth for reducing the HVAC load. By far, the most popular proposal is to reduce and or limit the amount of cooling. One strategy proposed is to shut the HVAC off when the bus needs power to climb a hill or to conserve the power to allow the bus to finish the route. Another approach is to only cool the bus to 78-80 degrees F, rather than the commonly applied 68-72 degrees F. It has also been suggested that a temperature delta be used based on the outside ambient temperature. If the temperature delta is set at 15 degrees to control the cooling demand, it means that the bus interior would only cool to 85 degrees F on a 100 degree F day. While all of these approaches seem plausible, and some have been applied in various markets, you would have to agree that some of these approaches will not be welcomed in certain areas of the US. Imagine getting on a bus on a 110-degree day in Phoenix while the interior is only 95 degrees F. All-electric HVAC specifications: This is an area that highlights the conflicting interests. Operators are now writing specifications for their all-electric buses, and guess what? They have the same HVAC cooling requirements as were used for conventional diesel and CNG-driven buses. While it is true that the specifications should not be the same because the allelectric system provides constant cooling capacity rather than variable capacity based on engine speed, it doesn’t look like operators are ready to give up the cooling they have become accustomed to. Based on the specifications, we continue to build systems with excess capacity that will never get used, and with excess power that must be managed. In summary: With these conflicting objectives, misaligned expectations and the absence of an effective communication forum, we are likely to hit a wall somewhere along the way. Success is dependent on all of the stakeholders working together. Each may have to give up something to achieve the end goal, which is a highly efficient package that does not sacrifice passenger comfort. If we don’t, people may abandon bus travel. Steve D. Johnson, Sr. serves as product marketing manager, Bus HVAC, at Thermo King, Minneapolis, MN. Thermo King is a world leader in transport temperature control systems for buses. Thermo King also manufactures auxiliary power units, which dramatically reduce engine idling. All Thermo King products are backed by a nationwide dealer network. Visit www.thermoking.com.
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All-electric HVAC changes maintenance practices By Steve D. Johnson
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y now you know that certain components like mechanical compressors, clutches, belts, hoses and fittings will go away with the all-electric HVAC. These will be replaced by electrically-driven components and lead to the most important change technicians will see, exposure to high voltage. For the end user, technicians will have to be properly trained, and perhaps even certified to service these high voltage systems. For the suppliers, it means proper marking and warnings, detailed service procedures, and, most importantly, a safe environment for servicing and reliable safety disconnect systems. Couple the HVAC and the all-electric battery bus with its own (and even more complex) high voltage systems, and it is easy to see that maintenance as we know it will experience quite an extensive transformation. While training and most likely certification will be required to service the new systems, and will demand some investment from the end user, there are some tremendous benefits as a result of this major step change. Consider the items that go away and the time and cost associated with checking, diagnosing and replacing parts. A simple and easy-to-understand example is the mechanical compressor, and the clutch, belts, hoses and fittings that need to be checked every 6,000 miles on a conventional system. With an all-electric HVAC, they aren’t there to be checked, or to fail. So, what maintenance is required for the all-electric HVAC? As with the conventional HVAC, the all-electric HVAC requires a visual and running check each day before it goes on the route. The 6,000-hour inspection includes only an air filter change unless the technician sees or hears something unusual, which may occasionally be the case. The best way to ensure that your all-electric HVAC will run trouble-free during the cooling season is to do a thorough and comprehensive pre-season inspection just as many of us do with our home HVAC unit. A pre-season inspection should cover the following:
HvAC Pre-Run Inspection: (Note: Do items 2, 5, 6, 8 and 9 every month or 6,000 miles.) 1. Inspect and wash evaporator and condenser coils with warm soapy water. Rinse thoroughly. High pressure recommended. 2. Insure that drain lines are clear and that the drain outlet check valves are in place. 3. Inspect evaporator, condenser and compressor motormounting hardware. Ensure that all is tight and in good condition. 4. Check fans and blowers to ensure all turn freely without interference or noise. 5. V isually inspect electrical connections and wiring for corrosion and chafing. Clean and/or repair as necessary. 6. Inspect all electrical panels, terminal boards, and contactors in and out of the control box for signs of arching, heat or loose connections. 7. Re-torque all contactor wire mounting hardware per the torque specifications in the service manual. If dirt or lint is present, clean with a nylon brush and spray with contact cleaner as needed. Check cover for proper seal. Replace any missing hardware. 8. Inspect all refrigerant connections for signs of oil residue. (Oil residue usually indicates a present or past refrigerant leak.) Clean and note location on inspection sheet for immediate attention. 9. R eplace return air filter(s). Running Inspection: (Note: Do items 1 and 2 every month or 6,000 miles.) 1. Start bus and run the HVAC in the full cool mode. The set point may need to be adjusted down or the unit may need to run in the heat mode for a short time to simulate a load on the evaporator. An ambient temperature above 70 degrees Fahrenheit works best. 2. Listen for any unusual noises or vibration. If present, identify and take corrective action. 3. Continue to let the bus and HVAC system to run if no issues were identified. Check the liquid line sight glass for bubbles. Using the controller key pad, access system pressures. Record pressures, ambient and interior temperatures. We should highlight at this point that items 5, 6, and 7 on the pre-run inspection list is where the technician will be working in a high voltage environment and precautions should be taken. Also worth noting is the difference between the all–electric HVAC maintenance schedule and the conventional system schedule is a 50% reduction in labor hours, which does not take into account the parts that are not there and will never need to be replaced. While little mention is made of maintenance savings in the energy efficiency and sustainability discussion, it is certainly an important element of the all-electric value proposition. Steve D. Johnson, Sr. serves as product marketing manager, Bus HVAC, at Thermo King, Minneapolis, MN. Thermo King is a world leader in transport temperature control systems for buses. Thermo King also manufactures auxiliary power units, which dramatically reduce engine idling. All Thermo King products are backed by a nationwide dealer network. Visit www.thermoking.com.
