If you live in California, you've probably heard about Title 24，California Building Standards Code，the state's energy code for buildings. But what does it actually mean for your windows and doors? Let's break it down in plain English, so you can save money, stay comfortable, and avoid fines. Image source: Internet Title 24 U-Factor Requirements: What You Need to Know U-Factor tells you how well a window or door blocks heat loss. Think of it like a winter jacket: Lower numbers = better insulation. In California's climate (yes, even chilly San Francisco nights!), aim for U-Factor ratings below 0.30. This keeps your home cozy in winter and cool in summer without overworking your AC or heater. Visible Transmittance (VT): Balance Light and Heat in California VT measures how much natural light your glass lets through (rated 0–1). Higher VT = brighter rooms. But here's the catch: Too much sunlight can heat up your home. Modern Low-E coatings solve this by letting light in while blocking UV rays. It's like sunglasses for your windows—bright but energy-smart. California Climates solution: Energy-Efficient Windows and doors Factory-built products need permanent NFRC labels. Here' some solutions for specific areas for you as reference, for Los Angeles and San Francisco homes：first recommend 6+12A+6 with double Low E, filled with argon gas. cheaper option 5+20A+5 with Low E. Ready to Upgrade? Don't stress about codes—we've got California Building Standards Code covered. Explore our California-made collection (aluminum windows and doors) or consultant (wsa +8618922126334) today. Save energy, stay compliant, and enjoy your home year-round!