Simulation of passive cooling and natural facade driven ventilation

In many design cases, energy as well as occupant comfort are the relevant criteria which are studied using computer simulation programs. Comfort evaluations cover air quality, thermal, visual and acoustical comfort. For all these individual aspects, specific simulation programs are available today, but very few programs allow for the integrated evaluation of several or all relevant parameters. Heat transport, ventilation and lighting are physically coupled and therefore must be integrally modelled in the simulation process. This paper gives a short description of the concept used for the coupling of the air flow simulation code COMVEN with the building and systems simulation code TRNSYS. Then, two application examples typical for a building design study situation are presented. The first example shows a multi-storey school building which is passively cooled at night-time due to natural stack airflow. The influence of the operation of the openings on the maximum room temperatures is discussed for a hot summer period case. The facade of the building of example 1 shall be retrofitted with glazed outer facade. In example 2 the natural ventilation of this building is studied. Ventilation is provided by naturally driven shaft ventilation through the facade spaces. Control strategies for the openings and the blinds are discussed in respect to overheating risk and minimum air flow rates. (author)