Relevance of CO2 based IAQ Indicators: Lessons from a Long-term Monitoring of two Nearly Zero Energy Houses

France is committed to minimizing its greenhouse gas emissions by focusing on the most energy-consuming sector, the residential and tertiary building sector. The renovation of existing buildings and the construction of energy efficient ones are therefore proposed as a possible solution. However, the concept of efficiency is ambiguous and difficult to measure and compare without common parameters and indicators. Indeed, a performance indicator is a decision support tool that describe the specific situation of something based on certain parameters.