🌿 Measurement of the A-weighted sound level in rooms of residential buildings and buildings of public use — the method of PN-87/B-02156 and its status today

Environment PN-87/B-02156

Overview

The subject of the standard — to quote the PKN catalogue card — is the methods of measurement and assessment of the A-weighted sound level in rooms intended for the presence of people in residential buildings, buildings of collective residence and buildings of public use, and of the equipment in the technical rooms of those buildings. The standard was published on 6 July 1987, has 4 pages, was led by Technical Committee 253 for Architectural Acoustics, and replaced PN-B-02151:1970. By this method the noise penetrating into rooms from outside and that from the equipment of the technical fittings of the building is measured: ventilation, heat substations, lifts, garage doors, pumps.

The status of the standard has to be known, because it is sometimes a source of misunderstandings. PKN withdrew PN-B-02156:1987 on 17 December 2012. Earlier, after the amendment of the technical conditions of 12 March 2009, the regulation indicated precisely this standard for the assessment of the noise emission of the technical fittings of a building — which was criticised even then, the European PN-ISO 16032 (that was the number then; today PN-EN ISO 16032) being pointed to as a method with unambiguously defined conditions of operation of the equipment tested. Since 1 August 2024, after the change of the technical conditions, PN-B-02156:1987 is no longer referred to in the regulation: measurements of installation noise are carried out by the standard method according to PN-EN ISO 10052 or — in disputed situations — by the more accurate method according to PN-EN ISO 16032, and the admissible levels are given by PN-B-02151-2:2018-01. The withdrawal of the standard does not however invalidate the accreditations in which it figures: a laboratory may still have it in its scope and carry out tests at the express wish of the client, but the result no longer serves to demonstrate conformity with the technical conditions.

The differences between the old and the new methods are not cosmetic. According to PN-87/B-02156 only the A-weighted sound level is measured: the mean one in the case of steady noise or the maximum one with the time weighting „slow" for non-steady noise. The measuring points are three, in the diffuse field, and the final result is the highest level in the room (in the European standards — the mean level of the determinations). The equivalent level is determined not for the working cycle of the equipment but for a period of time equal to half an hour at night and 8 hours during the day, taking into account the breaks in the operation of the equipment. The effect is that for the same source the two methods give different figures — in the comparative studies of the Building Research Institute the levels corrected according to PN-87/B-02156 were almost always lower than those determined according to PN-EN ISO 16032:2006.

THE SCALE OF CITATIONS AND A CORRECTION OF THE KEY (23.09.2026). The key "PN-B-02156" gave 3 entries at 2 laboratories. The scopes write this standard almost exclusively in the old scheme — "PN-87/B-02156" 72 times, including one record with the annotation "(bez p.6.3)" [without clause 6.3] — against two records "PN-B-02156:1987" and one without a date. After the key was changed to "PN-87/B-02156" the tab shows 73 entries at 42 laboratories.

Method principle

The A-weighted sound level is measured in the room with the doors and the windows closed, at at least three points distributed in the diffuse field: not closer than 1 m from a wall or another strongly reflecting surface, 1.2 m above the floor and 1.5 m from the windows; the microphone is placed 0.5 m from the operator, with the diaphragm directed towards the ceiling, and only the two persons operating the meter are present in the room. For steady noise the mean level is determined, for non-steady noise — the maximum level with the time weighting „slow". The assessment time T is chosen so that all the changes of the sound level characteristic of the given situation or source occur within it: in residential buildings, buildings of collective residence, hospitals and sanatoria by day these are the least favourable 8 hours without interruption within the period 6.00–22.00, at night the least favourable 0.5 hour within the period 22.00–6.00; in buildings of public use — the time of use of the room by the given group of people in accordance with its intended purpose, and where the use is longer than 8 hours the least favourable 8 hours. From the result (the highest in the room) a correction is subtracted resulting from the influence of the acoustic background, from 0 to −3 dB depending on the difference between the level of the noise and the level of the background, and in unfurnished rooms in addition a correction resulting from the sound absorption of the room. The noise may be assessed only when the difference between the measured A-weighted sound level and the level of the acoustic background is greater than 3 dB.

