Go to contents 03
Modelling of User Activities in Building Design
EKHOLM, Anders
Professor of Architectural and Building Design Methodology, School of Architecture, Lund Institute
of Technology, Lund University
http://www.caad.lth.se/ Anders.Ekholm@caad.lth.se
Architects manage not only information about the building but also about the user
organisation. Therefore, information systems for architectural design must be able to handle
both building and organisational data. The paper describes architectural design as a
creative problem solving process, and presents a recently developed prototype application
for user activity modelling built as an add-on to ArchiCAD.
Keywords: Architectural design, problem solving, user activity modelling, model based
CAD
Introduction built environment but also the user organisation
activities (Ekholm 1987). The building design process
Revolutions in architectural design starts with describing the user organization and its
practise requirements on the building, then, gradually the focus
During the last 10-15 years the personal computer is shifted towards the building, its construction and
together with different software for visualisation, maintenance.
calculation and simulation have revolutionised The design process is a process of search and
architectural design practise. For most tasks the gradual development (Simon 1981). It is less a matter
drawing-table has been abandoned in favour of the of choice among ready-made alternatives than a
computer platform. Currently, a second revolution matter of creative problem solving. A requirement on
takes place where building CAD programs are shifting computer support for design is that both functional
focus from drawing to modelling. requirements and technical solutions can be creatively
The shift from drawing to modelling means that combined.
the design, i.e. the conceptual model of the designed The use of model based design and information
object, is represented externally, outside the mind of management systems in the early stages during the
the designer. This requires that both the process of programming and proposal stages, as well as in the
design and the objects of design must be problemized: facility management stages, put new requirements on
What is design, and what is designed? CAD systems. This paper reports results from the
The general idea is that model oriented CAD- development of a prototype program for user activity
programs enable the designer to develop an object modelling. It also reflects on how user activity
based “product” model of the building. Building product modelling fits into the building design process.
models enable computer integrated construction and This research has applied a generic conceptual
facility management processes, CIC/FM, (Björk 1995). framework based on Mario Bunge’s Treatise on Basic
It also enables new ways of managing and structuring Philosophy (Bunge 1977, 1979,1983 and 1985). The
design information (Eastman 1999). concepts used in this paper have been presented in
However, building design is a complex process earlier writings by the author, the interested reader is
involving knowledge not only of the building or the recommended e.g. (Ekholm 1987, 1994 and 2001,
and Ekholm and Fridqvist 1996, 1998 and 2000).
Architectural Information Management – 03 Design Process 2 67
Go to contents 03
A conceptual framework for building artefacts to be designed. However, following Bunge
design there are generic theories of artefacts and of
intellectual work that could be applied in every design
Design as creative problem solving field. The following sections outline some generic
The development of architectural design systems aspects of the substantive and methodological
must be based on knowledge of the architectural knowledge that is relevant for architects as well as
design process. Before discussing the subject of other designers.
architectural design some general aspects of design
are necessary to clarify. The verb design means “to Systems and properties
conceive and plan out in the mind”, and the noun A basic concept in a description of the concrete world
design means “a mental project or scheme in which is that of system. A system is a complex thing with
means to an end are laid out” (Webster’s 1999). bonding relations among its parts, it has composition,
Accordingly, a design (verb) process results in a environment and structure, both intrinsic and extrinsic.
design (noun). A process is a sequence of events in a system; an
Design may be seen as a problem solving process activity is a goal-directed process. The terms ‘process’
similar to problem solving in everyday life or in science. or ‘activity’ may also be used to designate the system
In general, “a problem arises when a living creature itself since it is a characteristic feature. An artefact is
has a goal and does not know how this goal is to be a man-made or man-controlled system; it is made with
reached” (Duncker 1945). A problem can be defined a purpose to make certain activities possible. A human
as lack of knowledge about a thing or process, in activity system that involves the use of artefacts is
relation to some background knowledge (Bunge also called a sociotechnical system. Work is a specific
1983:271). Problem solving in general is a process of kind of activity, it is a useful activity. A sociotechnical
purposeful exploration (ibid:234). The specific system engaged in some work activity is in
character of a design problem is to define a management science called an ”organisation” (Child
satisfactory state of a thing or process and devise a 1984), ”human activity system” (Checkland 1981), or
cause of action that results in this state. ”enterprise” (Bubenko 1993).
A problem solution, also called hypothesis, To adopt a view, or aspect, on a system is to
describes the object or its state in a way that is observe a specific set of properties. Of specific interest
satisfactory, and eventually enables a test. The test to design are the functional and compositional views.
may be theoretical, relating the solution to existing A functional view focuses on the system’s extrinsic
knowledge, or empirical, involving an experiment or properties, its relations to the environment, while a
construction and test of an artefact. During a design compositional view focuses on intrinsic properties, i.e.
process, hypotheses and tests are made alternately the compositional parts from which it is assembled.
and properties of the intended artefact are determined See Figure 1.
in an incrementally.
