Short answer: A Title 24 result depends on where the building is (its climate zone), how it is built (insulation, windows and orientation), and what equipment it uses (heating, cooling and water heating). Size and unit count affect how much there is to model and the report price.
Several key variables determine what your Title 24 report requires and whether your project passes compliance on the first run. Understanding these factors can help you make smarter design decisions early — before expensive changes become necessary.
Climate Zone
California has 16 climate zones, each with different baseline energy budgets. Hotter inland zones face stricter cooling requirements, while coastal zones have more moderate thresholds. Your climate zone is determined by your project address — you do not need to look it up yourself, though you can explore the climate zone pages or read how climate zones affect a Title 24 report.
Building Envelope
Your insulation levels (walls, roofs, floors) and window performance (U-factor and Solar Heat Gain Coefficient) directly impact whether your project passes. Upgrading insulation or selecting better-performing windows is often the most cost-effective path to compliance when a project falls short on the first model run.
Window Area and Orientation
How much glass a building has, and which way it faces, matters as much as the window ratings. Large west- and south-facing windows bring in afternoon sun and add cooling load, especially in hot inland zones. The model uses the site plan's orientation to place each window, which is why a north arrow on the plans matters. Window alterations have their own rules — see our window replacement Title 24 service.
HVAC System Type and Efficiency
Heat pumps generally perform better in Title 24 modeling than traditional gas furnace and AC combinations, particularly under the current 2025 code, which strengthened electrification-related compliance pathways. Mini-splits, ducted heat pumps, and high-efficiency systems all affect the outcome. Duct location matters too: ducts inside conditioned space lose less energy than ducts in a hot attic. See the HVAC replacement Title 24 service for changeouts.
Water Heating
Water heating is a large share of a home's modeled energy use. A heat pump water heater typically helps compliance, while gas and electric resistance heaters are modeled differently. Choosing the water heater early avoids re-running the model later.
Field-Verified Measures
Some features only count if a HERS (ECC) rater verifies them after installation — for example duct sealing, refrigerant charge and quality insulation installation. The report lists these, and they must be completed in the field. See HERS rater vs Title 24 report.
Square Footage and Unit Count
Larger buildings and multi-unit projects require more modeling time and may involve additional compliance measures. Square footage and unit count also affect the pricing of your report — see Title 24 report cost.
Frequently Asked Questions
What if my design does not comply on the first run?
We identify which inputs are holding it back and suggest practical changes, such as better windows, more insulation or a different system. Title 24 calculations explains the trade-offs, and Title 24 requirements lists what applies regardless.
What do I need to provide?
Plans showing the layout, windows, construction and equipment. See what documents to upload.
Does my climate zone change the price?
No. Pricing is based on report type, square footage and unit count, not location.