This principle means that people with diverse abilities can use the space. This includes both the main purpose of the space (for example, if the space is theater, there needs to be a barrier-free entrance) and necessary accompanying spaces (for the theater, a bathroom and concessions if present - for a home: kitchen, bathroom, bedroom, and living space). A general rule of thumb is that you don’t want any potential occupant to be unable to access any area, no matter their size or abilities.
This principle has to do with the way that different people approach various tasks in the space. Are the controls easy to operate? Are they in an easy reach range? Are there different options for people of different heights? ADA compliant counter height is 32-34” to accommodate wheelchair users, but universal design would recommend multiple counter heights to accommodate a range of users from children to very tall adults.
Similar to the 2nd principle, this principle advocates for the easiest possible operability - but while the 2nd principle deals with the physical labor of operability, the 3rd principle focuses on the mental labor. Object controls should be easy to understand. Instructions, when necessary, should be clear and simple. Language barriers for people who speak a different language and all those, including young children, who cannot read, should be accounted for - intuitive pictures and symbols should be used when possible.
This principle highlights what measures are needed for people of varying abilities to be safe. Clearly outlined, accessible egress falls into this category, but so does a simple baby gate in front of a stairway. This principle is best described through examples, so here are a few more:
- High levels of value contrast between vertical surfaces for those with low depth perception (value contrast as opposed to simple color contrast to include those with color blindness)
- Textured transitions and thresholds for those with low or no vision - think of the “dots” at sidewalk corners that can be felt through shoes or with a cane
- Alarms that use flashing lights as well as sound for those who are deaf
- Panic bars on exit doors that can be opened by leaning against them, rather than requiring any motor skill
Another safety-oriented principle, the 5th principal speaks to the completion of specific tasks in the space, rather than generalized movement through it. Add as much additional time/additional opportunities to keep occupants safe or correct a mistake into your design. For example, soft close drawer glides give someone additional time to move their hands out of the way. Machines that utilize confirmation screens gives someone an additional opportunity to correct their mistake if they made the wrong selection. Outlet covers and child-safe locks could also fall into this category, and a GFCI receptacle, which is fail-safed by definition, certainly does.
To achieve this principle, consider how you can optimize the energy usage of the occupants. Controls like faucets and switches should be in an easy reach range. Regularly used items should be located at heights that do not require bending or stretching. Hardware should be easily graspable and sensors should be used where possible. The varying counter heights I mentioned in the 2nd principle are another good example of reducing physical effort - tasks should be able to be performed in a neutral, comfortable posture.
This principle includes both ergonomics and accessible clearances. This is one area where ADA guidelines will be very helpful in determining the amount of space required for various mobility devices in each application. Going beyond ADA, however, accessible spaces are not merely checkboxes here but central focuses of the design. This goes for your means of egress as well: accessible entrances, corridors, and elevators should not be relegated to the side but at least as visible if not more so than routes unusable by those with mobility devices. To briefly touch on ergonomics, the concept of multiple heights/scale applies to seating as well as work surfaces. Make sure to account for a variety of sizes of people in your furniture and your equipment (bathroom fixtures, etc.).
These are the seven principles of Universal Design. While this is only a brief summary, I hope you are able to see the underlying philosophy: that a good design should intentionally include everyone, and make everyone’s functions within the space easier. Karel Dollekens famously said, "People aren't disabled. The environment they live in is." When it comes to our work as interior designers, we have a lot of control over exactly how disabled a person is in our built environments, and I believe it is our call to set up occupants to fully use and thrive in our spaces.