Ontario is a fast-growing San Bernardino County city in the Inland Empire with strong residential and multifamily activity.
Ontario sits in Climate Zone 10 where the Inland Empire's hot climate drives strong Title 24 requirements for cooling efficiency, envelope insulation, and solar PV compliance under the 2025 code.
Ontario projects are reviewed by the City of Ontario Building and Safety Division. We format every report for Ontario submission.
We prepare Title 24 reports for all project types in Ontario:
- New single-family home construction
- Room additions of any size
- ADUs and Junior ADUs including garage conversions
- Remodels and alterations affecting insulation, windows, or mechanical systems
- Multifamily duplexes, triplexes, and fourplexes
- HVAC replacement projects
- Window replacement projects
We also serve all surrounding San Bernardino County communities and cities throughout California.
Title 24 Projects in Ontario
Ontario is effectively two cities from a building standpoint. The older neighborhoods in the northern and central parts of the city are made up of established single-family homes and small apartment buildings, while the southern part of the city — the former agricultural land known as Ontario Ranch — is being built out as large master-planned neighborhoods of new homes and multifamily housing.
Large production developments usually handle their energy documentation at the tract level, so for individual owners the typical Ontario projects are in the older part of the city: ADUs and garage conversions on existing lots, room additions, and alterations such as replacing a worn-out air conditioner with a heat pump or swapping original windows. In Climate Zone 10, cooling dominates, so duct location, attic insulation and west-facing glass are the details most likely to need attention. Custom homes and small infill multifamily projects need a full performance model, including solar PV where it applies.
See HVAC replacement Title 24 for equipment changeouts and ADU Title 24 reports for backyard units.
Region, climate zone and nearby cities
Ontario is part of our Inland Empire and Southern California coverage and is listed in Climate Zone 10; the address and ZIP code set the exact zone. We also serve Rancho Cucamonga, Chino, Fontana and Pomona.
