Bespoke AHU Do Not Mean Expensive
By Alun Thomas, Engineer Director, June 2014
Every building is created and constructed to meet the customers’ exact requirements and the process is bespoke in every way, yet we insist on using our ‘Tetris Toolkit’ of ventilation components (fans, coils, filters) to try to create an adequate solution with the parts available to us from our supplies – the proverbial ‘square peg in a round hole’. The result is that designers are accepting units that are either too close to the design envelope (running the risk of the unit not performing), or the customer is paying too much for the ‘next size up’ model. In the current economic climate, I fear the former is becoming more prevalent as the supply chain is being pressured to cut costs in order to be competitive.
So what’s the problem with a standard range?
As far as fixed unit sizes are concerned; this restriction is in place for most AHU manufacturers, where economy of scale and set engineering resource only allows them to develop a number of fixed unit models in set ranges and defined performances. These units are normally launched as a range of products with fixed model numbers.
But what if the customer needs a unit which is just outside of one of the performance curves as per the red dot shown in the graph? What options are available?
- The consultant can look at the ventilation loads in more detail, tweaking the occupancy levels and heating/cooling loads to suit the unit or the space available. The unit would then perhaps deliver the duty under ideal conditions; however, once the filters become loaded and the coils become fouled, the end result would be an under performing system running 24/7 with no additional capacity.
- Financial pressures and economic climate could force the contractor to take the risk and offer the size 8 unit, hoping that there would be enough safety factor in the consultants’ design to ensure the unit goes unnoticed. We have all lost projects to contractors who are willing to cut cos when times are tough; these systems often cause problems and the ventilation industry is affected as the confidence weakens.
- Others might convince a client that they should purchase the oversize unit and then de-rate it. The client not only pays for the additional unit cost, but also the additional costs associated with the infrastructure to support this larger unit.
- Some might consider developing a custom unit for the client at extra cost, involving the development of a brand new product to deliver the required performance, conversion of the design into an AHU that can be manufactured with all of the 300 or so metal parts needed to build the unit, and the resource needed to produce a non-standard AHU with offline testing and validation. The increase in cost is predominantly due to these additional processes. Not only is the bespoke unit more expensive than the standard option, but there are more room for human error.
- None of these options seem to be in the interest of the customer, the profession or the industry, so we need a new option. What if we could make you an AHU with the individual components you need, in sizes that can grow and shrink to the millimetre to fit your exact requirements? Well we can.
Imagine a panel on an AHU. Some are larger or thicker than others; some have handles, hinges or portholes. But at the end of the day, it is still a panel. Nuaire has developed a technique to grow, stretch and tweak AHU components using a system known as ‘Parametric Design’.
The basis of the system starts with our AireCAD system, which allows us to drag and drop components into position to create the basic AHU you are looking for. The overall dimensions of the unit can be specified, the components can be customised and the data sheets can be provided to the consultants for discussion and approval. Up to this point, the system is very fluid and allows all parties to change the AHU as they wish – tracked using unique reference numbers and revision control. A great example of this was an MOD project in which we were asked to slice the unit sections to fit through a doorway. By providing this ‘cheese slice’ effect we could ensure that the quality and integrity of the unit was maintained.
Once the unit has been finalised and ordered, it is launched into the second stage of the system – where the magic happens. From this point there are no further changes permitted and the unique reference number is loaded into our ‘Parametric Design’ system. Here individual parts are imported into a model and then stretched or shrunk in order to ensure a perfectly designed AHU. Every part in the system is uniquely numbered and can be traced back to the parent unit without fail. All of the components are fully designed, developed and tooled ready for the machine without any human intervention.
The individual parts are then taken to a fully automated manufacturing facility, a recent £2 million investment for Nuaire. Here the parts are automatically punched, folded and delivered to the production area ready to be assembled.
This system is working so well for us that we are now finding it is easier to totally rebuild new bespoke units on our software than it is to tweak one of our existing units using the traditional method.
Pioneering the new approach above, Nuaire can ensure repeatable and consistent quality with every component - totally bespoke units without the tailored price tag.