The BAS Industry & Graphics End users generally judge the BAS vendors' product through the capabilities of the graphics engine.

Nirosha Munasinghe MBusIT BSc BE (Hons) (Melb) Product Development Manager, Open General  Contributing Editor

Integrated engineering environment, graphical programming and innovative hardware are a common set of products in the BAS industry. The common functionality of these products is for an engineer to complete the project to specification. The hardware is in a plant room or under the roof line never to be seen by the end user. The programming environment may be used a few times through the life cycle of the building to re-tune or re-commission the building.  Then, what tool is most used throughout the lifecycle of the building? Graphics. It is clearly evident that the graphical display panels generated to illustrate the operation and behavior of the mechanical components of a building is most the exposed to the end user. Graphic display panels have evolved over the last two years as energy reporting becomes mandatory to achieve ratings.  The graphics are the central point of access for the end user to expose the invisible and make it visible. In busy facilities such as hotels and universities, graphics are used to navigate the building almost 365 days, 24/7. Therefore, end users generally judge the BAS vendors' product through the capabilities of the graphics engine.  This article examines the human perceptions and useability factors that should be applied when designing an interactive display panel. 

BAS graphical display panel can be classified as a human computer interaction (HCI).  Every day we interact with graphical user interfaces, from the PC, mobile phone to entertainment systems.   The key component of these products is the graphical user interface. A product can have a solid backend but if it contains an average user interface, the product will be rated poorly.  The ultimate goal in designing an interactive graphical system is for end user to use it effectively to achieve efficiency, without stress. The two key principles when designing a user interface is to know your end user and usability.

Qualifying the end user not only involves investigating the capabilities and skill sets but also general human behavior and perception concepts. When using a graphical user interface, the eye, brain and memory play a key role in driving the system. The human eye and brain is pivotal to interpreting color characteristics of a graphic. The cerebral cortex, the outermost to the cerebrum to the brain plays a key role in memory, attention and perceptual awareness.  About 60% of the cerebral cortex of the brain is involved with vision. Some common characteristics of color vision in graphics follows:

• Blue alone tends to be poorly perceived
  
• Greatest color discrimination is in the green to yellow range
• Color blindness: red-green, blue-yellow, achromatic
• Use familiar color codings, e.g. red for stop or alarm, green for go
• Avoid use of extreme changes in hue in adjacent high-saturation colors
• For item differentiation, use maximum of five colors to match the user’s short term memory capacity
  

Human memory also plays a key role when using a graphical user interface.  Memory can be classified into long and short term. Long term memory is lifelong with infinite capacity. Short term memory lasts for a finite duration. For example, remembering a few steps of an unfamiliar process.  Memory can be also be classified into the following categories:

Human computer interaction depends on sensory and procedural long term memory.  When driving an unfamiliar user interface, the general  process of the brain is to use the long term memory to ask, have I used a similar user interface before? by observing it using sight as a sensor memory; and then using procedural memory to drive the user interface similar to past used actions. For example if there is a button on the screen, most would know that a click will navigate to the indicated content. In a BAS context, if a system tree structure is observed, most would know from past procedural memory that it displays the BAS network with respective controllers.

What are some human computer interaction concepts that can be used by user interface designers to synergize with general human perceptions?

The second key principle under consideration when designing a user interface is the usability of the system.  Usability factors in an interactive system follow:

[an error occurred while processing this directive] The usability factors need to be analyzed after the development of a graphical user interface. Some common techniques used to analyze usability follow:

• Cognitive Walkthrough:  Step through the designed user interface with the sequence of interface actions required to complete each task. As you walk through each step ask:

1. Will the correct action be made sufficiently evident to the user?
2. Will the user connect to the correct action’s description with what they are trying to do?
3. Will the user interpret the system’s response to the chosen action correctly? Will the user know if they have made a right or wrong choice?

• Prototype: Design the master layout of the user interface and let the end user evaluate for feedback.
• Interviews:  After the end user has used the interface, organise a short interview with user to obtain feedback of the system.
• Questionnaires: Send a questionnaire to the end user to obtain feedback. It is less costly per person compared to interviews and can potentially obtain data from a larger number of people. Typical questions should include, multiple choice, tick boxes, rating on scale, short text and open ended free text comments.
  
• Observation:  Observe the user in action. It can be a person observing the actions without influencing performance activities or recording the screen activity.
  

It becomes almost impossible to perform usability analysis in the BAS industry due to strict time pressures and due to graphical displays being one of the last components to be completed in a project. However, solid graphical user interface generally leads to satisfied customers, which will benefit the BAS industry's value chain. Therefore, if an investment is made to properly design a graphical panel display for one customer with human perception and usability concepts applied during the design phase, the solution can be duplicated on other similar projects.  It is becoming very important for BAS vendors to make sure their system integrators are designing attractive and user friendly graphical panels as they becomes the show case of the vendor’s entire product line.

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