What is the Advantage and Disadvantage of school bus air conditioner

Bus HVAC (heating, ventilation and air conditioning) Systems is the cooling, dehumidification and filtration of the air within the passenger compartment of a bus. An air conditioning system consists of compressor, condenser, evaporator, and controls. Surely you know what each component means, but do you know how it works? Click to read How Does Bus Air Conditioning System Work?

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Why Bus Air Conditioning System?

◆ For coach. An air conditioning system is considered a major coach component. The use of modern air conditioning system in coach bus ensures a comfortable coach climate, gets travelers safe and pleasant on a long-distance travelling. Thanks to reliable Guchen bus air conditioning system, lots of overseas consumers arrive at their destination feeling rested and relaxed.

◆ For school bus. As technology improves and demand for air-conditioned school buses rises. School buses without air conditioners are a health and safety issue, not a luxury issue. A school bus without A/C may cause students - especially younger students - passing out due to heat. For student safety, it’s necessary to outfit school buses with air conditioning system, no matter the seat time’s long or short.

◆ For tourist bus and double-decker bus tours. An important condition for a successful trip is having a smooth and comfortable bus ride. For all tourists, it can be a relaxed ride if bus tours have air conditioning. As we all know, buses are enclosed spaces, so the HVAC system has to be kept on to ensure air circulation and proper temperature for every rider.

◆ For city bus, shuttle bus. Passengers comfort and satisfaction is directly linked to the A/C system running on a city bus. The trend of outfitting transit buses with A/C unit is nothing new nowadays. Optimum air conditioning and climate control systems must be selected to increase passenger comfort, and are also necessary for the health of elderly and disabled passengers. A new bus air-conditioning system helps maximize thermal comfort, and manufacturers of bus HVAC systems are aware of the comforts that a air-conditioned city bus can provide to general public.

◆ For electric bus, such as trolleybus. The use of modern and comfortable air-conditioned electric bus provides an optimum climate environment for the bus driver and for the passengers.
For example, every year, Mecca, the holy city of Islam in Saudi Arabia, receives around 3 million Muslims from around the world during the month of Dhual-Hijjah in Hajj. Transporting all of these pilgrims becomes a challenge. Steps are taken to establish services and facilities to improve transportation and sanitation. With the installation of electric bus air conditioner, to a great extent, it ensures the well-being, safety and comfort of the pilgrims. At the same time, electric buses reduces emission and pollution.

3 Types of Air-con Systems Used in Today’s Buses

Bus air conditioners are classified into groups based on AC compressor drive types. The following lists 3 types of bus air-con systems according to their drive systems.

Bock AC Compressor

• Sub Engine Driven Type

It is a stand-alone complete air conditioning system - an individual internal-combustion engine driving AC compressor. The AC units are specially designed for medium to long coach.

Advantages of auxiliary/donkey engine driven AC compressor:

1) The AC compressor runs on a donkey engine, preferable scroll, which can generate enough power to operate the air conditioning system, to give more constant system performance.

2) Isolation of an individual engine won’t be affected by the main engine, which means, the shutdown of main engine doesn’t affect the normal operation of AC unit.

3) Increases system cooling run-time during summer operation, thus increasing A/C system reliability.

Guchen DD series bus air conditioner is a sub engine driven type A/C system, designed for 12-14m long coach.

• Main Engine Driven Type

The AC compressor is powered by a drive belt directly coupled to the crankshaft of the bus propulsion engine, and no additional donkey engine is provided - traditional engine-driven compressor.

It was researched that a bus air conditioning system with a standard belt-driven compressor uses 10%-15% of the main engine power. The A/C units are mainly used for van, minibus, 7-12m city bus, or 7-13m coach, a compact solution for road vehicles with small & confined space in its rear or front engine side.

How many kinds of main engine driven bus air-conditioning system are supplied at Guchen Industry?

The answer is 3;

>> SD Series;

>> BD Series;

>> PD Series.

• Electrically-driven Type

The power to operate the electric compressor is supplied by the car battery. This system is a solid choice for all-electric bus. Reduced fuel consumption, zero-emission, minimal energy use, no noise, easy thermostatic control, all those tangible energy and economic benefits make electric bus air conditioners huge market potential.

