Title 24 FAQS

Got a question that hasn’t been answered on this page? Click here to email our team. You can also view our Title 24 User Manual here.

I wish to do Title 24 Compliance; should I download “IESVE for Architects” or “IESVE for Engineers” on the IES website?

You’ll need two downloads; ‘IESVE for Engineers’ (http://www.iesve.com/software/download/ve-for-engineers) and ‘CBECC-Com’ (http://bees.archenergy.com/software.html).

Once IESVE for Engineers is installed, you’ll be prompted to request license keys. When the license is activated, you’ll have a free 30-day trial. If you plan to attend Title 24 training at one of the Utilities, please activate your license keys at least two days in advance of the training, as the software licenses are activated manually at IES.

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Should I use CBECC-Com version 3 or 3a as the ruleset engine when using IES-VE 2014 Feature Pack 2?

A note about VE 2014 Feature Pack 2 (the current release: Jan 2015) and CBECC-Com versions. Users may be aware that FP2 will run with either of CBECC v3 or v3a. However the VE is currently approved against CBECC v3 only.

Therefore Title24 users, especially those expecting to generate any certificates in the next few weeks, are advised to remain on, or revert to, CBECC v3. This is available from: http://bees.archenergy.com/archive.html

If there is a reason to retain an existing CBECC v3a installation, then you can make it invisible to VE by (prior to re-installing v3) renaming these two folders, also re-creating any associated shortcuts.

  •  \Program Files (x86)\CBECC-Com 2013\
  • <Libraries>\Documents\CBECC-Com 2013 Data\
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How much is IESVE software for Title 24 Compliance and how do I purchase it?

The software comes as cheap as $250 and you can access an annual license by contacting Title24@iesve.com.  Don’t forget to ask if there are any active software promotions on. A 20% discount can be offered if the number of seats is 5 or more.

VE-Compliance

Standalone

LAN (Site)

Annual

Rolling

Annual

Rolling

 IES Title 24
 Provides Title 24 Performance
(California Code Compliance)
 Complete with 1x seat of ModelIT
 (Additional seats at current list price)

$250

$400

$300

$500

An annual license requires renewal every year. A Rolling license option is a onetime software purchase, which also requires 15% as an annual fee.  The 15% maintenance fee is for ongoing software upgrades and technical support.

Technical support (email, forum and phone) is included with any software purchase.

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What is the difference between using the ‘Title 24’ Application in IESVE and using CBECC-Com which is developed by NORESCO (formerly AEC)?

The Title 24 Application in IESVE uses the CBECC-Com software ‘under-the-hood’ for doing Title 24 Compliance. The idea mandated by the CEC is that every software vendor should generate the same results, because it uses the same CBECC-Com software and rulesets.  However, there are still some differences, namely:

1.  CBECC-Com on its own uses a 2-Dimensional model geometry approach, which cannot account for solar shading or daylighting in the compliance calculation.  
     IESVE provides a free 3-Dimensional Application called ModelIT (http://www.iesve.com/software/ve-for-engineers/module/ModelIT/486) for generating the building model geometry.  
     Optionally, CBECC-Com can be linked with the 3-Dimensional geometry approach, which requires the purchase of SketchUp software from Trimble (http://www.sketchup.com/download).
2.  The Title 24 application uses command such as copy and paste for quicker population of building data. It is also possible to move some thermal data from project to project.
3.  IES provides technical support by phone and email.
4.  The two IESVE applications ModelIT (for Geometry) and Title 24 (for Compliance) are fully interoperable. There is no loss of information when revisions to the model geometry are made.

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What is the 3-D Model application used and can I perform my own geometry imports?

The geometry tool is called ModelIT; and yes, you can import your own 2-D (CAD) drawing or 3-D geometry from an alternative software package such as SketchUp, Revit, Vectorworks, etc. Further details can be found here: www.iesve.com/software/ve-for-engineers/module/ModelIT/486

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Is IES an approved software vendor for Title 24 compliance modeling in California?

