Building maintenance str strategy: a new new manag managem ement ent approach R.M.W. R.M.W. Horner, Horner, M.A. M.A . E Ell-Haram -Haramand A.K A.K.. Mun Munns ns
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Constr Constr uction M anagement anagement Res Researc ar ch Unit Un it , Depart Depart ment of Civi l Engine Engi nee er ing, in g, Uni U ni ver ver sit y of Dunde Dun dee e, Dundee D undee,, Scotland Scotland
Introduction Building maintenance is a major activity in most countries. It is estimated that in theUnite United d Ki Kingdomit curren currentl tly y accoun accounts ts for for expenditure nditureof some£20 bill billion (Technol (Technology Fore Foresight sight Constr Constructi uction on Sector Sector Pane Panel, 199 1995) 5).. Accordi A ccordingl ngly, y, any reduction in resources applied to building maintenance will have a visible effect on the nati nationa onall economy. For For this this re reason, ason, a current current research project project supporte supported by EPSRC at the University of Dundee is paying particular attention to the devel developm opment of a new mainte maintenance management approach approach aime aimed at reducing ducing the maintenance costs of existing building stock. Th T heeasiest way to cut maint intenancecosts is to stop doing ing maint intenance. T his approach approach is sim simple, ple, but the long-term results results are usually usually very costly costly. Thus, T hus, the goal of the new approach is to carry out as little maintenance as possible as infrequently as possible while at the same time preserving the availability of the servi rvices fac faciilitie ties, the bui building elements and thewhole building. building. In In other words, maintenance should be carried out only when necessary to ensure the continued, safe and profitable use of the building at acceptable levels of satisfaction or when there is the possibility of extending the useful life of the elements of the building. Finding an appropriate maintenance strategy is the most difficult task facing maintenance management in determining an optimal approac approach h to reducing reducing the finan financial cial expendi xpenditure ture and and total li l ife cycl cycle costs. costs. Thi T his s paper describes a new, systematic framework for selecting a suitable maintenan aintenance cestrate strategy for f or each each indivi individua duall item tem in a buil building. Building maintenance Building maintenance is defined as “work undertaken in order to keep, restore or improve every part of a building, its services and surrounds, to a currently accepted standard, and to sustain the utility and value of the building” (Seeley, 1976). The T heobjectives of bui buillding ding maint mainte enance nanceare therefore refore (Al (Alner and Fellows, Fellows, 1990): Thefina financial ial su support of th the Eng Engine ineering ring and Phys Physic ica al Sc Sciences Research rch Council is is grat ratefully fully acknowledged.
Jour Journa nal of Quality lity in Main Mainte tenance Enginee ngineering, ri ng, Vol. Vol . 3 No. 4, 1997, pp. 273-280. ©MCB © MCB University University Press, Pr ess, 1355-2511
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to ensure that the buildings buil dings and and the their associate associated d service rvi ces are are in a safe safe condition;
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to ensure nsure that the the buil building dings s are are fit fit for use use;
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to ensu ensure re that that the cond condii tion ti on of the building buil ding me meets al al l statuto statutory ry requirements;
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to carr carry y out out themaintena aintenance ncework nece necessary ssary to to maintain thevalue of the physical assets of the building stock; and
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to carry out thework necessary ssary to mainta maintaiin the the quali quality ty of thebuilding. building.
In maintaining a building, there are usually several strategic options available to manage management, and many many alter alternati native ve deci decisi sions ons to be conside considered. red. The T here re is, is, ffor or exampl xample e, the possibil possibility of re reducing the thedem demand for mainte aintenance nanceby addressing the actual causeof fail failur ure eand identifyi identifying ng its its consequences. For instance, it it may be necessary to decide whether to repair or replace an item, and whether to carry out periodic maintenance at fixed intervals or simply to respond to the requests of the the users. users. T hus, buil building ding mai mainten ntenance ance can be divi divide ded d into into three three strategies: •
corre rrective ive;
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preventive ive;
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condition ition-based.
