🌿 Noise from the service equipment of a building — the survey method: a hand-held meter, sweeping with the microphone, three determinations in the room

Environment PN-EN ISO 10052

Overview

The standard specifies simplified methods of field measurement of four things at once: the airborne sound insulation between rooms, the impact sound insulation of floors, the airborne sound insulation of a façade, and the sound levels in rooms originating from service equipment. This entry concerns the last of these applications — installation noise, because it is that one which in Poland is cited alongside the engineering method. The methods apply in dwellings or rooms of comparable dimensions, no larger than 150 m³. For sound insulation the results are frequency-dependent (octave bands) and are converted into single-number quantities according to ISO 717-1 and ISO 717-2; for noise from service equipment the results are given directly as A- or C-weighted sound levels — without an intermediate calculation on the spectrum.

What the simplification consists in and what it costs. The introduction to the standard says it plainly: the approach of the survey methods consists in simplifying the measurement of sound pressure levels in rooms by using a hand-held sound level meter and manually sweeping the microphone through the space of the room, and the correction for the reverberation time may either be estimated from tabulated values or be based on a measurement. The price is the uncertainty — the standard stipulates that the uncertainty of a measurement obtained by the survey method is by assumption (a priori) greater than the uncertainty proper to the corresponding engineering-grade methods, and itself names those methods: for sound insulation ISO 16283-1, -2 and -3, and for noise from service equipment — ISO 16032. The survey methods may be used for screening tests of the acoustic properties of buildings, but they are not intended for measuring the acoustic properties of building elements.

When the survey method and when the engineering method. The survey method is the method of first choice in everyday practice: in dwellings and rooms of comparable dimensions, when investigating a complaint, when checking an installation after adjustment, when screening a whole building, when the noise level clearly departs from the permissible value and when a result as an A-weighted sound level suffices. It is also resorted to because it is quick and cheap — one meter, one person, a few minutes per room. The engineering method according to PN-EN ISO 16032 is chosen when the survey method ceases to suffice: in disputed and acceptance cases, where the result is close to the permissible value, where the difference between the noise and the background is small or the levels are very low, where the character of the spectrum has to be recognised (a tonal or low-frequency component), and also where the room exceeds 150 m³ — because then the survey method is simply outside its scope, whereas the engineering method reaches up to about 300 m³. The Building Research Institute (ITB), comparing the two methods, drew attention to one more practical difference which settles the choice (a note on the designations: "the 2004 edition" is the European EN/ISO document, "PN-EN ISO 10052:2005(U)" is its Polish implementation by endorsement, and "PN-EN ISO 10052:2007" the national edition with a translation; it is one document in three guises, not three different standards): in the survey method — in the wording of the edition PN-EN ISO 10052:2005(U) — the results of the measurements are not corrected at all for the influence of the background noise, and where the difference between the noise level and the background level is less than 6 dB, the report must state that the result is influenced by the background noise and is affected by an unknown error. The engineering method in such a situation does apply a background correction and still gives a usable result. So if it is already clear at the survey stage that the equipment barely stands out from the background, the survey method will not lead to a decision.

Place in the Polish regulations. Annex 1 to the regulation on technical conditions, in the wording in force since 1 August 2024, cites at § 326(1) and § 326(4) both measuring standards: PN-EN ISO 10052:2007 „Metoda uproszczona" [the survey method] and PN-EN ISO 16032:2006 „Metoda dokładna" [the engineering method], and takes the permissible sound levels in rooms from PN-B-02151-2:2018-01. The regulation does not divide the cases between the two methods — the decision on the choice belongs to the laboratory and the client, and the justification of the choice should appear in the test report.

Status of the standard and the trap of editions. The current edition is PN-EN ISO 10052:2021-12 (implementing EN ISO 10052:2021 and ISO 10052:2021): the English version published on 21 December 2021 (46 pages), the Polish version on 20 November 2023 (40 pages), KT 253 for Architectural Acoustics. It superseded PN-EN ISO 10052:2007 (published on 29 May 2007, withdrawn on 21 December 2021) together with its additional element A1:2010. A practical note: Annex 1 to the technical conditions still cites the withdrawn PN-EN ISO 10052:2007 — the laboratory has to decide consciously which edition it is using and to record this in the test report. The second edition of the standard differs from the first not only editorially: it absorbed the amendment Amd 1:2010, updated the normative references, extended the scope to results for heavy/soft impact sources given as maximum A-weighted levels, added two definitions (Li,Fmax and LiA,Fmax) and a test procedure for such sources. What also changed was the very wording of the averaging for installation noise. We know it from the PREVIEWS of both editions and not from their full texts, which we have not checked: in the 2004 edition the formula combined two microphone positions with the weights 1/3 (the position near the corner) and 2/3 (the position in the reverberant field), whereas in the 2021 edition the same calculation was written as the energetic average of three determinations. This agrees with the description given by the Building Research Institute for the 2005 edition: the measurements are made at two microphone positions — one in a corner and one in the diffuse field — whereby at the corner position one determination is made (for one operating cycle of the equipment) and in the diffuse field two determinations (for two cycles), and from these three values the average A- or C-weighted sound level is determined.