Yes!  IES is approved by the CEC, please see: http://www.energy.ca.gov/title24/2013standards/2013_computer_prog_list.html

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What Compliance paths are available, non-residential and residential?

IESVE supports the Non-Residential option only for Title 24 (2013 Standards), although there is a Space Function type called “High-Rise Residential Living Spaces” which could be used for a mixed-use building. Please note that the Non-Residential path is taking the performance approach only, and generates the associated Compliance reports. The compliance types are further detailed below. This may be applied for new construction, existing or alterations.

 

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Does the IES Title 24 Tool automatically generate the compliance forms?

Yes, the tool generates the NRCC-PRF-01 compliance forms; also known as the Certificate of Compliance. You can view an example of a Certificate of Compliance here.

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I am doing envelope only or envelope and lighting only Compliance. Do I need to specify the HVAC system in the Title 24 Application?

No. When doing either of these, you need to create the model building geometry in ModelIT (http://www.iesve.com/software/ve-for-engineers/module/ModelIT/486). All rooms need to be assigned a space function in the Title 24 Application. If doing envelope and lighting compliance, (NewEnvelopeAndLighting is selected for the Compliance Type in the Building Data dialog). You will also need to input the details of the proposed lighting design. If doing envelope only compliance (Compliance Type set to NewEnvelope) then the default lighting power density data for the space functions should be left as default in the model – any user entries will be replaced.

You do need to assign Thermal Zones to the rooms in the Tools: Mechanical section but you do NOT need to specify any HVAC systems. Thermal zones are required to allow the rules to assign HVAC equipment for the proposed and baseline models.

When compliance analysis is performed, the proposed model will use the user specified envelope. For envelope only compliance, the proposed and standard (or baseline) models will use identical interior loads, using the default values assigned to the space functions being used. For envelope and lighting compliance, the standard (or baseline) models will use the default lighting power while the proposed model will include the user supplied lighting system. For both compliance types, the HVAC system type will be the same. The rules used to define and size the baseline system for a complete building analysis will be used for both the baseline and proposed models. Sizing of the proposed may be different due to differences in heating and cooling loads due to differences in the envelope and lighting systems.

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What if a material being used in my design is not listed in the material library?

You will need to select a material from the Project Materials library with similar thermal properties to the material being used. This CEC approach is mandated and is not an IES-VE limitation.

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Once the proposed compliance model is built, do we need to change anything on the baseline case, or will the baseline be generated automatically?

The standard model (or baseline) is automatically generated.  The user cannot make changes.

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What are the options for specifying lighting? Is lighting power density the only method used?

There are two options; the Area Category Method and the Tailored Method.

Lighting in the Area Category Method can be defined as a lighting power density (W/sf).  Alternatively, lighting systems can be defined by the Tailored Method which requires the definition of each lighting fixture and quantity of each fixture in the space.

Each lighting system can be assigned to a daylit area type for use with daylighting controls: Skylit, the portion of the floor that receives daylight from a skylight; Primary Sidelit, portion of the floor that receives the highest amount of daylight from a window; Secondary Sidelit, portion of the floor that receives a lower, but still useful, amount of light from a window; or none for that portion of the space which is not daylit.

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I’m getting too many unmet load hours. What is the process for compliance when CBECC-Com (using IES Title 24 Application) determines the HVAC system for the proposed building is undersized?

When the simulation has more than 150 hours of unmet load hours, the HVAC system capacities must be manually increased to meet the load, even if that doesn’t represent the actual HVAC system. Remember to increase both airflow and coil capacities. There is an exceptional condition that should be marked “Yes” when this is done, and a note will be added to the compliance report.

Please note there is a known issue as of this date (January 15th) in CBECC-Com for the Assembly space function that is causing a lot of unmet heating hours, due to the temperature schedule.

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I am receiving errors with room names. Can you offer any general guidance for the 3D model?

