Usability is one of the key ATTs of software design. There is a relationship between it and flexibil- ity. The relationship is based on providing simplicity to make the designed facility usable and at the same time flexible in incorporating new EU needs as they emerge.
Each design should adapt to the surrounding area to achieve EU comfort. One of the design roles that should be considered is to create the design that is easy to use. The EU can be the owner of the space, worker, and resident and maintenance personnel. Thus the need to design for usability is one of the major issues which should be considered. Before starting the discussion in terms of passive design for usability, the meaning of usability should be understood as follows:
ISO 9241-11 (1998) defines usability as “A product can be used by specified users to achieve spec-
ified goals with effectiveness, efficiency and satisfaction in a specified context of use”. This definition is centred on three angles, each of which touches EUs directly. In terms of effectiveness, this is de- fined as “Accuracy and completeness with which users achieve specified goals”. This refers to the
ability of users to complete their functions. Efficiency is defined as “Resources expended in relation
to the accuracy and completeness with which users achieve goals” - what is the effort demanded to achieve and complete the tasks. Satisfaction is “Freedom from discomfort and positive attitudes to- wards the use of the product”. This gives an indicator about the EUs’ feelings when they use the
design.
“The definition of usability is traditionally associated with these five usability attributes: learna- bility, efficiency, memorability, errors and satisfaction” (Wilson, 2009). Learnability refers to some tasks which can be done by the system. Efficiency reflects on increasing the productivity of the EU based on the efficiency of the system. The third point (memorability) refers to the ease of remember- ing the system after a period of time by a casual U. Errors indicates how the designer is able to reduce the predicted errors in the system, as well as how to reduce the possible errors by the EU – and if an error happens, to what extent the system can be recovered to be as it was. Finally, satisfaction is how to please the EU when they use the system.
Bevan et al (1991) defined usability as “a function of the particular user or class of users being
studied, the task they perform, and environment in which they work”. This gives an indicator to under- stand the nature of the U and their function, on the one hand. On the other hand, it reflects the importance of understanding the type of the building and its components and functions in order to match EU functions with design ATTs. Eason (1988) defined usability as “the degree to which users
are able to use the system with the skills, knowledge, stereotypes and experience they can bring to bear”. In this research this key ATT is defined as: a set of attributes that relate to operability and com- pliance of passive design strategies to regulation standards and user operational efficiency. This ATT is composed from three main S-ATTs which will be described as follows:
4.4.1 Operability
This S-ATT has many measurements which should be applied in a PD space. Without these meas- urements the EU of the space will find it hard to use. Several of the measurements have been identified by various authors.
Lund (2001) stated that the location of equipment or service should be optimum to serve the EU. It should be adjacent to the EU and easy to use. Its placement should be optimised for the EU as well as simple to comprehend. This is not limited to adjustments; also, high capacity equipment and services should be selected. All of these ATTs should be considered with regard to colour and appearance in parallel with quality.
Nylåna (2005) claimed that the EU should have an opportunity to reorganise or redesign the space. It should be legitimate for them to do this function and operate without any effort, as well as to create the suitable space with an aesthetic appearance. The suitability of the space should cope with the local regulations. The designer should also consider the size of the human form. Nylåna (2005) has referred to the importance of considering human scale. This gives a clear indicator that the designers should
have a clear knowledge about the standard human scale to apply in PDS to enable the EU to operate their functions in the space. By considering the three dimensions of space to meet EUs’ scale, of course, means to avoid undersizing an area, which should be coupled with the current regulations and the suitable interior space size which can attract the EU to use it. Baker and Steemers (2000) claimed that any spaces can take the advantages of the surrounding environment (passive zone). The ideal ceil- ing in this zone will be twice the floor ceiling height or 5.5 metres. Also, they added an instance that the atrium can increase the ceiling height. This can have a clear impact on usable floor area.
