A large-scale test set-up was designed to evaluate the volatile organic compound (VOC) emissions of building materials in a real room situation but under laboratory conditions. Two model rooms (ModR) with a volume of 30 m 3 each were constructed of the wood-based building materials X-lam and OSB, respectively. Temperature and relative humidity (RH) inside the ModR were kept in a range of 21°C-25°C and 45%-55% RH. VOCs were collected at 13 different times over a period of 23 weeks, and the total VOC (TVOC) concentration was calculated from GC/MS data. Results were quantified as toluene equivalents (TE). In the X-lam-ModR, the TVOC concentration decreased by 64% over the whole measurement period from 115 to 41 μg m -3 TE. Terpenes were the most abundant substance group and accounted, on average, for 80% of the TVOC concentration. In the OSB-ModR, the TVOC concentration decreased by 72% from 443 to 124 μg m -3 TE. Aldehydes showed the highest concentrations, accounting, on average, for 52% of the TVOC, while 38% were terpenes. The results show that this type of test provides realistic data for the praxis.