Title 24 gives you two ways to comply. One is a fixed recipe that is cheap and fast to document; the other energy-models your whole building and buys you design freedom. See which one fits your project.
Every result is a planning estimate, not a quote or an engineering determination. Real numbers depend on site conditions, existing structure, engineering requirements, and your jurisdiction’s current fee schedule. For structural and engineering work we coordinate with a licensed engineer — we do not perform or stamp engineering ourselves. Get a project-specific estimate before committing to a budget.
The prescriptive path is a recipe. Title 24 publishes a package of minimum values for your climate zone — wall and ceiling insulation, window U-factor and solar heat gain coefficient, duct sealing, water heating — and if you meet every single line, you comply. There is no trading. Miss one item and the package fails, even if you exceeded everything else. In exchange it is quick to document, cheap to produce, and easy for a plan checker to verify.
The performance path is a model. The compliance software simulates a full year of energy use for your actual building and compares it against a reference building of the same size and shape built to the prescriptive standard. As long as your design uses no more energy than that reference, you comply — no matter how you got there. Extra glazing is paid for with better windows, more insulation, a heat pump, tighter ducts, or added photovoltaics.
Neither path is more or less legal than the other. The performance path is not a loophole and it is not a fallback for a failing design. It is simply the route most contemporary residential architecture takes, because open plans, big sliders and vaulted ceilings do not fit inside a fixed recipe written around a conventional box.
This is the part people underestimate. The compliance path is not just paperwork — it dictates what has to be drawn and specified.
On the prescriptive path, the drawings carry the standard package: insulation callouts on the sections, a window schedule with U-factor and SHGC columns, duct sealing and leakage notes, and the mandatory measures sheet. It is predictable, and the values rarely move once set.
On the performance path, the model dictates the specification, and the specification is binding. If the model needed U-0.28 glass to pass, the window schedule has to say U-0.28 and the installed windows have to match. Substituting a cheaper unit during construction invalidates the compliance and shows up at final inspection. The same applies to insulation, duct location, equipment efficiency and any photovoltaic capacity the model relied on.
That is why the energy report and the drawing set should be produced together rather than bought from two vendors who never speak. We prepare the Title 24 CF1R energy calculations and the permit set as one coordinated package, so what the model assumed is what the drawings show and what gets built.
Not inherently. It is a fully recognised compliance route and plan checkers see it constantly. It requires more modeling work up front and produces a longer CF1R, but a correctly modeled and correctly drawn project is no harder to approve than a prescriptive one. No firm can promise a plan check outcome either way.
Yes, and it happens often — usually when a window gets bigger or a wall opens up and the prescriptive glazing budget breaks. The catch is timing. Switching after the drawings are complete means revising schedules, sections and notes to match the new model, so it is much cheaper to decide early.
No. The mandatory measures apply on both paths without exception. Air sealing, insulation quality, duct sealing, lighting and water heating requirements are the floor. The performance path only lets you trade against the prescriptive package that sits above that floor.
Sometimes. It costs more to document, but it can let you avoid an expensive envelope upgrade by trading against something cheaper, such as a heat pump water heater or additional solar capacity. On a project with a lot of glass it is usually the only realistic route, so the comparison is less about savings than about keeping the design you wanted.
Tell us what you're building and we'll get back to you with next steps — usually within one business day.
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Yuna Drafting