The research programme, dealing with air transport in and through the building envelope, is ongoing and this presentation will summarize work done, point to ongoing activities and also invite communication. The programme has been presented previously and has three parts, modelling of convective processes in building components, systems modelling and analysis of air transport in and through the building envelope as part of a whole building, and air tightness for the building process, including transformation and demonstration of results for practical use. Predictive modelling to evaluate air movements in and through the building envelope, are coupled to the outside climate and pressure situation. A major aim of the programme is to analyse problems of relevance to the building process. This has included site inventories, modelling of typical situations and laboratory testing for input data and validation. The objective has also been to develop tools to help designing and evaluating building elements and to give a basis for estimating the convective transport of heat and moisture in the envelope. The programme is a joint activity between SP Technical Research Institute of Sweden, Chalmers University of Technology and the building industry. It has been found that many types of damages and problems are caused by poor airtightness, that airtightness is seldom given the proper consideration and that there is a major need for information on the effect of poor airtightness. Conclusions are that it is important to get developers/clients to treat airtightness more seriously and make them (more) aware of the potential damage that can be caused by poor airtightness, together with the “cost” of this and induce them to specify and monitor airtightness requirements more clearly.