Regulatory references: environmental and building acoustics

Statutes and decrees apply whether or not a party invokes them, within their own scope and from their date of entry into force. Technical standards — ISO, IEC, UNI — are not statutes: they are voluntary, and become binding in three ways: when a decree invokes them, when a contract adopts them, or when a court takes them as the assessment criterion. It is the same document; what changes is the basis on which it applies, and that basis belongs in the report. The first of the three has a consequence that changes everything, set out in Technical standards invoked by a statute: the decree freezes the edition it names, so standards the issuing body withdrew twenty years ago are in force in Italy.

In Italy, ISO and IEC standards enter the technical framework as adopted UNI EN ISO and CEI EN documents, with their own number and year, which can differ from the international ones. The tables below cite the ISO and IEC designations, which identify the technical document; in a report it is better to cite the adoption in force where one exists, because that is the document an opposing party will look for.

Who intervenes, and in what order

Before the standards it helps to know who to turn to. The chain is not hierarchical: it is a sequence of distinct competences, and skipping a link usually lengthens the process rather than shortening it.

Three things this table makes explicit.

The technician and the authority are different links. A party’s report, even signed by a qualified technician on the ENTECA register, is not an official finding: it serves to ground a complaint or a defence. The finding with administrative effect is made by ARPA on the authority’s instruction.

The three routes — administrative, criminal, civil — are independent and can run together. Each has a different threshold condition, and the outcome of one does not decide the others: a mayor’s order can issue without any offence, and a finding on normal tolerability can stand without any administrative limit being exceeded.

For worker noise the chain is a different one. It does not run through the Municipality or ARPA: enforcement lies with the ASL and the Labour Inspectorate, and the source is Legislative Decree 81/08, not Law 447/95.

European directives

Directives do not apply directly: they apply through the Italian instrument that transposes them. Citing them is useful when the counterparty is foreign, or when the rationale of a threshold is under discussion.

Statutes and decrees: environmental acoustics

Airport noise has a descriptor of its own

The three transport infrastructures have three distinct frameworks, and they are not interchangeable: the descriptor, the geometry and the governing act all change.

The airport is the one that departs furthest, on two points that change the work.

The descriptor. Not L_Aeq over the daytime and night-time reference periods, but LVA, a quantity built on airport operations. An LVA value and an L_Aeq,TR value are comparable neither with each other nor with the DPCM 14/11/1997 tables.

The geometry. There are no buffer strips at a fixed distance from the axis as for roads and railways: there is an airport surrounding bounded by the 60 dB(A) LVA contour, divided into protection zones A, B and C by Ministerial Decree 3/12/1999, each with its admitted land uses. It is a zoning of its own, standing alongside municipal acoustic classification rather than replacing it.

The contours are updated by the operator and checked by the airport commissions; the current list of sector references is maintained by ENAC.

Immission limits run through municipal zoning

The DPCM 14/11/1997 values do not apply directly to an address: they apply to the acoustic class that address falls in, and the classification is adopted by the Municipality. Before comparing a level with a limit, the class has to be established — and whether the Municipality has approved a zoning plan at all: if it has not, the transitional regime of Article 6 of DPCM 1/3/1991 applies, with different limits.

“The limit is 55 dB(A)” says nothing without the class. It is also why a calculation tool, this site included, can at most compare a number with a threshold chosen by hand.

The differential criterion has applicability thresholds

The two thresholds of the differential criterion are 5 dB by day and 3 dB by night. Whether the criterion applies at all is decided by Article 4 of DPCM 14/11/1997, which excludes it when the ambient level is low: 50/40 dB(A) with windows open, 35/25 dB(A) with windows closed (day/night). Below those values the noise is deemed negligible and the differential is not assessed.

The detail is on the dedicated differential criterion page. Quoting 5 and 3 without the exemptions makes the criterion look always applicable.

Administrative and civil are two distinct judgements

The differential criterion and the zone limits belong to administrative law: whoever breaches them answers to the authority. Between private parties the case rests instead on Article 844 of the Civil Code, the normal tolerability of emissions, which is a different criterion assessed by the judge case by case.

The two paths do not coincide, in either direction. Meeting the administrative limits does not rule out that an emission exceeds normal tolerability; exceeding an administrative limit does not by itself decide a civil case. A report intended for court has to say which of the two planes it sits on, because they are two different questions put to two different judges. The sources for those two planes are in the dedicated section below.

