Title 24 Energy Compliance for Non-Residential/Commercial projects

What You Need to Know

The information given here assumes that the owner/client wishes to be most cost-effective in minimizing overall design and construction costs. The information also holds true for those who desire maximum design flexibility. For those who desire maximum efficiency, Title 24 compliance is a low level formality that should be met without difficulty.

Non-residential Title 24 is divided up into three distinct areas:

the Envelope, that is, the exterior surfaces of the building/space
Lighting
Mechanical Systems

In theory, energy compliance documentation is required for all but very simple projects that involve one, or more, of these three disciplines. All new lighting installations are now governed by Title 24. When space conditioning equipment will not be installed immediately, but there is a chance it may be installed in the future, Title 24 envelope compliance is highly advisable. As soon as a space is conditioned for the first time, all of Title 24 will kick in.

Unfortunately, there are often logistical roadblocks that prevent optimum cost-effectiveness in Title 24 compliance. Foremost among these roadblocks are the discreet divisions that exist between the various design disciplines: architecture, mechanical engineering, electrical engineering, interior design, etc. The standard operating procedure involves a sequential design process in which each discipline tries hard not to step on the toes of other disciplines. Feedback from one disicipline to another is generally minimized. The idea of adding another discipline—energy engineering—into the mix is generally discouraged by the practicioners of the various engineering disciplines, who carefully guard aspects of Title 24 that relate to them. Ironically, if the advice given on this page were put into the hands of a quality, experienced Title 24 energy analyst, these engineers would have less to worry about, and virtually nothing to guard against.

Often, the Title 24 energy analyst is hired by the architect to handle only the architect's portion of the design: the envelope. In the case of simple tenant improvements, the analyst may be hired only for lighting compliance. The standard operating procedure noted above is not optimal from a construction standpoint, because it prevents energy trade-offs between disciplines. The only way to make the most of a building's entire budget is to combine as many aspects of the design as possible into a single computerized performance analysis. The 2005 Title 24 standards have made all aspects of energy compliance "tight," and have piled new requirements high on the prescriptive approach, so combined performance analysis is all the more important.

Envelope: The prescriptive standard requires tinted double glazing throughout the state. More tinting, and better U-factors are required in the harsher climates. "Cool roofs" are required on low-sloped structures. Skylights with automatic daylighting controls are required in "big box" buildings. The performance method of compliance can minimize or eliminate some of these requirements, especially if combined with mechanical and/or lighting compliance. Insulation on top of T-bar ceilings is now deemed to be worthless.
Lighting: Allowable lighting power densities have now been ratcheted down to very low levels for all types of occupancies. For example, the standard for office buildings is now 1.1 Watts/ft ², which corresponds to two F32T8 tubes with electronic ballast for every 57 square feet of floor area. There are three different methods to determine lighting compliance, but it is difficult to predict which one will yield the most flexibility. The "tailored approach" gives extra allowances for display lighting. There are some significant mandatory measures, including system timeclock(s) and various switching requirements, but these have no bearing on compliance calculations.
Mechanical: Systems must be properly sized, and must meet new federal efficiency standards. Also, units larger than 6 1/4 tons must have an integrated economizer (higher cooling efficiencs are an allowed alternative in some climates). The prescriptive standards require HERS verified "tight ducts" in some cases. There are some very significant mandatory measures and new "acceptance requirements", but these have no bearing on compliance calculations.

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