The refurbishing to an energy efficient standard leads to tight buildings (whole envelope: windows, walls, etc.) and affects the indoor climate. In case of refurbishing the inhabitants or users are not adapted to this new situation. Therefore the air exchange rates could be lower than required if no mechanical ventilation is installed or the system performance is not optimised. Then, in trying to increase the energy performance of buildings, the indoor environment quality is often degraded due to the lack of exchange with the outdoor environment.People in Europe spend more than 90 % of their time indoors (living, working, and transportation). In more than 40 % of the enclosed spaces, people suffer from health- and comfortable related complains and illness. Already in 1984 the WHO reported an “increased frequency in buildings with indoor climate problems”. The complexity of the problem and the fact of building related symptom clusters were later described as “Sick Building Syndrome”.The main objective of the project is to develop innovative solutions for better monitoring the indoor environment quality and to investigate active and passive systems for improving it. The focus lies on cost-effective solutions to ensure a wide application of the developed systems. The project is based on three main objectives:- Development of monitoring systems (wireless and/or partly wired) to detect insufficient comfort and health parameter. It is foreseen to develop a modular version for allowing normal end users making a quick check of the indoor air quality.- Development of control systems for indoor environments which could be based on passive elements like cost effective photo catalytic materials or PCMs and active systems which control the air flow rates based on the monitoring data.- Modelling of indoor environments for the assessment and validation of monitoring data and to optimise with respect to energy efficiency the control parameters and systems.