One of the key areas to providing Comfort on a minibus is providing ventilation and a means of controlling the temperature.
Ventilation on a minibus is provided by opening windows and roof vents. There is no minimum standard for ventilation and so
on a basic minibus only the cab windows provide any circulation of air. For many customer types additional ventilation is seen as a
necessity, but the number and type of windows or vents needs to be considered and should form part of your specification.
Ventilation options on a minibus are usually: sliding windows; coach-style opening vents, fixed vents, spinning and electric vents,
which may all be specified either on their own or in conjunction with sliding windows and coach style roof vents.
The standard base vehicle heating system can provide heat to the whole vehicle. That said, due to the volume of air in a large vehicle it would take a long time for the passenger at the rear of the vehicle to feel any benefit. Additional heating may be specified in the form of diesel fired heaters. These provide heating which is independent of the base vehicle system.
Various power outputs are available the most suitable of which is determined by the size of the vehicle and the frequency of opening and closing doors.
In addition to ventilation and heating it is possible to add air conditioning. While it can be prohibitively expensive, a system appropriate for the size of the vehicle can provide the same cooling function found in a modern car. However please note: Systems come with differing capabilities. A unit suitable for a mini will not be adequate for a full size 17-seat minibus. If the unit is not of a sufficient size, at the source you will feel cold air but it will not have the capacity to reduce the temperature to the whole vehicle.
The difference between having cold air at source versus providing a specific temperature throughout the vehicle comes at a high cost. If an additional £3,000 or more sounds prohibitively expensive, consider adding other forms of ventilation as a less expensive alternative.
There are a number of options for additional air conditioning 
Sliding windows are relatively inexpensive and effective Independent heating ensures the whole saloon is warmed Coach style roof vents provide extra light as well as fresh air 
Vents connected to a spinning external rotor work well to reduce condensation Electric blown-air fan units like this are simple and effective
