by Gianguido Piani and Tina Saetre
The use of computer systems for building-maintenance planning, scheduling and optimising is becoming more common nowadays in Sweden. Building-maintenance planning is discussed in general first, followed by a description of a computer database system which has recently been developed for the purpose. The article also contains an introduction to the historical and present situation of building renewal in Sweden.
Maintenance planning for buildings is still a novelty; its importance is only recently beginning to be understood, although in other engineering sectors maintenance planning is a basic fact of life.
Cities and towns in modern western society may now be regarded as being fully built: most infrastructures are already in place and attention is shifting from construction to conservation. Maintenance is becoming more and more important, especially when the increasing age of the buildings is reflected in higher repair costs.
Effective maintenance planning today requires the use of computer-supported data bases; this represents a new dimension in computer application in building technology after the introduction of CAD techniques and computer-controlled HVAC. Maintenance planning helps to rationalise the efforts to keep buildings in proper condition and should thus be seriously considered by real estate managers.
The aim of this article is to describe building maintenance management as presently carried out in Sweden and also a computer-supported maintenance planning system. The system is based on experience gained in Sweden and on the analysis of special needs by some users (building owners, public services); it was developed by the engineering company VIAK in Stockholm between 1984 and 1987.
Historical background
The need for proper maintenance of buildings is clearly evident in Sweden. Basic maintenance operations are called for both by a cold climate and by legislation that requires good quality in the living environment. Hence, for instance, it is unthinkable not to keep the heating plant always in top condition.
The majority of buildings in Sweden were built during the last 100 years. In Stockholm, Gothenburg and Malmoe the central area is composed of buildings from 1880-1930: around the centre there are often groupings of houses built in the functionalist period (1930-50), the first suburbs (1960) and finally the tall buildings of “the million programme” (1965-75).
The “million programme” provided for the construction of 100,000 apartments per year during a 10-year period. Its urgency was dictated by the quick growth of the larger cities when people moved there from rural areas, pushing up the need for new dwellings.
Because of the shortage of time and cost limitations there was no choice but to emphasise quantity over quality, and, to build quickly, new construction techniques had to be used even if they were still unproven. The result today is that a large number of buildings have major defects in layout, design and materials.
Following completion of the “million programme”, new examples of innovative architecture have found their place as a reaction to the grey concrete buildings of the previous years.
In the 1960s and 1970s many old buildings were torn down: now the cultural and political approach has changed and the public is very careful about the old buildings that are left.
It should also not be forgotten that Swedes have a somewhat different relation to their living environment than most other European populations because of the closer contact to nature which they can enjoy. Buildings are usually very close to woods and lakes — important elements in the Swedish way of life. In addition, the most common dwellings are still one-family units and rows of houses, with easy access to green areas.
The internal and external details of most Swedish buildings have above all been designed from a practical rather than an aesthetic viewpoint (coloured or decorated tiles are still considered a luxury). Water pipes are built along and not inside the walls. Bathroom and kitchen elements (bath-tub, shower, sink, wc, refrigerator, oven) are part of the house and have to be renewed every 10 to 20 years. The house-owner is responsible for the renewal and bears the related costs.
The building renewal programme
Housing policy is strictly controlled in Sweden through regulations and via credit programmes. These controls are very effective because in most cases for a private owner it is impossible to finance major building or renewal work without making use of public loans.
In 1973-76, following the energy crisis, the first major programme of state loans for building maintenance was carried out, directed toward energy-saving measures. Since then the programme has been extended to other kinds of building maintenance or improvements.
The ROT programme (Renovering, Ombyggnad, Tillbyggnad, ie renewal, rebuilding, extension) was introduced at the end of the 1970s, providing for subsidised loans and giving special advantages for renewal and maintenance works, on the condition that the work is officially approved and the required building standards are followed.
The ROT programme was drawn up to keep workers in the building sector employed after the completion of the “million programme”; it is thus principally a measure of labour policy. A second major reason for the ROT programme arises from the problems related to the new buildings: the unproven construction methods started to show problems almost at once.
