The information gained as a result of the two user studies was used to further develop the requirements for the heat pump. Rather than developing a more complex tree, the information was used to develop specification statements. Each of the final requirements in the requirement tree (the boxes lowest on each branch)
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formed a specification statement. A classification was then assigned to each of the specifications, indicating whether the product ‘must’, ‘should’ or ‘could’ address the specification. Pahl and Beitz (1984) state the importance of giving requirements with specific terms and quantifiable where possible as well as the need to prioritise requirements in relation to importance. Each specification was then explained in more detail, where appropriate, with justification given from the data collected.
Finally the author identified whether the specification had been identified through literature, interviews with technology developers or data collected from users. Pahl and Beitz (1984) suggest that recording where the requirement originates from is a useful practice, particularly when the requirement may be challenged or changed.
The specifications are presented in full in Appendix I. They remain organised in the product lifecycle stages as shown by the examples in Figure 42. These specifications could form part of the product design specification, which is a conclusion to the task clarification stage of a typical engineering design process and is necessary before conceptual design takes place.
Figure 42: Example requirements within the product lifecycle
Information collated about the requirements from the technology developers and users was then used to add more information to each specification, along with grading them according to their level of importance. At this stage, a small number of specifications were either removed or combined whilst in others, wording was improved to ensure the specification could be easily understood. The specifications
Purchase • e.g. The heat pump should not cost more than x 1.5 the cost of a standard boiler
Installation
• e.g. The heat pump must be less then 1.7m (H) x 1.49m (W) x 1.2m (H)
Use • e.g. The heat pump should provide water up to 55̊°C
Removal &
Disposal
• e.g.The heat pump must be safe to remove
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were intended to be of use to the technology developer without a UCD practitioner on hand to explain further, therefore clear wording was important. Figure 43 below gives an example of a specification and identifies the information included; all of the specifications are displayed in this format.
Figure 43: Requirement explanation diagram
As shown in this example, there are three levels of detail given. The first provides the basic information needed to follow the specification, the second expands on this and provides some rationale for the specification, whilst the third provides more detailed reasoning for the specification and where relevant, findings from user research.
Results show how the comments from householders could be translated into a format that engineers could use within their technology development processes.
Through the provision of requirements in a form familiar to them (as design specifications), the technology developers in the project were able to understand how the collection of qualitative data could inform the design of their products within the context of their engineering driven product development process. This was illustrated by one project partner who commented:
“Interacting with you at this early stage of development of our technologies is a good thing....From my experience in design and manufacturing, there is a tendency
for technologists to completely ignore what the consumer thinks and just focus on the products”.
Expanded requirement (where necessary)
Requirement number
Evidence and further explanation (where required)
Level of importance Requirement text Requirement origin
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In Table 19 below, a sample of the final list of specifications have been given to demonstrate the output of this activity. The full list of requirements can be found in Appendix I.
Table 19: Sample of UCD specifications
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6.7 Critique and limitations to the study & potential improvements
The process followed to develop the requirement trees and specifications was effective. However, there were some limitations to the approach. Due to the way the research project was structured and the previous experience of the technology developers, some conceptual design had already begun for the heat pumps in this case example. In an ideal scenario, requirement trees and UCD specifications would be produced before this stage and would then be iterated through the development process.Once developed, the requirement trees contained a significant amount of information. This was difficult to manipulate in the ‘tree’ form. The author found that by inserting the data into Microsoft Excel (2010a) it was easier to manipulate and to add additional requirements, although it did then lose the ‘tree like’
structure. There is some scope for the development of a software tool to help with this process and the translation from requirements into specifications.
This way of accumulating and developing requirements and translating them into specifications was very successful and enabled communication and effective working with the technology developer. This is demonstrated in part through the changes made to the heat pump design as a result of conversations that took place around the requirements and specifications. For example, the relocation of the heat pump extractor and the development of a split system design.
The author was acutely aware of the tension caused by needing to gather specific user requirements for a diverse range of technologies whilst still seeking to understand how the design of these technologies could be refined through understanding of everyday practices and routines. Analysis of the data from householders allowed the comments made by participants to be collated and translated into implications and then requirements. The conversion of the data from householders’ comments into requirement trees provided a structured and succinct approach to reporting the findings in a format that was in some way familiar (with the use of constraints and requirements) and useful to the technology developers. By structuring aspects of the data collection around the requirement
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trees, it was also possible to identify questions that would specifically address the needs of the technology developers. The requirement trees were well received by the technology developers and enabled large quantities of qualitative information to be represented in a way that is meaningful within the context of an engineering‐
driven product development process. The method also enabled clear communication of how the objectives had been developed thus far.