Corr ecti ve mai nt enanc nan ce
Corr Corrective ctive maintenance aintenanceis the simple simplest ttyp ype e of maintenanc maintenance e strategy strategy,, where an element in a building is used until it breaks down. It covers all activities, including replacement or repair of an element that has failed to a point at which it cannot perform its required function. Corrective maintenance is sometimes referre referred to to as fail failure-base ure-based or unplanne unplanned mai maintenanc ntenance e. Corrective Corrective maintenanc ntenance e tasks often often take place places in in an ad hoc manner in i n response to brea breakdowns kdowns or user requests requests (David (Davi d and Ar A rthur, 1989) 1989).. T hus, corre corr ective ctive maintena aintenance nce can be extremely expensive for two reasons: (1) T hefailur ail ure eof an item itemcan cause causea large am amount of of conse conseque quential ntial damage damage to other elements in the building. For example, failure of the roof could cause damage to the ceiling and the interior of the building. (2) Fail Failure of of an item can can occur occur at a tim time which which is inco i nconvenient to both the user and themaintaini aintaining ng authority. authority. Thi T his s can make manpowe anpowerr and spare parts planning extremely difficult. However, corrective maintenance is still an important part of any maintenance manage anagement strate strategy, as as we shal shall seelater in this this paper. paper. It I t is is from from such such work that we can can gathe gather vital vital predicti predictive ve inform information.
Prevent Prevent ive mai nt enance nan ce
Preventive maintenance was introduced to overcome the disadvantages of corre corrective ctivemainte aintenance nance, by re reducing the probabil bility of occur occurrenc rence eof fail failure ure and and avoi avoiding ding sudden fail failur ure e. Thi T his s strate strategy gy is i s referre referred to as tim time-based maint mainte enance nance, planned maintenance or cyclic maintenance. Preventive maintenance tasks are performed in accordance with a predetermined plan at regular, fixed intervals, which may be based for example on operating time. Such a strategy is freque requentl ntly y appl applied to external or inte i nterrnal paint work. work. The T he foll following are the advantages of preventi preventive ve over over correcti corrective ve maintenanc aintenance e (R (Raymond aymond and Joan, J oan, 1991): •
maintena aintenance ncecan can be pl planne anned ahead and and perf performe ormed when when it it is i s convenient venient to the building’s user;
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maintena aintenance ncecosts costs can bereduce reduced by avoiding avoiding the cost cost of conse consequential ntial damage;
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downtim downtime e, thetim timethat that an element of thebuilding building or thewhol wholebuilding building is out of service, can be minimized so the habitability of the building can be increase increased; and
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thehealth health and safety of the user can beimproved.
Neverthele theless, pre preventive ventive maintenance aintenancehas some some disadvantage disadvantages whi which must be minim nimized zed (El (El-Haram -Haram, 1995): •
Plann Pl anne ed maintena aintenanc nce e is performe rformed irres irrespe pective ctive of the conditi condition on of the buil building ding elements. Consequentl quently, y, a large large numbe numberr of unnecessary tasks, will be carried out on elements that could have remained in a safe and acceptable operating condition for a much longer time.
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T he conditi condition on of an element may end up worse than it was be before, ore, as as a result of human error during the execution of the maintenance task.
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Plan Pl anne ned d mainte maintena nanc nce e tasks tasks are usua usuallly very very dem demanding anding in i n ter terms of spare parts and labour.
