More and more buildings are designed with displacement ventilation (DV) systems for the cooling and the ventilation of their rooms. DV systems are actually known to lead to energy savings and excellent indoor air quality conditions compared with mixing ventilation systems. The main drawback of the DV systems is the possibility for high vertical temperature gradient and/or cold draft effects. Experimental and numerical studies on DV have led to the development of general models and guidelines for the design of such systems. However, a review of recent literature showed that there is a need for the validation and improvement of those models. Especially, the performance of DV systems in cold climate conditions has to be better understood. Experimental data is needed also to validate the models in heating conditions. Whole field methods, such as Infrared thermography (IRT) and Particle image velocimetry (PIV), have been used in laboratory for the detailed study of clear zones, close to diffusers. These methods allow for the visualization and detailed measurement of temperature and velocity fields. This paper presents IRT and PIV measurements taken in situ. Located in Montreal, the building investigated is equipped with an underfloor air distribution system (UFAD) operated in a displacement mode. The images, recorded during winter conditions, have shown different effects of perimeter conditions on the air stratification and flow in comparison with conditions found in the center of the buildings. Taking into consideration the characteristics of the building envelope, the needs for perimeter heating devices to supply the heating loads was also assessed.