Reviewing legal framework and performance assessment tools for residential ventilation systems

The field research project MONICAIR indicates that ventilation systems that fully comply with Dutch building codes show large differences in their IAQ-performance in habitable rooms during heating season and do not always achieve acceptable IAQ-levels [lit.1]. The results indicate that there are considerable differences in the actually achieved air-exchange rates per person during presence in habitable rooms. System averages on CO2-excess doses per heating season (an indicator for the duration and the amount of the excess above 1200 ppm CO2) vary from 68 to 349 kppmh per person. This roughly corresponds to situations in which either 7% or 35% of the time spent at home ventilation rates per person are insufficient. Variations between individual dwellings are even bigger with values ranging from 0 to 853 kppmh per person per heating season. These differences in habitable rooms occur despite the fact that the overall ventilation rates for all dwellings investigated are well above 10 l/s per person.  
Concerning the RH-levels, only limited exceedance of threshold values were monitored. Generally these levels are well below 70%  in all  rooms, and  only in bathrooms RH-values may rise above 70% for a period off - on average - less than two hours per day. Periods with RH-values less than 30% occur in all rooms of all dwellings and last on average 4 to 6 hours per day.   Other recently concluded monitoring studies further substantiate the results from the MONICAIR field research [lit.2,3]. These results point to the conclusion that the assumption that all code compliant ventilation systems perform comparable on IAQ, is clearly not justified. In consequence, the declaration of the Energy performance of ventilation systems has limited meaning as long as a direct link to a properly assessed  IAQ-performance is lacking. 
Current building codes, test standards and determination methods apparently are not sufficient to ensure the required air exchange rates in habitable rooms and consequently reduce the exposure to human odours (hygienic threshold values) and all other indoor pollutants.  
In respect to these findings the MONICAIR consortium reviewed the existing Dutch building codes and related test- and determination method to determine if and where the legal framework and related guidelines can be further refined to ensure a minimal IAQ-performance of ventilation systems. On several topics the legal framework and related assessment and test tools can be further expanded and refined. But the key item here is the fact that an actual performance requirement is missing, as well as a proper test protocol for assessing the performance of a ventilation system on its primary function “diluting concentrations of indoor pollutants by exchanging air and thus reducing exposure”.