The qualified technician, concretely

Legislative Decree 42/2017 does more than name the role. Registration in the national list requires a technical or scientific degree and a qualifying course of at least 180 hours, of which at least 60 of practical exercises, with a final assessment; maintaining it requires at least 30 hours of continuing education every five years, spread over a minimum of three. The list is managed by the Ministry of the Environment and Energy Security and published through ISPRA’s ENTECA platform.

The technical activities under Law 447/95 are reserved to those on the register. A calculation run by anyone remains a calculation; an assessment meant to have effect is signed by a registered technician, who answers for it. No software changes that, and “certified software” is not a category the Italian framework provides for.

Statutes and decrees: building acoustics

DPCM 5/12/1997 and UNI 11367 are not the same thing and do not replace each other, and they are frequently confused. The decree sets a binding minimum threshold, the same for everyone. The UNI standard defines a voluntary scale of classes: a building can meet the decree and land in class III or IV. Saying “classified in class II” does not say the decree is met, and saying “compliant with the DPCM” does not assign a class.

History of the acoustic references for schools

They still turn up in reports and tender documents, and whoever meets them needs to know where the path ended.

Where the path ended. The binding insulation requirements now sit in DPCM 5/12/1997; the internal acoustic quality of classrooms — reverberation and intelligibility — in UNI 11532-2:2020, which the CAM invoke explicitly for schools; and in public works Ministerial Decree 24/11/2025 makes at least class II of UNI 11367 binding.

Why the difference matters. A single 1.2 s T60 and a per-octave-band requirement depending on classroom volume are not the same constraint, and do not yield the same design: the former can be met by a classroom that remains unintelligible at the frequencies carrying the consonants. If a tender document still shows the 1967 figure, the first thing to settle is which requirement is being adopted.

Shows, events and dance venues

Here noise is the service being sold, not a by-product of production, and the framework is its own. Two planes not to be confused: protecting those inside and protecting those outside.

Three distinct planes, and an assessment that mixes them is of no use.

Inside and outside are two checks. DPCM 215/1999 protects the audience inside the venue; the DPCM 14/11/1997 limits and the differential criterion protect receivers outside. Meeting one says nothing about the other, and a report covering only one must say which.

Staff are a third plane. Anyone working in a dance venue or on a stage is an exposed worker: Legislative Decree 81/08, Title VIII Chapter II applies, with its own L_EX,8h and action values, and enforcement runs through the ASL and the Labour Inspectorate rather than the Municipality.

Temporary activities live on derogation, and the derogation is municipal. How many evenings, which hours, which levels, with how much notice: this is not in national law, it is in the regional statute and the municipal by-law. It is the first thing to obtain, before any calculation.

Wind farms

A source with a framework of its own, and not arbitrarily so: the noise of a wind turbine varies with wind speed — the same quantity that drives the background noise. Measuring it with the ordinary procedure does not work.

Three points that decide a wind-farm assessment.

The plant is a fixed source. It follows that the differential criterion of DPCM 14/11/1997 applies, with one particularity: the assessment is carried out at building façades.

Wind moves the source and the background together. The turbine level rises with wind speed, and so does the noise of vegetation and of obstacles around the microphone. Without the simultaneous meteorological recording that the 2022 decree requires, the difference between the two is not determinable — and it is the difference, not the level, that the differential criterion assesses.

The nameplate L_WA is not the level at the receiver. IEC 61400-11 measures close to the machine by construction. Getting to the receiver is a propagation calculation, and over wind-farm distances the limits of ISO 9613-2 weigh more than they do for a nearby industrial source: this is the case where the choice of model has to be declared alongside the result.

The regional and municipal layer

The tables above are national, and they are not enough. Between the statute and the site there are two layers that decide what actually applies:

• Regional statutes and executive resolutions. Law 447/95 assigns the Regions their own competences, and every Region has legislated: criteria for acoustic zoning, procedures for impact and climate assessments, technician requirements, derogations for temporary activities and construction sites. Much of this sits not in the regional statute but in executive resolutions (delibere di Giunta) which the statute invokes and which have to be obtained separately. Two identical sites in two different Regions can face different procedures.

• The municipal council resolution approving the PCA. The Acoustic Zoning Plan is the act assigning a class to each portion of the territory, and it takes effect through the resolution that approves it: that resolution, with its number and date, is the source to cite — not “the municipality’s zoning”. The PCA also sets the transition strips between non-contiguous classes and the areas designated for temporary events.

