Compliance with the General Noise Regulation: A technical and legal requirement

When planning to build, extend, or alter a building, or to undertake a development in Portugal, it is often necessary to submit a Study Confirming Compliance with the General Noise Regulation (RGR). This technical document has become a mandatory element in various urban planning procedures, ensuring that the acoustic environment of cities and territories is protected and that the population’s quality of life remains safeguarded.

Example of an “Urban Noise Map”

What is a Study Confirming Compliance with the General Noise Regulation?

This study is a specialised technical report whose main purpose is to certify that an urban development operation complies with the legal requirements set out in the General Noise Regulation (RGR), approved by Decree-Law No. 9/2007. It is not a simple declaration of responsibility or a generic statement. It is a technically substantiated analysis, prepared by qualified acoustics professionals, that assesses whether the proposed project respects the regulatory noise exposure limits and discomfort criteria established by law.

When is it required?

The submission of this study is mandatory in several situations, including:

• Urban development projects.

• Urbanisation works in areas not covered by a detailed plan.

• Building works (new construction, extensions, reconstructions, or alterations) with potential noise impact.

• Changes in building use.

• Whenever the project may introduce new noise-sensitive receptors (housing, schools, hospitals) or new noise sources.

This requirement is currently defined in Ordinance No. 71-A/2024, which lists the documents required for procedures under the Legal Framework for Urbanisation and Building (RJUE).

The difference between “attesting” and “demonstrating”

It is important to distinguish between two types of acoustic documentation:

• Compliance Attestation Study (EAC-RGR): Based on existing data (Municipal Master Plan, Acoustic Zone Classification, existing Noise Maps). This analytical study verifies compliance using available information.

• Compliance Demonstration Study (EDC-RGR): Involves on-site acoustic measurements, predictive modelling, and laboratory testing. It is more detailed and typically required in more advanced licensing stages.

What should a Compliance Study with the RGR include?

A suitable study should contain:

• Description and location of the project and its regulatory context.

• Identification of the zone’s acoustic classification (sensitive, mixed, or unclassified area).

• Identification of existing noise sources (traffic, railways, commercial or industrial activity).

• Identification of new noise sources resulting from the project (equipment, access roads, generated traffic).

• Identification of existing and proposed sensitive receptors.

• Evaluation of compliance with RGR requirements, including:

  • Maximum Exposure Criteria: Lden and Ln limits defined in Article 11 of the RGR.

  • Disturbance Criteria: Difference between ambient and residual noise levels, as detailed in Annex I of the RGR.

• Conclusions on compliance.

• Recommendations and constraints for future design stages (e.g., acoustic insulation measures).

The importance of Acoustic Zone Classification

According to the RGR, municipalities must classify their territory into “sensitive zones” (for housing, schools, hospitals, or recreation) and “mixed zones” (for other uses). This classification determines the applicable noise limits. Every compliance study must specify the zone’s classification and verify that predicted noise levels remain within legal thresholds.

Who can prepare this study?

It must be prepared by specialists in acoustics — typically engineers with specific training in this field. When acoustic measurements are necessary, these must be conducted by entities accredited by the Portuguese Accreditation Institute (IPAC). Professionals must have in-depth knowledge of relevant legislation, acoustic measurement standards (NP ISO 1996), and be proficient in acoustic modelling tools.

Connection with the RJUE and Licensing Process

Within the urban licensing process, this study forms part of the pre-approval documentation. Municipalities must refuse licenses or authorisations for projects that do not comply with the RGR. It may be requested at different procedural stages:

• Preliminary information: simplified study without detailed modelling.

• Licensing or prior notification: full study, potentially requiring calculations and simulations.

• Occupancy authorisation: verification through acoustic testing and compliance checks.

Practical examples

• Case 1 – Residential building near a road: The study must check if traffic noise meets the limit for sensitive zones, proposing insulation measures when required.

• Case 2 – Rural housing development: Must ensure that new homes are not exposed to excessive noise from agricultural or transport activities.

• Case 3 – Commercial building extension: Must assess the impact of additional traffic and equipment noise, ensuring compliance with disturbance criteria for neighbouring receptors.

Ambient noise limit values

According to the RGR:

• Near major transport infrastructure: Lden ≤ 65 dB(A), Ln ≤ 55 dB(A).

• Sensitive zones: Lden ≤ 55 dB(A), Ln ≤ 45 dB(A).

• Mixed zones: Lden ≤ 65 dB(A), Ln ≤ 55 dB(A).

Lden represents the day-evening-night noise indicator, and Ln refers to nighttime levels.

Consequences of non-compliance

Failure to comply with the RGR has serious legal implications. Municipalities must reject projects that do not meet acoustic standards. Violations constitute environmental infractions punishable by fines. Furthermore, works carried out without a required study or in breach of the RGR may be suspended or require costly corrective actions.

Guidance for Developers and Property Owners

• Confirm with the municipality whether the study is mandatory.

• Hire accredited professionals experienced in environmental acoustics.

• Review the Municipal Master Plan and acoustic zoning for your project’s area.

• Plan acoustic mitigation measures from the design phase.

• Treat this study as a key requirement — it may determine your project’s feasibility.

Key takeaway

The Study of Compliance with the General Noise Regulation is not a mere formality — it represents a commitment to environmental quality and public wellbeing. In an increasingly urbanised country, where noise is a major environmental concern, ensuring that new developments comply with legal noise exposure limits is a collective responsibility. Proper acoustic planning from the early design stage prevents future disputes, increases property value, and guarantees the constitutional right to peace and health.