Applications

• Acceptance of residential buildings and buildings of public use — assessment of the noise from the technical fittings (ventilation, heat substations, lifts, garage doors, pumps)
• Complaints of residents about noise penetrating into a dwelling from the installations of the building or from service premises
• Archival and comparative tests — repetition of a measurement carried out earlier by the same method, where an earlier report has to be referred to
• Measurements at the express wish of a client aware that the standard is withdrawn and does not serve to demonstrate conformity with the technical conditions

Key parameters

Standard

Standard number

PN-B-02156:1987 (PN-87/B-02156)

Title (PL)

Akustyka budowlana — Metody pomiaru poziomu dźwięku A w budynkach

Step-by-step procedure

1. Recognition of the object and of the source

   Establish what source is to be assessed: noise penetrating from outside or noise from the equipment of the technical fittings of the building. Draw up a plan of the room with the position of the source and of the planned measuring points.

2. Choice of the assessment time T

   In residential buildings, buildings of collective residence, hospitals and sanatoria: by day the least favourable 8 h without interruption within 6.00–22.00, at night the least favourable 0.5 h within 22.00–6.00. In buildings of public use — the time of use of the room by the given group of people; where the use is longer than 8 h take the least favourable 8 h. Choose the assessment time so that all the changes of level characteristic of the given situation or source occur within it.

3. Preparation of the room

   Carry out the measurements with the doors and the windows closed. Only the two persons operating the meter may be present in the room. When measuring noise penetrating from outside, switch off the sources of noise inside the room.

4. Distribution of the measuring points

   Determine at least three points in the diffuse field: not closer than 1 m from a wall or another strongly reflecting surface, 1.2 m above the floor and 1.5 m from the windows. Set the microphone 0.5 m from the operator, with the diaphragm directed towards the ceiling.

5. Measurement of the A-weighted sound level

   For steady noise determine the mean level, for non-steady noise — the maximum level with the time weighting „slow". The equivalent level is determined for a period of time equal to 0.5 h at night or 8 h during the day, taking into account the breaks in the operation of the equipment, and not for the working cycle of the equipment.

6. Measurement of the acoustic background

   Measure the level of the background at the same points with the source tested switched off. The noise may be assessed only when the difference between the measured A-weighted sound level and the level of the background is greater than 3 dB.

7. Corrections and the result

   Take as the result the highest level in the room and subtract from it the correction resulting from the influence of the acoustic background (from 0 to −3 dB depending on the difference of the levels). In unfurnished rooms subtract in addition the correction resulting from the sound absorption of the room.

8. Comparison and report

   Relate the result to the admissible values. Note: the admissible values are given today by PN-B-02151-2:2018-01 (the indices LAeq,nT and LAFmax,nT determined according to PN-EN ISO 10052 or PN-EN ISO 16032), and not by the replaced PN-87/B-02151/02. In the report state expressly that the measurement was carried out by the method of a withdrawn standard, and give what the result does not prove.

Required equipment and apparatus

Health and safety (OHS)

• A night measurement in a dwelling means work in premises used by people — arrange with the residents the extent of the entry, the time of presence and the switching-off of equipment, and treat the result and the photographs as data covered by the privacy of the premises.
• The forcing of equipment to operate for the measurement (a lift, a garage door, a heat substation, a pressure booster) is carried out only by a person authorised to operate it; do not interfere on your own in the installations of the building.
• The technical rooms of a building are sometimes zones of noise exceeding the admissible values in the working environment — for the time of the stay in a lift machine room, a fan room or a heat substation use hearing protectors.
• The standard is withdrawn: before accepting the order inform the client in writing that the result will not demonstrate conformity with the technical conditions in force since 1 August 2024, and agree whether a measurement according to PN-EN ISO 10052 or PN-EN ISO 16032 ought not to be carried out.
• Do not confuse PN-B-02156 (methods of measurement) with PN-B-02151 (requirements and admissible values) — a confusion of the numbers in the report is a formal nonconformity and not an editorial trifle.

Frequently asked questions