• Municipal urban-policing and acoustics by-laws. Hours, noisy activities, derogations for sites and events: these live here, not in the PCA, and they are the source that decides whether an activity is allowed in a given time band.

• The municipal noise abatement plan. Provided for by Article 7 of Law 447/95, it is an instrument distinct from the PCA and mandatory in two cases: where limit values are exceeded, and where the zoning places adjacent areas more than 5 dB of class apart. It sets out the interventions, their priority and their funding. For a designer it is the source that says whether an area is already covered by a programmed intervention — information that changes the assessment of a new development.

Zoning is not universal, and whether it exists must be checked. Without an approved PCA the DPCM 14/11/1997 limits cannot be applied and the transitional regime of Article 6 of DPCM 1/3/1991 takes over — with different values, given in the table above. Where to look: the municipality’s official register and website for the resolution and the maps; the regional portal or the competent ARPA, which publish the progress of zoning across the territory; and in many Regions a catalogue of approved PCAs.

What to ask the Municipality for, concretely. These are public documents, and where they are not already published they are obtained through a freedom-of-information request:

• the resolution approving the PCA and the classification maps, with the accompanying technical report;
• the municipal noise abatement plan, if adopted, and the implementation status of the works it provides for;
• the municipal by-law on acoustics and the urban policing by-law, with hours and prescriptions for noisy activities;
• the criteria and forms for derogation authorisations for temporary activities, construction sites and events;
• any transition strips between non-adjacent classes and the areas designated for events, which the PCA identifies by name.

Operational consequence: before opening a national table, obtain the resolution approving the municipality’s PCA and check the regional framework, executive resolutions included. Neither is in this page, and neither can be derived from the technical standards.

The sources that decide a dispute between private parties

The tables above are administrative law and technical standards. A dispute between neighbours is not decided by those.

Three consequences that change a technical report.

Normal tolerability is not a numerical threshold. Article 844 sets no decibels: the judge sets the limit in the specific case, “having regard also to the condition of the locality”. The administrative differential criterion can be adopted as a parameter, but it is not one by law — and exceeding an administrative limit does not by itself decide the civil case, just as meeting it does not rule it out.

The condition of the locality enters the judgement. The same level can be tolerable in an industrial area and not in a residential one, and this does not follow from the municipal acoustic class but from the judge’s assessment.

The line between civil and criminal is the audience, not the level. A very high noise disturbing two flats stays a civil matter; a lower noise capable of disturbing an indeterminate number of people may fall under Article 659. A report intended for criminal proceedings has to document the spread, not only the level.

Interpretative sources

These are not standards, and must not be cited as such. They tell you how the administration reads a rule when the text is ambiguous.

Practical rule. In a report the three categories must be kept separate and qualified: a binding rule, a voluntary technical standard and a ministerial opinion carry three different weights, and presenting them in a row without distinguishing them is the first thing an opposing party attacks.

Technical standards invoked by a statute

A UNI, ISO or IEC standard is voluntary: it binds whoever adopted it by contract or chose to declare conformity to it. It becomes binding on everyone when a statute invokes it — and then the edition the statute names applies, not the current one. The issuing body may have withdrawn and replaced it twenty years ago: for the decree it still exists, and on a measurement headed for litigation that is the one that applies.

In practice the instrument used conforms to IEC 61672-1 and not to EN 60651, which has not been on the market for years. The report settles this in two lines: which standard the decree prescribes, which standard the instrument used meets, and why the second covers the first. It is the first thing an opposing party attacks, and it is closed before the question is put.

The converse holds equally: a new standard does not enter a decree by virtue of having been published. UNI 11367 has existed since 2010, and since 2023 in a second edition, but it is not a legal requirement — it becomes one where a specification or a CAM invokes it.

UNI standards

ISO standards: environmental and outdoor acoustics

ISO standards: room and building acoustics

ISO standards: vibration

IEC standards: instrumentation

Why the three parts matter. A datasheet declaring “conforms to IEC 61672-1 class 1” says what the instrument should do. Part -2 is the standard under which that model was approved; part -3 is the one under which the individual unit is periodically verified. A measurement headed for a dispute needs all three: the calibration certificate, the class of the field calibrator used, and the date of the last periodic verification.

The meter class enters the uncertainty budget

The difference between class 1 and class 2 is not accuracy “in general”: it is different acceptance limits and different operating temperature ranges. On a measurement that has to be compared with a statutory threshold, that difference enters the uncertainty budget — and a 1 dB margin against the limit does not survive an instrument with a ±1.4 dB tolerance at the reference frequency. It is why Ministerial Decree 16/03/1998 prescribes the class.

