Assesment of performance of innovative ventilation systems: Use and limit of multicriteria analysis

Building sealing may affect the total air change by decreasing the leakages and question the ability for ventilation systems to reach their goal of providing an acceptable indoor air quality. Improving energy performance must not impair indoor air quality.
The QUAD-BBC study has led to define four groups of pollutants representative of similar behaviour, use or effect: CO2 as a marker linked to human occupancy, NO2, SO2 (dwellings) and O3 (offices) linked to occupants activities, CO and 7 VOC linked to materials, activities and behaviour and PM2.5 and PM10. The indexes related to these pollutants are calculated in occupancy periods only. Scenarios for pollutant emissions and occupancy have been determined and used as inputs for simulation through an improved version of SIMBAD (coupling airing and thermal effects). Calculation results have provided flows and patterns for each room, energy needs for auxiliaries and heating, pollutant concentrations for each species and in each room as well as more synthetics indexes.
The initial objective of the project was to develop a single criteria of indoor air quality (multi-pollutants) and to provide a reference system for each building based upon this index. Calculations have shown huge difficulties in reaching this objective. The lack of reliability of pollutant emissions’ data in particular have led to propose a set of indexes and a method for comparison of systems rather than an absolute reference. Yet a graphical representation of these criteria helps a fast comprehension of the pros and cons of different systems and help comparison.