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APTA showcases the future for electric vehicles – but there are plenty of opportunities in the present By Steve D. Johnson
If you attended the APTA EXPO this past year, you noticed that everyone who had an electric vehicle showed it. You also noticed that there are some new players in the market building electric vehicles. Finally, you noticed that nearly every supplier selling mechanical accessories now has an electrically-driven alternative. The future of transit was on display and the public is very excited. However, the reality is that this is going to be a rather slow and lengthy transformation. Consider that Los Angeles has committed to switch its entire fleet of over 2,000 buses to zero emission by 2040. That is very aggressive considering that by 2040, diesel, CNG and hybrid electric drivetrains will still be more than 50 percent of all deliveries according to some market research forecasts. What this means for most fleets in North America is that we will be living with diesel, CNG and hybrid electrics for a long time to come. The race to zero emissions is more like a marathon as opposed to a 100-meter dash. For the current bus population, efficiency improvements and emission reduction are still, and will remain as important objectives in the drive to reduce Green House Gases (GHG) and our overall carbon footprint. Given that the average fleet will have a complete turnover of buses at least twice in the next 25 years, what can we be doing in the interim as the new zero emission buses are integrated into the fleets? Here are a few suggestions: • Identify and specify fuel reduction technologies for the HVAC, your largest single load. • Consider the horsepower requirements for accessories and choose the most efficient. • Add electrically-driven accessories wherever possible. This could include radiator fans, power steering, doors and the HVAC. Let’s focus on the HVAC since that is what this series is about. Currently, the estimated population of standard diesel and CNG driven buses with all-electric HVAC is just over 3,000. There are many who are not aware of the fact that you can have an all-electric HVAC on a conventional bus, nor are they aware of the tremendous benefits. One good example is Miami-Dade Transit. The managers there had a vision which was to take a hybrid bus, add electric cooling fans and a self-powered all-electric HVAC, and test against the fleet for fuel
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HvAC economy. The hypothesis was to get a 7 percent contribution from each component – the hybrid drive, the electric cooling fans and the HVAC – for a total 21 percent improvement. In 2011 MiamiDade put five hybrid buses of this configuration into service. In July 2012, the Miami Today News posted a story that said the five hybrids were 32 percent more efficient than the fleet. While it is not clear what the exact percentage contribution was for each in this case, the next example clearly shows that the HVAC was a major contributor. At a press conference during the 2014 APTA EXPO, Antelope Valley Transit Authority reported a fuel savings of $4,000 per bus annually, for 29 diesel buses in the fleet with the self-powered all-electric HVAC. Both properties are in high-use HVAC areas and it should be noted that the level of fuel consumption reduction is related to how much HVAC is used, but in all cases an improvement should be seen. There are other significant benefits of all-electric HVAC not related to fuel. The mechanical compressor with its valves and fittings, the clutch and the connecting hoses are gone. Going away with them is the potential for failure and many hours of preventative maintenance. The savings in labor alone amounts to 50 percent when compared to a conventional HVAC. Also, the unit is sealed and tested at the factory so the risk for errors associated with field plumbing are eliminated. The value proposition is solid. There is a cost premium associated with the self-contained all-electric HVAC but the savings in fuel, labor and provides the payback in three to five years. Those savings will continue for the next seven to nine years, giving you lower operating costs and the opportunity to contribute to a sustainable planet. By the time you get your first zero-emission bus you will be very familiar with the all-electric HVAC that will come with it. Steve D. Johnson, Sr. serves as product marketing manager, Bus HVAC, at Thermo King, Minneapolis, MN. Thermo King is a world leader in transport temperature control systems for buses. Thermo King also manufactures auxiliary power units, which dramatically reduce engine idling. All Thermo King products are backed by a nationwide dealer network. Visit www.thermoking.com. Miami-Dade found that hybrid buses with electric HVAC were 32 percent more efficient than the rest of the fleet.
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