Title-24 Question of the Week

How do I calculate the conditioned floor area of a building?

For the purposes of Title-24 energy code compliance analysis the Conditioned Floor Area (CFA) is the total floor area (in square feet) of enclosed conditioned space on all floors of a building, as measured at the floor level of the exterior surfaces of exterior walls enclosing the conditioned space.  This term is also referred to in the Title-24 Energy Code simply as the floor area.

This is an important value for the purpose of compliance since the annual energy use is divided by this value to obtain the energy budget.  In the prescriptive packages, the maximum fenestration (glazing) area is expressed as a percentage of conditioned floor area.

CFA is calculated from the plan dimensions of the building, including the floor area of all conditioned and indirectly conditioned space on all floors.  It includes lofts, mezzanines but does not include covered walkways, open roofed-over areas, porches, pipe trenches, exterior terraces or steps, chimneys, roof overhangs or parking garages.  Unheated basements or closets for central gas forced air furnaces are not included, unless they are shown to be indirectly conditioned.

The floor area of an interior stairway is determined as the CFA beneath the stairs and the tread area of the stairs themselves.

The diagram below provides an example of how CFA is calculated (click on image to enlarge):

/by
, ,

California Votes to Require Solar PV for new homes by 2020

The California Energy Commission voted 5-0 Wednesday, May 9, to adopt new energy building standards requiring solar panels for virtually all new homes built in the state starting in 2020.

..Article in Orange County Register

/by

New Title-24 residential ventilation requirements

The current 2016 Title-24 Building Energy Code Standards contains new indoor ventilation requirements.  California has adopted the residential standards of ASHRAE 62.2  All low-rise residential buildings must have a whole house ventilation system that provides a calculated minimum amount of outdoor air by using either a continuously running bathroom fan or a supply or return air ventilation thru a central HVAC system. The minimum ventilation volume must be a minimum of 1 cfm for each 100 sq. ft. of floor area plus 7.5 cfm for each occupant. The number of occupants is determined by multiplying the number of bedrooms and then adding one. For example a 3 bedroom, 1,800 square foot townhouse would require 48 cfm of continuous ventilation.  Additional calculations are required if the fan will be running intermittently thru-out the day as the fan will need to provide a larger airflow when running.

.

.

Broan has introduced a bathroom fan/smart switch system that meets this requirement.  It keeps track of the total usage of the fan thru-out the day and if fall short of the required number of air changes it will automatically turn on and run until the required airchanges have been satisfied.  It also meets the maximum sound level requirement at 0.70 sones.  It also coordinates with other fans normally installed in the house, such as the range hood to meet the calculated minimum cfm required.  This new requirement takes effect January 1, 2010 when California adopts the 2008 Title-24 Building Energy Standards.

/by
, ,

Title-24 Question of the Week

What is a NFRC window label & why do I need it?

.

The 2016 California Title-24 Building Energy Standards require that the efficiency of windows and doors be documented in the Title-24 compliance calculations using one of two allowable methods.  NFRC or the default assumptions.  We’ll address both methods:

.

NFRC:

.

The NFRC (National Fenestration and Rating Council) is a non-profit organization which oversees and sponsors an energy efficient certification and labeling program to document the thermal performance of windows, doors, and skylights.

.

California’s Title-24 Energy Code requires that U-factor, SHGC values used in Title-24 compliance reports be backed up by NFRC documentation as well as a temporary label on the actual window/door available for inspection during construction.  The temporary label shows the U-factor and SHGC for each rated window and door.  This label must also show that the window meets the air infiltration criteria.  This temporary label must not be removed before inspection by the building official at final inspection.  There also is a permanent label is usually inscribed on the spacer, or etched on the glass, or engraved on the frame and includes a number or code to allow tracking back to the original performance information on file with the NFRC.

.

Default tables:

.

Many times window and door manufactures have not gone thru the NFRC testing procedure or the windows/doors are essentially site built which makes it impossible to test the actual performance of these windows and doors.  In this case your only option is the default assumption method.

.

This involves modeling your project for Title-24 compliance using the C.E.C.’s default U-factors and SHGC values from the default tables (Tables 110-6-A and 110-6-B in the Title-24 standards).  These default values are assumptions based on window and framing types.  If the windows and doors are using these default tables for their performance numbers (U-factor & SHGC) they also must have a label that uses the phrase “CEC Default U-factor” and “CEC Default SHGC” in front of or before the U-factor or SHGC.  These phrases cannot be simply used in a small print footnote on the label.

.

If default performance values are used then the Title-24 energy calculations also must use the same values in the compliance report.  Most windows and and door that are tested and labled by the NFRC have U-factors and SHGC values that are significantly better than the default values from the tables.  This can often make the difference between passing and failing the Title-24 energy code standards so it is to your advantage to use the NFRC testing data in the Title-24 compliance calculations rather than using the default numbers from the tables.

.

Overlooking this crucial item in the Title-24 report can result in huge problems during construction.  It is not uncommon for the installing window contractor to bid on the project without ever consulting the approved Title-24 energy code report.  If the Title-24 report is calling out for NFRC compliant windows and doors and the contractor orders and installs non-NFRC products the project is in real trouble.  During the course of construction the building inspector normally will go thru the project looking for the NFRC stickers on the windows/doors and compare them with the approved Title-24 Certificate of Compliance.  If there are discrepancies noted, or the windows/doors have no NFRC stickers, or are site-built then the builder must either revised the Title-24 compliance report to demonstrate that the project will comply with the default assumptions in table 110-6 (U-factor and SHGC) or replace the windows/doors with NFRC compliant ones.

.