Simon (1981) has envisioned a unified science
of design as a possible research objective, while
Bunge (1985:227) has questioned this on the grounds
that “every design problem calls for specialized
knowledge as well as creative imagination”. The
knowledge needed in different fields of design is so Figure 1. Functional and
diverse, e.g. concerning functions and materials, that compositional views on
it is impossible to learn to design apart from the systems
68 Architectural Information Management – 03 Design Process 2
Go to contents 03
Figure 2. The building design The problem solving cycle analysis during the facility management stage. See
process Figure 2.
Every design process is initiated by a problem. The
problem definition is followed first by synthesis, leading
to a tentative solution, and then by analysis,
investigating the proposed solution. The synthesis
question is: Which object has these properties? And
the analysis question is the inverse: Which properties
does this object have? Synthesis may be regarded
as proceeding top-down, from a functional view on
the object, while analysis proceeds bottom-up, from
a compositional view. The result of analysis is added
to the background knowledge. The design cycle, by
Simon (1981:149) called the Generator-Test Cycle,
proceeds until a satisfactory solution has been
developed. The cycle is illustrated below in Figure 2.
A design problem may be characterised as open Model based CAD-systems for building design may
or closed, and the process of problem solving routine support the fundamental design steps of problem
or innovative. To a closed problem the determining definition, synthesis and analysis. An application that
factors and their combinations are well known; it may allows the development of a user activity description
be solved by a routine that consists in selecting a assists the problem definition work, while the building
prototype solution and determining the values of its design application assists the synthesis work and
attributes. To an open problem, neither the determining allows the designer to document the building property
factors nor their combinations are known. A prototype decisions. Building analysis includes technical
solution cannot be applied since new kinds of things performance analysis, cost calculations as well as
or processes must be explored or invented. Open usability analysis. Spatial performance may be
problems have been called called ”wicked” (Rittel analysed visually, but certain analyses would be
1984). possible to automate, e.g. fire escape routes,
ventilation, and lighting levels. The test results are
User activity information in architectural used as background knowledge for subsequent
design design process cycles
When an organisation is formed or changed, it may
require a new or renewed building. The process of Information systems for building
acquiring a suitable building starts with a description design
of the organisation and its activities. The activity
description is used as a basis for developing a space Static and dynamic information systems
function program which defines requirements on the An information system is a computer based system
building’s spaces. The following step includes which makes it possible to store and retrieve
development of a building program which defines information of relevance to the information needs of
additional requirements on the building. The building a user. It consists of a conceptual schema, an
program together with the activity description and the information base and an information processor (ISO
space program are used as a background for building 1985:15). The conceptual schema is a generic
design, but can also be used for building performance conceptual representation of the objects that the
system handles information about, it is made up of
Architectural Information Management – 03 Design Process 2 69
Go to contents 03
entities, attributes and relations between entities. The have other activities as functional parts or itself be a
information base holds the attribute values. The functional part of other activities. Activities are
information processor is a software tool that makes it composed of Person and Equipment. The constituent
possible to query and update the conceptual schema Person and Equipment may be determined for an
and the information base. Activity at any level in the “hierarchy”. Activities may
Information systems can be characterised as have Name, Description, Duration, and Relations.
dynamic or static concerning the possibility for the There are four Relations that can be specifically
user to define new attributes in the conceptual shown: Visibility, Sound, Distance, and Adjacency.
schema, and to classify model objects. These two These may have values which, however, can only be
characteristics are mutually independent. In a static described, functionality is not implemented. A Person
system, the model objects have to retain their can only exist within an Activity. Equipment may be
classification once instantiated into the model. In a composed of other Equipment, and can exist
dynamic system the user can reclassify model objects independently during the time period between the
during modelling. The user cannot create new classes Activities in which it appear. Figure 3 shows an
or attributes in a static system, which is possible in example of the user interface.
the dynamic system.
A model based CAD-system based on a fixed Further investigations
classification schema is not suitable for use in the The Activity add-on was tested by modelling a small
earliest, most dynamic phases of design, since the school and its classes during a day, a comprehensive
fixed schema is at odds with the evolving semantics presentation is made in (Ekholm 2001). Activity
of design (Eastman and Siabiris 1995).The modelling applications may strongly enhance the
BAS•CAAD system developed by Ekholm and functionality of building design software, especially in
Fridqvist (1998) and also presented in (Fridqvist 2000) the problem definition and analysis phases of design.
is an example of a fully dynamic system, while the The integration of activity objects in software for
Activity add-on presented in the following sections is building design opens new possibilities for building
static concerning definition of new attributes, but to design methods development.
