Architectural design projects are characterised by a high level of complexity. This level of complexity may be attributed to the high number of constraints that apply to architectural design projects. Along with planning, energy performance and fire safety regulations, current designers have to face constraining factors related to budget, acoustics, orientation, wind turbulence, accessibility for the disabled, and so forth. It thus appears that all sorts of restrictions and regulations steer the design process implicitly and explicitly in certain directions as soon as architectural designers aim at satisfying design briefs. In this research, we aim at analysing the impact of parameters and constraints on the design process. We wish to investigate how designers in practice deal with parameters and constraints. How do they interpret incoming parameters or constraints? Are constraints considered to be limitative (constraining), or are they key reference points in a variety of parametric possibilities? Are constraints omnipresent during the design process or are they considered only until they have been 'resolved'? To make an analysis of the role of constraints and parameters in the design process, we have studied four design sessions in a particular design use case, which will be presented briefly in this paper. In each of these design sessions, the design was not only re-evaluated, but it was also redirected in response to certain constraints that were not met (yet). In analysing these four sessions, we used linkography as a method, because this appeared to be one of the better options to obtain a more quantitative assessment of the design process. The linkography method was combined with an interview of the student design team, in order to check the correctness of our conclusions.

1. Analysing the impact of constraints on
decision-making by architectural designers
Pieter Pauwels, Tiemen Strobbe, Jeroen Derboven, Ronald De Meyer
Department of Architecture and Urban Planning
Ghent University, Belgium

2. UGent SmartLab
Ghent, Belgium
Ghent University
Faculty of Engineering and
Architecture
Department of Architecture
and Urban Planning
UGent SmartLab
Ronald De Meyer Pieter Pauwels Ruben Verstraeten Tiemen Strobbe

3. THE ARCHITECTURAL DESIGN
PROCESS

4. Constraints in design
high number of constraints apply to architectural design
projects:
– urban planning regulations
– energy performance regulations
– fire safety regulations
– budget
– acoustics
– orientation
– wind turbulence
– accessibility for the disabled
– …

5. What is the impact of parameters and
constraints on the design process
• how do designers in practice deal with parameters and constraints?
• how do designers in practice interpret incoming parameters or
constraints?
• are constraints considered to be limitative (constraining), or are
they key reference points in a variety of parametric possibilities?
• are constraints omnipresent during the design process or are they
considered only until they have been 'resolved'?
• which parameters are chosen by designer to reply to a specific
design situation with a number of given constraints?
• where does parametric freedom and parametric creativity come
from?

6. the architectural design process
The designer as a reflective practitioner – D. Schön, 1983
information /
experience

7. the design process as a sequence of
design situations or ‘snapshots’
A design situation is not considered as a design ‘problem’
that is defined by a well-structured set of constraints, and in
which a number of adjustable parameters is available.
Instead, a design situation is now understood as a snapshot,
in terms of time, in the overall design process, in which a
limited number of constraints and parameters are taken
into account by a designer, in order to ‘satisfice’ the design
situation, as interpreted at that moment, into an alternative
design situation.

8. designer as interacting decision-maker

9. METHOD OF ANALYSIS:
LINKOGRAPHY

10. design moves and design episodes
Definition of a design move by Goldschmidt:
“a step, an act, an operation which transforms the design situation relative to the
state in which it was prior to that move.”
Definition of a design episode by Seitamaa-Hakkarainen:
“segments of activity aimed at reaching a certain goal; [they] are usually decisions
concerning design elements. Each episode contains a unique goal (design element)
that will be structured and solved during an episode. When the goal is accomplished or
changed, that design episode ends.”

11. Use case presented at NordDesign2014 conference
Pauwels P, Morkel J, Bod R (2014)
Reasoning processes involved in ICT-mediated design communication
NordDesign2014

12. the linkograph
Pauwels P, Morkel J, Bod R (2014)
Additional Data NordDesign2014 Article.
http://users.ugent.be/~pipauwel/experimentaldataskypemorkelpauwels2013.html

13. annotation of design moves
using the FBS ontology
original image in
J.S. Gero. Design prototypes: a knowledge representation schema for design.
AI Magazine 11 (1990 ) pp. 26-36.

14. general linkograph statistics
104 design moves
306 links
Link Index: 2,94
10 design episodes:
1. the new idea design moves 11-20
2. web browsing design moves 21-28
3. plan and section design moves 29-40
4. Skype invite design moves 41-44
5. dynamic vs. classical design moves 45-64
6. central position of tower design moves 65-79
7. plan-section relationship design moves 80-91
8. floor-roof design moves 92-98
9. context design moves 99-104
10. conclusion plan-section design moves 105-114

16. design episodes
within design episodes

17. layering design episodes

18. diverse design episodes over time
time
…
…
sketching
ICT

19. CASE STUDY: DESIGN OF A HIGH-RISE
BUILDING SITE

20. context of the case study
• team of two students, one design teacher
• design studio Architecture & Construction, Department of Architecture
and Urban Planning, Ghent University
• duration: begin October 2013 – end December 2013
• four design sessions analysed:
– 23 October 2013
– 30 October 2013
– 11 December 2013
– 18 December 2013
• task: design the refurbishment of three outdated high-rise apartment
buildings using a co-housing concept
• challenge: A particularly high number of constraints was included in the
design brief of this studio, including constraints regarding fire safety,
building use (co-housing living units), comfort, sunlight penetration,
accessibility, privacy, wind turbulence, structure, and so forth.

