Frequently Asked Questions

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Errors

You are trying to run calculations that are related to the California Title 24 code.  In order to run these calculations, you must select a location that is in the list of California locations.  If you did not intend to run a Title 24 code calculation, then you need to select a different calculation.  California locations have a Climate Zone selection between 1 and 16.

 You can navigate to the top level of the Building Tree, and in the General tab, hit the Select button to select a location that is in California.

 If you did not intend to run a Title 24 calculation, click on the Calculations button at the bottom left of the screen.  In the list that appears above this selection, you will find all of the different calculations that can be run.  Ensure that all Title 24 calculations do not have their boxes checked, and check the appropriate box for the type of calculation you intend to run.

 You can now click the Calculate button on the menu bar to rerun your calculations.


You have selected the option to run a calculation that has not been activated on your computer. This usually means that you either have not purchased this particular calculation module, or you have not entered the necessary activation code to enable this calculation.

You can verify what calculations are activated on your computer by clicking on Help | Activated Modules. If you have the activation code that was sent by EnergySoft Sales, you can enter this under Help | Software Activation.

If you think this is a calculation that you have purchased, you can contact sales@energysoft.com for further help.

If this is not a calculation that you have purchased, click on the Calculations button on the bottom left. Above this button a list of calculations will appear. Find the calculation in this list and uncheck the box that tells EnergyPro to run the calculation.


You are trying to run a Lowrise Residential Calculation for this project, but it appears you have no valid Zones/Rooms entered that are designated as either Single Family or Multi-Family.

Begin by checking each Zone for a valid occupancy type. Below each Zone, verify that you have entered a square footage for each of the Rooms.

If you did not intend to run Lowrise Residential Calculations, you need to uncheck the option to run this calculation. Click on the Calculations button on the bottom left. Above this button a list of calculations will appear. Find the calculation in this list and uncheck the box that tells EnergyPro to run the calculation.


You have input a project with the Number of Dwelling Units input as greater than 2 and the building is designated as having more than 3 Stories. The Standards consider this building to be a Highrise Residential Occupancy.

You have checked the calculation option to perform a Lowrise Residential calculations, which would not be appropriate for this type of building.

You can change the Number of Dwelling Units at the Zone level of the tree, Dwelling Units tab. You can change the number of stories at the Zone level of the tree, General tab.

If you did not intend to run Lowrise Residential Calculations, you need to uncheck the option to run this calculation. Click on the Calculations button on the bottom left. Above this button a list of calculations will appear. Find the calculation in this list and uncheck the box that tells EnergyPro to run this calculation.


At the Zone level of the tree, you have input the Number of Floors as zero. You must enter a valid number that is one or greater.

At the Zone level of the tree, in the General tab, enter a valid number greater than zero.


When describing an HVAC system that uses a water heater to provide the hot ware for the space heat (Combined Hydronic), the software will perform calculations for the boiler that account for both the Domestic Hot Water usage as well as space heating usage.

Since the calculations must be done for both the HVAC and DHW usage, you must include BOTH calculations in your scope under the calculation options when modeling this type of system.

One option is to change the system type to a conventional system at the System Level of the Tree, Residential tab.

Your other option is to select the Calculations on the lower left. In the list that appears above, select the specific calculation you are running. On the right, check the options to include both Mechanical and DHW calculations.


At the top level of the Building Tree, you have selected a Location for the building, but the weather file associated with this location is missing from your computer. This weather file is required in order to perform the calculation you have specified.

At the top level of the Building Tree, click on the option for User Defined on the location. Now click on the Edit option and see what weather file location is specified.

You must now verify that this weather file location selected has a valid weather file located in the Program Files\EnergyPro 6\Weather folder on your hard drive.

In most cases, you should not specify your own location data. We suggest you uncheck the option for User Defined data and pick a stock location from the list of locations.


Your Domestic Hot Water heater has an invalid Energy Factor. Select the Libraries button on the bottom left. In the list that appears above, select the DHW/Boiler library. You will see your water heater listed in the library.

Verify that you have the correct type of water heater selected (Gas Fired, Electric, Heat Pump, etc).

Now verify that you have a valid Energy Factor input for the water heater. EnergyPro will list the valid range of Energy Factors that you must conform to.


Your Domestic Hot Water heater has an invalid Recovery Efficiency. Select the Libraries button on the bottom left. In the list that appears above, select the DHW/Boiler library. You will see your water heater listed in the library.

Verify that you have the correct type of water heater selected (Gas Fired, Electric, Heat Pump, etc).

Now verify that you have a valid Recovery Efficiency input for the water heater. EnergyPro will list the valid range of Recovery Efficiencies that you must conform to.


