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Airplanes: A Modern Conditioned Environment

The cold temperatures you might experience on an airplane are, surprisingly, not the airline’s attempt to accustom you to the UK’s rainy climate after time spent somewhere warmer. Airplanes have a bad reputation as being germ-harbouring havens for all kinds of illnesses and bacteria, but in reality, modern planes come with advanced circulation and temperature control systems. Read on to discover more about the environment in airplanes, as well as our best tips for ensuring your time spent in the plane is as comfortable as possible in such a heavily conditioned environment.

How is air circulated?

In order to burn effectively and produce the energy needed to keep the plane in flight, jet engines have an air compressor system, which also provides air for de-icing, hydraulic and cargo systems, as well as fresh air for the cabin.

The outside air, once compressed, is then filtered for any harmful ozone gases found in the atmosphere at such a height, as well as providing sterile, germ-free air. The fresh air is then passed through air conditioners to obtain an optimum temperature of 18 to 24°C.

To increase fuel efficiency, approximately 50% of cabin air is recirculated – and any recirculated air is passed through HEPA (high efficiency particulate air) filters, similar to the kind used in hospitals. Any waste air is exhausted to the outside atmosphere through outlet valves in the fuselage.

Why is it so cold on airplanes?

Airplanes are kept cool largely for the benefit of the passengers and crew. With so many people all in one space, a considerable amount of heat is given off, so the temperature needs to be closely controlled. In terms of practicality, it’s easier to add layers and get warm under blankets or jumpers than it is to cool down.

Also, as the oxygen levels in planes are slightly lower than at sea level, there is a slightly higher risk of people fainting. However, keeping the airplane cool significantly reduces the chances of this.

Humidity levels

At around 12% humidity, the air in the cabin is dryer than you’ll find in most deserts. The main reason for this is that commercial jets fly at heights of over 30,000 feet, and outside temperatures at this height can reach -50 to -60°C. As such, the atmosphere inside the cabin can feel uncomfortably dry.

Today’s planes are largely made of aluminum, which can be damaged if humidity levels inside get too high. However, new planes are increasingly being made of carbon fibre, meaning the planes of the future might have a much more pleasant conditioned environment. Some tips for ensuring your flight is as comfortable as possible include:

  • Drink plenty of water – this will help combat the dry environment by keeping you hydrated.
  • Keep your skin hydrated – moisturise your skin before boarding the plane, and apply more as necessary throughout your flight.
  • Wear comfortable clothes, with plenty of layers – ensures you’ll be warm and cosy throughout the flight.
  • Find something enjoyable to do – whether that’s reading a book, a magazine or watching a film, passing the time can be a relaxing and enjoyable part of the flight.


Established in 1968, Conditioned Environment Mechanical Services has become the premier choice for a range of air conditioning services throughout London. We have an experienced team of designers and engineers to ensure all your individual requirements are met, including ventilation, air conditioning and heating services across the commercial and domestic sectors. We provide high quality services at the best prices, simply get in touch today, and our friendly team will be happy to help out.