Infiltration in buildings is a process which is not well understood. Since J.B. Dick studied this type of infiltration in the 1950's there has not been much progress in this research field until recently. Energy crises in the last decade have forced almost everyone in the world to pay attention to infiltration of buildings. Speculative figures appear in literature about energy losses due to infiltration, but few measurements are available. An enormous number of questions arise, for example:

• Can we predict infiltration with models and with what accuracy?
• Do we have enough suitable information for these models?
• Is there any information about pressure distribution on real buildings which is usable for existing prediction models?
• Are the available figures about air leakage coefficients of our building envelopes respresentive for our present buildings
• What is the infiltration rate in existing and occupied buildings?
• What is the occupancy effect on infiltration etc.?

In spite of multiple efforts, research to answer these questions has barely begun. In April 1978, investigators from several parts of the world discussed the problem of infiltration and at an International Energy Agency meeting in Paris. A successful meeting augurs well for future investigations. Nevertheless, one of the problems in studying infiltration has been the difficulty in measuring pressure distribution on real buildings, before accurate and usable electronic pressure transducers became available.