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Creating Acoustically Correct Interiors

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Architectural acoustics can be about achieving good speech intelligibility in a public space like airport, enhancing the quality of music in a concert hall or noise control in offices. However, there is still a major lack of awareness about the importance of this specialized science. Focusing on the subject of acoustics and its relevance in interiors in India, Buildotech & Knauf AMF organized a panel discussion in Chennai in March. The topic of conversation was “Aesthetic & Acoustic aspects of Interior Ceilings & Wall Systems”

Interior space acoustic involves the science of limiting and/or controlling noise transmission from one space to another to ensure space functionality and speech privacy. Considering that the typical sound paths are ceilings and room partitions, Andreas Riedl, Sales Director, Asia-Pacific & Gulf of Knauf AMF, started off the event with a presentation on the Company’s high performance products for these applications. According to him, the major factors influencing architects decision on material choices for interiors are aesthetics, acoustics and environment-sensitivity. As designers no longer want the same white stretches of ceilings, Knauf AMF offers range of surface designs breaking away from the monotonous pale ceilings. Also special light fittings and sound systems built in tiles provide ambient lighting and surround sound without the fixtures being visible. In terms of eco-sensitivity, he informed, the company recycled 100% of all the wastage during production and took back wastage from job sites as well to recycle. In its manufacturing and material transportation process also, Knauf stress is on minimum carbon emissions.

Taking forward from there, the panelists – Acoustic Consultant Dr. Kandaswamy Subramaniam of P.S Subramaniam Associates; Ar. Oscar Concessao from Oscar & Ponni Architects; Ar. Kishore Panikker, Partner Architecture Red and Teddy D’Souza, Director-Operations, Knauf India Pvt Ltd addressed the delegates present on various related issues, specific to Indian building industry.

Agreeing with Reidl Dr. Kandaswamy said, “Aesthetics and function go hand in hand. Apart from acoustics, fire protection should be necessarily considered opting for materials used as per National Building Code”. Pointing out the major flaw in the Indian mindset, Teddy added, “What we call false ceiling, is generally used for aesthetic purposes to hide wiring cabling ducts etc. Internationally, these are termed as suspended ceilings and all standards are written for suspended ceilings. The Company has been in India for last 10 years and is still evolving with the Indian design industry. There are three major requirements of an interior space- aesthetics, acoustics and safety. And all are equally important. According to the particular function of space, one element may take precedence. Like in corridors which also functions as escape routes in case of an emergency, fire resistance is more important than aesthetics or acoustics. In a Managing Director office however, acoustics would be of prime importance but in general office, space aesthetics, acoustics and safety, all take equal importance”.

All panelists concurred that building owners and many design professionals still believed that sound absorption solves all acoustic problems. Teddy said, “It is the sound insulation that has to be angled first and then sound absorption comes in play and when talking of sound insulation, the whole gambit has to be taken in to account like doors, windows, walls etc.” Talking of acoustics from architect’s point of view, Oscar added, “Apart from the green material of the ceiling, its sound quality should also be prescribed in the ratings as noise nuisance can be detrimental to the building occupant’s health.” He called upon consultants like Dr. Kandaswamy to take the initiative of taking up the matter with suitable government authorities and media publications like Buildotech to highlight this issue for more relevant discussions among various stakeholders. He added, “Clients budgets are concentrated on the HVAC, lighting, wall treatments etc. but ceilings are not important for them to spend money. Therefore, developers and building owners need to be educated that the interior acoustics is an integral part of providing comfort and increase productivity of the people working in an office or any other space.”

“Ceilings are the fifth dimension which till now was looked upon only to add aesthetic appeal to the interiors. However, acoustics, an oft neglected property should be given due importance, especially in Indian green standards.”

– Ar. Oscar Concessao

Architect Kishore brought in a completely different angle to the topic of discussion when he said, “In most buildings, the floor to ceiling heights are limited and with structural elements like beams, they get even lower. Another point worth considering is that when a suspended ceiling is installed, the quality of interior workmanship decreases. For instance, the cuts in partitions for ducts to go from one space to another are not sealed properly as they are hidden above the ceiling, but once the ducts are exposed the insulation quality and its maintenance also becomes better as they are exposed. Same is the case with cable trays and light fittings which when exposed are installed with finer workmanship and add value to the interiors. Therefore, solutions other than end to end suspended ceilings should be explored.”

“With limited floor to ceiling heights available, the designers are increasingly opting to do away with suspended ceilings. With open plan offices and exposed ducting becoming a vogue, it gives rise to a situation where there are not enough vertical or horizontal surfaces for sound absorption.”

– Ar. Kishore Panikker

Teddy, agreeing with Kishore, said, “Not only in India, but globally the trend is of minimalist interiors and exposed concrete surfaces. In addition, the function of the building whether it is school, hotel or restaurant will require different approach. Moreover, with new HVAC technologies like chilled beams and chilled water pipes embedded in walls, continuous ceilings are not feasible as they will cut off the efficacy of these new systems.

Responding to the query on new solutions, Teddy added, “As per the research, if acoustics is underrated, the secondary sound or echo will envelope the first sound and it will not be heard clearly. Alternatively, if the acoustics is overrated or the silence is too powerful, even a slight tap will feel like a noise. Thus correct acoustic balance is important whether it’s an open plenum office or closed partitioned space. If the designers want to avoid continuous ceiling membrane dividing the space, the solution available are baffles and ceiling clouds. These are intermittent acoustic materials installed as per the requirement. For example, ceiling clouds are installed in restaurants over the sitting areas or in offices near the workspaces. As they are suspended in the air the back of the tile also adds to the acoustic efficiency, reducing the overall material requirement and cost. The industry is evolving from traditional grid tile ceilings into more innovative products like clouds and baffles to be in sync with the new design trends and building system innovations.”

Dr. Kandaswamy clarified, “For open ceiling spaces, there are existing standards which specify using acoustic material next to the workstation so as to transfer maximum speech intelligibility in that area. It is not the reverberation time but the early decay time that is important, which is also influences the speech transfer index (STI). Clouds and baffles are basically diffusers which absorb part of the energy and throw it back in a diffused state. Thus the wavelength is reduced and the reverberation time drops down as required. By using clouds or baffles, minimum material is used in a concentrated area with better speech intelligibility. We are doing a project in Chennai where the baffles have been tried and tested and are working well.”

Kishore pointed out the aesthetic advantage of these new systems: “The conventional grid pattern suspended ceilings limited the design options for various interior elements like lighting and air-conditioning diffusers in ceilings which by default had to follow the ceiling framework and in turn would set the pattern for layout, furniture and other accessories. In my view, these new materials are a great innovation as they will give the designer an opportunity to play with not only the ceiling design but other interior elements as well.”

Dr. Kandaswamy elaborated “Apart from acoustic performance, another technology that we are working with is, called acoustic capacity. This means that in any predefined space as per its acoustic capacity, the number of people using it should be controlled. Such as if a hall can offer proper acoustic to only 500 people, not more than that number should be allowed to use that space. In a project which included a library and a small museum, this concept was very successful. The space with no acoustic or ceiling absorber material functioned well as the architect through design controlled the number of people using the space as per its acoustic capacity. The advantages of the concept are that a designer gets more creative freedom as lesser functional elements like acoustic absorber etc. have to be accommodated and for client it means lesser project cost.”

“In my experience, the acoustics is not an issue that is to be dealt only in the treatment of interiors, but the shape of the building and its structure also plays an important role in the acoustic quality of the space.”

– Teddy D’Souza

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