Maintenance is an important part of the management of the physical assets of a property. Once the building services are installed, it is necessary to care for them to ensure they continue to operate correctly and do not deteriorate.

Traditionally, maintenance has been based on preserving the physical assets using failure prevention and asset care, which may conflict with business requirements. This has usually used preventive maintenance schedules that contain generic tasks and frequencies, which may lead to ineffective maintenance by either inadequate or unnecessary work.

The purpose of maintenance should be to ensure that the service levels required by the business of an organisation are sustained. Schedules should be customised to take account of the diversity of plant and their operational circumstances.

An important objective of maintenance must be to add value to the business process. Most business procedures seek to add value and maintenance should be considered as an integral part of this.

A company would be at significant risk if it did not, as a minimum, comply with legal requirements.

The consequence of a failure is about how it affects the business. Some failures can cause more damage than others; some failures have longer-term consequences. Prevention needs to be prioritised so that those failures that may cause the most damage will be addressed in preference to others.

If the consequence of a failure will have a significant impact on the business function, and the likelihood of it happening is high, then the organisation is at a high risk. Considerable effort must be made to avoid, eliminate or minimise such a consequence. If, on the other hand, the consequence of failure is not significant, then it is not worth carrying out preventive maintenance beyond basic housekeeping measures such as cleaning and lubrication.

The consequence of failure of a plant item will also depend on the way it is operated. For example, where there is redundant equipment, the consequence of failure of the duty item can be small since the standby equipment can be used to continue the function. However, should the standby equipment also fail, the consequence can be serious.

The objective of BSRIA's latest guidance on Business Focused Maintenance is to achieve a level of maintenance which matches the strategic service level requirements expressed in terms of availability and quality. It is not the same as maintaining a physical asset to keep it in good condition, as the level of service may not depend on the operational capabilities of the asset. The consequence of failure of the asset may even be acceptable under certain circumstances. The emphasis of BFM is on functional outputs and failure consequences rather than maintaining assets in good condition.

The BFM strategy uses key questions which should be answered when developing a preventive maintenance regime:

• What equipment is critical to business operation to warrant maintenance?
• What are the common causes of equipment failure?
• Are the causes detectable?
• Could maintenance prevent the causes from occurring?
• How should equipment be maintained?
• What is the frequency of maintenance?
• Where should it be maintained?
• Who should maintain it?
• How can the maintenance be cost-effective?

The maintenance tasks described in the schedules developed by BSRIA provide advice and information in relation to some of these questions. Answers to the other questions are site specific and are best determined through discussion with those with detailed plant knowledge.

Figure 1 helps identify the level of consequence or likelihood of failure that can be accepted. Note that the shape of each area of the curve will change according to what risks are acceptable to an organisation.

In the absence of good reliability data, it is sensible to rank the possibility of a failure being realised depending on local conditions. The following indicates common conditions that can aggravate conditions leading to a failure:

• the level of engineering - over-engineered plant is less likely to fail than that which is operating near limits,
• the quality of design, fabrication, installation, and commissioning
• abuse
• age, wear and tear
• inappropriate maintenance
• improper operation
• operating hours: (eg 8 hours a week or 168 hours a week).
• internal and external environment
• plant loading: plant may experience different loads - some may be lightly loaded whereas other may be operating at full load for most of the time. For some plant items the load cycles.

The likelihood of failure can be ranked on a scale of 1 to 10. The items of plant that are subjected to more of such conditions should be ranked high compared to the others.

The frequency of inspection and tests relates to the chance of failure conditions being detected before failures occur. The more frequently such tests and inspections (condition monitoring tasks) are carried out the more likely it is that the failure conditions will be detected before any harm is done. However, there will be cost and operational implications in doing so. It is necessary to achieve a balance between the risk of a failure and the implications of doing more condition monitoring.

Scheduled restoration tasks are only feasible if the failure mechanism is related to the age or other similar operational parameters, such as the hours of operation. Contrary to popular belief, research has shown that the majority of plant items do not wear out (although components such as seals, pump impellors, lamps, valve seats do), but rather are subject to either random failures throughout their life, or fail as a consequence of infant mortality, ie they fail during the first few hours or weeks of life due to issues such as:

• poor design, installation, commissioning, or operation
• unnecessary or excessively invasive maintenance
• bad workmanship.

A correct maintenance regime will help to avoid, minimise or prevent some failures but is quite unlikely to completely stop them from happening. The reasons for this vary from randomness of failures to changing conditions that can aggravate failures. A part of the risk management process, therefore, is to take appropriate steps to manage and recover from failure conditions if they occur. This will obviously reduce the level of risk associated with a failure if it occurs.

Sometimes it is possible to continue to provide a desired level of service or to minimise the effects of a failure, even in the case of the failure of a function of an item. Some common means of achieving this are:

• the use of standby plant
• separating essential loads from those which are non-essential
• availability of alternative plant to provide the function (eg multiple plant sharing between services via cross over connections)
• availability of alternative services to support the business need (eg possibility of using alternative accommodation)
• hiring plant
• agreeing with local/specialist suppliers to provide replacement
• components/complete repairs within an acceptable time.

For information about this work please contact BSRIA's FM Engineering Centre on 01344 426586 or email FM@bsria.co.uk

This work has been undertaken as part of the DTI's Partners in Innovation scheme together with a number of partners from industry including Imperial College, Lloyds TSB, TAC (UK) Ltd, Colt Services ltd, Amey Comax, IGS Services Ltd.