{"id":9821,"date":"2024-09-11T17:44:44","date_gmt":"2024-09-11T15:44:44","guid":{"rendered":"https:\/\/www.brasseurs-air-re2020.com\/what-are-the-fundamentals-and-what-are-the-acoustic-regulations-for-commercial-buildings-equipped-with-ceiling-fans\/"},"modified":"2026-07-13T21:33:44","modified_gmt":"2026-07-13T19:33:44","slug":"what-are-the-fundamentals-and-what-are-the-acoustic-regulations-for-commercial-buildings-equipped-with-ceiling-fans","status":"publish","type":"post","link":"https:\/\/www.brasseurs-air-re2020.com\/en\/what-are-the-fundamentals-and-what-are-the-acoustic-regulations-for-commercial-buildings-equipped-with-ceiling-fans\/","title":{"rendered":"What are the fundamentals and what are the acoustic regulations for commercial buildings equipped with ceiling fans?"},"content":{"rendered":"
\"image_pdf\"T\u00e9l\u00e9charger l\u2019article en PDF<\/span><\/a><\/div>

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In 2003, a series of decrees and a circular were published updating acoustic regulations for commercial buildings.<\/p>\n

<\/p>\n

At that time, ceiling fans were virtually non-existent throughout mainland France.<\/p>\n

<\/p>\n

Nearly two decades later, the RE2020 has been published, and it clearly gives ceiling fans a higher profile in terms of summer comfort.<\/p>\n

<\/p>\n

Taking account of the 2003 regulations, which are still in force, has become an important issue for designers. That’s why this article covers both the fundamentals of acoustics and the practical aspects of implementing the official texts<\/strong>.<\/p>\n

<\/p>\n

We are focusing here on subjects relating to educational establishments<\/strong>, although we also provide links to texts relating to health establishments and hotels<\/strong>.<\/p>\n

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Decibels and decibels A – dB and dB(A)<\/h2>\n

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What is a decibel (dB)?<\/h3>\n

<\/p>\n

A decibel represents the ratio between two power values<\/strong> expressed in W[i]<\/a>. The decibel uses a logarithmic scale<\/strong>, which makes it possible to reduce a very wide range of physical powers to a smaller numerical range. For example, at a 2,000-strong rock concert, 10,000 W of power may be mobilised. However, the maximum dB measured [ii]<\/a>is of the order of 115 to 120 dB. The scale is therefore smaller and easier to use. With the logarithmic scale, an increase of 10 dB corresponds to a 10-fold increase in sound intensity<\/strong>. So a 20 dB sound is 10 times more intense than a 10 dB sound. The name of the unit of sound measurement, the bel<\/strong>, comes from the name of the inventor Alexander Graham Bell<\/strong>, known for his patent on the telephone[iii]<\/a>. One decibel is one tenth of a bel.<\/p>\n

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What is the difference between dB and dB(A)?<\/h2>\n

<\/p>\n

The dB establishes a simple ratio between two power values in W.<\/p>\n

<\/p>\n

The dB(A) takes into account the sensitivity of the human ear to different frequencies<\/strong> (from bass to treble).<\/p>\n

<\/p>\n

The ear can perceive a range of frequencies from 20 Hz to 20 kHz, but is generally most sensitive to frequencies between 2 and 5 kHz.<\/p>\n

<\/p>\n

dB(A) weights the different sound frequency ranges<\/strong> to better represent human hearing perception. The calculation based on the so-called \u2018A-weighting\u2019 system is defined by standard NF EN 61672-1.<\/p>\n

<\/p>\n

dB(A) is measured with a sound level meter<\/strong>.<\/p>\n

[\/et_pb_text][\/et_pb_column][\/et_pb_row][et_pb_row _builder_version=”4.21.0″ _module_preset=”default” custom_margin=”||||false|false” custom_padding=”||0px||false|false” global_colors_info=”{}”][et_pb_column type=”4_4″ _builder_version=”4.16″ _module_preset=”default” global_colors_info=”{}”][et_pb_text ul_item_indent=”25px” _builder_version=”4.27.0″ _module_preset=”default” header_2_font=”|600|||||||” header_2_text_color=”gcid-70ff693f-6f97-4074-be90-9adb196c4afe” header_3_font=”|600|||||||” header_3_text_color=”gcid-70ff693f-6f97-4074-be90-9adb196c4afe” header_4_font=”|600|||||||” custom_margin=”||15px||false|false” custom_padding=”||0px|||” global_colors_info=”{%22gcid-70ff693f-6f97-4074-be90-9adb196c4afe%22:%91%22header_3_text_color%22,%22header_3_text_color%22,%22header_2_text_color%22%93}”]<\/p>\n

