Low costs of living
NF 15 and NF 40 standards characterize with very low costs of maintenance.
NF15 – takes only 15 kWh per 1m2 a year.
NF40 – takes only 40 kWh per 1m2 a year.
It means that in a NF15 standard, for a 100m2 house it takes only 1500 kWh a year to heat it up in conditions characteristic for the North-Eastern Europe (cold winter, hot summer). It is mostly 5-6 times less than in traditional house made in classic technologies.