As the Title 24 module in the VE runs the CBECC-Com Ruleset & EnergyPlus simulation engine for compliance, there are a few limitations with regards to naming the rooms. Please note that these issues do not exist elsewhere in the VE:

  • The &, >, <, and $ symbols cannot be used.
  • No more than 10 rooms allowed per thermal zone.
  • Duplicate room names are not allowed. Each room and each zone must have a unique name.
  • Rooms on different floors cannot be on the same thermal zone.
  • The analysis will not be successful with any space or surface polygon (PolyLp in CBECC-Com) containing more than 120 vertices due to a limitation in the EnergyPlus simulation.
  • Self-shading surfaces (from ModelIT) are not accounted for in the Title 24 calculation.

Another common issue we see coming through to our technical support team is a mismatch on ventilation information.  Some entries include 15 cfm/person, for example, but then the ventilation source is set as cfm/ft2.  The CBECC ruleset will then check for the cfm/ft2 value, which is 0, and gives an error about not enough ventilation.

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How does the Title 24 application (using CBECC-Com) use daylighting controls in the simulation and what inputs are required?

CBECC-Com determines daylit zones from the geometry of the space and the locations of skylights and windows when valid fenestration constructions have been assigned. When lighting power is above 120 W in a daylit zone, daylighting controls are required. Daylighting inputs include the amount of lighting controlled and the daylighting control type. Three types of controls are available: Continuous, Continuous Plus Off, and Stepped Switching. The Continuous controls can operate at any fraction between the minimum and maximum power output. With the Continuous Plus Off controls, the minimum power output is zero. The Stepped Switching controls changes the lighting power output in discrete uniform steps.

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My project is using packaged single zone rooftop units. When I enter my systems and attempt a Title 24 compliance analysis, I get an error message that terminal units are required. My project doesn't have terminal units. What is the problem?

The Title 24 Application does not use Apache, but rather EnergyPlus. Terminal units are required by EnergyPlus as the connection between an air system and a thermal zone. In your case the terminal units would have a type of "Uncontrolled" and corresponds to the grill through which supply air enters the space.

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How can I claim Power Adjustment Fraction (PAF) credits in the Title 24 Application for the lighting in my space?

In CBECC-Com interior lights can be modelled by either simply specifying the lighting power density, or by building up a detailed lighting system. PAF credits can be claimed only with the InteriorLightingSystem method. Within the ‘Space Data>Interior Lighting’ tab, choose the PAF credit type applicable for your lighting system derived from the of ‘Lighting Controls’ drop down menu. The software will auto populate the PAF fraction and adjust the total lighting power based on the selection.

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What are the import/export options available in IES-VE for Title 24?

Imports include SketchUp, AutoCAD, ArchiCAD, Affinity and anything supporting gbXML or IFC (e.g. from Revit or Vectorworks). There is a gbXML export, as well as copy/paste and import/export functionality when dealing with tabular edits (spreadsheet-style) for speedy population of models.

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None of the ‘Compliance Types’ allow for lighting layout design in the Title 24 Application (with CBECC-Com). Are there other applications in IESVE that consider this issue?

Yes, IES have alternative analyses for lighting design.

1.  The FlucsPro and LightPro applications allow for a detailed lighting layouts and analysis, with resultant room-by-room LPDs (W/sf). Example outputs & LPD results are shown below.
     AND / OR
2.  The RadianceIES (Day-Lighting Harvesting Simulation) and ApacheSim (Hourly Annual Energy Simulation) applications allow coupling of daylight harvesting and lighting energy simulation.
     Software prices are shown below. Please contact title24@iesve.com to ask about available discounts.

Software prices are shown below. Please contact title24@iesve.com to ask about available discounts.

IES VE Applications

Standalone

LAN (Site)

Annual

Rolling

Annual

Rolling

FlucsPro (Lighting Design & Analysis)

$300

$700

$500

$1,200

LightPro (Luminaire Placement & Database)

$100

$250

$200

$400

RadianceIES (Day-Light & Glare Simulation)

$800

$2,000

$1,300

$3,200

ApacheSim (Hourly Annual Energy Simulation)

$1,000

$2,400

$1,600

$4,000

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The Title 24 Application (with CBECC-Com) doesn’t have any HVAC sizing capabilities. Can I use other applications in IESVE for sizing HVAC systems?

