Measurements of structure-borne sound from building service equipment by a substitution method—Round robin comparisons

A pilot project has been performed with a round robin comparison (inter-laboratory test), where a modified heavy-duty washing machine has been circulated for tests among 6 laboratories. The main goal of this pilot project was to find out whether a simple substitution method could be applied to estimate the structure-borne sound pressure level of some typical building service equipments. First, the vibration levels of a heavy low mobility test floor are measured when a machine with high internal mobility operates on this floor. Then, the vibration levels are measured at the same positions on the same floor when a standardized tapping machine (ISO 140-7) operates in the same positions as the test machine. The differences between the vibration level are then calculated. The difference may be used to compare the performance of different machines at one site or to estimate the sound pressure level in other buildings with heavy floors. In its simplest form, this can be made in the same way as for floorings, i.e., first calculating the normalized impact sound pressure level (EN 12354-2) and then subtracting the vibration level difference of the actual machine compared to the tapping machine. It remains to apply this method in the field and to compare estimated sound pressure levels with measured.