Top-selling electric bus air conditioners at Guchen Industry:

ED-03 integrated rooftop mounted electric air conditioning system

ES-05 integrated roof top electric air conditioner

Board member Colleen Locke, who is also the district’s liaison with state and federal government officials, recently met with staffers of Rep. Elise Stefanik to discuss Title I funding, additional statewide funding for English as a second language students, the Individual Disability Education Program, public school staffing shortages and the rollout of zero-emission electric school buses. Established in New York’s -23 fiscal year budget in April , the Electric School Bus Roadmap is the state’s goal to transition all school buses in the state to zero-emission operation by . This mandate is the first of its kind in the country. The first milestone on this roadmap will occur on July 1, , when all school buses purchased in the state must be zero-emission.

According to the World Resources Institute, an institute that conducts policy research about global environmental issues, New York has the second-largest school bus fleet in the United States — about 50,000 school buses that transport two million students. Lake Placid’s fleet consists of 11 buses that transport about 250 students daily — a little under half of the students enrolled in the district.

“We are at the very beginning stages. We are to the point of, we know there’s a mandate starting in ,” Assistant Superintendent for Business, Finance and Support Services Dana Wood told the News Wednesday, Sept. 27. “So, I’ve reviewed (the roadmap), I’ve talked to other school districts in terms of their thought process on it as well, but that is really the extent of where we are. Really just in the information stage.”

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Terrain and temperatures

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According to Locke, Stefanik’s staffers said the North Country is a “little bubble” that may face difficulty in implementing a fully electric school bus fleet due to its cold climate and mountainous terrain.

“I think we invite some of the policymakers in Albany to come up here on one of those 30-below mornings when we’re still open,” Locke said. “Invite them to take a twirl down through the (Wilmington) Notch and around the countryside and see if they get back here with the bus still running.”

Electric buses have been tested in cold, snowy and mountainous terrains similar to the North Country, though none have made their way to the North Country so far. The closest district to receive an electric bus grant is the Adirondack Central School District in Boonville.

A case study conducted by the Blue Bird Corporation — an American school bus manufacturer — at West Grand School District in Kremmling, Colorado, measured the reliability and endurance of a a Blue Bird Type-D All-American Electric Bus in low temperatures and on steep, unstable terrains. During the yearlong case study, the temperatures in November and December “averaged between -33 and -18 Fahrenheit” and “only rose above freezing five afternoons.” It was tested on elevation gains of up to 1,500 feet and routes up to 78 miles long. The bus driver did need to maintain a 25% base charge on the bus for the winter months to compensate for the extra energy used by heating systems. Additionally, any bus garages that house an electric bus must have heating for winter months to protect the batteries from freezing temperatures.

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In another case earlier this year, the Chicago Transit Authority introduced an electric bus to its fleet with more mixed results than West Grand School District’s. Chicago’s average winter temperatures are warmer than Lake Placid’s and its terrain is urban rather than rural and mountainous. Cold winter weather became an issue for the CTA, the Associated Press reported in March. When it’s cold outside the lithium-ion batteries that run the buses are less efficient and the buses’ mileage also drops. This is because more power is being diverted to heating the interior of the bus, which runs all day and also continually opens its doors to let passengers on and off.

Chicago bus drivers monitor the bus battery level at all times. If the level sinks below 50%, they are supposed to top off the charge at one of the chargers at either end of the bus’s route. Each one-way trip on that bus route is 10 miles and costs about 8% of the bus’s battery. The range is about 100 miles at a full charge. That means drivers would need to top up after six one-way trips.

School buses do not operate continuously from the morning to the evening, which makes them more likely candidates for electrification than buses operated by municipalities. They can be charged overnight and even in between morning and afternoon routes.

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Savings or costs?

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Board member Ryan St. Louis expressed concern that the Electric School Bus Roadmap was going to create “more burden on the school district and more burden on the taxpayers to comply with some law or mandate.”

Diesel school buses typically cost approximately $100,000 to $200,000 each, while electric school buses of comparable size typically cost approximately $300,000 to $400,000. Chargers are another added expense, with top-of-the-line charges clocking in around $40,000.

The Nelson A. Rockefeller Institute of Government, a public policy think tank operated through SUNY, released a report about meeting the state’s electric busing mandate last November following a symposium on the same topic. The report said that New York’s school-financing structure stands as a potential roadblock to electrification. School districts are not allowed to increase their tax levy by more than 2% or the value of inflation, “after adjusting for district-specific circumstances,” unless a school district’s budget is approved by a supermajority of voters.

The state also gives districts Transportation Aid, which partially reimburses bus-related contracts, purchases and operations. Bus fleet electrification can fall under these expenses. However, according to the report, even districts that receive relatively high amounts of Transportation Aid will still see “significant local expense” when electrifying their fleets.

