e-News #91: Title 24 2013 Update

November 22, 2013
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The 2013 Title 24 Standards have undergone a number of changes

to improve the energy performance of new and existing buildings. In addition to increased stringency, the Standards have increased in scope to include requirements for covered processes -- data centers, laboratories, kitchen exhaust systems, parking garages -- and they have increased in extent to include commissioning requirements and additional acceptance test requirements for systems and components. A few of the many key changes to the 2013 Standards follow.

For full text on applicability of the requirements, how they should be applied, and specific exceptions, consult the Standards, Reference Appendices, and Residential & Nonresidential Compliance manuals.  An updated set of Standards documentation and manuals is maintained by the California Energy Commission.

Summary of Nonresidential Changes

A high-level summary of the changes to nonresidential new construction is shown in Table 1. This list does not cover every change to the Standards for 2013, but provides a summary of significant changes.





Covered Processes


Minimum Insulation Commissioning (>10,000 ft2) Site-bulit Fenestration Limits (1,000 ft2)


Commissioning (>10,000 ft2)


Path A/Path B chiller Efficiency

Commissioning (>10,000 ft2)

Refrigerated Warehouses

Garage Exhaust


Cool Roof

Fenestration Performance

Site-Bulit Fenestration Limits (1,000 ft2)
Retail Lighting

Single Zone VAV

Cooling Tower Efficiency

Data Centers


Kitchen Exhaust
Acceptance Tests   Demand Response

Fault Detection and Diagnostics

SAT Reset

Condenser Water Reset (when used)

  Table 1: Summary of changes in nonresidential new construction.

Building-Wide New Requirements

A few important requirements were added to the 2013 Standards. A full commissioning is required for new nonresidential and high-rise residential buildings above 10,000 ft2. The requirements, documented in Section 120.8, include not only functional performance testing, but also design review and other commissioning activities, and they now include review of building envelope and lighting features, in addition to HVAC systems.  For smaller buildings, only a design review is required.

Also new in 2013 Title 24 are requirements for electrical power distribution systems (130.5). The requirements include various levels of disaggregation and submetering based on the connected load (VA). These requirements also apply when new electrical distribution systems and panels are installed in existing buildings. The intent is to provide greater access to end use information which can be used for diagnostics and tracking energy use.

Nonresidential buildings permitted after January 1, 2014, must comply with requirements for “solar-ready” access (110.10).  The installation of photovoltaic panels is not required, but the buildings must have a minimum available roof space and established connection points to facilitate the addition of photovoltaic panels at a later date. The “solar zone” space where panels can be installed must be within 110 and 270 degrees of true north and comprise at least 15 percent of the roof area, excluding skylights. This measure is designed to make it easier for the building to comply with the long-term policy directive of the Energy Commission and CPUC to have not only new buildings, but also existing buildings, achieve zero net-energy goals.

Building Envelope

Title -24-2013-code -changes
What will Title 24 Changes Do? In their publication What’s New in the 2013 Code?, the University of California, Davis’ California Lighting Technology Center noted that California’s new Building Energy  Efficiency Standards “…improve the energy efficiency of homes by 25 percent and make nonresidential buildings 30 percent more efficient than the previous 2008 standards.”

For the building envelope, the major changes include the introduction of mandatory minimum insulation requirements for opaque envelope components, increased fenestration performance  that include new visible transmittance requirements, and tighter limits of 1,000 ft2 of site-built fenestration that can use center-of-glass performance values to determine whole window U-factor and SHGC used for compliance. Above this fenestration area limit, default values of Standards’ Tables 110.6-A and 110.6-B must be used.  Since the default values in the these tables in Section 110.6 of the Standards will not meet prescriptive fenestration performance requirements (140.3), the performance method will need to be used to demonstrate compliance with the Standards.