The problem is that often times there is no margin within the Title-24 analysis to absorb the significant penalty for using the default tables for U-factor and SHGC values.  This penalty is significant especially with metal framed windows/doors.

.

The lesson is clear, Title-24 compliance should be a central topic for discussion with window/door suppliers and installers when they are bidding on the project, not pushed off with vague assurances which later could bring the project to a standstill when this comes to light during construction.

 

 

 

/by
, , , ,

Santa Monica adopts Zero Net Energy Code for all new single family construction

.

.

On May 1, 2017 Santa Monica became the first city to adopt zero-net energy (ZNE) requirements.  The State of California is planning to implement such a code state-wide but this will not be implemented until the 2020 T-24 code cycle so Santa Monica is out in front with net-zero.

.

The basic premise of ZNE requires projects to generate enough of their own energy from renewable energy sources (solar PV for example), to equal what they use from the utility grid over the course of a year.  For now this requirement only applies to new residential projects, not additions or alterations.

.

However the ZNE requirement is parallel to the city’s Energy Reach Code which requires all new low-rise residential projects to be designed to use 15% less energy than the allowable energy budget established by the 2016 California Energy Code (Title-24).  This presents some challenges as projects that may comply with the reach code (15% better than T-24) may not comply as a ZNE project.  Conversely projects that can demonstrate ZNE compliance may still fall short of the 15% better than T-24 energy use.  One does not always equal the other.

.

This new code update became effective May 1, 2017.  This emphasizes the importance of getting your Title-24 Energy Consultant involved in your project early in the design process as most projects will struggle to comply and will involve a lot of back and forth as different design and energy saving strategies are modeled, tested and revised to get the project over the finish line cost-effectively.

.

.

Link to news release

.

.

Link to detailed ZNE and Reach Code explanation

.

.

.

.

/by

Title-24 Question of The Week

.

Question: What is a high performance attic?

.

Answer: The new 2016 Title-24 Building Efficiency Standards now has prescriptive requirements for high performance attics using a number of construction methods.  The underlying principle for all methods involves reducing attic temperatures with the additional benefit of improving the performance of HVAC ducts that travel thru the attic.  This goal can be accomplished by using a standard ventilated attic configuration with energy saving improvements, or by constructing an unventilated attic that behaves thermally like a conditioned space.

Ventilated Attic:

Ventilated attic option provides for two basic paths toward compliance.  The first path is called Ducts In Conditioned Space or DCS.  The DCS option is achieved when the ducts and the air handlers are within the thermal envelope and air barrier of the building.  This option involves constructing a standard vented attic with an additional layer of insulation directly underneath or above the roof deck as follows:

ou will need to use the larger of either the rated wattage of the recessed can fixture that is listed on the UL label or the wattage indicated in Table 6-3 found on page 6-15 of the 2008 Residential Compliance Manual.  The wattage assumptions in Table 6-3 vary depending on the size of the recessed fixture (diameter of the aperture) and the ceiling height.   click on table below to enlarge

.

.

/by

New Title-24 HVAC Fan Airflow requirements.

.

The new 2016 Title-24 Energy Code requires that new HVAC systems meet minimum airflow requirements and supply fan efficiencies.

.

Studies have shown that a significant number of HVAC installations suffer from low airflow problems.  Typically the main culprit is undersized return air design.

.

The new T-24 energy code requires that the airflow at the return be verified by an independent HERS rater to meet the minimum requirement of 350 cfm per ton of A/C capacity.  Installing HVAC contractors will need to make sure their installations will meet this minimum requirement, actually good duct design can result in up to 400 cfm per ton so the State minimum requirement of 350 cfm per ton is not overly restrictive.

.

A second option, only available to systems without zoning dampers, is to size the return ducts according to the new Tables 150.0-C and D in the T-24 Efficiency Standards and then have a HERS Rater visually verify that the installed duct system meets the design criteria of those tables.  see tables below:

.

.

.

.


/by

Architects CF-1R Signature requirements

.

The new 2016 Title-24 Energy Code requires that all CF-1R forms must be registered and signed off by the architect/designer of record.

.

This process begins with the architect registering with either CalCerts or CHEERS, two of the approved HERS providers in the State.  We suggest you register with both as some of your projects will be uploaded to either provider.

.

Registration with either provider is no charge to the architect

.

Here is the link for architects to register with CalCerts, the form is called a “Builder Signature Form” but can be used by architects as well:

.

Training video: how to register your company with CalCerts

.

.

.

.

.

/by

HERS duct tests are now mandatory statewide

.

The new 2016 Title-24 Building Efficiency Standards  require mandatory HERS duct testing for all new construction and HVAC changeouts where the ducts are altered.

.

In addition minimum airflow requirements must be met and tested by an independant HERS rater.

.

We recommend HVAC installers become familiar with these new rules and perform their own “rough-in” duct tests prior to completion of the project to insure the ducts are not leaking before drywall installation.

.

Also, remember that all gaps between the supply/return boots and the surrounding drywall must be sealed (caulking is fine) before the HERS duct test.  The HERS rater must visually verify that these gaps are sealed.  Most importantly if they are not sealed it is likely the system will fail the duct tests.

.

We are state certified HERS raters, for any questions about duct testing or to schedule us for duct testing on your next project call us at (800) 700-0131

.

Or email us at: mark@energycode.com


.

.

.

.

/by

New 2008 Title-24 Energy Standards

The new 2008 Title-24 Building Energy Standards have been formally adopted by the California Energy Commission and are slated to be enforced in April of 2009. Click below for a summary of the Residential and the Non-Residential changes.

2008 Title-24 summary

/by