Design pressure difference for self adjusting air inlets.

At present the design pressure difference for air inlets in The Netherlands is 1 Pascal. This paperinvestigates the question whether or not this value is still appropriate.In recent years the airtightness of dwellings has improved remarkably. Self adjusting air inletshave been introduced on the market. What is the effect of these changing building features onthe pressure difference over the building envelope? To answer this question more insight isneeded in the pressure differences that appear in reality during the year, and on the way theydepend on building features.A mulitizone air flow model has been used to calculate the pressure differences during areference year. Building types are: a) an existing dwelling with conventional air inlets and b) anew built dwelling with improved airtightness and self adjusting air inlets. This type of dwellingwill be built in large numbers for the following years in the Netherlands.The calculations allow for the following conclusions: The design air pressure difference increases as a result of improved airtightness and theapplication of self adjusting air inlets. For new built dwellings in the center of the country the design pressure difference can beraised to 2 Pascal. Other building locations (near coast) and better building airtightness may lead to stillhigher design pressure differences. These will have to be calculated separately.The advantages of working with higher design pressure differences, applicable to the situation: Ventilation energy losses decrease Deviations from the ideal ventilation pattern will decrease, which will improve indoor airquality Less or smaller air inlets will be needed, which saves costs