Architects are accustomed to using rules of thumb in the early stages of design: daylight penetration equals 2 times the window height; East-West orientation is better than North-South; office buildings are always internally loaded.
We know that these approximations frequently lead in the wrong direction because of normal variations in building use, context, and building form. (For instance, see this article by Ara Massey of SLATERPAULL Architects, or our whitepaper, Four Rules of Thumb That Can Lead You Astray.) That’s a strong case for using real performance analysis to inform design decisions.
However, sometimes the rules of thumb are correct. When performance analysis simply confirms your intuition, it’s tempting to think that it provided no value. But here are three things that analysis can do that even the best rules of thumb can’t:
Perhaps a rule of thumb can tell you that the optimal shading length for your building is 4 feet. But how much benefit does that shading provide for your specific design? And is it more beneficial than specifying better windows, or improving the insulation, or simply changing the shape of the glazing? Case in point: while trying to find optimum insulation levels, Sefaira customer Solid Green discovered that reflectivity was actually more important. That’s hard to discover from a rule of thumb.
At their best (i.e., when they work) rules of thumb can guide you toward the best case scenario. But what happens when constraints of program, site, or user experience lead you in a different direction? Rules of thumb say you should avoid East and West glazing. But how bad would it be to include west-facing glazing to take advantage of a great view? And could the negative consequences be avoided by adding shading or better windows? These questions of tradeoffs are easily answered with performance analysis, but difficult to approximate with rules of thumb.
Even when rules of thumb are correct, you still need to sell your design — communicate the benefits of your decisions to your client, the building owner, and other stakeholders. Real numbers can help you construct a solid argument, clearly articulate costs and benefits, and have more directed and constructive conversations. When we asked our customers about the benefits of Sefaira, many told us that it helped them save time discussing (or justifying) design decisions, and helped them to create more compelling arguments for bids and proposals.
These added benefits don’t have to come at a steep cost. Performance analysis can be a seamless part of the design process, and can be deployed in an incremental, lightweight way. When compared to the best rules of thumb, analysis allows you to make even better design decisions, and to establish the value of these decisions with your clients, prospects, and colleagues.