Acoustics and noise in the era of low-carbon and energy transition

1 - Acoustics and timber construction

Driven mainly by the challenges of sustainable development, low-carbon and societal concerns, wood constructions are becoming increasingly popular in the design of new and renovation programs, whatever the purpose (housing, offices, hotels, cultural facilities). From an acoustic point of view, these new complexes in the French construction landscape raise a number of related issues:

The acoustic behaviour of these laminates (significantly different from much more solid laminates such as concrete);
The technical feasibility of certain architectural choices, such as the desire to keep the wooden floor exposed or to construct high-rise buildings;
The comfort provided by the sound of wooden buildings, which differs from that of heavy masonry such as concrete.

One of the objectives of the acoustic design office is to verify in situ the acoustic performance finally achieved, using standardized tests. Thus, the success of a project depends on the combination of two technical criteria: firstly, the final performance that enables the objectives set at the design stage to be achieved (at the very least, regulatory requirements, certification label, specifications), and secondly, the consistency between the performance calculated during the design phases and the performance measured after construction. The aim is to ensure that sound spaces meet user expectations and add significant value to real estate assets.

At present, the only authoritative document on wood acoustic design in France is the Acoubois study carried out by the CSTB[1], which proposes solutions adapted to housing. Finally, conferences and working groups such as the AdivBOIS association, which focus on the subject, aim to share in situ or laboratory results on very specific tests (e.g., the feasibility of wire separators between spaces). Over and above purely technical information, European theses and research groups have already identified the most sensitive aspect of wood acoustic design: the low-frequency behavior of partition walls. A priori, it's common practice to take a detailed look at these low-frequency behaviors in any design.

Accessible knowledge almost systematically steers timber acoustic design towards over-dimensioning (to ensure that the most demanding objectives are met without risk), in the absence of absolute design, which would enable each separator to be dimensioned for each program or use. This has a number of consequences:

Greater partition wall thicknesses, resulting in loss of floor space;
Fewer storeys than with a traditional masonry construction system, with consequences for height limits imposed by local planning regulations;

In the absence of a reliable predictive model, only feedback can be used to determine the feasibility of implementing separative systems that have not yet been tested in the laboratory.

Noise and the acoustic dimensioning required to protect against it are complex subjects, and paradoxically noise-related issues have a hard time being heard, even though they are becoming a strategic issue for users.

2 - A sound report

For a large part of the population, the comparison of the sound environment before and during confinement has left its mark. A significant change in the perception of noise was felt, and a new awareness was established. Many people have realized the importance of a quiet city, and the choice of quiet living spaces appears even more markedly as a high-value-added need to preserve one's health and enjoy a minimum quality of life. Spaces are refocused on the human being, and his or her well-being is at the heart of our considerations.

Urban concentration inevitably leads to noise, and surveys place noise at the top of the list of problems French people complain about:

Nearly half (40-50%) say they are bothered by noise, see it as a health risk, and believe that the noise situation in the city has deteriorated in recent years;
A very large majority (90%) consider noise to be a hindrance to the definition of their ideal home;
60% of French people are disturbed by noise in the workplace, according to a Malakoff Médéric study.

In addition to these figures, the annual loss due to poor sound quality in existing buildings resulting from excessive noise exposure is estimated at over 57 billion euros per year in terms of health costs, absenteeism, reduced productivity, late schooling, etc. Another observation: an acoustician is often called in as a last resort, and sometimes only when the user complains repeatedly. It is important to take acoustic aspects into account in the initial design phase of any type of operation, so as to play a part in raising awareness of this issue, which is closely linked to the urban noise footprint of our living spaces.

3 - Housing regulations: food for thought

A place's noise footprint is an integral part of people's quality of life. Real estate, a high-stakes sector, is one of the levers that can change everything.

The QUALITEL barometer, carried out in 2017, ranks acoustics as one of the top three "plagues" in French housing. In Paris, Europe's second noisiest city, it's even the main source of dissatisfaction for residents.

In addition to the 1999 acoustic regulations for new housing, whose requirements represent the strict minimum to be achieved to make a dwelling fit for its purpose, the regulatory requirements published in 2017 are necessary for renovation operations, but concern only the consideration of insulation against external noise.

How can we support you in your construction or renovation projects?

Faced with regulations that aim for a minimum of acoustic comfort but not the absence of discomfort, here are a few tips:

The choice of plot: carrying out an in situ environmental acoustic diagnosis, or even a vibration diagnosis, at the initial stage of a project, allows us to take into account the site's noise context, as well as a precise assessment of the acoustic challenges of the plot. Societal and economic issues can thus be anticipated, and the building permit can be secured, thus avoiding the pitfalls that can arise if these issues are brought to light too late. By dealing with projects right from the planning stage, L'Acousticien supports developers, property developers, architects and design offices in their efforts to achieve a controlled noise environment. The decree of November 27, 2012 on the certification of compliance with acoustic regulations for new housing, requires proof that a housing project has been monitored from design through to acceptance, including site supervision.

Similarly, for any energy-efficiency renovation, whether or not the building is exposed to noise, it is recommended that an acoustic study establish the initial intrinsic characteristics of the building, define the improvement objectives and the technical solutions to be implemented to achieve them. Acoustic objectives can be graduated according to the initial situation, and the scope of the work. Two types of acoustic renovation are often encountered:
Buildings exposed to low or moderate noise levels, where soundproofing against external noise is not essential, and which by their very nature require special attention to interior sound insulation between rooms;
Buildings exposed to high façade noise, which must be insulated from external noise (2017 regulations) as a priority, without forgetting to pay attention to insulation between premises, likely to cause more significant emergences than before, synonymous with proven discomfort.

Beyond the current health context, acoustic comfort remains at the forefront of our minds, leading us to take a closer look at sound spaces as a response to many of the current and future challenges we face. The aim is to work together towards urban requalification, the restoration of spaces compatible with the transition to a healthy footprint in terms of ecology, carbon and sound ambience. This encourages different disciplines to work together. This has been the case at Sinteo for the past ten years, where our multi-disciplinary approach enables us to integrate acoustic issues as far upstream as possible in the design phases. We develop methods, and support and educate our customers in their implementation.

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Taking acoustic comfort into account leads us to consider sound spaces more carefully, as a response to many of the current and future challenges we face.

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When acoustics lend an ear to biodiversity.

14/01/2022

In the shadow of climate change, there's a subject that gets far less media coverage than global warming, but which could make a big splash. It's the state of sound on our planet, and in particular in the living world. There's no such thing as silence on Earth; noise is constantly being heard. Sometimes a source of annoyance, noise is above all a vector of information as surprising as it is varied.