Condit ion-b ion -base ased d m ain tenance
Condition-based maintenance is defined as: “Maintenance carried out in response to a significant deterioration in a unit as indicated by a change in monitored parameter of the unit condition or performance” (Kelly and Harris, 1978). The T he condi conditi tion-base on-based mainte maintenance concept recognize recognizes that that a change in in conditi condition on and/or and/or pe performa rformance nceof an ite item m is the principal principal reason reason for car carryi rying out mainte aintenance. T hus, the optim optimal tim time to perf perfor orm m mainte aintenance is determined ned from a condition survey used to determine the actual state of each constituent item in a buil building. ding. In thi this s strate strategy, gy, mainte aintenance nance tasks are determined determined and and planned by effi fficientl ciently y moni onitoring toring the bui building’s ding’s elem elements such as walls, wall s, floo fl oors, rs, roof and service equipment such as boilers, pumps, and heating system, to identify which element or piece of equipment requires maintenance before a major failure occurs. To gain the full advantage of applying condition-based
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maintenance, the condition of an item must be monitored to identify whether there is any evide vidence of change from a norm normal to an abnorm bnormal conditi condition. on. Thi T his s can bedoneby selecting selecting theparam parameter which whi ch best describe describes s the conditi ondition on of of the item and monitoring changes using suitable condition monitoring tools. Condi Condition ti on asse assessme ssments can vary from fr om sim simple ple visual inspecti nspections ons to more more advanced inspections using a variety of condition monitoring tools and techniques.
A new approach to maintenance maintenance management Current building maintenance strategies, whether based on planned or unplanne unplanned maintenance ntenance, are most li likely to be budget dri driven. ven. Thi T his s means that maintenance is not carried out according to actual need, but is dictated by financial priorities decided at the time or during the previous 12 months. A lthough theoretically oreticall y the budge budget should be built built up as a resul resultt of estim stimated needs, it is almost invariably based on previous years’ figures, modified for changes in the number of buildings, specially agreed programmes of planned maintenanc aintenance e and inf infllation ation fore for ecasts (Spedding, 1987 1987). ). Thr T hree ee methods are currently used for constructing a budget for estate-based management organizations; none is entirely satisfactory and each produces a different budget budget (Lee (Lee, 1987): (1) Base this this year’ year’s s budget on last last year’s ar’s expe expenditur nditure e with with an allowa allowance ncefor inflation. (2) Use the Departme Department of E nvironm nvironment (DoE) or other other form for mula for f or calculati calcul ating ng the the maintenance aintenanceelement of the estate budget. (3) Use a stock condit conditiion sur surve vey y to quanti quantify fy the size size of the maintenance aintenance task. In contrast to to theway that current current buil building ding maint mainte enance nancestrate strategi gie es are selected, cted, the new maintenance management approach is based on the failure consequence quences of each item item in a buil building. ding. Thus, T hus, the objecti objective ve of of mainte aintenance nance management is to prevent, to minimize and to repair building defects by enhanced planning and implementation using appropriate materials and tools at the right time and minimum total life-cycle cost.
T he maintenance manag managem ement deci decisi sion on diagram Th T he maint intenance management decisio ision n diag iagram ram is a log logica ical p pro roc cess used to sel select an appropri appropriate and and cost-eff cost-effe ective ctive mainte aintenancestrate strategy gy for each item item or group of items in a building. Its objective is to determine the best combination of maintenance maintenancestrate strategi gie es for for a buil building ding by selecti selecting ng the opti optim mummainte aintenance nance strategy for each individual item in the building, taking into consideration health, safety and satisfaction of the user and the costs of maintenance tasks. Th T he firs first step in develop loping ing the maint intenance management decisio ision n diag iagram ram is to carry out a comprehensive review of all constituent items in a building. Th T his can bedoneby breakin king thebuildin ilding g down int into thephysica ical elements and
items of each functional system and subsystem. Engineering failure analysis provides insight into the type of failures that an item in a building is likely to experie xperience. So each each ite item withi within n the buildi building ng should be analysed from fromthe poi point of vie vi ew of fail failure. ure. It It is is espe especial ciallly im important portant to identi identiffy the conse conseque quences of failure ailure.. The T he enginee ngineering ri ng tool tool which which is used used to perform rform this task is is a failure fail ure mode, eff effe ect and conse consequences analysis analysi s (FM (FMECoA) CoA) (El-Har (El -Haram amet al ., ., 1996). As As a a l result of this analysis, all the constituent items in the building can be divided into two groups depending on the significance of the consequences of failure (El (El-Haram -Haramand Kneze Knezevic, vic, 1995 1995). Signif icant it ems
