This paper describes work currently being carried out to evaluate the environmental impact and energy savings potential from the application of passive ventilation cooling in urban buildings. The work is carried out as part of an ALTENER project focussing on solar and passive ventilation for urban buildings. The study involves the collection of information for current building stock in four European countries; UK, France, Spain and Greece. It includes data on the percentage of buildings by type (residential and non-domestic such as offices and educational) in each country and the percentage of urban building in relation to the total building stock. Such information is difficult to obtain in the same form for each country and the collected data are presented in as meaningful a form as possible. In particular, an attempt was made to define the 'urbanness' of buildings in relation to data available from national surveys. An estimate of possible environmental impact benefits for a case-study office building based on the UK ecopoints method is presented.