Recently (2012), for the first time, the Italian law established that the "absorption values of the electromagnetic field due to buildings" have to be considered in the estimated assessments carried out before installing any fixed telecommunications apparatus. This important norm may cause several effects in the application to the reality so Italian Ministry of Environment and Protection of Land and Sea assigned to the national Institute for the Environmental Research (ISPRA) together with the network of environmental regional Agencies (ARPA), the major role in the defining of an applicative protocol. Arpa Umbria was in the working group with ISPRA and has performed a measurement campaign to empirically support the national protocol definition; moreover, in synergy with University of Perugia, both with "in field" and numerical approach, has analyzed the behavior of penetration loss in presence of building with apertures. This paper deals with the adopted approach and presents the results obtained.