What this description does not contain: we have not seen the full text of the standard — PKN and ISO supply it for a fee. The scope, the introduction, the normative references and the definitions (including the formulae for the service equipment sound level and for its standardised and normalised form) are given from the preview of ISO 10052:2021, covering clauses 1–4. Clause 5 (apparatus — and hence the admissible accuracy class of the meter), clause 6 (the procedure, including 6.3.4 — the way of guiding the microphone, the averaging times, the distances from the walls) and Annex B (the operating conditions and cycles of equipment) are not in the preview and we do not reproduce them here. Figures coming from earlier editions — two measuring positions with the weights 1/3 and 2/3 and the threshold of 6 dB above the background — are expressly marked below as belonging to the 2004/2007 edition.

Method principle

The sound level from service equipment is measured in the receiving room with a hand-held sound level meter, guiding the microphone by manually sweeping the space of the room instead of using a grid of fixed points. Three determinations are made: one near a corner of the room and two in the reverberant field. The service equipment sound level is their energetic average: L_XY = 10 lg[(10^(L_XY,1/10) + 10^(L_XY,2/10) + 10^(L_XY,3/10))/3] dB, where L_XY,1 is the weighted level obtained at position 1 near the corner, and L_XY,2 and L_XY,3 are the levels from two measurements at position 2, in the reverberant field of the room. The index X denotes the frequency weighting used (A or C), the index Y the time weighting (F, S or the equivalent level Leq); the standard stipulates that different measures L_XY are not comparable with one another and that only results obtained with the same measurement parameters may be set side by side. If the result is to be given as standardised, the reverberation index k is subtracted: L_XY,nT = L_XY − k, whereby for installation noise k is calculated from the arithmetic mean of the reverberation times measured in the octave bands 500 Hz, 1 kHz and 2 kHz as k = 10 lg{1/3[(T500 + T1000 + T2000)/T₀]} dB with T₀ = 0.5 s; for the normalised form L_XY,n = L_XY − k − 10 lg[A₀T₀/(0.16 V)] dB, where A₀ = 10 m² and V is the volume of the receiving room. The reverberation correction may — and this is the essence of the simplification — be estimated from the tabulated values given in the standard instead of measuring the reverberation time. The result for noise from equipment is given directly as an A- or C-weighted sound level, without a calculation on the spectrum.

Applications

• Investigating an occupant’s complaint about noise from ventilation, a heat substation, a heat pump, a pressure-booster set or a lift — a quick measurement in a dwelling of up to 150 m³
• Screening tests of the acoustic properties of a building before a decision on a full test by the engineering method
• Checking the effect of an adjustment or a replacement of equipment: a measurement before and after, made by the same method and with the same parameters
• Acceptance measurements of installation noise in residential and public buildings, where the result clearly departs from the permissible value according to PN-B-02151-2:2018-01
• Field measurements of airborne and impact sound insulation and of façade sound insulation — the other three applications of the same standard, also in the survey version
• Choosing the further course of action: the survey method establishes whether the case requires the more expensive test by the engineering method according to PN-EN ISO 16032

Key parameters

Standard

Standard number

PN-EN ISO 10052:2021-12

Title (PL)

Akustyka — Pomiary terenowe izolacyjności od dźwięków powietrznych i uderzeniowych oraz hałasu od urządzeń wyposażenia technicznego — Metoda uproszczona

Title (EN)

Acoustics — Field measurements of airborne and impact sound insulation and of service equipment sound — Survey method

Step-by-step procedure

1. Checking the range of application

   Establish the volume of the receiving room. The method applies in dwellings or rooms of comparable dimensions, no larger than 150 m³. Above that volume the survey method must not be used — the proper one is the engineering method according to PN-EN ISO 16032, reaching up to about 300 m³.

2. Deciding the choice of method

   Agree with the client whether a survey result will suffice. The survey method is suitable for investigating a complaint, for screening and for checking the effect of an adjustment; it is not suitable for measuring the acoustic properties of building elements, and its uncertainty is by assumption greater than in the engineering method. If the case is disputed or the result will be close to the permissible value — propose the engineering method at once.

