Do the generally recognized rules of the technology require a controlled ventilation in dwellings?

Due to practiced building practice in the past decades the preservation of a sufficientroom air quality usually proved as unproblematic. The necessary air-change wasalready regularly ensured by the so called free ventilation of dwellings, i.e. overexisting building leakages. For this neither purposeful constructional measures norspecial user support was required. Due to newer, more energy efficient buildingmethods, as they are in the meantime also prescribed, this state of affairs howeverfundamentally changed. Since both after public and relevant DIN regulations theairtightness of the building envelope is to be ensured, now to the ventilation overbuilding leakages an only subordinated meaning is attached. Additional ventilationmeasures are therefore required for sufficient ventilation of dwellings.Such additional ventilation measures according to the regulations of the present setof rules compellingly do not presuppose the planning of appropriate constructionalmeasures, like in particular a controlled ventilation. Without such constructionalmeasures however, a sufficient ventilation of dwellings is ensured only if additionallya user-supported ventilation takes place. A user-supported ventilation for thesecuring of a sufficient air-change only corresponds to the generally recognized rulesof the technology however, if this has been experienced as a technically suitable,appropriate and necessary measure acknowledgment in general building practice.To which extent the securing of a sufficient change of air can be left to the useralone, is appraised differently in the iurisdiction and literature. A view is advancedhowever predominantly that a dwelling must be constituted in a way, that thenecessary room air quality is ensured with normal user behavior and withoutspecial ventilation measures or complex ventilation measures4 of the user arenecessary. A sufficient room air quality requires that a change of air is guaranteed by0,5 h-1 after the gained findings in science, as they already entered into the relevantsets of rules. After the view represented predominantly in the technical literature suchan air change can be reached with the prescribed close building envelope howeveronly, if the user several times daily, if not even approximately every two hours carriesout a windows ventilation in the way of impact- and/or cross-ventilation.Regarding such an extent of nessessary ventilation arrangements to be taken by theuser, it appears to be highly questionable whether the taking of such measures canbe required regularly according to the today's understanding of a normal occupancybehavior and the demands made in present practice to the general housing comfort. If one comes however to the result, that a ventilation over building leakages ashitherto is no longer permissible according to the generally recognized rules of thetechnology, and that it is also not compatible with the generally acknowledged rulesof technology, to leave the necessary additional ventilation measures to the useralone, then this only permits the conclusion, that a sufficient air interchange, how it isnecessary for the preservation of room air quality, is only to be guaranteed byappropriate constructional measures. As such a constructional measure thecontrolled ventilation is to be regarded.In the technical science it is, so far evidently, not challenged, that a sufficient room airquality can be ensured by a controlled ventilation. Due to continuing practicalexperience the controlled ventilation proved to that extent to be technically suitable.Even if at present it still should be regarded as questionable, whether therequirement of a controlled dwelling ventilation, with the involved in the execution ofconstruction work be regarded as throughout well-known and also as necessarilyrecognition, the presumption is justified considering the argued situation, that thisrealization will increasingly become generally accepted. This already applies alonewith regard to the fact, that a planner exposes himself to monumentaly substantialliability risks, if he does not point out to the owner, that a sufficient room air qualitywithout a controlled ventilation is only guaranteed, if the user takes stepts toextensive ventilation measures. Not later than this insight became generallyaccepted, one will have to regard the requirement of a controlled ventilation asgenerally acknowledged rule of technology.