some extent dynamic concerning reclassification of In this prototype it has not been possible to
model objects. implement a relation between activities and building
spaces, or functions to manage all the information
The Activity add-on prototype needed for space function programming. Several
The ideas of user activity modelling from the aspects could be investigated in further
BAS•CAAD project were implemented in the Activity implementations, for example:
add-on project. An add-on is a separate program that • Illustration of user activities and how they are
expands the functionality of a another program, and accommodated in the building
can only be run within this. The Activity add-on was • Spatial lay-out which coordinates spatial
developed for the established architectural design requirements of buildings and activities
software ArchiCAD. It has its own user interface • Temporal space use analysis for different use
accessible from the interface of ArchiCAD, e.g. new during a time period
menus, dialogue boxes, floating palettes, etc. • Versatility analysis of the building’s capacity to
The basic entity of the Activity add-on is the accommodate different activities
Activity. It is based on a functional view on an • Space function programs for building design and
organisation or part of an organisation. An Activity may facility management
70 Architectural Information Management – 03 Design Process 2
Go to contents 03
Fig 3: User interface from the
Activity Add-on
• Libraries of activity systems together with their Bunge M. 1977. Ontology I: The Furniture of the
building requirements World, Vol. 3 of Treatise on Basic Philosophy.
• Process modelling representing input and output Reidel, Dordrecht and Boston.
of processes. Bunge M. 1979. Ontology II: A World of Systems,
Vol. 4 of Treatise on Basic Philosophy. Reidel,
References Dordrecht and Boston.
Björk B.-C. 1995. Requirements and information Bunge M. 1983. Epistemology and Methodology I:
structures for building product data models. Exploring the World, Vol. 5 of Treatise on Basic
VTT Publications 245 (Technical research Philosophy. Reidel, Dordrecht and Boston.
centre of Finland, Espoo) Bunge M. 1985. Epistemology and Methodology III:
Eastman C. 1999. Building Product Models: Philosophy of Science and Technology, Vol. 7 of
Computer Environments Supporting Design and Treatise on Basic Philosophy. Reidel, Dordrecht
Construction. CRC Pr, London. and Boston.
Bubenko jr J. A., 1993, ”Extending the scope of Checkland P. 1981. Systems Thinking, Systems
information modelling”, Report No. DSV 93-034. Practice. John Wiley & Sons, Chichester.
Department of Computer and Systems Science, Child J. 1984. Organization: A guide to problems
KTH, Stockholm. and practice. Paul Chapman Publ. London.
Architectural Information Management – 03 Design Process 2 71
Go to contents 03
Duncker K. 1945, On problem-solving Ekholm A. and S. Fridqvist, 1996, “Modelling of user
Psychological Monograph 58, No. 270. Quoted organisations, buildings and spaces for the
from (Bunge 1983:235). design process”. In Turk Z. (ed.) Construction
Eastman C. M. and A. Siabiris 1995. “A generic on the Information Highway. Proceedings from
building product model incorporating building the CIB W78 Workshop, 10-12 June 1996,
type information”. Automation in Construction, Bled, Slovenia.
3(4), p. 283-304. Fridqvist S. 2000, Property-oriented information
Ekholm A. 2001. “Activity objects in CAD programs systems for design. Prototypes for the
for building design”. Forthcoming in BAS·CAAD project. (Diss.) Lund Institute of
Proceedings from CAADFutures 2001. TUE, Technology, Lund University, Lund
Eindhoven. ISO 1985, Concepts and terminology for the
Ekholm A., 1994, “A systemic approach to building conceptual schema and the information base
modelling – analysis of some object-oriented ISO/DTR 9007 (TC97), also SIS teknisk rapport
building product models”. In: Björk, B.-C. (ed.) 311. SIS, Stockholm.
CIB W78 Workshop, Aug. 22-24 1994, Esbo, Palladio, A. 1997, Four books on architecture.
Finland. Translation by R. Tavernor and R Schofield.
Ekholm A., 1987, Systemet Människa- MIT Press, Cambridge.
Byggnadsverk - Ett ontologiskt perspektiv. Rittel H. 1984, In N. Cross Developments in Design
Statens råd för byggnadsforskning R22:1987, Methodology. John Wiley and Sons, London.
Stockholm. Simon H. 1981, The Sciences of the Artificial. MIT
Ekholm A. and S. Fridqvist, 2000, “A concept of Press, Cambridge.
space for building classification, product Schenck D. A., and P. R. Wilson, 1994, Information
modelling, and design”. Automation in modelling: The EXPRESS Way. Oxford
Construction, 9(3), p. 315-328. University Press, Oxford.
Ekholm A. and S. Fridqvist, 1998, “A dynamic The Swedish Building Centre 1999. BSAB 96 The
information system for design applied to the Swedish construction industry classification
construction context”. In: Björk B.-C. and A. system. The Swedish Building Centre,
Jägbeck (eds) The Life-Cycle of IT Innovations: Stockholm.
Proceedings of the CIB W78 Conference, June Webster’s 1979, Webster’s New Collegiate
3-5, 1998. Royal Institute of Technology, Dictionary. G&C Merriam Co., Springfield,
Stockholm. Massachusetts.
72 Architectural Information Management – 03 Design Process 2