Nylåna (2005), Jensø (2011) and Brown and Cole (2009) agreed about the importance of homoge- neous functions of spaces. The functions of the space can be assessed as to whether or not they are working well together. This cannot be without simplifying the design and considering the connections between the places in a way that will be clear for EUs and comprehendable to use; also, the designer should link between the aesthetics of the spaces or functions in a way that can be a magnet for the EU to use the space. Light House Sustainable Building Centre and Wimmers (2009) indicated that the ideal design should maximise usable space to the outside wall area. This will lead to operate the de- sign function whether this fulfils EU needs optimally or not. This will facilitate the EU to carry out their functions very easily.
The floor surface of the space should be easy to walk on. Mitchell (2011) confirms the need to avoid steep floor and steps. This will make the space easier to use as well as enabling EUs with differ- ent levels of ability to operate in it. The usable space can lead to avoiding any obstacle of the space function as well as meeting Health & Safety requirements’and simple to use at the same time. Part of usability is to consider appearance such as colour or kind of material in a way that motivates the EU to use the space. This should be done without any conflicts with any local organisation regulations.
Nylåna (2005) and Brown and Cole (2009) also point out that part of usability is to provide tech- nology and elements that are easy to use and which facilitate EU functions. This to some extent meets the aim of PDS which is to rely on environmental conditions instead of using mechanical elements, which of course, simplifies the design and elements. Simple technology can help the EU to compre- hend it easily. The selected technology should also be attractive, to motivate the EU to use it.
Brown and Cole (2009) point out the importance of reducing the need to use technology or con- trols. Also, they, eMi2 (2006) and Barlex (2006) declared that the element should be easy to control at the same time as the indoor environment. The need to control the indoor environment is due to the various changes EUs go through in terms of their skin to various climate changes. Hampton (2011) claimed that any PBD which does not satisfy the EU by providing usable controls can be classified as a failed design.
The best kind of control is a manual one; this will be ease to use and will not demand expertise or learning. The control methods should be simple and easy for the EU to access as well as to compre- hend. This will reflect on their operation when they use it, which is confirmed by Brown et al (2010) and Brown and Cole (2009), when they claimed that it was important to locate equipment controls
close to the EU and for the controls to be clear to them. Simplifying the design and appearance of the controls will directly achieve the usability requirement.
Both Nylåna (2005) and Blakstad et al (2008) point out that the space area should accommodate different EU needs. This means the designer should take into account several points regarding the number of EUs. In this case, EUs can be classified into three categories, as follows: fixed number (the actual user), variable number (visitor) and rare number (maintenance/technical). The designer should provide extra areas in the space to allow for changeable or rare EUs, to help them carry out their func- tion when they use the space. This kind of space that accommodates several kinds of EU can lead to motivate and attract EUs to use it. In addition, it will be easier for all of them to comprehend how to use it. Nylåna (2005) indicated that the spaces should be adjacent to each other. This is part and parcel of the legibility and operation of the space, which of course will enhance EU comprehension of the design when considering this adjacent space; otherwise, spreading the function can lead to confusing the EU and losing the usability of the space. Brown and Cole (2009) and Jensø (2011) referred to the ability of the EU to use features of space and elements easily as part of usability. Also, Mitchell (2011) and Jensø (2011) claimed that the area should be under the EU’s power to change it, more or less. This gives the EU the freedom to operate the space as they want. Blakstad et al (2008) declared usability can be applied through avoiding non-functional and narrow space at the space level, but at the whole building level part of usability is to consider the relationship between functions and spaces. eMi2 (2006) articulated that design space should be related to physical size of equipment.
Brown et al (2010) indicated that the space should respond to the EU ecologically. When the space meets the ecological points such as light or air, this will of course reflect on EU comfort which is a kind of design attractiveness. Natural lighting will make the space more visible, which of course, is legibility. This will enhance the role of the EU to comprehend the space, and will also add touches of beauty to the space through colour appearance and renewable air. This will reflect on the EU role to operate their function simply.
