California Association of Building Energy Consultants

Know the Prescriptive Package Energy Home Design

The Energy Code has a baseline of energy features required for a new residential home design called the "Prescriptive Package". Every method of energy compliance calculation is weighed against this baseline "Prescriptive Package". And like a prescription, it outlines minimum required energy features and design limitations for new homes that must be followed without deviation. This is helpful information when designing a home with the intention of meeting the 2008 Energy Code Requirements.

Thankfully, the Energy Code also allows energy compliance to be met using a Performance Method of compliance with the use of a computer program. In the Performance Method of compliance the home is compared to the "Prescriptive Package" requirements. If the home is designed below any "Prescriptive Package" requirements other areas of energy products can be boosted up beyond the "Prescriptive Package" requirements to make up for the designed energy features below the "Prescriptive Package" requirements.

Thus it is helpful to know the "Prescriptive Package" minimum requirements for a home in the Climate Zone location of the home.

The "Prescriptive Package" Requirements for Climates Zones 11 and 12 that cover much of the Northern California area climate zones that have heating and cooling needs (Sacramento, Roseville, Rocklin, Granite Bay, Elk Grove, Stockton, Modesto, Auburn for instance) are shown below in the table from the 2008 Building Energy Efficiency Standards Residential Compliance Manual. All 16 climate zones are listed in this table across the top of the table. For climate zones 11 and 12 simply look across the table and then follow each column down the list for the minimum required energy feature.

A couple of the difficult design areas of the "Prescriptive Package" requirements are:

  1. 5% glazing on the West facing wall of the home
  2. Cool Roof Products required for all roof surfaces with a greater than 2:12 pitch

These requirements are easily deleted with the Performance Method of compliance with increased HVAC equipment efficiencies, increase energy ratings for windows and/or overhangs greater than three (3) feet. This is why energy compliance under the Performance Method is preferred. This method provides for the greatest of flexibility in meeting the complex and strict California Energy Code.

Standards Table 151-C Component Package D

Table showing the Prescriptive Package for a specific set of components like insultation, radiant barrier, roofing, etc.

As always, I am available to discuss the best method of Title 24 compliance. Contact me …