New recommendations for environmental noise levels have been issued in Sweden. The permissible levels at facades of new buildings have been increased, which has resulted in a risk for higher indoor low frequency noise levels, since the recommended indoor levels are A-weighted. The additional Swedish low frequency third octave band requirements might be violated. Therefore, there is a need for reviewing how well façade insulation properties are manifested in measurements, and how accurate the measurement results indicate the indoor noise situation from the residents' perspective. In this paper, the results of façade insulation measurements are compared with corresponding models, with a special attention to associated challenges (e.g. to establish representative microphone positions in low frequency sound fields). The measurements are performed in a demonstrator house, which replicates a modern single family house. The models are evaluated both with respect to the total sound energy integrated over the entire room volumes, and as sampled sound fields, where the sample points may correspond to microphone positions. The congruence of the measured and the modelled results are analysed and discussed, as well as the relevance of different approaches.