VENTILATION FOR BUILDINGS: DESIGN CRITERIA FOR THE IN- DOOR ENVIRONMENT - A NEW INITIATIVE

Within the framework of CEN TC 156, efforts have been made over many years to replace the ventilation standards specific to various countries with a single European standard. The draft standard prENV 1752 "Design Criteria for the Indoor Environment" was rejected in the final vote by a majority of countries and later published as a Technical Report (CR 1752). Switzerland rejected the draft standard in the final vote on the grounds that the ventilation rates proposed in the final version are unrealistic, that the procedure for determining design ventilation rates does not reflect the needs of and options available to practicians, and that the standard takes insufficient account of characteristics unique to certain countries. To achieve the acceptance of a majority, a future standard will only govern the procedure and principles according to which ventilation rates are determined. The exact specification of ventilation rates is to be left to individual countries. Concrete guidance on the constraints relevant in practice will, however, have to be formulated in an appendix to the standard. The following parameters have a critical influence on the design ventilation rates (the vo lume of outside air or air actually introduced into the space) - the impairment of the air quality caused by the occupants - emissions from materials in the room - activities such as smoking - the quality of the outside air - the thermal load Further, account needs to be taken of the type of space and of the differing requirements in respect of thermal and air quality comfort. Guidance is also required on monitoring and optimization, maintenance and upkeep, with references to the associated CEN standards or proposals either published or in preparation. Finally, reference needs to be made to acoustic comfort.