Archify Connect: Understanding Louvre Performance

Archify Connect is our web series that responds to the increasing demand for virtual learning and networking. Our latest session was held on the 15th of February 2024 and was presented by Construction Specialties. Below is a transcript of the presentation.

Our topic today will be Understanding Louvre Performance by Construction Specialties.

Thank you to everybody who's participating in today's webinar. Before we start, I'd like to give acknowledgement of country.

Construction Specialties Australia acknowledges the traditional custodians of the lands on which we operate throughout Australia and recognises their continuing connection to the land, waters and culture. We pay our respects to them and elders past and present.

Elise was kind enough to introduce Steve and I to you all. Both Steve and I have been with Construction Specialties for over five years. Our roles include assisting engineers, architects and builders in our product specialisation and specification for commercial projects. We are here to help for your louvre selection needs.

So just to start, the objectives of today's presentation are:

• the difference between a conventional louvre and a performance louvre is what standards apply to a performance louvre.

• How to reduce the plant room size, and free area, is this enough;

• How to correctly specify louvres.

While we won't discuss today's window and glass louvres and sun shading, this may be an opportunity for another presentation.

So, what is the Louvre? There are two spellings you get out in the market.

In simple terms, a louvre is a set of overlapping slats designed to allow air and sunlight to come in while keeping rain out. They're fitted to doors and wall openings and as you can see, they're an example of a timber louvre on the slide. This was a specification, my colleague Steve, he has been with us for a long time, put together back in 1818 and it needed a bit of makeup to get it back to its former glory. Louvre can be made from timber; they can be made from steel or aluminium. Aluminium is probably the most flexible product because it can be extruded and formed into most shapes with different thicknesses and different strengths.

CS Group - We're a global manufacturer of architectural building products that are designed to improve the functionality and lifecycle of buildings they become part of. As you can see our projects where our louvres have been used in Europe, Australia and around the world. Just to give you a brief introduction to CS Group or Construction Specialties, as we're known, we're a privately owned group founded in 1948 in the US, and we're still family-owned with sales and manufacturing hubs all around the globe, with obviously a big presence in North America and the UK, in Europe, we've got a growing presence in Australia and the Australasian region. We're a building products innovator and manufacturer with an in-house test facility and a wealth of experienced personnel around the world.

In terms of design options, obviously for louvres, colour, size, and patterns are important, but there are many other aspects to louvre selection based on aesthetic and engineering purposes, which we'll cover during today's presentation.

So why do we need louvres on a building? They provide building ventilation for HVAC systems and ensure the efficient operation of plant and equipment. They're there for air performance, both air intake and exhaust, rain resistance performance that keeps our wind driven rain, and most importantly for aesthetics as well. Louvres can be a major design element on a building, or they can simply disappear into the facade of that building.

We now want to talk a bit about the louvres themselves and how they're how they're made up and the different components of those. So, louvres can be manufactured as a panel and delivered as a unitised system to a site where it may be constructed on-site. But essentially, the elements are the same for all types of louvre systems. The critical elements are the blades, they're the separating louvre blades, and these may be horizontal, or they do come in vertical alignments as well. There's a Head section, similar to a window frame, which is at the top of the louvre system, there's a Sill section at the bottom and sometimes in that Sill section there's also a Subsill that is an additional water barrier and protective barrier that's used on a building detail. Jambs and Mullions create the vertical supports on the sides and these may be visible or concealed depending on the design type or the louvre system that's selected for the application.

So, drilling down a bit more into the Louvre itself and looking inside the louvres, we look at the Louvre blades and this is a detail on a single stage. Single stage is just a single flat louvre profile, a very simple, traditional louvre solution and these blades have changed over time. They started off as a flatter blade, and then you can see some J and K and then drainable blades. So very quickly, there was an indication that these things kind of let some water and weather through. So, they looked at ways of developing these to make them a little bit more weather-resistant.

As the progressed through design, these essentially all aluminium extruded as John mentioned, but they became drainable allowing water to catch onto those blades so which drags water across to the side and then down some channelling in the Jambs and Mullions sections or on the right we see this more space age, futuristic blade, nice curved blades, quite unique. And that's where the premise on weather-resistant and storm-resistant louvres comes, you can see there's a hook shape, we're going to have a closer look at that in a second.

