Envirotainer builds containers that are specialized in transporting of temperature sensitive products these containers are customized for airplanes. The containers are then leased to other companies, most often to pharmaceutical companies. Envirotainer are based in Lagga, Knivsta. It is also here where the production of the containers is held. The container RAP T2 was designed in the early 80ies. The RAP T2 contains a fleet of about 1220 containers spread all over the world. This container model needs an update in order to optimize its performance. One of the improvements is achieved by optimizing the UA-value that is too high. A lower UA-value gives the performance of the container more endurance and more stability. Initial testing that was made in the beginning of the project showed that the floor in the container was the biggest stand alone module benefiter of the high UA-value. With that knowledge it was decided that my work should be about the possibility to improve the construction with a new insulation material that would optimize the UA-value. The work started off with an investigation of insulation materials. The most interesting insulation materials were weighted against each other. The result showed that Divinycell was the best insulation material for the design. Then different concepts were made, concept A were the whole floor was redesigned and concept B were an extra insulation module was designed to fit the existing floor. The concepts were weighted against each other in order to choose the final concept. Concept A was the best alternative and was chosen. The concept was then designed in PTC Creo. A prototype was built for UA-value testing. The prototype was then tested and measured against the original container in order to see how much the UA-value was lowered with the new design. And the result of the test showed an improvement of almost 37 %. The UA-value went from 25,40 W/K with the original container design to 16,05 W/K with the prototype design. This shows that an update of the floor design is in order to make the container performance better and more stabile.