Frequently Asked Questions

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5. Nonresidential Title 24

At the top level of the Building Tree, in the PV+Batt tab, we offer the option to input a Battery Storage System, however there are some important restrictions on the use of this feature as follows:
  • Battery storage must be fed via a PV system, so you must input an appropriately sized PV system in this same tab.
  • Battery storage and PV are not recognized in the Nonresidential calculations for the purposes of Title 24 Compliance, although it is recognized for Above Code purposes.
  • Battery storage and PV are only recognized for New Construction projects, not for Additions and/or Alterations.
When inputting the Battery system, you will need to indicate the size of the battery, as well as the strategy used to charge the battery.  In most cases this will be the Basic charging selection.  In addition, you will need to indicate the efficiency of the system used to charge the battery as well as to discharge the battery.

Yes, unlike the older forms, the new forms have sections at the beginning that confirm if the building complies based upon the information you have input.  You will generally find a section related to the Controls, as well as related to other aspects such as the installed wattage, etc.

 


It is important to make sure all relevant sections of the form are completed, and make sure you have input any Mandatory controls.  These are input at the Top level of the Tree, Forms tab.  In particular, any options selected here that have an asterisk (eg lighting control options) must include a valid explanation of the reason for the exemption.

 


Select the Assembly Library by clicking on the Libraries in the bottom left corner and selecting the library in the list that appears above.  Now in the right pane, select your roof assembly.  Check the box that indicates the roofing is CRRC-1 certified, then enter your roof reflectance and emittance.  This data will come from your roof properties, typically obtained from the Cool Roof Rating Council website.


This would require us to review a detailed set of plans and specifications for the project. Our software support services are confined to issues related to running the software, not how to design a building to be in compliance so this is not something you should contact us about.  However, we do realize the new codes are much tougher so we have compiled some ideas below for you to consider.

In addition, getting a better idea of what the Standard Building looks like so you will understand the budget would be a good idea. There are a lot of online resources to help you understand the energy code including trainings offered by the utilities.  Our support forums also will give you the opportunity to see how other users are getting their buildings to comply.


They are just warnings, if you feel your inputs are set properly then it is fine to ignore them.  EnergyPro sets standards for these inputs and gives you a warning if anything is more than 30% outside of that range.


There is no set limit to the length of names in the building tree, but CBECC adds data to the field names to keep track of the parent/child relationships and interactions. So you might want to try limiting names to 25 characters.


Only fixed Overhangs and Side Fins are recognized in the modeling tools, the CEC does not currently recognize other devices such as shade screens or blinds.


The calculation engines in EnergyPro that are now used for Title 24 code compliance are developed and maintained by the California Energy Commission. The new Residential and Nonresidential calculation engines they provide are significantly slower than the prior ResSim and DOE-2 engines we provided in older versions of EnergyPro. The new engines incorporate CSE and EnergyPlus, which are more powerful than the older calculations, and simulate the zones much more thoroughly, resulting in longer simulation runtimes.

Try to keep the number of zones in your model to an absolute minimum, but it is not unusual to see run times of over an hour on more complex models.

To speed up run times, you can select the Quick Analysis option, which will run a partial year simulation.  In the bottom left, click on the Calculations.  In the list that appears above, select either Res T24 Performance or NR T24 Performance.  On the right will appear the option for Quick Analysis.  This will cut your runtime in half.  However that option will trigger a report that includes a watermark that states “Not useable for compliance” since you must run the full year for code compliance.

Another option is to check the box for “Do Not Generate PRF01/CF1R”  This will skip the report generation feature that occurs at the end and can save additional time, but you will not get the Title 24 reports needed for permitting.


Prescriptive measures are the values of the standard package A in that climate zone – it is also the design of the baseline building; mandatory measures have to be meet no matter what. For example if a building may comply using the performance approach, with only R-7 insulation in a raised floor, but R-19 must be installed because that is the mandatory minimum.


Interior surfaces are surfaces between two spaces and can be either walls, ceilings or floors.  Note that interior walls can also contain doors.  If you have an interior window, treat it as an interior door in an interior wall.  Insert an interior surface in the room and set it adjacent to the other room.  If you do not set it adjacent to another room, or you set it adjacent to itself, it is treated as adiabatic.


For Title-24 compliance purposes, the CEC requires cooling to be included in the proposed building model.  When modeling a low-rise residential project, the software will include a default cooling system when calculating the results.  This system is defined automatically and you have no option to change the definition of the system.  When modeling a nonresidential project, you are responsible to define the default cooling system for your project, you cannot leave it undefined.  This would be a code minimum efficiency cooling system included as part of your model.

If you find your cooling numbers are causing the building not to comply, review your window inputs and in particular the SHGC since that will affect the cooling usage of the default system.


No, the standard building is a fixed entity based upon Title 24 guidelines, and the CEC does not permit you to change this.  To see the building comparison that Title 24 uses in the standard design, look at the Residential and Nonresidential Alternative Calculation Method Manuals.


The baseline building is a Packaged DX system in this case.  This system may not have pumps and has no cooling tower, so the reported energy will be zero.  This is a standard comparison that is dictated by the code you are comparing to and the software cannot change what the budget building looks like.


All nonresidential forms are certificates of compliance and should go on the plans.


Below is a list of tabs in which you need to enter information for a non-residential title 24 calculation. You will not need to enter every available input in each tab.

Building icon:

Building Icon

Project Design Data, Project Title, Designer, Lighting Designer (if lighting is part of your scope), Mechanical Designer (if Mechanical is part of your scope), Outdoor (if outdoor lighting is in your scope)

Plant Icon:

Plant Icon

Heating Hot Water (if you have a boiler for space heating which is separate from the domestic hot water heater), Chiller Water (if you have a built up HVAC system with a chiller) Hydronic (if you have a ground coupled system) Domestic Hot Water (unless DHW is not in the scope), Renewables (if there is a solar hot water heater you would model it here, you can ignore the Solar Space Heating and electricity production inputs)

System Icon:

System Icon

General, Distribution, MCH-2 (if your model includes MCH-2 features)

Zone Icon:

Zone Icon

         

General, Lighting, Mechanical (if you have zonal mechanical boxes or wish to adjust the ventilation)

Room Icon:

Room Icon

General, Infiltration, Occupant, Receptacle/Process, exhaust fan, lighting (if you are taking task or daylighting credits).

Within the Room icon, you will enter building assemblies such as Roofs, Walls and floors by right clicking on the room icon and selecting Add …

 


You probably have a wall, roof or floor selected that has a name which does not match the actual R value of the assembly.  See screenshot below.  You can name a wall anything you want.  The actual R value that will be used in the calculation and will show up on the report is highlighted in the screenshot.  You will need to select a different assembly with the proper R value.

 

Building ASssembly R Value


If you select the Calculation option on the bottom left side of the screen, then select the T24 Performance calculation (either Res or NR) in the list that appears above this selection, you will see an option to “View CBECC Log”. If you click on this button, you will see the CEC log file reporting the results of the simulation. Note that this file will not exist unless you first uncheck the option for “Delete Temporary Files”, then click on calculate to run the simulation. At the end of the simulation you can view this log file and see what problems you have.


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