Title 24 2008 New Requirements

Title 24 2008 New Requirements

Posted on 04. Aug, 2009 by in Regulatory Changes

I know we’ve published several of these, but this is updated to show more specifics. These are the requirements that will be in effect when the new 2008 Title 24 goes “live” in January 2010.

These requirements reference two compliance methods, a prescriptive method and a performance method. The prescriptive method is simpler but offers less flexibility, whereas the performance method uses a software modeling program with a detailed series of inputs that can be modified to test various trade-offs. We at Green Compliance Plus use the performance method.

FENESTRATION: The compliance model standard design (the hypothetical building that your design has to meet or beat) has been upgraded such that the fenestration has to have a U-factor of 0.40 for all climate zones except Climate Zone 15, where it has been reduced to 0.35. All fenestration will be required to have both permanent and temporary labels.

All CF-1R, CF-6R and CF-4R documentation must now be filed online with a HERS Service Provider.

NEW STATE OVERSIGHT REQUIREMENTS: The state will be using these electronic filings to check on building department inspectors.

This new measure of a surface’s reflecting ability has been added to the code, along with new requirements for low-sloped and steep-sloped roofs. A steep slope is greater than 2:12 or 9.5 degrees.


  • Zoned heating controls, when using the performance method for Title 24 calculation.
  • Distributed energy storage
  • Evaporatively cooled condensers
  • Evaporative coolers
  • Controlled ventilation crawl space
  • Cooling coil air flows that exceed prescriptive requirements
  • Fan watt draws that are leass than the prescriptive requirement of 0.58 watts per CFM
  • Low leakage air ducts in conditioned spaces
  • Solar water heating can be used as a trade-off when using the performance method.
Blown in insulation is one way to make existing homes more efficient

Blown in insulation is one way to make existing homes more efficient


  • Building Envelope: There are several revisions to the mandatory requirements for insulation and roofing.
  • Mechanical Ventilation: These are Indoor Air Quality requirements which generally follow ASHRAE <http://www.ashrae.org/> Guideline 62.2. All low-rise residential construction will be required to have a whole-house ventilation system. Operable windows are not an approved ventilation system. The system shall have MERV 6 or better filtration system.
  • Forced-Air Systems: There are new prescriptive requirements for forced-air systems. Fan watt draw limitations (no more than 0.8 watts per CFM) and minimum air flow rates for ventilation have been added to the new code.
  • Calculation of Heating and Cooling Loads: Heating and cooling loads must be fully calculated even when using the Prescriptive Method. This is already done in the performance method.
  • Spas & Pools: Time clocks and two flow speeds will be required on all spa pumps in order to limit flow velocity.
  • Refrigerant Charge: When using the prescriptive method, it will be almost impossible to avoid a HERS verification of the refrigerant charge if you provide any form of air-conditioning. If you install a split system, it must be verified by a HERS rater.
  • Hot Water Piping: Under-slab insulation of hot water piping will be required.
  • Refrigerant charge measurement is now a prescriptive requirement in Climate Zones 2 and 8-15.
  • Lighting Controls: New mandatory requirements for lighting controls.


  • Metal Frame Walls: Metal frame wall assemblies can be used, if the spray-on polyurethane foam is verified by a HERS rater before the sheet rock is put on.
  • Existing Wood-Framed Walls: Existing R-11 wood framed walls need not comply with R-13, if performance method is used.
  • Solar water heating can be used as a trade-off when using the performance method.

Still have questions on Title 24? Visit the Title 24 home page on the California Energy Commission’s web site.

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2 Responses to “Title 24 2008 New Requirements”

  1. Skippy

    07. Aug, 2009

    Ground source heat pumps provide heating, air conditioning, and, if so equipped, supply the house with hot water. They are smaller than a traditional heating/cooling unit and can easily be retrofitted into any home. The mechanical components are safely located underground or within the home – which eliminates fears of vandalism or theft. With extreme durability the parts can last a generation and require very little maintenance. These systems do not have fans, so instead of hearing and feeling blasts of air, you will enjoy a quiet, consistent temperature throughout the day. Geothermal heat pumps can even improve your health and reduce allergies because they excel at humidity control, thus there is a reduced chance for mold and mildew growth.

  2. cna training

    20. Aug, 2010

    Wow this is a great resource.. I’m enjoying it.. good article

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