Most of us are familiar with the universal remote control. This device is supposed to aid with the growing number of hand held remotes that sprout each time we purchase a new piece of home entertainment equipment. The DVD, TV, CD, receiver, and VCR are somewhat under control with various universal remotes that reduce the control dilemma to (hopefully) one single device. That one device will have upwards of 50 buttons and usually requires a manual close by. Usability of the universal remote control is directly determined by its interface engineering.

Today’s homes are a much richer environment with sophisticated automation systems, elaborate high fidelity audio and theatre systems, lighting control, and home based personal computers. The problem of gaining simplified home owner control of these complex systems is a problem on a much larger scale. The issue with designing a good control interface is a matter of blending physical design (bezel, housing, etc) with digital design (software buttons, graphics, etc).

Effective control in the home demands masterful interface design. The topic of human interface design is expansive and complex. Even in the focused realm of home controls the topic is too large to make meaningful conclusions in a single article. For that reason, this article will focus on LCD based displays and even focus a bit more on touch screen control systems.

Human Interface

The purpose of installing home control, home audio, and broadband is to enrich the living environment. For some, enriching the environment truly is adding a new gadget; however, the excitement of a new gadget wears very thin if the purchaser has to constantly refer to the instruction manual or if the device is simply awkward to use. Poor interface design causes disuse and dissatisfaction.

The person using the device must be first and foremost in the psyche of designer. The experience must also be noted as a fusion of a physical platform (the bezel, buttons, LEDs, etc) and a software platform (graphics, sound, text). The user experience must presented in an informative interface to reduce support calls, a consistent interface to integrate disparate operations, and an engaging interface to invite use. This combination will reduce support costs and raise revenues through additional sales.

Figure 1- CorAccess Companion 6. Fusion of physical and digital design.

The goal is to humanize the complex environment that is growing in the home. The more human the approach to design the more accepted the solution becomes. The more accepted the solution the greater the usage, utility and ultimately value.

Physical Interface

The software interface tends to be the first concern of design; however, the best software will never overcome a poor physical design. The physical interface is the tangible component of the design that houses the digital portion and is often an extension of the digital interface.

One example is the design of wireless webtablets. This may seem to be a fairly straightforward task of enclosing an LCD in a mechanical housing. But many considerations from color to texture, to weight, to button placement, to expansion slot placement, to ruggedization must be balanced to find the correct mix. In a webtablet design there is considerable thought around the weight of the device. First thought would be to make the device as light as possible, but interestingly, in consumer testing a device that is too light feels cheap. Furthermore, weight must be distributed correctly for right and left handed use.

The end user is not the only party affected by physical design. The installers appreciate when products allow them to accomplish their task efficiently. If installers are burdened by poor physical design there is friction that will reduce sales by their un-willingness to install and increased cost due to time required. Using a design that is familiar (e.g. standard gang boxes), using parts that installers are already likely to have (e.g. CAT5, DB9), and making setup straightforward will reduce unneeded complications.

The job of physical design is the realm of industrial designers who provide the look, feel and function while the mechanical engineers provide the technical realization of industrial design. Strong industrial design alongside strong mechanical engineering is a winning formula for the physical design.

Figure 2 – Design concepts for the CorAccess Companion. Physical design is about aesthetics and utility.

Form truly follows function. The physical aspects of a home control system are not trivial and must be carefully scrutinized to build an optimal platform. Considerations for installers and home owner are critical to the success of the platform. Done well, the physical interface enhances the software interface and provides a true centerpiece of a home.

Digital Interface

The digital interface is the software that produces the graphics, sounds, and text displayed on the screen. The digital interface provides the main control features in an LCD touch screen. Graphics, color, sound, and text are blended together to form the controls for CD playback, security system arming, light dimming or the many other functions of a sophisticated home control system.

The thoughts that should be driving the designers work should be centered on three concepts: predictable, engaging and informative. A predictable interface lets the end user understand what to expect from the device. An engaging interface draws the user into the device and invites them to explore the many features present. An informative interface provides easily understood context for the features that are presented. All three design considerations must be carefully adhered to from conceptual design to production.

The tools to produce a predictable, engaging, informative digital interface are workflow, layout, color, graphics, text, and in some cases sound. There are plenty of horror stories about bad graphical user interface design (I would recommend as a great place to review some), so a review here of what constitutes poor design is not necessary. It is more important here to discuss the tools and how they affect the triad of a successful design.

Figure 3 – Note the layout and graphics. Figure 4 – A simple layout change and adjusted graphics greatly improve the usability.

