The number of timber constructions rises steadily over the last decades. Besides the well established timber-frame constructions some other massive-wood building systems which are based on nailed, screwed and dowelled connections can be found on the market. In Austria, nine different companies are found which produce massive-wood building systems with different variations. With a simulation software for building physics the effect of the thermal storage capacity of the room temperature with its surroundings, during summer, was calculated. The results show that during a period of time of 24 hours, a high thermal storage capacity within the construction can minimize the variation of temperature in the room. By using air ventilation during the night is it possible to easily transport the heat from the walls and floors into the surrounding environment. However, this effect is slowed down by the facings usually installed in front of the walls and on the floors. The results show that in the case of reinforced-concrete buildings, designed with facings, a similar temperature variation can be reached when compared to timber-frame buildings, with lower thermal storage capacity. The effects of different shading and ventilation systems on the room temperature were also tested.