Lighting and Daylighting

For lighting, the new changes include mandatory daylighting controls in the primary sidelit zone (defined as space at a depth of one window head height from the window and projecting one-half head height laterally from the edge of the window. The Standards also have increased the number of required control steps for some types of luminaires (130.1).  There also are new requirements for bi-level occupancy controls in some spaces.  Demand responsive lighting controls are required for buildings with floor area above 10,000 ft2.   The 2013 Title 24 Standards require occupancy controls in most building spaces, with the exception of offices, and lighting must be completely shut off during unoccupied times.

The Standards still provide three methods for prescriptive lighting compliance: the complete building method, the area category method, and the tailored lighting method. Lighting power allowances in office buildings and parking garage buildings have been reduced slightly.  Grocery sales and office space allowances using the area category method also have been reduced.  Under the tailored lighting method, the allowed ornamental and special effect lighting has been reduced for several spaces, and the wall display lighting allowance has been reduced for museums, grocery sales areas, and retail showrooms.  Also, if the tailored lighting method is used, the extra allowance available for spaces with high ceilings has been reduced.


For HVAC, new mandatory requirements that distinguish Path A from Path B chillers are now in place.  Newly installed chillers must meet performance requirements of Path A -- chillers designed more for continuous operation -- or Path B -- chillers designed for overall performance at a variety of part-load conditions.  There are significant new commissioning requirements (120.8) that apply to HVAC systems, as well as applicable envelope and lighting systems.  A full commissioning scope is required for buildings greater than 10,000 ft2, while smaller buildings only need a simpler basis of design specification .

A new mandatory requirement for fault detection and diagnostic (FDD) controls has been added for packaged HVAC equipment that has nominal cooling capacity of 54,000 Btu/h or higher and airside economizers (120.2). Such controls are readily available for packaged units and include economizer checks and refrigerant diagnostics. Some have the capability to report to a centralized server so that alarms and logs from a number of units on one or more sites can be remotely tracked.

Large classroom spaces and multi-purpose rooms require occupancy sensor-based controls for HVAC ventilation (120.1, 120.2) which can setback the thermostat and reduce ventilation to a minimum rate when the room is unoccupied. Guestrooms of hotels and motels also require occupant-based controls that can turn off lighting and can either setback or turn on the HVAC unit or terminal unit.

There are new mandatory requirements for commercial boilers (120.9), including shut-off controls, variable-speed drives on combustion fan motors of 10 hp or greater, and maintenance of excess stack gas oxygen concentrations for boilers with capacity of 5 MMBtu/h or greater.

The Standards have extended prescriptive economizer requirements to include all units with a total cooling capacity of 54 kBtu/h or greater, added requirements for damper reliability and damper leakage testing, and included compressor turndown requirements for packaged DX equipment down to 35 percent of full load for units between 65 kBtu/h and 240 kBtu/h and down to 25 percent for units greater than 240 kBtu/h (Table 140.4-C). 

The control section of the Standards has been amended to restrict the use of enthalpy-based economizers. The requirements for variable air volume fan control for DX systems have been extended to units with total cooling capacity of 75 kBtu/h and above beginning January 1, 2014, and to units with total cooling capacity 65 kBtu/h and above beginning January 1, 2016 (140.4(l), Table 140.4-D).  Packaged units of this capacity range already are commercially available with variable-speed drive fans that are coupled with either multiple compressor stages or variable-capacity compressors for control.

Covered Processes

A number of new requirements have been added to the Standards to address energy use of covered processes. Mandatory requirements have been added for refrigerated warehouses and commercial refrigeration above 8,000 ft2, and garage exhaust CO controls now are required for systems with design airflow of 10,000 cfm or greater. New prescriptive requirements apply to data centers and any computer room with a load of 20 W/ft2or greater. The Standards now include packaged HVAC and economizer performance requirements in addition to control sequences, and they prohibit the use of non-adiabatic humidification. 

