In this contribution, investigations on multifunctional timber elements impregnated with phase change materials (PCM) are presented. The purpose of the PCM impregnation is a passive air-conditioning by structural timber elements like beams, walls or ceilings. PCM have the ability to take up substantial thermal energy within a narrow, latent temperature range without increasing their temperature. The high specific heat capacity combined with low additional mass can improve the room climate in timber buildings, which have often especially in the summer unpleasant temperature amplitudes without air-conditioning due to low thermal mass. In order to produce large size PCM-impregnated timber elements several investigations are performed. Besides fundamental impregnation and leakage tests for several wood species, also construction related investigations are carried out. Glue-lamination is important for producing large size structural elements. Thus, different adhesives like, epoxy resin, polyurethane and phenol-based resins are tested for suitability of gluing PCM-impregnated wood. This is also akey aspect for supressing leakage on the surface of the structural element by arranging there a thin layer of not impregnated wood. Other investigations are related to the experimental determination of the mechanical behaviour of PCM-impregnated wood and the combustion behaviour.