All you need to know about air conditioning Air conditioning has a negative image: it would make us less tolerable to temperature changes; it produces background noise; it causes draught; it can pollute the air; it is difficult to handle; it needs maintenance; and it uses a lot of energy. However, it is economically feasible to construct and maintain HVAC-systems that are well-designed from an energy perspective and also realise a healthy and comfortable indoor environment. The recommendations and information presented in this guide, are useful for architects, installers, consultants, and for persons who are responsible for the maintenance of HVAC-systems in a non-industrial environment: for example your own living environment, at school or in an office environment! The author Prof. dr. Philomena M. Bluyssen received her building engineering degree in 1986 at the Technical University of Eindhoven, and in 1990 her PhD at the Technical University of Denmark with a thesis on ‘Air quality evaluated by a trained panel’. After working for more than twenty years as a researcher with TNO, where she coordinated among others several European projects on optimisation of Indoor environment quality and energy use, she was appointed full Professor Indoor Environment in 2012 at the Faculty of Architecture and the Built Environment, of the Delft University of Technology in Delft. At the TU Delft she initiated the SenseLab (located in the Science Centre in Delft), a recently opened semi-lab environment partly open to the public, sponsored by 25 companies and organisations (https://www.delta.tudelft.nl/article/video-senselab-prevent-sick-building-syndrome). She is (co)author of more than 230 publications. For ‘The Indoor Environment Handbook: How to make buildings healthy and comfortable’, she was awarded the ‘Choice Outstanding Academic Titles of 2010 Award.’ Her book titled ‘The Healthy Indoor Environment – How to assess occupants’ wellbeing in buildings’, she received the IDEC 2016 Book Award from the Interior Design Educational Council. ‘All you need to know about indoor air– A simple guide for educating yourself to improve your indoor environment’, is a must to have.