This article is second in a series of metal ceiling tile articles looking at the advantages and disadvantages of the product in a variety of applications. Part One explored the allure and application of metal ceilings from an architect’s perspective, using the large-scale commercial Darling Quarter project in Sydney as a case study.
Metal ceilings may have seen recent use in large scale Australian commercial developments, particularly projects with a passive chilled beam cooling system, but this isn’t to say they are for every project.
Architecture firms Francis-Jones Morehen Thorp (FJMT) and Architectus used metal ceilings for this very application - the Darling Quarter project by FJMT and 1 Bligh Street by Architectus both incorporated metal ceilings to facilitate their passive chilled beam systems to an award winning effect.
However, Paul McDonald from Armstrong, the world’s largest acoustical suspended ceiling manufacturer, predicts that this form of cooling system may see a decline in Australia and be replaced by active chilled beam systems; a trend he says is currently being seen throughout Europe and America.
“Passive chilled beam systems are in decline in Europe and America, active chilled beam systems are on the rise and they do not require a metal ceiling tile,” he said.
Sean McPeake from FJMT was on the design team for the Darling Quarter project and said his decision to choose metal ceilings—a variety of perforated tiles from SAS International—over other options such as mineral fibre boards and timber tiles was based on its compatibility with a chilled beam system, its durability, and its sleek, commercial appearance.
Architecture & Design then put it to McDonald, whose company manufactures both metal and mineral fibre tiles, to delve a little deeper and explain why metal ceilings should be considered a superior product compared to the traditional mineral fibre tile.
His answer was surprising:
“Other than its compatibility with a passive chilled beam system, its perceived longevity and, according to some, its superior visual performance, the answer is not much,” he said.
“Mineral fibre tiles outperform metal ceiling tiles in terms of acoustic performance, light reflectance and cost effectiveness in almost every instance.”
Metal ceilings perform well in only one of the two main assessments for building sound performance—sound absorption and sound attenuation.
Sound absorption measures a material’s ability to absorb soundwaves, limit reverberation time and reduce ambient sound in the room.
McDonald notes that under this measure, a suspended metal ceiling with an acoustic insulation pad insert can absorb sound reasonably well. Below image: Ceiling Tiles UK.
But it is sound attenuation, the sound control between two spaces divided by a ceiling height partition, that he says mineral fibre tiles outperform the standard metal variety.
“Basically, with a metal ceiling pan the sound goes through and out the ceiling into an adjacent room - a real problem in boardrooms and private offices where speech privacy is essential," said McDonald. Image: Ceiling Tiles UK.
McDonald does note that to address this issue some manufactures are placing an additional layer of plasterboard on top of the acoustic insulation layer, which is on top of the metal tile layer.
What results is a composite product that is comparatively very expensive and essentially less sustainable. It is less sustainable because it fails under the subject of dematerialisation—the practice of using fewer materials to achieve the same outcome.
“Choosing this system is a pursuit of an aesthetic and what they feel is an additional longevity, but it’s at the cost of initial capital budget,” he said.
“It ends up in some case three times more in cost than a mineral fibre board.”
“In terms of acoustic performance, mineral fibre tiles are a better product.”
^Perforated metal ceiling tiles have a low light reflectance. Image: SAS International.
Another shortfall for perforated metal ceiling tiles (their most common application) is in light reflectance.
A mineral fibre tile has a light reflectance of 90 per cent which allows natural light to penetrate from the exterior and be reflected further into the building’s interior.
“In a lot of cases this can reduce the lighting burden and energy required to illuminate the building,” said McDonald.
Most metal tiles, however, are heavily perforated so they don’t have this reflectance and McDonald explains that this could amount to more traditional lighting being used.
^Cleaner-friendly metal ceiling tiles were chosen by Sean McPeake from FJMT for the Darling Quarter, Sydney project. Image: FJMT.
McPeake from FJMT says that one of the attractions of a metal ceiling tile is its easy maintenance and longevity.
“There is this perception that they are durable and are still going to look good in 10 -15 years,” he said.
“There is also an expectation that there will be certain reconfigurations of offices over the lifetime of their tenancies and metal tiles, unlike plasterboard and mineral fibre tiles, can be taken down and moved around with no ensuing damage.”
McPeake said plasterboard and mineral fibre tiles are also more brittle and susceptible to water stains and discolouration, and called attention to anyone who has worked in an office building to the common water marks and “unpleasant smell” that occur due to small air-conditioning leaks.
McDonald made two counterpoints to this assertion:
“Through our experience at Armstrong it is very rare that people will actually clean ceiling tiles, so it doesn’t matter if they are wipe-able”.
“To replace a mineral fibre tile is less expensive and they are more readily available through a well-developed network of distribution outlets around Australia”.
However, the continued use of passive chilled beam cooling systems in new commercial and office fitouts will ensure metal ceiling tiles remain a popular product for architects and builders. Furthermore, as long as they continue to be perceived as visually superior and more enduring than mineral fibre tiles, metal ceiling tiles will continue to be chosen on this merit.