So here, we will dive into these more storm-resistant louvre systems, you can see the profiles are quite different. They're quite an aerodynamic profile and the idea of that is to change the way the air passes through the louvre system and help drag the moisture out of the air and take it away from the building. So those little hooks are all very specifically engineered and modelled to do that. What we have, we've got the model designed at a weather-resistant, storm-resistant louvre systems and wind-driven rain is a critical part of that performance requirement.

So cross sections on different louvre types. So, you'll see different louvres available in the market depending on what the needs are for the project. So, we see some Y and Z blades and V blades and these systems can pose as a better sight-proof louvre or they may provide a weather resistance to some degree. We see that one with the hooks in the bottom left more as a storm-resistant louvre and then the one with the squiggly lines, that's an Acoustic Louvre so some louvres need to suppress the sounds that come through from the plant to the outside neighbouring area. Uniquely, there's also Sand Trap Louvres probably not so much of a requirement right here in Australia, but where there's dust, sand, etc. They’re quite widely used to stop that from getting through into the plant and equipment.

So here are some photos, and these are the kinds of things that we experienced when we were out on site and looking at projects that have been built and they're looking to improve on what their current outcomes are. Where the Louvre system is in these images is letting water through. You can see on the left they've got a nice big plastic tarp over the top of the plant. It's getting affected by the moisture. We see the water running down the wall, or it's all inside the building. You don't need to put up with that, there are louvre systems that you know, a range of manufacturers that manufacture that are essentially rain and weather-resistant and can help eliminate these problems. So, try not to get into the trap of just picking a normal louvre that that builder may just want to nominate because there are choices available for you as designers to avoid some of these problems for your clients and down the track when they're using their buildings.

But how do we measure louvres? And how do we compare one louvre versus another louvre? That is through standards. 

So, the standards then cover various aspects of the Louvre design and free area is a critical element, like how much air can pass through, air performance in terms of pressure drop, and how much resistance is this creating, and we'll talk a bit about that a bit later how that can impact on downstream equipment. Regarding the water penetration, we've seen photos and images there of the weather getting through and can a louvre help us with this wind-driven rain protection, sand rejection, structural integrity, making sure the blades are stiff and rigid and dimensionally stable, and noise attenuation in acoustic louvre systems where that's required.

So, three standards generally are utilised across the world. These are the standards that see our work with around the world and other companies will reference and call to. So, the Australian standard AS/NZS 4740 is our home standard for natural ventilation and louvres fall into that natural ventilation assessment and as rigour around how that is done. The AMCA 500-L is a US standard and can be a more severe test assessment to give you a high-performing louvre you know, slight chronic conditions and storm conditions. The British standard, the BS EN 13030 Standard, again, can assess the Louvre's performance. But what's common across all these three, there are similar sorts of test procedures and protocols, but primarily it's all focused on physical test rig apparatus testing, where actual louvres are subjected to rain, simulated rain, and simulated wind, to create a standardised method of assessing louvre systems.

This is a great image because it shows a cross-section of how these test standards work and function. The photo on the left is an apparatus of how that's done, you've got the big fan system on the left, and there's a water spray up against the louvre you can see a horizontal blade louvre. Then in the middle, there's a chamber that can collect and measure the volume of water that gets through or may or may not get through the Louvre system. And then on the right, there's an air draw system that simulates plant and equipment, air handling units, and HVAC systems that will be sucking air through that whole system. So really, these tests are designed to compare one system against another, but also to see where try and force these things to fail under test assessments. This is the Australian Standard Solution.

So, Wind Driven Rain test, this is just a close-up image of that.

There you can see those metal bars, they're sprays of water, they shoot out a measured volume of water against a louvre. This is a vertical louvre that's under test and behind that on the right, there is a big fan that's blowing air against that creating simulating storm wind conditions. So that's the face exposure of a louvre under the physical test rig.

What results do we get out of this? What does this tell us?

Well, what we're able to assess from that is that this is a table of two different test results, the top table is tested at 29 miles per hour or 30 meters per second and simulating 75 millimetres of rainfall intensity. The core velocities are the speed of the year that's been drawn through by the plant and equipment. and as it starts with zero and he ramps up 0.5. 1.0, 1.5, it increases that draw of the air, by that air is increasing in size and variable there is still a fan blowing wind-driven water spray against that louvre system, so it's looking to force that louvre to fail and in this particular example we see where the red arrow is the rating effectiveness is it's providing a Class A blue the system. What is Class A? Class A is primarily what you may be looking for in your particular solution we see down the bottom of the table that a Class A route louvre will reject 100% to 99% of the water. That means that keeps it out. So even under those low conditions of spray and the wind, with the air being pulled through the system, it's still keeping at least 99% of that water out. Then as you move down, and more water comes through that may drop down in its Class rating to B, C, or even D.