Uncertainty and the conformity decision

This is the standard most often missing from an acoustic report. A value of 54.8 dB(A) against a 55 limit is not “conforming” if the expanded uncertainty is ±1.5 dB: without a stated decision rule, that outcome is an unmotivated choice. The page on measurement uncertainty covers the budget; what matters here is the step after it — how a budget becomes a judgement.

Other European national systems

Vibration in construction has a German reference that circulates as a de facto standard well outside Germany: it is in the DIN table below, with the rest of the series.

Standards outside Italy and outside ISO/IEC

Needed when the client, the product or the datasheet comes from outside Europe. The American quantities are not translations of the ISO ones: STC, IIC and NRC are defined by their own methods, and treating them as synonyms of R_w, L_n,w and α_w produces comparisons that do not survive scrutiny.

United States — ANSI / ASA

United States — ASTM

Germany — DIN / VDI

A caution on comparing systems. National adoptions can sit on an earlier ISO edition: ASA/ANSI S12.54 adopts ISO 3744 in its 2010 version, not the 2025 one. On a job citing an American designation, check which ISO edition it corresponds to, because it need not be the one in force in Europe.

What changed in the edition in force

Only for editions published from 2011 on, that is less than fifteen years old. For the others — ISO 354:2003, ISO 3382-1:2009 and -2:2008, ISO 9613-1:1993, and the Italian statutes of the 1990s — whoever uses them has been working with that version for over a decade, and the change history adds nothing operational.

It serves one concrete purpose: re-reading earlier work. If a report was produced under the previous edition, these lines say whether the two results are comparable or not.

ISO 9613-2:2024 (ed. 2, January 2024) replaces the 1996 edition. The title changes from General method of calculation to engineering method for the prediction of sound pressure levels, and the rewrite concerns §7.4: the formulation of barrier diffraction loss changes, and so does the meteorological correction. Two reports citing “ISO 9613-2” without an edition may have used two different methods. That rewrite now has amendment ISO 9613-2:2024/DAmd 1 out for DIS ballot, restoring both formulas to their 1996 form, while the ISO catalogue already carries the third edition in drafting, marked “will replace ISO 9613-2:2024”: what changes, and by how much.

ISO 3744:2025 (ed. 4, December 2025) replaces the 2010 edition. The new edition removes the determination of sound energy level, for lack of use, and moves part of the test-environment qualification into ISO 26101-2; it clarifies cylindrical-surface measurements and adds Annex I on reducing uncertainty. The core measurement procedure and the standard deviation of reproducibility of the main procedure are unchanged, so results obtained under the 2010 edition remain comparable.

ISO 1996-1:2016 (ed. 3) replaces the 2003 edition with a technical revision: subclauses 3.6, 6.3.1, 6.5, 8.1, 8.2.1 i) and Annexes A, D, E, F, G, H were added or revised.

ISO 1996-2:2017 (ed. 3) replaces the 2007 edition with a technical revision. The change that bears on daily use is the residual sound parameter, defined as all sound not belonging to the specific source under investigation — a quantity distinct from the background noise level L_N. Anyone comparing a 2010 measurement with a current one has to check which of the two was used.

ISO 717-1:2020 replaces the 2013 edition. The changes are organisational: Annex G.6 was relocated from ISO 10140, as were the smoothed reference spectra of the sound reduction index of basic elements (from Annex B of ISO 10140-5:2018); references updated.

ISO 717-2:2020 replaces the 2013 edition and adds a new Annex D, with a method for rating heavy/soft impact sound insulation based on the A-weighted maximum impact sound pressure level.

ISO 12354-1:2017 is the ISO adoption of EN 12354-1:2000, which it replaces. The detailed model of ISO 12354-1 works in one-third-octave bands from 100 to 3150 Hz per ISO 717-1, extendable down to 50 Hz where element and junction data allow.

ISO 16283-1:2014 replaces ISO 140-4 for field measurements, and has an Amd 1:2017: the document applied in Europe is EN ISO 16283-1:2014+A1:2017, and citing 2014 alone omits the amendment. It covers volumes from 10 to 250 m³ over the 50 to 5000 Hz range.