The Zone input in the Building Tree does not have a valid Occupancy type selected. Navigate in the building tree to the zone, click on the pull-down for the Occupancy selection and select from the valid choices.

This type of error shows up when opening an older file from a prior code cycle in which the prior occupancy is no longer a valid occupancy in the new code cycle and requires you to reselect a valid occupancy under the new code.


The Zone input in the Building Tree has the same name as another Zone in the Building Tree. The CEC compliance engine requires unique Zone names to run and document the project properly.

Note that EnergyPro will shorten your Zone names to conform to the CEC Compliance Manager length requirements, so only the first 25 characters of the name you have input is used. Make sure the first 25 characters of the name are unique.


The HVAC System you have entered is not a Gas Furnace / Air Conditioner system, but is another type of system such as a Heat Pump, etc. The CEC has configured the Compliance Manager so that it will only allow the modeling of a Zonal Control system on conventional Furnace / AC systems.

You can still install this system, however you cannot take compliance credit for the home as being Zonal Control.

Zonal Control systems are specified under the Zone level of the tree, under the Occupancy type. If you have selected Res Sleeping or Res Living, this is considered Zonal Control.

You can change your HVAC system over to a conventional Furnace / AC system by editing the system at the System level of the Tree.

You can remove the Zonal Control designation at the Zone level of the tree by changing the Occupancy Type to Conditioned.


You are doing a Multi-Family project, and the total floor area entered under the Dwelling Units tab does not match the total floor area of the Zone. These two numbers must match.

At the Zone level of the tree, look at the Dwelling Units tab and make sure the total area (unit floor area times the number of units) matches the floor area for the zone. Do not use fractional values, as these usually do not add up.

In the Zone level of the tree, look at the entries for the Rooms under the Floor Area entry and be sure you have the correct numbers entered.


When modeling a project using the CBECC Com engine, the CEC requires that every zone have a valid floor to ensure a stable simulation within EnergyPlus.  This means you either need a slab-on-grade if this zone has a ground floor slab, an exterior raised floor if this zone is over open space or crawlspace, or an interior surface designated with a floor assembly.  The total of these surfaces needs to match the Conditioned Floor Area of the zone (which is the sum of the Room Floor Areas).


At the Zone level of the tree, under the Occupancy Type selection you have designated at least one Zone as being Res Living. This designation means this zone is a Residential Living Zone under the CEC modeling rules for Zonal Control systems. This means the home has an HVAC system that can independently serve the living and sleeping areas of the home. Please consult the CEC guidelines in the Residential Compliance Manual for the requirements of this system design.

No other Zone in the building tree has been designated as Res Sleeping. If you wish to take this modeling credit, you must edit another Zone in the tree, and designate the occupancy as Res Sleeping.

If you do not wish to model the system as Zonal Control, edit the Zone Occupancy and change the designation to Conditioned.


At the Zone level of the tree, under the Occupancy Type selection you have designated at least one Zone as being Res Sleeping. This designation means this zone is a Residential Sleeping Zone under the CEC modeling rules for Zonal Control systems. This means the home has an HVAC system that can independently serve the living and sleeping areas of the home. Please consult the CEC guidelines in the Residential Compliance Manual for the requirements of this system design.

No other Zone in the building tree has been designated as Res Living. If you wish to take this modeling credit, you must edit another Zone in the tree, and designate the occupancy as Res Living.

If you do not wish to model the system as Zonal Control, edit the Zone Occupancy and change the designation to Conditioned.


At the Zone level of the tree, the Zone Type is set to Conditioned, however other Zones in the building have this set to either Res Living or Res Sleeping, which denotes you have a Zonal Control system.

When modeling a Zonal Control system, all Zones must have the Zone Type set to either Res Living or Res Sleeping. Please consult the CEC guidelines in the Residential Compliance Manual for the requirements of this system design.

If you do not wish to model a Zonal Control system, set all Zone Types to Conditioned.


The building has a one or more floors input in the tree with a floor assembly that includes a Crawlspace. The input for the exterior perimeter of the Crawlspace (length facing to the outside) is too small for a crawlspace of this size.

If you did not mean to enter a floor with a crawlspace, find the raised floor selections in the building tree and select a different floor assembly that does not have a crawlspace.

To change the Crawlspace Perimeter, go to the top level of the building tree, select the Residential tab and enter the correct value.


Highrise Residential occupancies are mandated to have ventilation systems by the code (balanced, exhaust or supply).  These ventilation systems must be input at the Zone level of the Building Tree, Mechanical tab, in the Ventilation box.  Note that the HVAC system itself cannot provide the ventilation, although it could be provided by a Dedicated Outside Air System that feeds to the HVAC.  Each dwelling must be provided with ventilation according to the following formula:

CFM = Floor Area X 0.03 + (NBedrooms + 1) X 7.5  (NBedrooms cannot be less than 1)

You must ensure the ventilation input at the Zone meets this minimum criteria.  Note that the floor areas and bedrooms are input at the Zone level of the Tree, Dwelling Units tab.


