To limit the probability of the transmission of excessive noise or vibration, which could lead to occupants not using the fans or disabling them, which could lead to inadequate ventilation, which could lead to negative effects on the air quality of indoor spaces, which could lead to harm to persons.
To exempt fans and heat recovery ventilators fixed only to a concrete base from the requirement to install resilient mountings, on the basis that concrete is unlikely to transmit vibration generated by the equipment to occupied space.