Introduction, Purpose, and Scope

This commentary addresses the changes that became effective on October 1, 2005 to California’s Title 24 Regulations, as applicable to retail design and construction. It is important to recognize that most of the Title 24 changes relate to the “Prescriptive” method of analysis.  The prescriptive criteria applies to specific building elements, components, or systems and is used to define the “ideal or concept” building as the standard for comparison and compliance.   The “Performance” method of analysis compares the total energy consumption of a specific facility to the energy budget of the “ideal model”.  By this approach, for example, skylights could possibly be eliminated by improving other building features. 

Due to the range and complexity of current Title 24 revisions, this commentary cannot cover every possible retail situation and does not address distribution centers (warehousing).

Basic Issues and Questions

• The most significant change and the most FAQ pertains to skylights.  Will my retail store require skylights?  Not necessarily.  Stores with spaces greater than 25,000 square feet with ceiling heights greater than 15 feet DO require skylights by the prescriptive approach.

• Note, however, that a store with 30,000 square feet which is sub-divided by a full height partition to include a 6,000 square feet Stock Room would not require skylights, since the largest space would be 21,000 square feet.    

• As noted above, skylights may be eliminated by using the Performance approach.  In retail facilities, the most probable trade-off necessary to eliminate skylights will require a reduction in lighting power.

• When skylights are provided, controls must be included which reduce or eliminate artificial lighting whenever sufficient daylight is detected.   Skylight applications must adhere to a complex set of criteria and design methodology.

• The new regulations reduce the amount of energy which can be consumed for general indoor lighting.

• Lighting energy for unconditioned spaces is no longer exempt from the energy budget of the ideal model.  This would include, for example, parking garages.  Further,  a trade-off between lighting in conditioned and unconditioned spaces is not allowed (under the Performance method).

• The revised regulations set limits on outdoor lighting power and signage power.  Signage power limits apply to both indoor and outdoor signage. Under some circumstances, outdoor lighting must be controlled for two intensity levels.  Outdoor fixtures with lamps exceeding 175 watts must be shielded to reduce glare.

• The building envelope criteria has been revised to include a requirement for “cool roofs”, that is, roofs capable of reflecting heat in the summer.  Roofing products must be pre-approved by the California Energy Commission (CEC).

• West facing walls are now limited to 40% glass area and cannot be increased under a Performance trade-off.  Placing insulation on T-bar ceilings is not allowed, with a few exceptions.  Metal building roofs must have thermal breaks.

• Commissioning of mechanical and electrical equipment and systems which are prone to improper installation and operation is now required for facility acceptance by regulatory authorities.

• Demand controlled ventilation must be applied to places of assembly such as conference rooms and lounges.  This method of control senses carbon dioxide levels in the occupied space and increases or decreases outdoor air ventilation as required to maintain set point limits.  This criteria would apply to lunch rooms and break rooms in retail facilities.

• New Federal regulations require higher efficiency standards for HVAC equipment falling within the residential size range.  This criteria applies to California and all other States.  For retail facilities,  this could apply to small air conditioning systems serving lunch rooms, small offices, small computer rooms, etc.

• Larger HVAC systems and equipment, under Title 24, are required to incorporate variable speed drive controls for fans and pumps greater than 10 HP.  Improved efficiencies and controls are also required for large system components, such as chillers and cooling towers, and certain types of fan motors.

• Other Title 24 revisions include requirements related to ductwork insulation, ductwork sealing (air-tightness), and field testing for duct leakage.  These criteria apply primarily to ductwork in unconditioned spaces.

Summary and Conclusions

The design of retail stores for compliance with Title 24 is normally done under the “Performance” approach (by CASCO), using computer software to achieve a design which is consistent with the Client’s goals and objectives.  Each facility location must be analyzed separately due to the wide variations in California’s weather regions, building orientation to north, and other site specific variables that may apply.

The process of attempting to define prototype features and systems to conform to these new Title 24 requirements should consider the practical limitations posed by the range of these variables.  Rather than developing separate California prototypes for each variable, CASCO recommends using “notes to designer” to alert any professional using the prototype to Client preferences regarding approach to resolving specific Title 24 criteria and requirements.

Regardless of prototype configuration, each site specific project must be analyzed separately to demonstrate Title 24 compliance.     

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