Official policy has changed again to some extent in the recent years because of severe housing problems, particularly in the larger cities. Since the mid-1980s the state is again supporting new construction; this, however, is not a major change in direction, but rather an extension to the current building renewal programme.
Today, renewal and restoration are no longer considered unique events but an integral part of a complete maintenance programme. The renewal action is the start of a broad programme to keep the buildings in good state. This applies both to old buildings with historic-artistic value worthy of preservation, and to the newer ones because of their problems.
Maintenance planning
There are two basic approaches to maintenance: to do it only when it is absolutely necessary, or to plan it.
Different kinds of maintenance may be identified as functions of their time-scale (see Table I).
Remedial maintenance, owing to its unforeseeable nature, is impossible to plan; repairs are part of the normal life of a building and cannot be considered for planned maintenance. However, knowledge about the type and frequency of breakdowns helps when planning preventive maintenance.
Some planning is possible where preventive maintenance is concerned, ie with actions taking place frequently but which cannot be exactly foreseen. Some HVAC computer-control systems offer the possibility of planning preventive maintenance actions. An example of this is the control/overhaul of mechanical equipment after a predetermined operational time has elapsed.
Maintenance actions to be carried out at intervals longer than a year are particularly suitable for planning; this kind of maintenance planning is the subject of the present article.
The two major goals of maintenance planning are (1) to reach a constant and rational distribution of costs and resources for the execution of periodical actions on the real estate and (2) to limit the probability of sudden breakdowns.
Maintenance planning allows not only a more rational use of resources but also provides occupants with a higher degree of comfort and lower total expenses for emergency repairs.
It is important to distribute the costs so that no peaks result and the outlays remain approximately at the same level each year. The same applies for the workload, which should be properly distributed around its average level. Co-ordination of maintenance works is also important, to minimise the inconvenience for the tenants and to make co-ordinated use of special work tools like cranes and scaffolding.
Last, a level yearly maintenance budget has a better chance of being accepted than one showing major changes from year to year.
To keep track manually of a large number of buildings and to plan and organise maintenance work is no easy task, unless the estate consists of only a few buildings. The solution is to leave the extensive calculations to a computer.
With its help it is possible to plan and distribute maintenance actions over a long time-scale, define detailed action plans, check the work execution, reschedule actions which could not be performed in time, compute statistics etc.
Building maintenance planning helps to answer the following questions:
- what has to be done, where and when?
- how much will it cost?
- how much is to be budgeted, eg with a specified interest rate?
- what is the effect of different strategies?
There follows the need to operate at several abstraction levels and within different time-frames. Budgeting may be done with raw figures; this will also influence the aspect of the detailed work plan.
Several computer maintenance planning systems were developed and used in Sweden during the 1970s and 1980s; almost all were originally designed for specific customers with their particular applications.
The system described here was developed by VIAK in Stockholm, though the operating principles of other systems of this kind are similar. The VIAK system was designed to be as comprehensive as possible and to satisfy the needs of several users. It is presently being used, among other applications, for maintenance planning of the subway stations and fixed installations (about 150 buildings) in Stockholm and the nearby region.
Work organisation
The core of the computer system is a data base consisting of three major files (collections of data): an object (property) file, a maintenance actions file and maintenance plan file. The data base may be extended by adding further information such as energy consumption statistics.
The object file is used to store information about the nature of the buildings and their structures, storeys, rooms.
Maintenance actions are described with a code, a text and further information such as cost per unit and a standard execution interval.
In the maintenance plan file, the various parts of the buildings/storeys/rooms are tied to the required maintenance actions. This file, the largest in the system, is used to store information collected in the course of field inspections.
The planning method is illustrated in Fig 1, which shows both the data processing and the manual work moments.
The preparatory work consists of storing information about the buildings and of defining the maintenance actions. Each object is given a unique code, used as a retrieval key in the file. The object code is followed by other data such as the building’s name, address, geographical location, area, and any other information that may be required later to sort and select objects into suitable groups.
