Materials like building products or furnishing present in climatically controlled or uncontrolled indoor environments influence the indoor air quality (IAQ) significantly. In this study, the contribution of formaldehyde emissions from building materials and influences of adsorption/desorption behavior to indoor air pollution is investigated in a custom-made test house environment, located in a climate-controlled 48 m(3) stainless steel chamber. The complete test house study comprised three experimental cycles applying different types of ceiling tiles as target building materials. In each cycle one type of ceiling tile was used, while the housing construction and fittings were left unchanged. One cycle was divided into three steps to differentiate the contribution of each material to the overall IAQ: after the background monitoring of the empty housing frame (Step I), ceiling tiles were installed in the house and the air quality was monitored for one week (Step II). Finally, furniture and carpet were introduced into the house and the air was again monitored for one week (Step III). Additionally, gypsum boards and ceiling tiles were characterized by determination of their emission, diffusion and adsorption/desorption rates with regard to formaldehyde. It is the most important finding of this study that the resulting formaldehyde concentration does not simply result from additive emissions from the materials involved. In fact, it can only be explained accurately when taking into account multiple parameters. (C) 2013 Elsevier Ltd. All rights reserved.