The Domestic Hot Water boiler you have input in the DHW/Boiler library has a Standby Loss value set to zero. The CEC requires a value for this type of water heater be entered that is greater than zero.

Check to make sure you intended to enter this type of water heater. Smaller, more common federally regulated water heaters do not require this input.

You can obtain this value from the manufacturer or from the CEC Appliance directory at www.energy.ca.gov. Click on the Libraries button on the bottom left. Select the DHW/Boiler Library in the list that appears above. Now find your water heater and enter the Standby Loss value.


You are trying to run a Nonresidential Calculation for this project, but it appears you have no valid Zones/Rooms entered that are designated as valid Nonresidential occupancy types.

Begin by checking each Zone for a valid occupancy type. Below each Zone, verify that you have entered a square footage for each of the Rooms.

If you did not intend to run Nonresidential Calculations, you need to uncheck the option to run this calculation. Click on the Calculations button on the bottom left. Above this button a list of calculations will appear. Find the calculation in this list and uncheck the box that tells EnergyPro to run the calculation.


A Domestic Hot Water heater has not been input. This selection is required for the calculations you are performing. At the Plant level of the tree, select the Domestic Hot Water tab. Select a DHW Boiler from the library of choices.


The Setpoint temperature for the heating side of the Hydronic loop is set to a temperature that is higher than the Cooling Tower minimum temperature. This Setpoint sets the lower limit of the condenser water loop on the Hydronic loop. Setting this temperature to a value that is higher than the high limit side set by the cooling tower will cause the boiler to try to heat the loop to this temperature while the tower is trying to cool the loop below this temperature.

A Setpoint temperature of 65 degrees is suggested for this input.

At the Plant level of the tree, In the Heating Hot Water Tab, lower the Boiler Setpoint temperature to a value that is below the cooling tower setpoint. As an alternative, go to the Hydronic tab and select the Cooling Tower and raise the Setpoint of the Cooling Tower above the boiler setting.


Zonal type systems such as Water Source Heat Pumps, Packaged Terminal Air Conditioners and Heat Pumps and Four Pipe fan Coil systems cannot be configured to serve more than one HVAC zone given the limitation of the thermostat controls.  The CEC CBECC engine enforces this rule.

At the Zone level of the tree, make sure the system only has one Zone in the tree below the System, or choose a different system type designed to serve more than one Zone.


A valid name is required for all Zones in the Building Tree. The name must have at least one letter, and should be a unique name. At the Zone level of the building tree, enter a valid name.


The Zone you have input is a Residential Occupancy, but you have set the Zone Type to Unconditioned. Residential Occupancies are required to be conditioned.
At the Zone level of the Building Tree, either change the Zone Type to Conditioned, or change the Occupancy to a Nonresidential selection.


The airflow rate input for the HVAC system is not valid when modeling a conventional HVAC system. The CEC restricts the airflow rate on conventional systems to a mandatory minimum of 350 cfm/ton of airflow to a maximum of 600 cfm/ton.

At the System level of the building tree, in the HERS tab, edit the airflow setting and set this number to a valid rate.

If you are modeling a Zonally Controlled system, this airflow rate is allowed to go lower than 350 cfm/ton. Zonally Controlled systems are multiple zone systems with dampers designed to independently control different areas of the home. See the Residential Compliance Manual for more information on this type of system.

If your system is Zonally Controlled, in the HERS tab you can check the box for Zonally Controlled and then a lower airflow number will be allowed.


Each wall/roof/floor/slab must have a valid construction assembly selected to perform the simulation. Leaving an assembly as “undefined” is not a valid choice. In this case, the surface has been designated as either New or Altered. In both cases, you must describe the new assembly. In the case of altered, this will describe the assembly after alterations are complete.

In the Building Tree, navigate to the surface and click on the New Assembly which is undefined and select a valid assembly from the construction assembly library.


The fenestration (window or skylight) has a glazing U-Factor that is not valid. You must input a valid U-Factor for the fenestration. The U-factor is the coefficient of conduction (heat transfer) for the fenestration product. This value is obtained from the manufacturer of the product.

In the Building Tree, navigate to the window or skylight and click on the fenestration selection. This will take you into the Fenestration Library where you can either select another product that is valid, or you can edit the fenestration U-Factor directly.


Each wall/roof/floor/slab must have a valid construction assembly selected to perform the simulation. Leaving an assembly as “undefined” is not a valid choice. In this case, the surface has been designated as either Existing or Altered. In both cases, you must describe the existing assembly. In the case of altered, this will describe the assembly before alterations are made.