New requirements also govern the efficiency of Type I and Type II kitchen exhaust hoods. When the design airflow for the hood exceeds 5,000 cfm, the Standards require the use of either transfer air for replacement, demand control ventilation, heat recovery, or a minimum of 75 percent of makeup air that is not mechanically cooled and either unheated or not heated to more than 60F (140.9b2). Buildings with laboratory exhaust hoods where the minimum circulation rate is 10 ACH or less are required to utilize variable flow to be able to modulate exhaust flow down to the larger of the minimum required regulation circulation rate or the flow required for pressurization (140.9c).


Summary of Residential Changes

Residential buildings, like nonresidential, are required to be “solar ready”, which includes a roof area of at least 250 ft2 to be available for installation of solar photovoltaic panels.  Table 2 shows changes in residential new construction.







Minimum Insulation

High Efficacy Lighting Requirements



Fenestration Performance Requirements

Window Area Limits


Single Zone VAV

Cooling Tower Efficiency

Acceptance Tests



Whole House Fan

Duct Insulation

Table 2: Summary of changes in residential new construction.


Envelope Changes

The Standards now include a prescriptive requirement for continuous insulation of R-4 to R-5 (about 1 inch of insulation board, depending on product) in addition to R-13 or high-density R-15 batt between the studs of a 2x4 wood-framed wall.  The Standards also require a minimum of R-13 batt insulation to be installed in 2x4 framed walls, and a minimum of R-19 batt insulation to be installed in 2x6 framed walls. Insulation requirements for other wall types such as mass walls have been updated as well.   There are stringent fenestration thermal performance requirements as well: a maximum U-factor of 0.32 in all climates and a solar heat gain coefficient (SHGC) of 0.25 in all climates except the north and central coast (CZ 1, 3 and 5).  (See Standards Section 140.3(a)5B, and Table 140.3-B).  Fenestration area is limited to 20 percent of gross wall area, and the fraction of wall area allowed for west-facing fenestration is even lower, 5 percent in all climates except the north and central coast.  Radiant barriers for roofs are now required in all climate zones except the north coast (CZ1) and mountains (CZ16).

Lighting Changes

There have been significant changes to lighting requirements.  Most spaces now require either high efficacy lighting or the use of vacancy sensors to control low-efficacy lights. The Standards now have specific definitions for high-efficacy lighting.  As shown in Table 3, the lighting must meet a minimum lumens/Watt standard to be classified as high-efficacy lighting.  Title 20 requirements also apply to high-efficacy lighting.


Luminaire Power RatingMinimum High Efficacy Requirement
<= 5 Watts 30 lumens/Watt
Over 5 Watts to 15 Watts 45 lumens/Watt
Over 15 Watts to 40 Watts 60 lumens/Watt
Over 40 Watts 90 lumens/Watt

Table 3:  High-efficacy lighting standards (Standards Table 150.0).

HVAC Changes

Federal law governs the efficiency requirements for air conditioners and most other major HVAC components. However, the Standards have become more stringent in the areas of testing and acceptance.  Whole-house fan efficacy must now be listed in the Appliance Efficiency database and provide a minimum of 2cfm/ft2 of conditioned floor area, and this applies to residential buildings in all climate zones.  The mandatory minimum duct insulation levels have also increased slightly, from R-4.2 to at least R-6 in all climates. 


Several new requirements apply to residential additions and alterations.  Altered fenestration must meet minimum performance requirements (U<0.40, SHGC<0.35).  Low-sloped roofs must meet minimum solar reflectance requirements and they can use a prescriptive tradeoff table (Table 150.2-A) to trade off reflectance with insulation.

The new duct sealing testing requirements apply to any modifications or additions of systems with 40 linear ft or more of ductwork in unconditioned space.  The alteration or replacement of any space conditioning system also triggers the duct sealing requirements.  Systems in the inland valley and desert climate zones (2, 8, 9, 10, 11, 12, 13, 14, and 15) require refrigerant charge testing and airflow testing to verify that airflow is at least 300 cfm per nominal ton of cooling.

