Noise from air conditioning can be measured according to two research methods as noise emission to the environment or in the context of the building facade insulation. Choosing the correct methodology, calibrating equipment, considering environmental factors, and isolating background noise ensure accurate, reliable AC noise assessments in compliance with ISO, EU, and AHRI standards.
Noise generated by air conditioners, especially by older type outdoor units, is the main source of noise nuisance for users. Vibrations caused by the operation of these devices can be transmitted through the building structure, spreading noise to other rooms. This problem is not limited to vibration transmission, as the increased engine work during air conditioning operation also contributes to increased noise levels. Such variability of sounds can be particularly annoying for people with increased acoustic sensitivity, because it is difficult to get used to the constant changes in noise level. Although newer generation air conditioning systems are characterized by much lower noise levels, thanks to advanced technologies and materials, the noise level that users can experience depends on many factors.
The manufacturer provides information about the generated sound level in the product specifications, but this information is not the only determinant of the perceived noise. Therefore, when choosing an air conditioner, it is worth paying attention not only to the technical data, but also to the location of the units and potential sound transmission paths in the building, in order to minimize the nuisance of noise.
Measuring the noise of an air conditioner is necessary to check whether the noise levels do not exceed the established standards for noise emissions into the environment. This measurement allows the identification of potential problems related to exceeding permissible noise levels, which can be not only annoying for people in the vicinity, but also contrary to applicable legal regulations.
A precise noise analysis allows you to understand whether the source of the problem is really the air conditioner, or other factors, such as insufficient sound insulation of the walls in the building. Depending on the nature of the problem, choosing the right measurement technique is key to obtaining reliable results. Conducting measurements in accordance with relevant standards and documents ensures the precision and objectivity of the results, which is essential for the proper diagnosis of a noise problem. This approach allows for effective actions aimed at reducing noise, whether by modernizing the air conditioning system or improving the building’s insulation, which contributes to improving the comfort of life of users and adapting to legal requirements.
Measuring the noise level generated by the air conditioning allows to determine whether the emitted sound exceeds the established permissible standards. This allows for legal action and claims against the owner of the air conditioning system, who in such a case is obliged to reduce the noise level. This not only improves the quality of life in the vicinity of the installation, but also ensures compliance with legal regulations concerning environmental protection and public health.
Furthermore, prolonged exposure to excessive noise can result in serious health consequences, including nervous system disorders, reduced quality of life, chronic fatigue, and even permanent hearing loss. That is why noise level monitoring is important not only from the point of view of compliance with standards, but also the protection of the health of people exposed to its effects.
Noise level measurements of air conditioning are carried out by specialized research laboratories equipped with appropriate equipment for this type of research. Although the legal regulations do not directly specify the requirements for companies performing these measurements, it is important that the institution has the necessary meters, which are regularly calibrated, and has the appropriate experience in performing acoustic measurements. This approach ensures the reliability of the results and their compliance with the applicable standards.
In the context of solving problems related to excessive noise from air conditioning devices, it is recommended to use the services of accredited laboratories. These laboratories meet strict criteria for quality and measurement accuracy, ensuring that measurement results are accurate and reliable. Accreditation of such a laboratory is a confirmation that the tests conducted by it are in accordance with international standards and that it has the appropriate knowledge and experience to assess the noise level generated by air conditioning systems.
EU directives and ISO standards, aim to control noise emissions from air conditioning units and ensure adequate sound insulation of building façades to protect occupants from environmental noise, covering two main areas:
Noise Emission to the Environment: In the European Union, the Environmental Noise Directive (END) (Directive 2002/49/EC) serves as the primary legislation for assessing and managing environmental noise. While the END focuses on mapping and action planning for major noise sources, specific product noise emissions, such as those from air conditioners, are addressed under the Ecodesign Directive (Directive 2009/125/EC). This directive includes implementing regulations that set maximum sound power levels for air conditioners to reduce noise pollution. For instance, Commission Regulation (EU) No 206/2012 outlines ecodesign requirements for air conditioners and comfort fans, specifying maximum sound power levels based on the unit’s capacity. These regulations ensure that products meet specific noise emission standards before they can be marketed within the EU.