Yes, IES have alternative analyses tools for HVAC sizing purposes. The HVAC sizing applications will allow you to calculate heating & cooling loads, min/max airflow requirement and AHU/Plant sizes. The methodology used is ASHRAE prescribed; Heat Balance Method.

1.  The ApacheLoads application allows for the calculation of heating & cooling load calculations at a room or zone level. This calculation utilizes a ‘simple’ or ‘ideal’ central HVAC system.
2.  The ApacheHVAC application allows for the calculation of heating & cooling load calculations at a system level. Coupling this application with the ApacheLoads application allows for detailed central plan   HVAC sizing and optimization. ApacheHVAC can also be coupled with the ApacheSim (Hourly Annual Energy Simulation) application to allow coupling of detailed HVAC systems integrated with hourly whole building energy simulation.

Software prices are shown below, as well as some example outputs and sizing reports. Please contact title24@iesve.com to ask about available discounts.

IES VE Applications

Standalone

LAN (Site)

Annual

Rolling

Annual

Rolling

ApacheLoads (ASHRAE HVAC Loads Calculation)

$400

$1,000

$700

$1,600

ApacheHVAC (HVAC System Optimization)

$500

$1,200

$800

$2,000

Other OPTIONAL Applications:

SunCast (Solar Analysis & Simulation)

$800

$2,000

$1,300

$3,200

ApacheSim (Hourly Annual Energy Simulation)

$1,000

$2,400

$1,600

$4,000


Custom ApacheHVAC system configuration are showing airside schematic layout with embedded waterside HVAC schematic layouts, as well as individual component (e.g. fan) performance curves:


HVAC Systems Loads reports are showing coil sizes, fan sizes, airflow rate requirements (minimum, maximum, outdoor air rates etc.).  HVAC Loads reports also include hot water and chilled water plant sizes and detailed room-level reports:

 

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I am receiving an error about a “non-convex space”. Is there a problem with my geometry, specifically with a ‘C-shaped’ or ‘L-shaped’ room?

This has been a common issue reported to our technical support team, but is not always reproducible.  To understand the limitations of model geometry in OpenStudio/EnergyPlus (called upon by CBECC-Com), please watch the YouTube clip: https://www.youtube.com/watch?v=GzJSHQHTHy4. There have been some instances whereby simple model geometry from ModelIT has to be further simplified, so that there are no ‘C-shaped’ or ‘L-shaped’ rooms.

Please be aware that cutting rooms into separate simple 4-sided entities might throw the daylight zoning calculation off.

A so-called “non-convex” space or zone is one where one or more surfaces cannot “see” one or more of the other surfaces in the space or zone. A common example would be an “L” shaped zone.

When CBECC-Com calls upon EnergyPlus to run its “Solar Distribution” model, it should not have the detailed “FullInteriorAndExterior” setting engaged. CBECC-Com is set to run a simpler solar distribution model called “FullExterior”. In this case, beam solar radiation entering the zone is assumed to fall on the floor, where it is absorbed according to the floor's solar absorptance. Then any radiation reflected by the floor is added to the transmitted diffuse radiation, which is assumed to be uniformly distributed on all interior surfaces. Non-convex spaces or zones should not create problems when FullExterior solar distribution is used.

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Can I use the Title 24 model for LEED submission (ASHRAE 90.1)?

You can use the same 3-D model, but not with the Title 24 Application. For ASHRAE 90.1 Compliance, you would rather open that same model and use the ASHRAE 90.1 Navigator which will automate the 90.1 modeling and reports (for LEED submittal). It also provides a detailed workflow so to accurately account for all building energy end-uses:

Software prices for the ASHRAE 90.1 Navigator can be found by contacting title24@iesve.com.

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