22. method used for each
of the four design sessions
• design session = weekly slideshow presentation,
with drawings showing the recent status and
advancements of their design.
• organised as feedback session between students
and teacher
• Duration per design session: varies between one
and two hours
=> Everything recorded and transcribed for
linkograph study

25. LINKOGRAPH STUDY

26. Session 1 – 23 October 2013
linkograph

27. annotation of design moves
using the FBS ontology
original image in
J.S. Gero. Design prototypes: a knowledge representation schema for design.
AI Magazine 11 (1990 ) pp. 26-36.

28. Session 1 – 23 October 2013
FBS statistics
451 design moves
977 links
Link Index (LI): 2,17
Issue distribution:
R 74 16,4 %
F 26 5,8 %
Be 57 12,6 %
Bs 200 44,3 %
S 85 18,8 %
D 9 2 %

29. Session 2 – 30 October 2013
linkograph

30. Session 2 – 30 October 2013
FBS statistics
616 design moves
1509 links
Link Index (LI): 2,45
Issue distribution:
R 30 4,9 %
F 30 4,9 %
Be 97 15,9 %
Bs 272 44,7 %
S 163 26,8 %
D 17 2,8 %

31. Session 2 – 11 December 2013
linkograph

32. Session 3 – 11 December 2013
FBS statistics
1189 design moves
2392 links
Link Index (LI): 2,01
Issue distribution:
R 69 6,2 %
F 37 3,3 %
Be 126 11,3 %
Bs 562 50,4 %
S 269 24,1 %
D 53 4,7 %

33. Session 4 – 18 December 2013
linkograph

34. Session 4 – 18 December 2013
FBS statistics
372 design moves
761 links
Link Index (LI): 2,05
Issue distribution:
R 9 2,6 %
F 4 1,1 %
Be 11 3,2 %
Bs 170 48,7 %
S 95 27,2 %
D 60 17,2 %

35. ‘first sight’ findings
• Link Index (LI): each session has a notably high link index (from 2,01 to 2,45)
– cfr. Goldschmidt (1992) marks a LI value of 0,83 as low and a LI value of 1,73 as high
– High productivity in terms of LI for all four design sessions
– the second session was most productive
• Influence of ‘requirements’:
– 16,4% of the design moves in session 1 was related to requirements, contrasting significantly
with the values for the other sessions (4,9%; 6,2%; 2,6%).
– design requirements are apparently mainly considered at the beginning of the design process,
when still relating closely to the design brief.
– Later design stages are considerably more occupied by design moves that are annotated as
‘Structure (S)’ or ‘Expected Behaviour (Be)’.
– design requirements (constraints) are communicated and considered from the design brief,
after which they are considered as ‘known’ and make place for ‘expected behaviour’.
• design moves that are annotated as ‘Function (F)’ decrease in share (5,8% -> ; 4,9%
-> 3,3% -> 1,1%)
– the functions and overall program of the design tends to gradually stabilise during the design
process
– might explain the decreasing need to return to design requirements.

36. comparison of FBS statistics

37. Confirmation after
interviewing the students
• Interviews conducted with the student designers
in order to further confirm ‘first sight’ findings
• Results:
– Confirmation of findings
– Additional statements about the design process:
• At the beginning: large number of constraints and
requirements experienced => a burden / challenge for the
students
• this gradually improved: “more building features got ‘fixed’,
thereby addressing a number of constraints that did not
have to be considered any more as long as these building
features remained fixed”
• (co-evolution of problem and solution in practice)

38. conclusion
- Are constraints in architectural design considered to be limitative
(constraining), or are they key reference points in a variety of parametric
possibilities?
=> Both. Limitative, yet necessary point of reference in order to be able to
narrow problem scope
- Are constraints omnipresent during the design process or are they considered
only until they have been 'resolved'?
=> Requirements mainly handled towards the beginning of the design
process. Later on, they are considered to be ‘handled’ -> remain (implicitly)
present in the form of function (F), structure (S), or behaviour (Be-Bs) moves
- Where does parametric freedom and parametric creativity come from?
=> at every consecutive design situation, a manageable number of
constraints is selected by the designers from the virtually unlimited number
of constraints present from the design brief, thereby deliberately leaving
open a useful number of parameters, allowing for the desired level of
parametric freedom and parametric creativity.

39. Thank you
Pieter Pauwels
Ghent University
pipauwel.pauwels@ugent.be