Code End User Factors References
CA1 Optimum position of service and passive element or equipment for operability
Lund (2001). CA2 Consider the dimensions of passive spaces to suit
human scale (avoiding undersize or oversize areas)
Nylåna (2005) CA3 Group homogeneous passive functions together for
efficient operability
Nylåna (2005), Jensø (2011) and Brown and Cole (2009)
CA4 Avoid slopes and steps of passive space floors Mitchell (2011) CA5 Incorporate passive design technologies which are
easy to operate by multiple users
Nylåna (2005) and Brown and Cole (2009) CA6 Accessible passive design controls for multiple
users
Brown and Cole (2009), eMi2 (2006), Barlex (2006), Brown et al (2010)
CA7 Design passive space that is well-suited for multi- user activities and capabilities
Nylåna (2005), Blakstad et al (2008), Brown and Cole (2009), Jensø (2011), Mitchell (2011), eMi2 (2006) CA8 Space to provide multi-user comfort (light, fresh
air, optimal temperature)
Brown et al (2010)
4.4.2 Human behaviour
The EU forms the backbone of usability as various authors confirm the need to focus on EU be- haviour and aspects to harness the equipment and spaces to meet their need. Rasila, Rothe and Kerosuo (2010) said part of usability is to consider seeing, smelling, hearing, feeling and sensing of users during designing for usability. These aspects should be enhanced when designing or selecting elements or equipment to facilitate the space for EU, which of course should be recognised by the de- signer. This helps the EU to comprehend the space usage easily. If this is considered by the designer, it will offer indoor comfort, which is part of design attractiveness.
Hansen et al (2005) said that achieving usability is to reduce EU feelings of stress. This is, of course, to help them to operate their function without any effort. As the EU’s mood can reflect on their performance the designer should recognise how to reduce the EU’s stress through providing the strat- egies that help them to perform their function easily. Also, the colour of the space and its finish, or the building’s shape can help to reduce EU stress without ignoring compliance with regulations.
Relating the EU to their culture and identity when designing the space can enhance usability (Blakstad Siri et al, 2008 and Hansen et al, 2005). Many people are obsessed with their identity which, when it is considered through designing the space, can enable them to carry out their function easily. For example, considering privacy in some societies can help the EU to operate the function easily. This will demand that the designer recognises the EU’s culture and understands how it works in order to provide an appropriate space for them. The building’s identity could be part of its attrac- tiveness and lead to make EUs enthusiasm and proud of it. This will be reflected in their productivity and attendance. Many regulations of countries, such as the UK, and organisations consider culture and identity in building styles.
Mitchell (2011), Brown et al (2010), Haron and Hamad (2011) and Hansen et al (2005) declared the importance to enhance health, life safety and well-being. If all of these EUFs are achieved, it will lead to increase the rate of usability through promotion of EU comfort and other factors. Well-being is part of attractiveness design, whereas health and safety can enhance the user operability when they are using the space. For this reason, the designer should be aware of the health and safety aspects for ful- filling EU needs. At the same time, they should learn how to apply safety aspects in the design in a way that will not be difficult for the user to determine. Usually safety of the space is part of an organi- sation’s regulations.
Code End User Factors References
CB1 Reduce user stress and feelings of frustration due to lack of space
Hansen et al (2005) CB2 Consider safety, health and physical well-
being needs for multiple users of passive buildings
Mitchell (2011), Brown et al (2010), Haron and Hamad (2011) and Hansen et al (2005)
CB3 Consider different sensing, smelling, hearing, feeling and seeing of users in passive space
design
CB4 Consider users’ cultural image, identity, life- style, psychological needs and perceptions in line with passive lighting, ventilation and thermal comfort strategies
Blakstad Siri et al (2008) and Hansen et al (2005).
Table 4-17: Passive design for Usability: Sub-Attribute: Human Behaviour