[EN 15665:2009, 3.5]:level of required performance.NOTE Requirements can be, for example, “maximum of 100 hours above 70 % in living room”, “less than10 minutes to reach 25 % of initial “, “less than 800 10-6 CO2 (generally named ppm) as an average”, “minimum of 8 l/s in toilet”, “35 l/s for global ventilation in standard inside/outside conditions”.