IEC 61672-1:2013 (ed. 2.0) replaces the 2002 edition, and the change is in the conformance criterion. In the first edition conformance required the measured deviation extended by the uncertainty to fall within the tolerance limits; in the second it requires the measured deviation not to exceed the acceptance limits and the measurement uncertainty not to exceed the maximum permitted, both at a 95 % coverage probability. This is not a trim: two instruments judged conforming under the two editions need not be the same set.

IEC 61260-1:2014 replaces IEC 61260:1995 and its Amd 1:2001, and splits the single document into three parts (specifications, pattern evaluation tests, periodic tests). Technical changes that matter: performance class 0 was removed, design goals may be base-10 only, the reference environmental conditions move from 20 °C / 65 % RH to 23 °C / 50 % RH, and tolerance limits now account for measurement uncertainty, which the 1995 edition did not consider.

IEC 60268-16:2020 (ed. 5.0) replaces the 2011 edition. It changed the male test-signal spectrum, with significant reductions in the 125 and 250 Hz bands. An STI value measured under the fourth edition and one measured under the fifth are not directly comparable.

UNI 11367:2023 replaces UNI 11367:2010, with a revision of the normative references and an update to some clauses. The framework — four classes from I to IV, in-situ assessment — is unchanged.

UNI 11532-1:2018 and UNI 11532-2:2020 turned UNI 11532 from a single standard into a series: Part 1 carries the general requirements common to all sectors, Part 2 the education sector. Part 2 has two corrigenda, EC1:2020 and EC2:2023.

UNI 9614:2017 replaces the 2004 edition and is not a cosmetic update: it introduces a different assessment approach, taken from the Norwegian standard NS 8176, and refers to ISO 2631-2:2003 for measurement methods. A 2010 report and a 2020 one are not comparable by default.

UNI 9916:2014 replaces the 2004 edition (in force since 16 January 2014). It classifies structures into fourteen categories and considers the frequency range from 0.1 to 150 Hz.

Legislative Decree 42/2017 replaced the regime in which recognition of the qualified technician was regional: it establishes the national register at the Ministry of the Environment, fed by the Regions and published through ISPRA, and introduces mandatory continuing education — at least 30 hours every five years, over a minimum of three. Those recognised under the previous regime carried over into the register; the training obligation, by contrast, is new.

Ministerial Decree 24/11/2025 (building CAM) replaces Decree 256/2022 and the corrective Decree of 5 August 2024, in force since 1 February 2026. The framework is aligned to the 2023 Public Contracts Code, with changes on design, construction products, waste management, ESG criteria and site personnel.

How to cite a standard in a report

Three points an opposing party checks first.

Write the edition. “Per ISO 9613-2” does not identify a method: between the 1996 and the 2024 editions the formulation of barrier diffraction changed, so two reports citing the same standard without an edition may have used two different methods. The same holds for UNI 9614, where the 2017 edition introduced an assessment approach different from its predecessor.

State the basis on which a voluntary standard applies. A contract, a local regulation, or a criterion adopted by a court: three different things, and an opposing party’s first question is which of the three.

Scope bounds what the standard can conclude. UNI 9614 excludes structural damage, so it does not support the conclusion that a building is undamaged. Symmetrically, UNI 9916 says nothing about disturbance to people.

Limits of this page

• It carries the references, not the text of the standards. Limit values, formulas and procedures live in the original documents — paywalled for technical standards, in the Official Gazette for statutes and decrees.
• It does not cover machinery acoustics (the Machinery Directive and its dedicated ISO series), forensic acoustics, construction-product certification, or occupational exposure beyond the reference to Legislative Decree 81/08.
• Outside Italy it covers ANSI/ASA, ASTM, DIN, VDI and the two construction BS documents, the systems most often met on a job. It does not cover the rest of the BS catalogue beyond the EN adoptions, nor the Japanese (JIS), Chinese (GB) or Australian/New Zealand (AS/NZS) systems.
• It does not replace an opinion. Establishing which standard applies to a specific case, and on what basis, is precisely the activity reserved to the qualified technician.

References

Italian legal texts: Normattiva (text in force) and Gazzetta Ufficiale (text as published). National register of qualified acoustics technicians: ENTECA — ISPRA. Technical standard catalogues: ISO, IEC, UNI. Progress of Italian standards projects: UNI and ANIT, which publishes technical updates on drafts in preparation — that is how to follow UNI 11532-3.

The figure on the inter-laboratory reproducibility of ISO 354 comes from the literature supporting the revision of the standard (round-robin comparisons between laboratories).

Related pages on this site: differential criterion, road noise limits, reverberation time, vibration in buildings, LEX,8h.