Other state funding and grants are available through the Environmental Protection Agency’s Clean School Bus Program and its new Clean Heavy Duty Vehicles Program. In November , New Yorkers voted to pass the Clean Water, Clean Air and Green Jobs Environmental Bond Act of , which included $500 million to aid school districts in bus fleet electrification.

LPCSD is aware of the grant funding available for electric buses. However, according to Wood, these grants may be hard for LPCSD to obtain.

“There is available funds, but what I’ve found for our district is a lot of times these types of grants, we don’t meet the criteria,” he said. “We’re not considered a high-needs district. As a result, money like this is rarely provided to us.”

Despite the higher overhead cost of electric buses, they often cost less to operate than diesel buses. West Grand School District calculated $3,633 in fuel savings and $1,796 in maintenance savings during the year it incorporated one electric bus into its fleet. The CTA calculated that it costs $3.08 per mile to operate a diesel bus, $2.63 per mile for a diesel-electric hybrid and $2.01 per mile for an electric bus.

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Sustainability

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Locke also raised concerns about the permanency of the mandate.

“We have a governor that may not be there in ,” she said. “She may be replaced and then this law or whatever they’re suggesting may be repealed.”

She also expressed reservations about the sustainability of the buses.

“We’re in kind of, like, this utopia feeling that we’re going to switch to electric busing and then the environment’s all going to be all wonderful again,” she said. “But, if you talk to anybody in the electric industry, they’re going to tell you, ‘Guess how we make it?’ And, not to mention, where are we plugging all of these buses in?”

According to the Rockefeller Institute’s report, the production and operation of electric school buses still generates greenhouse gases, though it generates them at a lower rate than other types of buses. The U.S. Department of Transportation had similar findings when studying electric buses: “Each zero emission bus will reduce carbon emissions by upwards of 270,000 pounds per year compared to diesel and (compressed natural gas) buses.”

“If you look at the state of California now, the issues they have in California with Gov. Newsom saying they don’t have enough outlets or whatever, the charging stations,” Locke said. “They have blackouts, they have everything. So, it all sounds really good that, you know, we’re proposing this in the state of New York, but if it really turns into fruition, who knows? And the cost of these buses, I don’t know. They should be having a hybrid bus where it’s gas and electric, but that’s just my thought. I think on paper it looks fun, but in reality, who knows?”

Newsom has not said that the state does not have enough EV chargers. In August , California announced a ban on new gasoline vehicle purchases by , necessitating an effort to build up the charging infrastructure in the state. The state is on track to have 250,000 publicly-available electric vehicle chargers by . As of , California had 903,620 electric vehicle registrations, leading the country by a wide margin. According to a report by the state government, California would need 1.2 million EV chargers to support 8 million EVs. This is a ratio of one charger per 6.6 EVs. As of December , California’s ratio stood at one charger per 11.3 EVs — that’s 80,000 publicly available chargers for the 903,620 registered EVs in the state. These figures do not include any privately-owned EV chargers in residents’ homes.

EVs have not been causally linked to any blackouts in California. The Los Angeles Times reported in July that California has experienced increased blackouts in recent years, though these blackouts are attributed to extensive use of air conditioning during extreme heat waves. During heat waves in the summers of and , Californians were asked by California’s independent grid operator to voluntarily refrain from charging EVs — as well as running major appliances and excessive air conditioning — during a five-hour window in the evening in an effort to reduce strain on the power grid already pushed to its limits by widespread use of air conditioning. The state did not ask EV owners to refrain from charging their cars altogether.

There are hybrid school buses on the market. However, New York’s Electric School Bus Roadmap is unclear about the permissibility of districts purchasing hybrid models.

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Next steps

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Wood has communicated with other school districts about their approach to the zero-emission mandate.

“In the sense it is a mandate, what the law says, starting in , you can only get electric buses here in New York state if you buy a new one,” he said at the Sept. 19 meeting. “And then by , your entire fleet has to be electric buses. I was talking to a superintendent yesterday … their plan is, they’re going to buy a whole bunch of diesel buses to get them through for the next five to 10years … stock up before you cannot get them any longer. … That’s probably what we’re going to do, too.”

Under the mandate, districts may not purchase diesel buses after July 1, . Districts may apply for an exemption that will grant a two-year extension of the deadline, but the July 1, extended deadline is final.

Wood said there are “too many unknowns” with electric buses right now, which is why LPCSD has elected to hold off on electrifying its fleet right away.

“We have, for all intents and purposes, four years,” he said. “We’re waiting for, hopefully, the technology to improve, so that battery life is bigger, longer. And, price, hoping that as that develops and all that the price point will come down.”

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