Significant items are those whose failure affects health, safety, environment or utili utility (including (including cos cost). t). rmine e health lth, Health, safety safety an d envir onment onment ally signifi cant it ems. ms. To determin safety and environmentally significant items (HSESIs), it is necessary to find out exactly exactly how the item itemmight affe affect the envir nvironment and the health alth and safety of the user when it fails. Niczyporuk (1994) defines a safe object as one which causes no hazard in relation to life, health or the environment. It is also defined as freedom from unacceptable risk or personal harm. Risk is the combined effect of the chances of occurrence of some undesirable failure and its conse conseque quences in in a give given n syste system. T hus, HSESI HSESIs s are those whose failur ail ure e create creates a possibility that the user could be injured or killed, or that environmental standards standards could could be brea breached. ched. item is util uti l i ty signifi signif i cant cant if the cost cost of of Ut ili ty signif icant icant item. A n item maintenance is less than the cost of failure. In determining the cost of failure, it is necessary to take account of any loss of availability which may result from the failure. ail ure. Thus, T hus, al all item tems whose failure ail ure is li l ikely to have have an effe ffect on on the revenue, direct and indirect maintenance costs, quality, user satisfaction, appearance, serviceability or availability of the building are potentially utility significant. Care should be taken to ensure that all items that have failure consequences are included in the list of significant items. Non-signi Non-signi fi cant i ems
Non-significant items are those items whose failure has no significant effect. Th T his means tha that the the failur failure e affe ffects neithe ither he health, lth, safety fety, environ vironment nor utility.
Selection of building maintenance strategy Once significant and non-significant items are identified, the next step is to select an appropriate maintenance strategy for each item in the building. Gene Generrally ally speaking, speaking, all three threetype types of mainte aintenance nance strate strategi gie es could be appl appliied to every very item temin thebuilding, buil ding, but only onewil will yie yield optimal result results. s. The T heprocess is illustrated in Figure 1.
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d e e s c a n ) b - a M n n e B o t i t C i i n ( d a n o m C
t n ) a I c S i f i N ( n g s i s - m e n t i o N
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Figure 1. Buildi Building ng maintenance nance decision diagram
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Corr ecti ve mai nt enan ce
Corrective maintenance is most likely to be the appropriate maintenance strategy for: • non-sig n-signific nifica ant ite i tems; and and •
utili utility signifi significant cant item items whose whose conditi condition on canno cannott be monit onitore ored d and and for which the cost of applying time-based preventive maintenance is less than the cost of applyi applying corrective corrective maint mainte enance nance.
Prevent Prevent ive mai nt enance nan ce
T ime ime-ba -based preve reventive tive mainte intenance is most likely likely to to be the the approp ropriate riate maintenance strategy for: •
health, health, safe safety ty and and environmentall ntally y signifi signif icant cant items whose whose conditi condition on cannot be monitor onitore ed;
•
health, health, safe safety ty and and environmentall ntally y signifi signif icant cant items whose whose conditi condition on can be monitored, but for which the online condition monitoring technique techniques s either are not avail vailable or are not not cost effe ffective; ctive; and utili utility signifi significant cant item items whose whose conditi condition on canno cannott be monit onitore ored d and and for which the cost of applying time-based preventive maintenance is less than the cost of applyi applying corrective corrective maint mainte enance nance.
•
Condit ion-b ion -base ased d m ain tenance
Condition-ba Conditi on-base sed d mai maintenanc ntenance e is most li likely to be the appropr appropriiate mainte aintenance nance strategy for: for: • health, health, safe safety ty and and environmentall ntally y signifi signif icant cant items whose whose conditi condition on can be monitored and for which on-line condition monitoring techniques are avail available and cost-eff cost-effe ective; ctive; •
utili utility signifi significant cant item items whos whose econdition ndition can can be bemoni onitored and and for which which condition-based monitoring techniques are available and cost-effective; and
•
utili utility signifi significant cant item items whos whose econdition ndition can can be bemoni onitored and and for which which the cost cost of applyi applying condition-ba conditi on-base sed maintenanc ntenance e is le l ess than the cost cost of applying applyi ng corrective corrective maint mainte enance nance.
