Proceso de Sistematización en la Biblioteca de la UPIICSA

A technique that has many similarities to the value tree and decision matrix is QFD or the

‘House of Quality’. Originally developed within Japanese manufacturing industries, it has been used to achieve considerable improvements in product design. It has recently been developed as a tool for use in construction projects (see Figure 23).

At first sight, the tool is complex in that it has six parts. However, it only requires an understanding of the principles of matrix analysis with the addition of quality and benchmark criteria (see Figure 24). The other advantage is that QFD carries forward, through the key stages of design development, the initial project values and criteria in a way that ensures everyone is consistently working to the same values. In this way there is little dispute, reinvention or interpretation of the initial client values at any stage in the project, thus increasing the efficiency of the design process. It is claimed that QFD can halve the time and effort of the design process because it enables consistency and the removal of ambiguity. The ‘rooms’ in the house of quality are as follows.

䊉 Room 1: The primary objective – The client must state clearly the primary objective of the project. This needs to be a brief statement that includes the key contribution that this project is intended to achieve.

䊉 Room 2: The whats – The client’s objectives are subdivided into ways that the overall objective can be satisfied in the same way that the value hierarchy is broken down. The requirement is that all of the issues, including those not normally stated such as robust structure, are also stated such that there are no areas missing. Each requirement in the list is then ranked for its importance.

Fig. 22. The VM decision matrix.

Requirements Importance

rating Comparative project analysis Project

Project Z Project Z A B C D

1 2 4

1 2 1

3 2 1

5

2

1

3

4 4 4 5

1 2 2

2

1

3

5 1 What No 1

What No 2

What No 3

What No 4

What No 5

Rating

1 2 3 4 5

Highest score Poor Good Highest

4

2

3

2

5

Fig. 23. QFD software for the briefing process.

Fig. 24. A benchmarking approach within QFD.

䊉 Room 3: The hows – A list of all of the ways of satisfying the whats is recorded across the top of the matrix.

䊉 Room 4: The relationship matrix – All of the hows are assessed against each of the whats on a sliding scale: 0 for no link, 3 for a partial satisfaction, and 9 for a strong satisfaction.

䊉 Room 5: Technical assessment – The scores for the hows are totalled, from which the most satisfactory method of solving the particular requirement can be seen. This can be given as an absolute score or a relative score.

䊉 Room 6: Competitor analysis – Quality is a subjective issue. Building design is more difficult than product design because a building cannot be put on the table, analysed and dissected like a consumer product. However, this section of the QFD approach helps overcome this basic limitation of a normal brief, where the quality is not quantified and is delivered largely through a faith in the lead architect and key designers’ ability based on past performance. QFD requires that the importance rating be set against an assessment of competitors’ performance. This statement first requires that competitors’

products are assessed, and secondly, a decision made as to whether the new product is to meet or exceed competitors’ products. Naturally this requires considerable research Fig. 25. A completed QFD matrix of a design element.

and evaluation, but this is the secret of this technique because every aspect of the new product has a measurable and visual goal. To apply this to buildings requires a similar research and evaluation of previously constructed buildings and a decision as to whether the new building is to be built to the same standards and quality or to a different standard.

Rooms 1–5 constitute a basic approach to the use of QFD. Room 6 involves benchmarking against external organizations, which requires significant data collection and analysis. This may be uneconomic for a one-off project.

Not everything can be dealt with in one matrix, particularly something as complex as all the requirements for a building. In practice, the QFD approach can operate at three levels within the briefing process. At the highest level it could set the detail for the functional brief. The systems that would satisfy the hows would form the whats for the next stage of system design during the development of the concept and scheme. The final stage would be detail design where the subsystems that satisfy the hows become the whats of the fine level solutions. Because of the consistency of the method, which links at all levels back to the satisfaction of the client’s real priorities, this is a very powerful way of recording the briefing process and the value judgements made within the process. Again, the judgements have to be made through consensus of all involved in the discussions.

To help in the process of deciding and selecting the most profitable ways of solving the whats, a correlation matrix is established that assesses the compatibility of the hows with each other. It is no good selecting a series of solutions from the hows if they will not work with one another. The correlation matrix is a simple approach to help avoid such incompatibilities.

By quantifying the basic briefing decisions the client and the whole team are aware of all of the implications in cost, production, and final quality of every aspect of the building from the beginning.