The Art of Air Movement

The following article was originally published in the July 2016 issue of ACR News.

Rick Edmondson, Chairman at Waterloo Air Products plc, outlines the importance of testing to ensure that air is delivered efficiently and comfortably – to the point of replicating the exact room.

Picture yourself in a hotel room. The bed looks comfy, the pillows are plumped up, the TV is set to your favourite channel. Time to put your feet up and relax. Except – there’s a little niggle. The air is blowing too fast, causing the curtains to rustle. It’s distracting, isn’t it? A small detail that punctures the perfection of the moment.

It’s our job to anticipate those challenges and prevent such things happening, by getting the air distribution exactly right for the space in question. If that means replicating the hotel room in all its detail, then that’s what we’ll do. Our test lab will become that hotel room – the bed, the desk, the TV, even down to the pictures on the wall – for the time it takes to measure the air flow and make sure that the curtain doesn’t move.

Like any distribution method, it’s a question of logistics – getting the best quality of product to the right people in an efficient, timely and safe manner. In this sense, air is no different than any other product, except that here the best delivery is one that you don’t notice.

For the people occupying the space, there are many key issues. Air should be distributed in a way that does not cause discomfort: too fast and it can be a nuisance, too slow and it does not circulate effectively. Similarly, air delivery needs to be silent and unobtrusive, rather than causing an unwelcome background noise.

We take a lot of care to create grilles, diffusers and other devices that complement the style of a room – in appearance, shape and colour – while still meeting the core requirement of well-distributed air. It’s a case of achieving that perfect fusion of form and function.

The science of air flow is complex. It’s a matter of balancing velocity and temperature, judging the distances between the air supply and the area where people live and breathe, and choosing the right distribution method for the project.

Understandably, there is a major theoretical element to this. To achieve the right results, Computational Fluid Dynamics (CFD) software is essential to study the behaviour of air in simulated environments and to map out the exact design features of the air distribution product.

These computations deliver outstanding, accurate results, but with something as variable as air, the theoretical calculations cannot be left to chance. The shape of a room – and even the layout of furniture, decorative features or other elements within it – can impact on the throw of diffusion. This is where a significant element of practical testing makes all the difference.

That’s why we have invested in two on-site labs for validating our CFD data. The two labs are dedicated to performance and noise and staffed by a CIBSE-registered technician, to give us a highly controlled arena to achieve optimum air distribution. For any product, we can plan, design and set up the lab for testing specific requirements.

Each lab is fitted with extensive air quality testing equipment that provides a rich insight into the performance of air flow under different parameters. We look at a range of criteria, including:

Room Temperature – with heated floor panels, and an adaptable hot/cold wall, we can simulate the varying thermal load in rooms, backed by hand-held devices to take detailed temperature readings at specific points of the room.

Room Size – our performance lab is fitted with a moveable ceiling. Similarly, the width and length can be adjusted to provide an exact match to the overall dimensions of any project.

Air Volume – we use Belimo Zth controllers to accurately measure and control required air volumes for any test.

Air Velocity – SWEMA Multipoint probes and software help us capture the speed of air flow at different points within the room, in order to confirm the optimum velocity at which air is released.

Air Patterns – sometimes, old-school methods are the best, which is why we use smoke machines to observe and demonstrate the precise behaviour of air for each specific product.

With these tests in place, the process for validating our CFD data is proven across all of our standard air distribution products. But what about bespoke projects? Much of our work is tailored to the specific needs of customers, whether products are adapted from our existing portfolio or developed from scratch.

For that reason, our lab facilities are also available to consultants for demonstrating products to clients and for engineers to investigate problems that may occur on-site. There are many benefits of bespoke testing. It helps architects to be more innovative in their designs without worrying about the impact on air distribution. It ensures that any issues are ironed out before the complex and costly process of building begins. And for us, each new challenge inspires fresh thinking that deepens our expertise when it comes to devising air distribution systems in the future.

The questions we’re asked to deal with vary considerably. For one project, the architect intended to use a curved ceiling. In theory, this might have caused issues with air flow because of the Coanda Effect. Would air move freely along the surface of the ceiling or would it get stuck in the convex section of the ceiling? Theoretical data suggested that, with the right air velocity and distribution method, there wouldn’t be an issue. But there was only one way to be sure, so we rigged the lab with a mock-up of the ceiling section and tested the scenario until we confirmed the optimum conditions, feeding back our findings to the architect for fine-tuning of the ceiling design.

As for the hotel room I mentioned? We really did that for a client. Nothing was left to chance, we conducted our tests with absolute precision. The end result was that air flowed with enough force to reach the other side of the room, but not so strong that it would disturb the curtains. By going to this level of detail, we developed a product that – like everything we do – passes the air distribution test. Comfortable, silent, effective and good-looking… and delivered right.

To learn more about our testing facilities, please visit
https://www.waterloo.co.uk/technical/testing-products/