Støjbudgetter

Støjbudgetter are planning tools used to manage cumulative noise exposure by allocating a permissible amount of noise to individual sources within a defined area, so that the combined level does not exceed a predefined limit. They are used in environmental, urban planning and design contexts to balance competing noise sources and protect quiet zones.

A budget is typically defined in terms of sound power levels (Lw) or sound pressure levels (Lp) and expressed in decibels (dB). Because the decibel scale is logarithmic, the total noise from several sources is not the simple sum of their dB values but the sum of their power terms. A common calculation uses Lw values and combines them with 10 log10 of the sum of 10^(Lw_i/10). In practice, conservative assumptions or scenario-based calculations are common to reflect propagation and shielding effects in the environment.

Støjbudgetter are used in urban planning and infrastructure projects to manage noise from traffic, rail, industry and entertainment within a district, or during building design to meet environmental or planning requirements. They enable cross-sector optimization: a quieter source can compensate for a louder one elsewhere, within the total budget, while ensuring that the overall community exposure remains within agreed limits.

Implementation typically follows these steps: establish a target budget or limit for the area; inventory potential noise sources and expected activity levels; assign portions of the budget to each source; run acoustic models or simulations; monitor actual noise levels and adjust as needed, with periodic reviews.

Advantages include transparent allocation, support for early design decisions and stakeholder agreement. Limitations involve dependence on forecasting accuracy, weather and propagation models, and the need for credible monitoring and governance to maintain the budget over time.