Conclusions To determine ine an optimal maint intenance strat rategy for for a buildin ilding g, it is necessary to integrate ntegrate thethree threetypes types of of maintenance aintenancestrategy strategy because because: •
not all all items are are sig sign nific ifi cant; nt;
• •
not not all signif significa icant nt item items can can beconditi nditio on mo monitored; condition ndition monitor onitoring ing tech technique niques are are not not always always avail availa able; ble; and and
•
the appli applica cation tion of of conditi condition on moni onitoring tech technique niques is not always always cos costteffective.
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T his approa roach will allow allow mainte intenance enginee ineers and managers to make decisions in advance about: • sel sel ecting the most most cost-e cost-effec ffecti tive ve maintenan aintenance ce strategy strategy for f or each each individual item in the building; and •
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the optimal ptimal allo all ocation cation of log logiistics reso resource urces such such as spa spare re parts, parts, tool tools, and personnel which are needed for the execution of maintenance activities.
Introduci ntroducing ng this this approach to buil building ding maintenanc aintenance e management is is expected xpected both to re reducebuil building ding maintenance aintenancecosts and to improve theheal health, safe safety and satisf satisfacti action on of of the the user. user. Al A lthough the paper paper has propose proposed a new approach to building maintenance management, testing of its effectiveness at this stage is hampered by the lack of reliable failure data and maintenance cost data. References A lner, G.R. and Fel Fellows, R.F. (1990), “Mainte “Maintenance nanceof loca local authori authority ty school buildi bui lding ng in UK: UK : a case Proceedin gs of t he In tern ati onal Sympos Symposium ium on Proper Proper ty M aint enance M anagement anagement study”, Procee , Singapor Singapore, e, pp. 90-9. and M oder oder nisation David, David, W.W. and Ar Arthur, B. (1989), “Management to maintain aintain quali quality in in buildi buil dings”, ngs”, Proceedings , Copenhagen, Copenhagen, pp. 212-18. of I mpleme mplementati ntati on of quali ty in constr onstr uction uction El-Haram, M., (1995), “Integration approach to condition-based reliability assessment and maintenance pl planni anning”, ng”, Ph Ph D. The T hesis, Unive University rsity of Exe E xete ter. El-Haram -Haram, M. M. and Kneze K nezevic, vic, J. J. (1995), “Pre “Predictor dictor based maintenance methodology”, Proceedings of the 5th I nter nati onal Logistics sympos symposium ium , UK, UK , pp. 187-94. El-Haram El -Haram, M., Horner, Horner, R.M. and Munns, A. A . (199 (1996), “Application pplication of RCM to building building mai maintenance nance strategies”, Procee UK , pp. 133-43. Proceedin gs of of the 6th I nt er nati onal L ogisti ogisti cs sympos symposium ium , UK, Kelly, A. A. and Harri Harris, M.J. M.J. (1978), M anageme L ondon. on. anagement nt of I ndustri al M aintenance aintenance, Butterworths, Lond Lee, R. R. (1987), Bui ldin g M aint enance M anagement , Willi Wil liam amColl Collins ins Sons Sons & Co. Ltd, Ltd, London. anagement Niczyporuk, Z.T. (1994), “Role of technical diagnostics in improvements of safety in coal mines”, Procee Proceedin gs In tern ati onal Confere Conference nce on Condit Condit ion M onit or ing , Swansea, UK, UK , pp. 34-50. Prevent ive M aint enance of Bui ldin gs Raymond, C.M. and Joan, J oan, C.F. (Eds) (1991), Prevent , Chapman and Hall, Hall, Lon L ondo don. n. nance Seeley, H. (1976), Buildin g Maint enance , Macmillan Press Ltd, London. anagement Spedding, dding, A. A . (1987) (Ed.), Bui ldi ng Mai nt enance Economics and M anagement , E. & F. N. Spon Ltd, London. Technology logy Fore Foresigh ight Construc truction tion Sector tor Pan Panel (1 (1995), Progress Progress T hrough Part nership (2): Construction , Office of Science and Technology, HMSO, February.
