I have already blogged on the topic of design principles: how to get good ones; more about design principles.  But I was stimulated by some questions from Hans-Christian Grung-Olsen.

Before I comment, let me clarify what I mean by “design principles”.   This is a jargon phrase referring to statements (usually single sentences) that a design team creates (or sometimes they are provided by the “client”) that define the most important guiding thoughts for the design work.  Imagine that you are redesigning your kitchen.  What would be the most important guiding statements that you might give to the kitchen designer?  “I want a light, bright kitchen that makes me want to jump out of bed for breakfast”.  “The design must enable us to have six people round the table”.  “The design must have an aisle near the cooker for preparing food and laying out dishes”. “Work surfaces should be xx inches high”.  “There should be two sinks, under the West window”.

As you think about these statements, you can see that some of them are very specific – “xx inches high”, while some are broader, allowing more flexibility for the designer to find a creative solution – “light and bright”.  Some design principles are about big structural choices “an isle near the cooker”, others are about minutiae “at least one power point with a slot I can use to charge my mobile phone”.

One question that Hans-Christian asked is about how to deal with all these different kinds of guiding statements.

Try to keep the number of statements (for each level of design work) to less than 10.  Three is often better than 23.  This is because the human mind finds it hard to be influenced by more than 6 or 7 thoughts at the same time.  Hence, if you want the designer to do good work, don’t given him or her more than six or seven thoughts at a time.  Additional statements can be added as the design work progresses to lower levels of detail. Bring in the statement about electric plugs, when the electrician is making choices about what plugs to place in the wall.  Bring in the statement about the height of work surfaces when the designer is working on the heights of work surfaces.

The first level of design is usually architectural or structural, so your first set of design statements should be aimed at giving architectural guidance.  Here, you can get the designer to help.  “Is this statement useful to you, at this stage of your design work, or is it too much detail or too constraining or too vague?”  Often the designer will respond “It feels too constraining.  Can we take the thought up a level?  You are saying you want an aisle near the cooker, but I am hearing that what you really need is somewhere to prepare food and lay out dishes.  If I come up with a design that fulfils this need, but does not involve an isle, would that be OK?” “You say you want two sinks under the West window.  How important is two sinks? How important is ‘under a window’?  Does it have to be the West window, why?”  So, you or the designer should probe every statement for its relevance to the design work that is being done now, and for the nature of the guidance that is contained in the statement.

When this process still leads to 20 statements, the designer should demand some forced ranking.  “Which are the most important 10?” or “If I have to make compromises, which of these would you be prepared to compromise in order to ensure the others are fully met.”

The designer then goes away and does a first draft or some options.  If the first draft is acceptable, the designer can then start working on the next level of detail: the positioning of lights, the material used for surfaces, the layout of cupboards or the positioning of electrical equipment. 

At this point the designer will want more guidance: statements that define requirements or preferences for this next level of detail.  There are often frustrations as these lower level design requirements become clear.  “I wish you had told me earlier that having the dishwasher near the plate cupboard is important to you. This probably means we should move the table closer to the door, and this means I will need to redesign the shape of the work surface”.  The lower-level requirements can sometimes turn out to influence higher-level design choices, causing some iteration and rework.  But this is a cost worth paying, for the benefit of having a manageable number of statements at the higher level. 

Hans-Christian also asked about design requirements that feel as though they are not specific to the design work that you are doing, but could have an influence.  For example, “I don’t want the kitchen to get too hot in summer” or “We should think about the impact on the environment” or “We might have grandchildren in the future”.  These kinds of statements should not be included in the 5-7 most influential design principles.  But there is no harm in thinking about them once a design has been developed: “are there any adjustments to this design that we might want to make because of our concern for the environment or because our daughter is getting married next year?”

Using design principles in design work is an art not a science.  There are two thoughts that will help you as you develop your approach: first, keep the number down (below 10); second, make sure each design principle is relevant to the level of the design work that is being done next.  And, of course, use some of the techniques described in my earlier blog for ensuring you have good quality statements.