There were certain limitations with this method relating to the stage of development of the technologies in question. In some cases, technology developers were unable to discuss requirements relating to the final product design, as they were too early in their design process to consider it. In addition, though it was intended to only provide constraints within the specifications, this was not always possible due to the development stage of the technology and therefore more ill‐
defined specifications were included. This could suggest a need for smaller, partial requirement trees to be produced at different intervals throughout the process, when appropriate for the stage of the product development, meaning more specific constraints could be added at later stages. This would however mean that those requirements not discussed until later stages in the design may incur costly changes. This supports the need for an iterative process where repeated contact is required between the UCD practitioner and the technology developer. In this research, the author endeavoured to perform this role. Regular interaction and communication between the UCD practitioner and technology developers enables an important relationship building process and for frequent changes/updates to be made.
As the technologies on which this research is focussed were in the embodiment stage of the design process, there was no option of presenting householders with a physical product to evaluate or offer their opinions on. Whilst this limited the amount of feedback householders were able to give, this was an expected consequence of studying technologies within a research and development project.
In order to reduce this limitation and based on information obtained from the pilot study, technology information cards were given to participants in the second home visit. These gave participants a brief background to the technologies and a
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reference point for the questions that followed, as suggested by Gilmore et al (1999), ensuring that the householders had enough information to understand the technology and therefore answer questions around its use (Gulliksen, 1999). The majority of participants found this information informative and interesting and were then able to offer thoughts on how the technology would work within their home.
In order for detailed discussion to be carried out with the technology developer, it was of great advantage for the UCD practitioner to have an understanding of the technology being developed. Not only did this enable discussion with the technology developer, but it also helped to have some understanding when designing questions relating to the technology and to answer any basic questions from users. In order to develop this understanding, the author investigated different sources of information such as heat pump manufacturer literature and online forums to approach the technology from both a developer and user perspective.
After the completion of the domestic water study, related data has since been reported by the Unilever (2011) which built on a study by the Energy Saving Trust (2008b). Whilst these studies report similar findings, they do not invalidate the results of the study reported in this chapter. The Unilever study (2011) used shower sensors attached to the shower plumbing to investigate water use, whilst the EST (2008b) used a regression model based on the number of occupants in a household.
These studies provided specific data relating to actual water usage, which the discount method used in this research was not able to do. However, as discussed, this study did not aim to provide accurate measurements of water usage and rather provided an insight into the practices that occur within a selection of households.
Therefore, the use of the discount methodology was able to provide technology developers with sufficient information at this stage. A significant part of this process was in relationship building with the technology developers, to provide them with information quickly, when needed. In contrast, the EST (2008b) and Unilever (2011) studies provided evidence of domestic water use data that was developed for a very different purpose to the study described here. These studies aimed to provide
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accurate data that could be compared with current assumptions. These data are therefore more reliable and replicable and may be useful to the technology developers at a later stage in their design process when more accurate information is required.
The methods used in homes were very effective for collecting the information required. The self‐reporting method meant that householders could record their practices with very little disturbance, as for example, fitting flow meters would have taken considerable time and would have discouraged participation because of the need for plumbing work. However, as a consequence of this, there is no certainty that all of the uses of hot water over the study period were recorded.
The study methods were designed to encourage the whole household to be involved with the data collection. Participants were provided with colourful
‘reminders’ to place around the house, and it was clear from the data sheets that children in the households had been able to record their own information. Informal feedback from participants suggested that the ‘reminders’ encouraged participation and regular data recording. The waterproof pens provided were problematic to use when the record sheets became damp (despite being made from waterproof paper), therefore in future studies, record sheets should be laminated to prevent any loss of information in this way.
There were a small number of other questions that were initially posed by the developer, however they were outside of the remit of the project and this research and would have required significant instrumentation and time, meaning increased disruption to householders. However, the combined approach of literature, discussion with technologists and a holistic research study ensured the presence of the user’s voice in the elicitation stage of the requirements and improved communication and relationship between the technology developers and the UCD practitioner.
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6.8 Chapter summary
This chapter aimed to find an appropriate method for communicating the needs of the user to technology developers by translating this data into a useable format.
The use of the requirement tree method enabled the collation and communication of this information in a structured and organised way.
The chapter details two studies which collected information from users, data from which were then used to enhance and develop the requirement tree and user centred design specifications. The technology developers were satisfied with the data collected, including the level of detail included and the speed at which results were delivered.
Cross (2008) highlights how requirement trees are beneficial, not just in their outcome, but in the process of developing them. In this research, changes were made to the technology design whist the process was still being carried out and the method not only improved the relationship between the technology developer and the UCD practitioner, but also helped to further the UCD practitioner’s understanding and knowledge of the technology. The study detailed here identifies how a UCD approach can be used successfully in different ways in order to provide approximate figures for early design stages.
The next chapter evaluates the impact of UCD both in the methods discussed in this chapter and the other work within this thesis.
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