Skip to main content
AG Millworks
Title 24 Compliance

Title 24 of the California Code of Regulations encompasses the state's Building Standards Code. Part 6 specifically pertains to the California Energy Code, which outlines energy conservation standards for residential and nonresidential buildings. This code aims to promote energy efficiency, reduce greenhouse gas emissions, and decrease energy consumption in buildings throughout the state. 

As energy efficiency leads to lower energy expenses for homeowners and mitigates environmental effects, building regulations play a crucial role in shaping California's future. Prior to issuing a building permit, municipalities in California mandate the submission of a Title 24 energy report (also known as Title 24 energy calculations). This report confirms compliance with Title 24 standards, ensuring that building designs align with the latest energy code.

Compliance Methods

There are two methods of compliance for Title 24: Prescriptive and Performance. Both reports require information pertaining to the energy efficiency and construction of the home.
•    The prescriptive method is the most time efficient and straightforward approach at meeting minimum energy requirements for a home or building. This approach is the simplest way to rate performance, but requires each component to meet established minimum efficiency values per climate zone.
•    The performance method offers unparalleled flexibility and precision in crafting an effective energy plan for homes or buildings. Utilizing certified component modeling software, the building's systems are analyzed comprehensively to establish an overarching energy allocation. For instance, the energy performance of windows and doors can be balanced against factors like wall insulation and electrical efficiency. Additionally, there's potential for trade-offs, such as combining less efficient windows with more efficient ones to achieve an overall product average.

What is Measured and How it Works

Windows and doors experience heat exchange through several mechanisms:
1.    Direct conduction and convection heat transfer occur through the glass or multi-layer glazing and framing.
2.    Thermal radiation occurs into and out of a house from objects at room temperature, such as exterior walls, windows, people, equipment, furniture, and interior walls.
3.    Solar radiation enters a house and is converted to heat when absorbed by building surfaces.
4.    Air leakage occurs through and around the window or door.

These properties can be measured and rated in the following way:


The U-Factor measures the rate of non-solar heat flow transmission through a window or door. NFRC U-Factor ratings encompass the overall performance of the window, taking into account frame and spacer materials. A lower U-Factor indicates higher energy efficiency for the window or door. The current U-Factor requirement for fenestration is a maximum of .30.

Solar Heat Gain Coefficient
Solar Heat Gain Coefficient

The Solar Heat Gain Coefficient (SHGC) represents the proportion of solar radiation that enters a home through a window or door, whether it's directly transmitted or absorbed and later released as heat indoors. A lower SHGC indicates reduced transmission of solar heat and enhanced shading capability. A product with a high SHGC rating is adept at capturing solar heat during winter, while one with a low SHGC rating excels at minimizing cooling loads in summer by preventing heat gain from the sun. In warmer regions like California, opting for windows or doors with lower SHGC values can significantly reduce air conditioning expenses. The current recommended SHGC rating for fenestration in most climate zones is a maximum of 0.23.

Visible Transmittance
Visible Transmittance

Visible Transmittance (VT) is a key identifier provided by the NFRC for doors and windows. It quantifies the amount of light passing through the glass of a window or door product. While VT doesn't directly impact heating and cooling efficiency, it plays a crucial role in various desirable features such as natural light, views, privacy, controlled glare, and minimizing interior fading from sunlight. Therefore, VT is a significant consideration when selecting energy-efficient fenestration products. A higher VT value indicates greater transmission of visible light. VT is typically expressed in fenestration as a numerical value ranging from 0 to 1.


Condensation Resistance (CR) assesses how effectively the interior resists condensation. When humid indoor air meets a cold surface like a window or door, it can lead to condensation in the form of water vapor, especially common in poorly insulated metal window and door products. Today, advancements like high-quality thermal breaks help minimize heat transfer through the frame, enhancing insulation and condensation resistance. Factors contributing to condensation resistance also encompass a well-designed frame with favorable U-factor values, as well as the integration of highly insulating glazing materials such as multiple glass panes, low-emissivity coatings, and specialized gas fills. The current recommended CR rating for fenestration is a minimum of 50.

The California Energy Commission periodically revises the energy standards to accommodate the evaluation and potential integration of emerging energy-efficient technologies and methodologies.

Our AG Millworks Door and Window Systems have consistently met or surpassed each revision of the California energy-efficient standards. Our products are listed under the NFRC website as Certified and Title 24 Prescriptive Compliant.

Homeowners, and ultimately the environment, are the primary beneficiaries of the Title 24 energy efficiency standards. Anticipated to result in a roughly 30% decrease in annual energy consumption for new homes, Californians stand to collectively save at least $100 million annually through reduced electricity expenses. This initiative not only fosters a diminished carbon footprint for Californians but also promotes a more comfortable and financially prudent lifestyle.


    About us

    Welcome to AG Millworks, where we combine extraordinary designs with traditional old world craftsmanship and innovation to produce ageless millwork creations that will bring your building project to life.

    rss feedemail usour twitterour facebook page pintrestlinkdin youtubeinstagram
    Phone:  (805) 644-4494
    3111 Golf Course Drive
    Ventura, California 93003