The second general coding operation is the identification of the separate maintenance actions; their description consists of a code, one or more texts, the normal periodicity, the used measure units and the costs per unit. Other data may be added according to requirements.
Maintenance actions are organised in groups and subgroups. For example, one group might be “technical installations”, a subgroup “sanitary fittings”, containing for its part a classification of all actions.
The hierarchical classification has shown itself to be useful and flexible for preparing effective maintenance plans.
It may be stating the obvious, but it is imperative that everything be well thought out in the preparatory work phase. It pays to think in advance of the questions that one wishes to have answered and plan the data organisation accordingly.
A decision must also be taken at an early stage on the desired level of detail. Too many details require an excessive amount of work to store and keep the information up to date. The bigger the quantity of information to be handled, the more work and the greater the risk of error.
After the preliminary operations have been completed, the current state of the property must be reported and stored. This is the most work-intensive phase prior to putting the system into service. Here it is necessary to define for each position, sub-unit, room or flat which actions are needed, the periodicity for their execution (if it differs from the standard) as well as the first year when it has to be done. Any quantities that cannot be defined on-site are calculated later with the help of drawings.
The description may be made at the desired detail level, but in practice sub-units of flats and rooms are seldom considered. It is not necessary to define the exact position of specific items (“window 25 in above the floor”), but rather the kind and quantity of the action to be performed (“frame insulation in room 42 planned for 1990”). The maintenance planning system is used as a budget planning aid, in some cases for portfolios of hundreds of buildings; even approximate descriptions are in almost all cases more than sufficient for this purpose.
The system also offers open fields for free text descriptions and special codes for activity and quality (eg action urgent/not urgent; action can/cannot be postponed etc).
The process of collecting and storing the maintenance plan data may take years if the real estate is big enough. Unlike the coding of the buildings and the maintenance actions, which are done in the office, the biggest part of the work has to be made with direct verification on site of the state of the buildings.
The computer as an aid
Once all the required information is stored in the computer it is possible to prepare maintenance plans describing what must be done, when and where. The maintenance plans may be selected on single buildings, parts of buildings and the year(s) of choice, or they may be arranged as budget summaries organised by object or maintenance action.
Examples of reports which may be generated are the following:
- property description
- maintenance actions’ description
- inspection reports
- work plans for one or more years
- total maintenance costs for selected buildings, type of action and/or time periods
- prediction of future costs
- simulated outcast of different action strategies.
The output is usually produced in the form of listings, but in some cases tables and graphs are also used. Objects, maintenance actions and execution periods may be grouped differently as required; this is, however, strongly dependent on how buildings and action groups are organised initially.
In Figs 2 and 3 examples are given of output listings from the planning system. The first one (Fig 2) is an example of maintenance plan for a given year; in Fig 3 is shown a general budget organised by buildings.
Maintenance costs may be computed for several years to come, usually a 10-year period. The initial outputs often show a poor distribution of the outlays and the workload over the years. Different strategies have then to be simulated in order to verify their effect on the annual budgets.
Simulation is made by rescheduling groups of maintenance actions for entire buildings or their parts (eg “Postpone one year all painting works planned for objects in Group B”) and verifying the effect of every change on the general budget.
After the general maintenance plan has been found to be satisfactory the separate actions are listed so that the detailed program matches the more general planning.
Typically, lists are printed out showing all programmed actions for a given year. These lists are used for preliminary on-site inspections to verify whether new needs have arisen, or whether less urgent problems could be dealt with at a later date.
When all actual actions have been defined, new printouts describing the action details and the necessary materials are produced. Procurement orders are placed on the base of these lists.
After the actual maintenance actions have been carried out, they are reported back to the computer to be rescheduled in the future as a function of their periodicity. The planned actions are also periodically checked against those already carried out to verify the execution state of the maintenance plan.
A very important feature of the system is its flexibility. It allows operations at several levels and may be used in an initial phase only for general planning, to be later developed for more detailed actions when the need arises and more exact data are available.
