Achieving the benefits of condition-based maintenance

Published:  01 July, 2004

Andy Thorn
The attractions of condition-based maintenance – Andy Thorn.

Condition-based maintenance is much less costly than taking action only when plant fails. Building-management systems are a vital tool in exploiting its benefits, as Andy Thorn explains.

Condition-based maintenance (CBM) of building-services plant has obvious attractions, not least of which are the cost savings it can make. The gains are greatest if the collection, reporting and analysis of data are automated. The most logical and cost-effective way of achieving this is through the building management system.

Lower bills

Unlike planned maintenance, which is done at set time intervals or after a piece of equipment has run for a specified number of hours, condition-based servicing is carried out only when the plant actually needs attention. This can mean lower repair and energy bills and improved plant performance. Minimising the risk of services failing also reduces the possibility of costly disruption to the business of the building user.

To be truly effective, CBM requires a regular flow of monitored data. Building-management systems are well placed to provide this. Sometimes they will already be measuring the appropriate variables for control purposes, particularly temperature data. When this is not the case, adding a few extra sensors will often be all that is needed.

The most common example of the use of a BMS in condition based maintenance is for indicating when the filters in air-handling units need to be replaced, which the system determines from differential-pressure readings. Condition monitoring of other types of plant may require it to measure a number of variables and then calculate operational efficiency. This is particularly worthwhile on items with high capital and operating costs, such as chillers and large boilers — for which it is especially important to maintain optimum performance.

Vibration monitoring

An increasingly popular CBM technique, and one highly relevant to building services, is vibration monitoring of rotating machinery. Normally based on piezo-electric technology, it can warn of various potentially serious problems on equipment such as fan and pump motors. Importantly, vibration sensors are low cost, easy to install and able to produce signals that can be output directly to a BMS. Depending on the amount of information available from a sensor, the BMS may be able to diagnose the cause of a problem, warning say that a bearing needs lubricating or a fan is out of balance.

Because vibration monitoring enables a more effective maintenance strategy, it should appeal to a wide range of users. It is of particular value where there is a high price to be paid if the services go down — for example, in data centres, clean rooms or operating theatres.

For a building-management system to be an effective CBM tool, it must be able to quickly send alarms to whoever needs to see them, on-site or off. Many BMSs meet this requirement by offering a variety of alarm-handling options. Bureau services, such as that operated by Trend can also offer a remote condition-monitoring service, to automatically compare actual and expected profiles for particular variables (e.g. boiler efficiency) and report any deviations. If sufficient data is available, it can even specify what remedial action is necessary.

Valuable asset

The practice of only carrying out building-services maintenance when plant actually fails is sadly far too common, presumably because it is thought to save money. Condition-based maintenance is, in fact, the lower-cost option. What is more, it enables building users and owners to make the most of a very valuable asset — their building management system.

Andy Thorn is commercial sales manager with Trend Control Systems Ltd, PO Box 34, Horsham, West Sussex RH12 2YF.

comments powered by Disqus



Welcome to Modern Building Services Online, the web edition of Modern Building Services (MBS) journal and the UK's most popular Building Services engineering site. Modern Building Services covers the entire Building Services Engineering industry. This site contains archived content from the journal, plus web-specific content.

When you go to our digital edition, you can also access the archive of digital editions.


Modern Building services has a group
on Linkedin - join us!


  • Mechanical Engineer

      Coventry University is a dynamic, modern university with a proud tradition as a provider of high quality education and a focus on applied research. The University ranked 13th in the Guardian University Guide 2019 and was voted ‘Modern University of the......

  • Energy and sustainability: Performance and analysis manager

     An exciting opportunity will arise shortly for an exceptional person with extensive experience of managing sustainability within large complex organisations. Can you demonstrate extensive experience of energy management, proven ability to drive program......

more jobs »


"Is the Building Services industry lagging behind in the implementation of BIM?"