The aviation industry is responsible for 2.5% of global CO2 emissions, emitting over one billion tonnes of CO2 in 2018 (Ritchie, 2020). The International Air Transport Association (IATA) committed to net-zero aviation by 2050 (International Air Transport Association, 2022). The first steps toward net-zero aviation can be taken in the ground operations. Air France KLM set the goal for net-zero ground operations by 2030 (KLM Royal Dutch Airlines, n.d. -b). The aircraft hangars are responsible for 67% of all ground operations emissions at KLM (Veldhuizen, van, 2022) and a large portion of those emissions can be regarded to the heating of the hangars.

The process of heating the hangar is neither efficient, nor effective, despite the large amount of energy it consumes. The opening of the hangar doors to pull aircraft in and out of the hangar cause the temperature inside the hangar to approach the outside temperature. It takes 4 to 6 hours for the hangar to be up to the desired temperature again, but oftentimes the hangar doors will have been opened before the desired temperature is reached. It was found that heat in the hangar is firstly needed for the mechanics working there and secondly for the aircraft when specific repairs with a curing element have to be performed. The fluctuations in temperature lead to thermal discomfort for the mechanics (Lampret et al., 2018) and negatively affect the drying times of sealants.

This study discovered potential energy savings of 69% when the base temperature would be lowered to 10°C and heat would be provided locally where it is needed. The 69% in energy savings can be translated to money savings of €60.000,- per winter month (December 2021 taken as reference), or close to €400.000,- per year and 436 tons of CO2.

Alongside the research into potential energy savings in the hangar, ideas were collected within the company. The ideas were visualized and feedback was gathered at different divisions within KLM. The ideas were divided into two main categories, namely Heat Conservation and Local Heating. In the course of the project it was chosen to focus on local heating. The heating analysis showed that conserving the heat in the hangar was not a feasible solution since the hangar doors are opened for too long for heat conservation to be effective. Furthermore, when the base temperature is lowered, and additional heating is done locally where needed, there is not a lot of heat to be preserved in the first place.

The study proposes to lower the base temperature in the hangar to 10°C and provide local heating for the mechanics through heated apparel. The aircraft is heated locally during the curing phase of composite repairs but is often not heated with other curing processes such as after paintjobs. It should be considered to heat the aircraft locally more often to ensure optimal fleet availability.