What is the difference between sound power and sound pressure?<\/h2>\n

<\/p>\n

The sound power L<\/strong>w<\/strong><\/sub> of the air curtain itself <\/strong>corresponds to the total sound energy emitted by a sound source. It is measured in the laboratory. L\u2019 stands for \u201clevel\u201d and \u201cW\u201d for \u201cWatt\u201d. Equipment manufacturers generally give LwA<\/sub> values translated into db(A).<\/p>\n

<\/p>\n

The sound pressure L<\/strong>p<\/strong><\/sub> measured in the room<\/strong> takes into account the sound power of the sound source and the environment around this source. It corresponds to the noise we hear.<\/p>\n

<\/p>\n

It will depend on a number of parameters: the number of air baffles, the acoustic characteristics of the walls, the distance between the ceiling fans and the measuring device, the air flow rate (and therefore the shape of the ceiling fans). It is called Lp<\/sub>; as above, the terms come from the English, \u2018L\u2019 for \u2018level\u2019 and \u2018p\u2019 for \u2018pressure\u2019.<\/p>\n

<\/p>\n

Sound pressure is generally expressed in dB(A) and is referred to as LpA.<\/sub> Standard NF EN ISO 3744 is used to calculate this value.<\/p>\n

<\/p>\n

Sound power can therefore be equated with the cause<\/strong>, and sound pressure with the effect<\/strong>.<\/p>\n

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The illustration below, taken from the BRASSE [iv]<\/a> project, shows the relationship between sound power and sound pressure:<\/p>\n

[\/et_pb_text][et_pb_image src=”https:\/\/www.brasseurs-air-re2020.com\/wp-content\/uploads\/2024\/09\/figure-1-relation-entre-puissance-et-pression-acoustique-01.jpg” alt=”Figure 1: Relationship between sound power and sound pressure” title_text=”Figure 1: Relationship between sound power and sound pressure” _builder_version=”4.27.0″ _module_preset=”default” custom_margin=”||10px||false|false” global_colors_info=”{}”][\/et_pb_image][et_pb_text ul_item_indent=”25px” _builder_version=”4.27.0″ _module_preset=”default” header_2_font=”|600|||||||” header_2_text_color=”gcid-70ff693f-6f97-4074-be90-9adb196c4afe” header_3_font=”|600|||||||” header_3_text_color=”gcid-70ff693f-6f97-4074-be90-9adb196c4afe” header_4_font=”|600|||||||” custom_margin=”||15px||false|false” custom_padding=”||0px|||” global_colors_info=”{%22gcid-70ff693f-6f97-4074-be90-9adb196c4afe%22:%91%22header_3_text_color%22,%22header_3_text_color%22,%22header_2_text_color%22%93}”]<\/p>\n

Figure 1: Relationship between sound power and sound pressure<\/em><\/p>\n

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The upper red stripe above symbolises the absorbent ceiling, while the lower double orange stripe represents a carpet laid on the floor.<\/p>\n

<\/p>\n

It appears that an absorbent ceiling <\/strong>is much more effective than a carpet.<\/strong><\/p>\n

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How do you define reverberation time?<\/h2>\n

<\/p>\n

The reverberation time of a room is the time required for the sound pressure to return to its initial level.<\/p>\n

<\/p>\n

In an enclosed space, sound bounces off surfaces such as the floor, walls, ceiling, windows or tables several times.<\/p>\n

<\/p>\n

Reverberation decreases when echoes encounter surfaces capable of absorbing sound, such as curtains, chairs or people. So when sound in a room takes 10 seconds to go from 90 dB to 30 dB, the reverberation time is 10 seconds.<\/p>\n

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Ceiling-mounted fans and educational establishments: what do the regulations say?<\/h2>\n

<\/p>\n

Two additional texts apply to these premises:<\/p>\n

<\/p>\n