An energy rating describes what a building was designed to do. The Infrastructure Condition Index (ICI™) describes whether the equipment inside it is still doing it. Both are useful. Folding one into the other makes both of them wrong.
A brand new 80% AFUE furnace is in excellent condition and is also an older generation of equipment. Both statements are true at the same time. A single blended score has to choose one, and whichever it chooses, it misleads someone.
We built it the other way for a while and it failed in exactly the ways you would predict. A new furnace read as poor condition. Gas water heaters were penalised against electric ones for being gas. Boilers were capped permanently because the technology tops out lower than a heat pump. None of that describes the state of the equipment, which is the thing a maintenance budget actually turns on.
So the ICI scores condition, and only condition: age against expected service life, documented service history, and measured component readings trending over time. Efficiency is reported beside it as its own fuel-aware fact, in the equipment's own metric, with its own comparison to what is sold today.
A home energy label is a point-in-time measurement. The day it is issued it is accurate. Then a heat pump loses charge, a filter goes unchanged for three years, a capacitor drifts, ducts leak, and the building quietly stops delivering the rating it was given. Nothing in the label updates, because nothing was watching the equipment.
That gap is where public money leaks. A retrofit programme pays for the efficiency once. Whether the building still has it in year six is not measured anywhere.
This is the part of the work that protects efficiency rather than just describing it. Because the registry holds the real service history and the measured readings on each unit, it can see decay coming: a component trending against its rated range, a service interval that has quietly stretched, a unit approaching the end of its life. Acting on those keeps equipment operating near its rated performance instead of drifting away from it, and it replaces parts and units on evidence rather than after a failure.
Put plainly: an energy label tells a household what their home was rated at. The registry tells them what it is doing now, what is decaying, and what to fix to keep the rating real. The two are complementary, and they are only complementary if they stay separate.
Every system carries its condition score with the reasoning behind it: the starting number, its source, and each adjustment with a reason and a point value. The number is auditable rather than asserted.
Beside it sits the efficiency fact, phrased so a homeowner can act on it. For an older furnace that reads: rated 80% AFUE, an older generation, where equipment sold today is typically 96% AFUE, so replacing it is an efficiency decision rather than a repair one. That sentence tells someone what kind of decision they are making, which is different from telling them their house scores a number.
And when a unit is replaced, the registry keeps the one that left: its final condition, its age at replacement, and the service history behind it. Over a portfolio and over years, that is a record of how long equipment actually lasts in real buildings under real maintenance, rather than how long a manufacturer says it should.
The registry covers building systems, with building systems as the proven core. Life-safety systems, including fire suppression and elevators, are deliberately out of scope.
The ICI is not an energy rating, not an inspection, and not a prediction of failure. It is a condition index built from documented evidence, and it says so on every report it produces.