FEATURE: Specify ductwork with the long-term in mind

Malcom Moss, President of the Association of Ductwork Contractors and Allied Services, why cost should not be the only consideration when specifying ductwork for ventilation systems, because it will only cost more in the long-term.


There is no doubt that the concentration on capital expenditure in construction projects frustrates many manufacturers who would prefer specifiers to consider the operational cost of products. Ductwork is no different. What’s more, there are excellent reasons for thinking about ductwork as a whole-life product because it can have significant impact on the operation of a building.


Quality of manufacture is one of the most important factors to consider when specifying ductwork. One of the main reasons for this is that there is a host of legislation and guidance on ductwork that specifiers, contractors and building owners need to be familiar with. In general terms, the legislation applies to manufacturing and installation standards; fire safety; and cleaning. Guidance has been produced by ADCAS itself, as well as the B&ES Ductwork Group and other bodies including BSRIA and British Standards.


Of course, adherance to regulations will add to the price of the product. But poor quality ductwork that is bought on a price-first basis is less likely to measure up to these standards. Clients who have broader considerations than price, will be more likely to have peace-of-mind that their ductwork complies with the latest legislation and guidance.


Another important factor to bear in mind when judging the quality of ductwork is that low quality ductwork, incorrectly installed can lead to poor performance of air movement systems. The guiding document in this area is DW144, which is recognized as the default specification for Sheet Metal Ductwork manufacture and installation.


However, it is difficult to ensure that end-users know they are buying good quality ductwork, because it is relatively easy for less robust manufacturers to pass off poor quality ductwork as fit-for-purpose. For example, without proper checks it is impossible to visually assess the construction and thickness of galvanised coating on ductwork.


While galvanising may not seem crucial to non-experts, it will have a considerable effect on lifetime performance of the system, and can lead to a requirement for early replacement. This would be a major cost for the building owner. This is why it is important for clients to deal with reputable suppliers, such as members of ADCAS.


Galvanvising is not the only matter to consider when appointing a ductwork contractor. Low prices are often linked to low quality in the overall ductwork manufacturing and installation process. Issues include use of lighter gauge steel, incorrect gaskets between joints, incorrect joint spacings and inadequate stiffening or supports. It is these problems that have long-term negative effects on the performance of ventilation systems. This adds to the cost of the ventilation system every day that it operates.


This is an important point to bear in mind as the property sector is now facing the likelihood that buildings below an F or G rating on their Energy Performance Certificates (EPCs) will not be permitted to be sold or let. Poorly performing, leaking ductwork which is wasting energy by causing fans to run unnecessarily, would therefore have a direct impact on the value and operational costs of a building.


When considering a cost-first approach to selecting a ductwork contractor, it is not only manufactured quality that should be considered. Companies which make very low bids for work must reduce their own costs by using cheaper materials – but they are also more prone to less robust business processes, a situation which can cause problems during the construction phase.


In the long-term, working with companies that focus on cost before quality can mean that you are working with organisations that do not meet high standards in terms of health and safety or quality. This increases risk in the contract chain because more client resources are needed to manage poor performance – and to rectify non-compliance.


For example, one significant development in legislation recently has been the Construction Products Regulations (CPR). Since July 2013 it has been mandatory for manufacturers supplying the European construction industry to draw up a declaration of performance and apply a CE marking to their products. This applies to any construction product covered by a ‘harmonised European Standard’ (hEN), or which conforms to a European Technical Assessment (ETA). ADCAS has issued guidance on this complex area that attempts to clarify the situation.


Whether it’s a small installation in a restaurant kitchen or a large-scale office project, the simple fact is that ductwork performs the role of a building’s lungs. Viewed as such, it seems counter-intuitive that clients and main contractors with an eye on their own good standing should be satisfied with the cheapest option.


It’s a choice that may see their building beginning to wheeze and splutter later in its lifetime – and cause their wallets to feel a good deal lighter in the process.

This feature was published in the February 2015 issue of HVR. If you would like to commission a similar feature please contact Karen Fletcher.



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