The table below is a more severe test. This is from the AMCA 500-L tests which have higher wind speed and see this is 50 miles per hour, 22 metres a second and up to eight inches or 200mil of rainfall intensity, so a far more severe test. They resulted in a Class A louvre in those lower core velocity values. But what we're seeing is many clients especially now with the advent of computers and data centers and these kinds of facilities that are paramount for keeping moisture out of the building. Designers are demanding these higher performance test requirements to be kind of their benchmarks or their accepted requirements with their clients.

Steve mentioned before AMCA testing, that this slide is an AMCA laboratory presentation that comparatively summarises the performance of conventional louvres versus wind-driven rain louvres or as they also known as Storm-resistant louvres. The testing was done using a 1.2-metre louvre sample, it was a one-hour test, and it was subjected to 13 metres per second wind velocity, and 75 millimetres per hour rainfall rate, that's the standard test as designated by Australian standards.

But what we found was, that there is a lot of water that comes through standard louvres, and even drainable louvres are not that much better. So, you talk of around that 30 litres per square metre, per hour of water will come into your building. So, it's not until you start looking at storm-resistant louvres, or wind-driven rain louvres. As Steve mentioned in the previous slide, they will block out upwards of 99% of the water coming into your building. As you can see there, is close to a tenfold improvement compared to conventional louvres. So, you've had wind-driven rain louvres that will provide the best performance and significantly minimise water penetration into the building. Given all the extreme weather events, even in the last few days, it's peace of mind knowing using a performance louvre, wind-driven rain louvres, that's going to stop a lot of that water coming to your building.

So how can we reduce plant room sizes?

We've got two scenarios here. We've got a conventional design, which uses a single-stage louvre or a standard louvre. So, there will be water coming into that building, so you need to protect that air handling unit. So, you need to build a drain to capture the water and to funnel it back out of the building. So, you need considerably more real estate. Although you're saving on the Louvre, it's costing you more than that extra real estate required. By going to a smart design, you're looking at using a performance louvre, it's going to stop a lot of the wind and rain coming into the building. So, you can have that air handling unit directly behind the Louvre and once again, you can optimise the real estate or the area that is required for the plant room and as you know, real estate's expensive all around the country. So, any saving in real estate is a really big saving. So, you might be paying a little bit more for the Performance Louvre, but you're saving a lot in terms of real estate. So better utilisation of building space is the key here with the smart design. But I guess the other big benefit is louvres are the first line of defence when it comes to stopping rain coming to your building so they will help eliminate water infiltration issues. Steve mentioned those before in an earlier slide, how they can be costly when it comes to remedial work after installation, so why not prevent that from happening in the first place by using a performance louvre to stop that water coming into your building in the first place?

Is 50% free area enough? We often hear that in the market “I need a louvre for my building, it's going to have 50% free area” Well these two scenarios do both provide 50% free area. But is that enough? The simple answer is no. The louvre design on the left shows a louvre that has got high ventilation, and minimal pressure drop, but poor rain defence, it's lets a lot of water, as we said in the early slides for those conventional louvres, going to a performance-type louvre, but still giving you a 50% free area, still give you that good ventilation, pressure drop probably will increase, but it's going to be very good in terms of rain defence protection. So, although, both scenarios give you 50% free area, you need to look at other factors because they do behave quite differently in reality.

50% free area - that shouldn't be used in isolation. Other factors also need to be considered probably, even obvious shows are more so in this slide, where this is the same Louvre model in three different sizes. You can see there how the free area can see significant change from a smaller size up to a larger size, that's close to a 15% difference in in free area across that. So, it probably really emphasizes that you can't just be reliant on free area for your loop of selection, you need to look at those other factors that Steve and I have covered previously.

