Existing residential housing has to become more sustainable to meet global CO2 reduction goals. Zero energy home refurbishment is one approach to achieve this. Rather than the currently common behaviour change approach, this study investigates residents’ experiences and practices with regard to their home environment. The study consists of interviews in 11 residents’ own homes. The residents live in homes in various levels of refurbishment, including zero energy. The study focuses particularly on ventilation. Ventilation is an issue that is understudied yet known to affect homes’ energy performance as well as residents’ comfort experience. The study reveals many issues with trust, understanding and unfavourable associations of ventilation systems. The study then presents a number of exemplary design directions that could address these issues. The implications are that practices should be studied more to reveal such issues, and that there is a need for better home systems design approaches.