HERS Summary of Residential Changes

The new code cycle also requires more HERS verification measures; some new verification tests have been added while the frequency of existing measures has increased.  The focus of HERS changes revolves around HVAC system verification.  Most notable is that duct sealing is now required in all climate zones for all projects – both new construction and alterations/additions – anytime more than 40’ of ducts are run in unconditioned space.  This is now a mandatory measure that cannot be traded off via the performance approach. Additionally, HERS raters now are required to verify the whole building ventilation requirements of ASHRAE 62.2 in all new buildings and in additions greater than 1,000 ft2.  Existing HERS measures also have been expanded to encompass more situations such as: verification of SEER in addition to EER, verification of refrigerant charge of package units, and verification of the location of ducts in conditioned space.

For a complete list of HERS measures, see the Residential Compliance Manual (page 2-36).

Moving Forward

The changes in the Title 24 Standards are far more encompassing than what has briefly been summarized here.  Becoming familiar with these changes by utilizing the many resources available will prove to be an instrumental investment in your own career as California accelerates the transition to zero net-energyi new and existing buildings.



Training Highlights

California utilities offer outstanding educational opportunities that focus on the design, construction and operation of energy-efficient buildings. Listed here are a few of the many upcoming classes and events; for complete schedules, visit each utility's website.

Inspecting Photovoltaic (PV) Systems for Code Compliance
December 4 (Wed 9:00am to 4:30pm)
PEC - San Francisco

Also available online! >

This advanced workshop is designed for building inspectors, plan checkers, fire officials, PV installers, designers, engineers, and architects who wish to stay current on the latest code compliance issues to help facilitate safe and long-lasting PV systems.

Title 24 Duct Installation Standards & Diagnostic Testing
December 4 (Wed 9:00am to 5:00pm)
This class will provide participants a review of the current Title 24 New Construction Standards for airtight ducts, test and documentation requirements, plus hands-on experience operating duct tester, flow hood, digital manometer, and blower door equipment.

Title 24 Standards Essentials — Refrigeration for Retail Food Stores - An Online Course
December 6 (Fri 9:00am to 12:00pm) December 9 (Mon 9:00am to 12:00pm) INTERNET

This is a highly interactive, one-day class that addresses what you need to know and do to meet the new California Building Energy Efficiency Standards specific to commercial refrigeration systems for both new construction and for alterations (retrofits) of retail food stores. Through presentation and scenario-based practice, participants will explore the mandatory requirements what triggers them, and more.


Commercial Package Unit Advanced Diagnostics
December 11 (Wed 9:00am to 5:00pm)

This 1-day class is ideal for HVAC contractors who wish to learn more about diagnosing charge and air flow issues with commercial packaged units. A portable commercial package unit is used which is capable of simulating multiple faults. Instructors can control and simulate faults for technicians to diagnose and correct. This course is ideal for contractors who perform maintenance on commercial packaged units.

Lighting for Office Applications: Title 24 2013 and Technology Update
December 12 (Thu 8:30am to 4:00pm)
Davis--CA Lighting Tech Center

This intermediate class is for professionals who design, specify, and/or inspect lighting installations in new and remodeled commercial office spaces. Class participants will gain a firm understanding of current code requirements for office lighting under Title 24, Part 6. The curriculum includes an overview of current lighting technologies, including LED luminaires and a tour of CLTC to view technology options that are available to meet, or exceed, code requirements.

Hands-on: LED Applications
December 19 (Thursday, 9:00 am to 4:30 pm)
San Francisco--PEC

Class will start off with a site tour of a DOE gateway project with an LED retrofit, guided by the lighting designer. Attendees will learn how to select and specify LED lamps and fixtures, and about the potential issues with LED applications. This class will provide hands-on access to a number of LED system components, controls, and fixtures samples.



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