If air conditioning (AC) is off or not working on public transport, it can be an unpleasant experience for the driver and passengers when the temperatures are high. It can be even worse when the bus is full of people generating body heat and what are the alternatives to air conditioning?
If the system is not working it is often due to the compressors not being serviced and the gas not being replaced, or it might be a more complex problem.
The system may simply be turned off to save money as air conditioning does in fact increase fuel consumption. Its effect depends on a number of factors, such as the outside temperature, humidity, and intensity of the sun. Research has found that by using your air conditioning to control the climate of your car,
These statistics are specific to cars, but buses pose more significant challenges due to their size and the important but variable heat source that is passengers. , which is typically how transit buses operate. With shorter trips, the air conditioning system doesn’t have enough time to reach its optimal efficiency, so the system has to work harder for the cooling required.
A local transit bus may travel 200 miles per day and achieve 4 miles per gallon (mpg), which equates to a $175 per day cost. In hot conditions, the use of AC in the bus may increase the daily costs by $43.
The effect of using air conditioning in hybrids, plug-in hybrids, and electric vehicles (EVs) can be even larger on a percentage basis. Air-conditioners usually consume the most electricity among all of the auxiliary components in an electric bus, .
An assessment of the electric bus system for Berlin found that energy consumption per km can increase by up to 56 % in electric buses due to the HVAC system, when there are extreme external temperature conditions.
Increased temperatures are obviously not ideal, but the health and safety risk is far more of a concern with the potential of the driver passing out or becoming unwell. So, what are the alternatives?
Air conditioning alternatives to improve fuel economy in hot weather
The vast majority of buses in London, New York, Montreal, Paris, Berlin and Madrid will have air-cooling or air conditioning units fitted but they might be broken or switched off.
What air conditioning alternatives do they have or how could they use air conditioning in a more efficient way?
Well, firstly they have the option of to maximise airflow and support cooling. Flettner® roof ventilators could be strategically located to keep the driver and passengers cool.
Unlike AC, they do not require power and operate at minimal speeds, harnessing the wind to help cooling and extract unwanted air-borne contaminants in the bus. With no electrical consumption or parts to fix or replace, a Flettner® ventilator is an eco-friendly and durable solution for organisations wanting to meet their environmental, social, and corporate governance (ESG) objectives.
While a Flettner® ventilator can’t replace air conditioning, it’s certainly a safe supporting solution to the dramatic cost implications of running air conditioning for long periods in warm temperatures.
Aside from installing a Flettner®, what other basic measures can you do to reduce the costs and reliance of air conditioning in a bus:
- At lower speeds open the windows and use the air conditioning at higher speeds.
- Don’t overuse AC or set the temperature lower than required.
- Park in places where there is shade or use a sunshade to reduce cabin temperatures.
- For a short time, drive with the windows open before using the air conditioning. Letting hot air out of the cabin initially will put less demand on the AC and help cool the bus faster.
- Don’t have AC running before driving. Turn the AC on after starting your drive or after airing the cabin briefly. Most AC systems tend to cool the vehicle faster while driving.
- Read the manual as each AC system is different. It will show you how to best use and maintain the AC system.
- For plug-in hybrids and electric vehicles, pre-cooling the cabin while plugged into the charger can extend the buses range. Also, using a warmer temperature setting for the AC will use less battery power.
Why not open a window?
An option, as listed above is to open windows but like air conditioning, it has its downsides:
- It can increase aerodynamic drag (wind resistance), making the bus use more energy to push through the air. This effect is quite small at low speeds, which is why it is suggested above but the impact is much greater at higher speeds.
- Human intervention is required as buses don’t typically have electric windows like cars. Someone must open them, which is unpredictable and can’t be controlled very easily.
- There is no control over the volume of airflow, so it is not a measured solution for continual cooling.
- It is a localised solution, so only one area of the vehicle has cooling, while other areas remain warm.
- External pollution can easily access the inside of the bus and is especially a problem in traffic within cities.
- Open windows are noisy, not just from the airflow but also from the sounds that can be heard outside.
- Windows must be shut overnight, so there is no ventilation. With a Flettner® ventilator installed there is a constant trickle of incoming air and extraction overnight and when stationary.
Support cooling in your bus with a Flettner® Ventilator
With the associated costs of running and maintaining air conditioning in buses, installing Flettner® ventilators offers positive benefits for cooling buses.
To find out more about how wind-powered ventilation can help cooling in buses, contact Flettner® today.