Workflow and Layout

Workflow and layout are companion design considerations. Workflow describes how each page of the user interface drives navigation through the system. Layout defines how elements are placed on each page.

Good workflow and layout drive the predictability of the system. Together they define the organization of the user experience. Workflow is an exercise in organizing common components together, balancing a need to reduce user interaction. Commonly used features should be readily accessible and should not require navigation through several screens.


It is very easy to try and use a full palette of 24 million (or more) colors. If you have them available, why not use them? Thoughtful use of color and reserving use of particular colors provides the grounds for an engaging interface. Over use of color will hide the functionality of the system. Under use of color will reduce pizzazz and leave a user with a hum-drum perception of the product.

A general color theme should be decided and used consistently throughout the design. Particular colors should be reserved to highlight functionality and the informative nature of the interface. An example is red for armed, green for unarmed, yellow for trouble. If red is used indiscriminately then the effect of red for determining arming status is drastically reduced.

High contrast in color choice is also important. This aids with quick reading of the display and also aids those that are less attune to color discrimination. Figure 5 illustrates two different uses of color. The top image has a reduced color palette but this is at the expense of readability. The bottom image uses color effectively to convey the company image.
Figure 5 The top image compared to the bottom image shows a contrast in use of color.


Just as with color, use of graphics can become an eyesore. Graphics should be used to enhance the readability of the interface. Graphics can be used in lieu of text when a picture can convey the message more clearly; however, do not fall into a trap of using graphics for every button, widget or background. Graphics should blend into the interface and not override it.


Use of text is determined by command of the spoken language. Text is the primary feedback and indicator to the end user. Poorly written text can lead to confusion and unnecessary support calls.

Simple changes to text on a screen can alleviate possible misunderstanding and frustration. An example is the following titles for a security arming screen. The titles are for a page in which the system is in countdown for final arming of the home security system.

System is Armed. Ready to Exit.

Arming System: Set to “Stay”

The top title gives the impression that the house is secure. Well if this was the case, then why is there a countdown timer? The second title correctly identifies that the system is not quite secure and provides further information that the mode has been set to “Stay”.

Another topic with good use of text is combining text and graphics. It is good practice to provide some textual content even when a graphic seems to be conveying the message. Clarity is the name of the game, and good use of text often provides the fine tuning required for clarity. Figure 6 shows two different progress bars. The first bar shows a color bar almost halfway across. The second bar has the same content but a simple indication of the actual percentage leaves no question as to the actual progress.

Figure 6 Graphical progress bar Progress bar indicating percentage complete.

Many home control systems today are attempting to display internet content. This merges the PC based world of internet browsing with the consumer world of electronic appliances (aptly named internet appliances). The use of internet content could be as simple as providing a web browser in the device or it could be reformatting the content to fit the form and function. One example is from a currently shipping product that provides headline news stories to a wall mounted 320X240 display. The screen size prohibits the use of a standard 800X600 webpage, so the content is reformatted for the display. Unfortunately the designed result is a list of headlines that are functionally useless because there is no context along with the headlines:
Stock Market Up March 18, 2002 4:00pm: Stock Market Up
Dow Takes a Hit March 19, 2002 4:00pm: Dow Takes a Hit
Example headlines from a wall mounted internet appliance. Without dates of the headlines who knows what is actually happening Simply adding a date and time conveys the true story and makes the screen useable.


Lutron Electronics
Adding sound to an interface should be done once graphics, text, color, workflow, and layout have been completed. Sound provides feedback that a button has been pressed or a task has completed. Sound can also be used to enhance the engaging factor of the product. Sounds should be somewhat subtle and natural: Button presses should be simple clicks or beeps, page changes should be simple scrapes. Remember to always provide a means for users to turn the feedback sounds off.
Digital interface design is a thoughtful application of workflow, color, graphics, text and sound. With these five factors to balance it takes time and diligent review to produce an optimal solution. The goal is to produce a digital experience that is predictable, engaging, and informative.

Letting Go

Remember that the control system interface occupies valuable and prominent real estate in a home. They are placed in important positions: by the front door, on the coffee table, in the main hallway, etc. There is limited wall space and the device should be an invited part of the home and not a distraction. If careful attention is paid to the physical and digital interfaces, the system will be used more often, and hopefully shown to visitors who will want the same system installed in their home.

About the Author

Mr. Wimsatt is the VP of Engineering for Coraccess Systems in Golden, Colorado. CorAccess ( ) is developing next generation software and hardware platforms for home control and automation. Mr. Wimsatt has an extensive background in design engineering from past positions at Apple Computer, IBM, Oracle and Qubit Technology. He can be reached via email at