Flexibility allows the system to be easily adapted for existing applications. This is very important for the user, who does not have to learn a new work method, but can use existing codes and structures in maintenance programming.
Structure of the computer system
The maintenance system described here is based on a so-called relational database. This kind of data base permits great flexibility, used only partially by the existing program modules; that is, the system is still open for additions and improvements. The user may decide himself about the required information and its presentation.
The basic structure of the maintenance planning data base is shown in Fig 4.
With the “query language” of the data base management system it is possible to access the stored data directly. A general example of “query to print” the maintenance plan for a given building and year is:
FOR building (A = 1000)
JOIN (B MATCHING ALL FROM maintenance_data)
AND (C WITH next_planned_year = 1989)
THEN PRINT ALL DATA FOR B, C
END
The user need not use this form of computer jargon to access the data base. It may, however, be useful when a quick report is needed in a form which is not implemented in the present modules.
The VIAK system is available on a VAX mini-computer running the VMS operating system and, in smaller on the VAX is multi-user, ie several users may access the computer work at their own sites accessing the system with a computer terminal via a modern connected to a telephone line.
Trials have also been conducted in the use of hand-held terminals to collect data in the field and transfer it later to the main computer, as well as the use of PCs as “smart terminals”, able to perform minor tasks locally and to connect themselves to the main computer facility when its support is needed.
After evaluation of existing data-base products, it has been found that the requirements of the maintenance system exceeded the capacity of products available until 1986. Readily available general-purpose systems do not easily support the complex data organisation needed to keep the data base compact and avoid unnecessary redundancies.
The final design is based on a mixture of relational data-base management systems (for VAX and IBM-PC) and in-house developed programs. The programming language Pascal has been used in both cases with satisfactory results.
Future prospects
All property managers have probably at some time or other thumbed through files looking for data on floor areas and found a number of different values for the same room.
The computer-supported maintenance system keeps all information in one place; there is no redundant, and possibly contradictory, information. If one wants to know the total number of laundry rooms, one asks for it and gets it.
Maintenance planning files may be organised to provide ready access to statistics on items such as the total cost of damage to buildings, all repairs needed to be done on roofs and facades or all painting work already carried out. If the tenants demand that a certain percentage of the maintenance budget is used for sprucing up the yard, or information is required on the maintenance costs in some commercial premises, the figures are immediately at hand via the computer terminal.
The manager of a small portfolio has usually quite good control of such information for the buildings for which he is responsible, and may even be able to keep up to date a certain amount of data about them. He probably knows his buildings faily well, so that he will be more interested in coupling the maintenance plan with other data affecting the building, such as rents, mortgages and energy statistics. Today one can store this kind of information on an ordinary PC.
Computer buffs are now dreaming about being able to offer even more integrated services. The property manager should be able to access quickly from his terminal relevant data about the condition of the buildings (data such as temperature, humidity and alarm values), as well as access the maintenance plans. He could also rearrange maintenance plans in the event of unforeseen changes in the buildings’ functions.
It remains to be seen to what extent this vision is realistic. The major obstacle today is not the technology, which in itself is more than sufficient, but the fact that products from different companies are not yet compatible with one another, so that their respective systems cannot be used together.
Conclusions
The use of maintenance planning methods with the help of digital computers is becoming more common in Sweden because of a growing need to rationalise. Building renewal and maintenance are of primary importance and require the optimal utilisation of available resources.
The main advantage of the computer system is seen when effective co-ordination of all related activities is possible: computer programs alone are not enough to produce good maintenance. The cost of the computer system is also only a small fraction of the total costs related to maintenance: the investment is justified when the electronic tool can act as catalyst for the coordination of the maintenance actions.
A precondition for the correct operation of the system is that the database is kept up to date. An interaction is called for where the computer returns the work plans on the bases of the input data and the actual needs. The loop is closed by carrying out the maintenance actions. The relevant part of human work acquires a new dimension of importance and efficiency thanks to the electronic programming.
Experience gained in Sweden so far suggests that the investment for the computer system, including its software, may be recovered in between two and five years.