So, when we summarize louvre performance factors, there are several factors and we've spoken a fair bit about rain defence and rain resistance of those Louvre systems. But the Louvre still needs to let air through the building. That's the whole concept of that to provide that for the building. So, the airflow and that volume of airflow that comes through and the values and measurements of that, are certainly a critical part of that design. So, there are all inputs that a manufacturer can help you with in terms of selecting a louvre system. The pressure drop is the resistance of the louvre system in its convoluted shape and profile that reduces the air passing through. So, a louvre may be very good from a weather perspective, as John just showed a couple of different examples of those louvres cross sections, but if they create too much of a pressure drop with the areas of slowdown too much, that can then create a backlog and problem for the plant and equipment in the air handling units and HVAC systems operating downstream. So, optimising on pressure drop, and reducing that pressure drop value can optimise the performance, the energy efficiency, which relates to sustainability, and wear and tear on that plant and equipment. So, optimising for pressure drop is also a critical part of that design and the free air velocity that just then is just another element of the air that can pass through that louvre system and feed the downstream air handling units and HVAC systems.

So critical is the element of pressure drop that under the National Construction Code under Section J that's been incorporated into the standard where there are parameters and specific parameters that have been set down by the NCC, to limit what those pressure drops are so that way you can't have to an excessive, so you want to be referencing in that National Construction Code to ensure that you're within compliance. But what we're seeing is deemed kind of relatively conservative, and we're often seeing engineers and mechanical engineers limiting that pressure drop to even lower values. So that way, the performance with a low-pressure drop louvre provides greater efficiency, sustainability and energy saving of plant and equipment operating downstream. So often, a requirement would be for a low-pressure drop louvre solution that is weather-resistant. So that's a kind of a typical feed analysis but it's now backed by the NCC.

So, it's probably we're probably getting to the nitty gritty now for specifiers. How to correctly specify performance louvres?

What we often see though, and we're still seeing it in the market is the basic Louvre specification, not a lot of information requested and with minimal information. There probably are quite several Louvre models that can meet the specifications, and by being so minimal, it can probably lead to the wrong Louvre being selected for your project.

So as suppliers of louvres, manufacturers of louvres, the part about us is education, educating the marketplace, and assisting with specification and what we'd like to see is the more detailed louvres specification and with the specification where, you know, this is more descriptive, you know, they're asking for a storm-resistant vertical louvre with a vertical orientation blade to repel up to 100% wind-driven rain. It's asking for a Louvre model and the name of the company that produces the Louvre. It's also asking for Class A rain defence, which the previous spec, the basic spec asked for at a specific performance level of 3.5 meters per second. So more specific, but probably the critical difference between this and the previous slide is it needs to be per the Australian standard, AS NZS 4740. So, it needs to be tested Louvre. So, where the basic specification had no reference to testing, and not all louvres in the marketplace are tested.

That's probably the key thing that this particular spec calls for, for a tested louvre, in this case, to performance standards, he talks about a specific free area for the louvre based on one meter by one-meter louvre sample, a certain intake figure, and most importantly, wind-driven rain performance - not less than 99%. So, it is calling for Class A, but at a particular test level of 200 millimetres per hour, and wind speed of 22 meters per second, which Steve covered those parts before which is part of a higher testing regime. It needs to be at a better design load of 1.5 kPa and needs to comply with the NCC and Australian Standards. So, it's very, very specific. It needs to have a frame depth of 127 millimetres. We've mentioned the vertical blade before, but even down to the Alloy content, you know, now I have 6063-T6. And the colour, the colour is very specific as well, along with a model number. So, I guess what we're saying here it's we're pushing for more comprehensive specifications, we believe they will help the specifier not only get the right louvre for the project, but it helps maintain that louvre so it gets used on the project, the last thing you want to do is because of an inadequate specification for the louvre to be, I guess swapped out with a more inferior model louvre. So very critical to have as much detail in the specifications as you can.

And most importantly, asked for certification. Ask the manufacturer or the supplier of the Louvre to provide their test data sheets, and performance details, but do not just ask them, ask for third-party or independent certification. We believe that having that third-party certification provides both you and the client comfort that the Louvre performance quality is known and meets the performance required for the project, which is critical because you want to have that comfort that you're putting forward the correct Louvre and it's going to meet the requirements of the job.

So, we've referenced several standards and various documents in this presentation. And, of course, the Australian Standard, AS NZS 4740, the British Standard, and the AMCA papers and some of the way they do their testing there. So, they're all the documents and they're all founded on physical testing to get true results in terms of how louvres perform under certain rain, wind and airflow requirements. They are so unique in terms of their specific test requirements. And the National Construction Code specifically looks at aspects of pressure drop, where you want to minimise your pressure drop, so you get greater efficiency and sustainability with downstream air handling equipment.

Steve and I would like to thank everyone who listened to today's webinar on Understanding Performance Louvres. We're happy to take questions after the presentation.