The first round of tools I built with AI were big: a mass timber designer, an acoustic ray tracer, an energy load calculator, a map of Christopher Alexander’s pattern language. Each one tries to do a lot. This fall, teaching building systems, I found myself building the opposite kind of tool: small, single-page instruments that each do one calculation, and do it in the open.
I’ve started calling them instruments rather than tools, because an instrument shows you a reading. It doesn’t make the decision for you.
The problem with the answer
Students are surrounded by software that returns a number. Drop a weather file into a plugin and you get degree days. Model a wall in an energy tool and you get a U-value. The number is usually right. The trouble is that the student can’t tell you why it’s right, what it assumed, or when it would be wrong, and those three things are the whole job when you’re the one stamping the drawings.
So every instrument follows one rule: the formula is on the screen, with your numbers in it. Move a slider and the arithmetic rewrites itself. You can’t get the answer without walking past the method.
The four instruments
EPW Reader. Drop an EnergyPlus weather file and read the four figures a climate analysis starts from: the annual swing, the design conditions, degree days, and humidity, wind, and sun. My favorite part is the degree-day slider. HDD 65 and HDD 50 for the same city differ by thousands, so the tool makes you pick the base and write it down. It also tells you, plainly, that it will not agree with Ladybug and that both are correct: one sums daily means, the other sums hours. Same file, same base, different answer. That’s a lesson no plugin would ever volunteer. It also flags that a “typical meteorological year” is stitched together from twelve different years: statistically representative, physically fictional.
Shadow Angles. Move the sun, turn the wall, stretch the overhang and the fins. The horizontal and vertical shadow angles recompute live from the textbook formulas, and the tool tells you the overhang depth or fin projection you’d need for full shade. It’s the diagram every architecture student draws once by hand, now something you can play with until it clicks.
U-Value Builder. Stack the layers of a wall, roof, or floor and mark the one the studs interrupt. The builder writes out the parallel-path calculation and shows why you add conductances, not resistances, when heat takes two paths at once. It also plots the temperature at every interface in the assembly, so you can see exactly where the wall gets cold enough to condense.
Daylight Depth. The simplest of the four, originally built for a workshop. The 2.5× rule says usable daylight reaches about two and a half times the window head height into a room. Raise the head and watch the daylit zone grow in section. It’s a rule of thumb, and the tool is honest about that, but it’s the rule of thumb that should shape a floor plate before anyone opens an energy model.
What I learned building them
In my Big Tent vs. Little Tent piece I wrote about the jump from tool user to toolmaker. Building with AI forces you to specify: judgment you normally carry around as instinct has to be stated precisely enough for a code generator to implement it. That was true of the big tools. It turned out to be even more true of the small ones.
To build the EPW Reader I had to decide which degree-day convention to use, then realize the students needed to see that there was a decision. To build the U-Value Builder I had to decide what it would refuse to do: windows, slab edges, below-grade walls. Each of those is a single number you look up, and pretending to calculate it would teach the wrong thing. Every one of those decisions is a teaching decision. The tool is just where they become visible.
A few principles I’d keep:
- One calculation per page. If a tool needs a tutorial, it’s two tools.
- Say what it doesn’t do. Each instrument ends with a short note on its limits and which proper software does the next step.
- Cite yourself. Every result comes with a copy-ready citation of the inputs and method, because a number without its assumptions is an incomplete entry.
- Nothing leaves the browser. No accounts, no uploads. Your weather file stays on your machine.
Use them
All four are free and live on the tools page. They were built for students, but they’re just as useful at a project kickoff when someone asks how deep the overhang needs to be and nobody wants to open Revit to find out.
This is a seed. As the semester goes on I expect to add more instruments, and I’ll update this note as they land.