4.3 Indoor noise

4.3.1 General

In principle, sound generated inside a building can be separated into two sources of transmission – airborne sound and sound transmitted through the building itself. Airborne sound, from human activities in adjacent living spaces or from mechanical noise, travels through air, walls, floors and ceilings. Building-transmitted sound can come from occupants in living spaces above, or low frequency noise transferred through the ground and buildings. Measures for controlling noise and reducing unwanted sound are interior sound reverberation reduction, inter-room noise transfer mitigation and exterior building skin augmentation. 

Reverberation time is an important parameter for the acoustical experience of indoor spaces. Buildings with ‘soft’ interior surfaces are often more appreciated by occupants and visitors.

 
Typical examples of expected reverberation time are; 3-10 seconds in a church; 2 seconds in a concert hall or auditorium; 0.6-1 second in a classroom: and 0.5 second in a home (SBI 2014b). Intelligibility of speech is often a key factor in a room – and large rooms, with hard, parallel surfaces, can be a challenge.

Stimulation/absence of stimulation: the level of stimulation from environmental factors (light, sound, air, temperature) should be higher during day than night.

Silence/sounds: the presence of sound and contact to sounds from outdoors are desirable during daytime, whereas quiet spaces are needed at night.

The correct internal acoustics can play a major role in overall well-being.

4.3.2 Bedroom, living room and kitchen

Adequate sound insulation between rooms and adjacent dwellings (neighbours) is important to acoustic privacy. Both quiet and noisy activities must be possible without disturbing others or being disturbed by others.

Noise at night is perceived as being particularly annoying, and special consideration must be taken with sound insulation of bedrooms (Miljøstyrelsen, 2010).

4.3.3 Mechanical equipment

Installation noise levels should be kept below 25-30 dB (A) in the main living spaces.

At night, even lower noise levels are desired. It is important that occupants can adjust the settings of ventilation systems manually in order to limit noise levels when needed. Noise from heating and cooling systems must also be limited. 

Modern, energy-efficient buildings have increasingly complex service systems (e.g. heat pumps) – the noise from these has been a problem in numerous cases.