Sound Insulation of Building Façades: The ISO standard ISO 16283-3:2016 titled “Acoustics — Field measurement of sound insulation in buildings and of building elements — Part 3: Façade sound insulation” specifies procedures to determine the airborne sound insulation of façade elements and whole façades. This standard provides methodologies for field measurements, ensuring consistent assessment of how building façades attenuate external noise, including that from air conditioning units. It has effectively replaced the earlier ISO 140-5:1998 standard, which dealt with similar measurements.
In the US, the Air-Conditioning, Heating, and Refrigeration Institute (AHRI) has established standards for measuring and rating the acoustic performance of HVAC equipment:
AHRI Standard 270: Focuses on the sound performance rating of outdoor unitary equipment, providing methods to measure and report sound pressure levels.
AHRI Standard 370: Addresses the sound rating of large outdoor refrigeration and air-conditioning equipment, outlining procedures to determine sound power levels.
These standards ensure consistent measurement techniques, facilitating accurate comparisons across different products and manufacturers.
Noise Rating (NR) curves are a set of standardized curves developed by the International Organization for Standardization (ISO) to evaluate acceptable indoor environments concerning hearing preservation, speech communication, and annoyance. Introduced in ISO Recommendation ISO/R 1996-1971, NR curves are commonly used in Europe to assess internal noise levels, particularly from mechanical sources like air conditioning systems in environments such as hotels, cinemas, and schools.
NR curves are utilized to measure and specify acceptable noise levels within indoor spaces. By comparing the noise spectrum of an air conditioning unit to the NR curves, one can determine if the noise levels are within acceptable limits for a given environment. This assessment helps ensure that the operation of HVAC equipment does not adversely affect occupant comfort or communication.
It’s important to note that while NR curves are prevalent in European practices, other regions may use different standards. For instance, the Noise Criterion (NC) curves are more commonly used in the United States for similar purposes.
Measuring noise from air conditioning systems involves distinct approaches across regions. The US emphasizes equipment-specific standards, the EU enforces product-specific noise emission limits alongside standardized measurement procedures, and Poland integrates EU directives with national regulations to ensure comprehensive noise management.
In Poland, to properly measure the noise from the air conditioning, the methodology describes two approaches to determining the equivalent sound level A: through direct measurements or calculations. It also requires an analysis of the operation of the noisy device to determine the periods in which the device emits more noise, if such noise is variable over time. This method allows for a more accurate assessment of the impact of air conditioning noise on the environment. Furthermore, measurement points should be located in places that are most exposed to noise: at a height of 1.5 meters in an undeveloped area or in a developed area from 0.5 to 2 meters from the elevations of the most exposed buildings, at the height of the window. In cases where measurements in these locations are not possible, the regulation recommends that they be taken at a height of 4 meters. By strictly following these guidelines, it is possible to obtain reliable data on the noise level generated by air conditioning units.
The duration of the noise measurement generated by the air conditioning depends on the characteristics of the emitted sound. For constant level noise, the process can be relatively fast and involve collecting a few samples over a short period. However, if the noise is characterized by a variable level, it is necessary to conduct a preliminary analysis of its nature, which may extend the entire measurement process. The measurement duration also includes preparatory activities, such as starting and calibrating the measuring equipment and properly positioning the measurement points. These steps are key to ensuring the accuracy and reliability of the results. Therefore, the total measurement time may vary, depending on the specifics of a given case and the requirements related to the precise noise level measurement.
It is necessary to use a class 1 accuracy meter, which must be calibrated using a class 1 accuracy standard sound source. In addition, the instruments must be calibrated no more than 2 years earlier, and the entire set must necessarily include a wind screen attached to the microphone. The measuring set must operate within the meteorological parameter ranges permitted by the manufacturer. If the manufacturer has not defined them, the following values are the limits for measurements: for temperature from -10°C to 50°C, humidity in the range from 25% to 90%, the average wind speed can be a maximum of 5 m/s and the atmospheric pressure should be in the range from 900 hPa to 1100 hPa.