3. Preparing the measuring chain

   Set up the hand-held sound level meter, check its sensitivity with an acoustic calibrator and record the result of the check. Set the frequency weighting (A or C) and the time weighting (F, S or measurement of the equivalent level) in accordance with the requirement to which the test is to be referred — the standard stipulates that results obtained with different parameters are not comparable.

4. Operating conditions and cycle of the equipment

   Take the operating conditions and cycles of the equipment under test from Annex B of the standard, unless they conflict with national requirements and regulations — then the national requirements take precedence. Agree with the building manager who will make the equipment run and in what cycle.

5. Determination 1 — the position near the corner

   Make one determination at position 1, near a corner of the room, guiding the microphone by manually sweeping the space — according to the ITB description for the 2005 edition one operating cycle of the equipment falls to it. Record the weighted level L_XY,1.

6. Determinations 2 and 3 — the position in the reverberant field

   Make two further determinations at position 2, in the reverberant field of the room, in the same way of guiding the microphone — according to the ITB description for the 2005 edition for two operating cycles of the equipment. Record the levels L_XY,2 and L_XY,3. (The details of guiding the microphone, the averaging times and the distances from the partitions are given in clause 6 of the standard, which we do not have from the preview — work directly with its text.)

7. Background noise

   Measure the background with the equipment under test switched off, in the same way and with the same settings of the meter. Note: in the wording of the edition PN-EN ISO 10052:2005(U) the results of the survey method are not corrected for the influence of the background noise, and where the difference between the noise level and the background level is less than 6 dB the report states that the result is influenced by the background noise and is affected by an unknown error — check the way of proceeding in the 2021 edition in clause 6 of the standard.

8. Energetic averaging

   Calculate the service equipment sound level as the energetic average of the three determinations: L_XY = 10 lg[(10^(L_XY,1/10) + 10^(L_XY,2/10) + 10^(L_XY,3/10))/3] dB.

9. The reverberation index k

   If the result is to be given as standardised or normalised, determine the reverberation index k: either from a measurement of the reverberation time or — and this is what the simplification consists in — by taking the tabulated value given in the standard. For noise from service equipment k is calculated from the arithmetic mean of the reverberation times in the octave bands 500 Hz, 1 kHz and 2 kHz: k = 10 lg{1/3[(T500 + T1000 + T2000)/T₀]} dB, T₀ = 0.5 s.

10. The standardised or normalised level

    Calculate L_XY,nT = L_XY − k or L_XY,n = L_XY − k − 10 lg[A₀T₀/(0.16 V)] dB, where A₀ = 10 m² and V is the volume of the receiving room in cubic metres. The choice of the form of the result follows from the requirement to which the test is to be referred.

11. Test report

    Give the resulting quantity in the notation of Table 1 of the standard (LASmax, LAFmax or their C-weighted counterparts, in the uncorrected, standardised or normalised version), the measurement parameters used, the operating conditions and cycle of the equipment, the background level, the way k was determined (measurement or table), the volume of the room and the edition of the standard. State expressly that the measurement was made by the survey method, of greater uncertainty, and that the permissible values are given by PN-B-02151-2:2018-01; if the result is to serve to demonstrate compliance with § 326 of the technical conditions — note that Annex 1 to the regulation cites the edition PN-EN ISO 10052:2007, withdrawn on 21 December 2021.

Required equipment and apparatus

Health and safety (OHS)

• A measurement in a dwelling, often in the evening or at night, means working in premises used by people — agree with the occupants the extent of entry, the time of presence and the switching off of equipment, and treat notes and photographs as data covered by the privacy of the dwelling.
• Making equipment run for the purposes of the measurement (a lift, a garage door, a heat substation, a pressure-booster set) is done only by a person authorised to operate it; do not interfere with the building installations yourself.
• Manual sweeping with the microphone means that the operator is in the measuring field — watch the distance of the body from the microphone and do not shield the source with yourself, because an error of handling enters the result directly here.
• Being in technical rooms where the equipment under test is running requires hearing protectors — the levels in a lift machine room or a fan room are sometimes higher than those permissible at workplaces.
• The method has by assumption a greater uncertainty than the engineering one: if the result comes out close to the permissible value or the difference from the background is small, it should not be presented as decisive — putting the matter honestly to the client is here an element of integrity, not a courtesy.
• Do not confuse the survey method (PN-EN ISO 10052) with the engineering method (PN-EN ISO 16032) or with the withdrawn national PN-B-02156: confusing the numbers of the standards in the test report is a formal non-conformity.

Frequently asked questions