In the Building Tree, navigate to the surface and click on the Existing Assembly which is undefined and select a valid assembly from the construction assembly library.


A valid selection for the Location (City) is required to perform calculations on your project. In the Building Tree, at the top level of the tree, General tab, click on the “Select” button and select a valid location from the list provided.


When modeling Packaged Multi-Zone Systems (System Type = Packaged MZ), the DOE-2 engine does not allow the use of a Water Cooled Condenser. This is a limitation of DOE-2, so you must either choose a different system type or remove the Water Cooled Condenser.

At the System level of the Building Tree, click on the Central System, this will take you into the Central System library. You can now select a different system, or edit the current system. You can change the System Type to another system, or navigate to the Cooling tab and change the Condenser Type to another choice.


The first zone listed below the HVAC system in the building tree represents the control zone when dealing with single zone systems. This zone will have a thermostat that will control the HVAC operation and cannot be input as an unconditioned zone.

In the building tree, at the System level of the tree, click and hold on a zone and you can then drag and drop that zone so that it is the first zone directly below the System icon.

Another option is you can edit the Zone and change the Zone Type to Conditioned.


The product is designated as having a Hydronic Heating system but no boiler has been specified. The boiler input is required when modeling Hydronic systems.

If you did not intend to model a Hydronic Heating system, navigate to the System level of the tree, and click on the Residential tab. Change the selection for the Hydronic Space Heating system to “None”.

If you did intend to model a Hydronic Heating system, navigate to the Plant level of the tree. If the system will be using a dedicated boiler, select a boiler from the library in the Heating Hot Water tab. If the system is a Combined Hydronic system (one that uses a common boiler for both space heating and domestic hot water), select a DHW boiler from the Domestic Hot Water tab.


When modeling Built-up VAV systems that include Fan Powered Zone Terminal Boxes, it is a requirement of the DOE-2 engine that you must have at least two zones.

If you did not intend to include Fan Powered Terminal Boxes, navigate to the Zone level of the tree, and select the Mechanical tab. You can now click on the Zone Terminal and select a different terminal box from the library, or you can edit your terminal box and change the type of box.

If you did intend to include Fan Powered Terminal Boxes, you just add an additional Conditioned Zone to this HVAC system (unconditioned zones don’t count).


Fan Powered Terminal Boxes (input at the Zone level of the building tree) can only be modeled with Chilled Water (Built-Up) Variable Air Volume (VAV) systems. This is a modeling limitation of the DOE-2 Simulation Engine. These types of terminal boxes cannot be selected when the system type is a Packaged VAV system.

At the Zone level of the Building Tree, in the Mechanical tab, you can select a different type of terminal box that is not fan powered, or you can edit the selected terminal box and change the type to a non-fan powered version.

At the System level of the Building Tree, you can select a different system type, or you can edit the current system type and change it to a Built-Up VAV system. However, keep in mind the Built-Up VAV system will require the definition of the chiller and pumps.

Some users have opted to model the fans as exhaust fans at the Room level of the building tree. Some have opted to model the DX compressor and an air cooled chiller and thus select the system type as Built-Up VAV.


You are trying to run a Nonresidential Calculation for this HVAC System, but it appears you have no valid Zones/Rooms entered that are designated as valid Nonresidential occupancy types.

Begin by checking each Zone for a valid occupancy type. Below each Zone, verify that you have entered a square footage for each of the Rooms.

If you did not intend to run Nonresidential Calculations, you need to uncheck the option to run this calculation. Click on the Calculations button on the bottom left. Above this button a list of calculations will appear. Find the calculation in this list and uncheck the box that tells EnergyPro to run the calculation.


Demand Control Ventilation (DCV) is a mandatory measure in the Title 24 Standards Section 120.1 in high density spaces. Zones that meet these criteria must be designated as having DCV controls to regulate the amount of outside air to the zone.

At the Zone level of the Building Tree, Mechanical tab, check the box for DCV, or at the General tab, select a different occupancy type that does not require the use of DCV.


Each HVAC system must have a valid central system selected to perform the simulation. Leaving a system as “undefined” is not a valid choice. In this case, the system has been designated as either Existing or Altered. In both cases, you must describe the existing system. In the case of altered, this will describe the system before alterations are made.

In the Building Tree, navigate to the System level of the tree and click on the Existing System which is undefined and select a valid system from the Central System library.


At the System level of the tree, in the Residential tab, you have indicated that you have a Whole House Fan (CFM and Watts have been input).  This feature is only available on a home that has an Attic space, since the WHF is designed to cool both the house and the attic.

At the System level of the Tree, Residential tab, you should zero out the CFM input, or you should change your roof configuration so that the house has an Attic instead of Cathedral Ceilings.


Demand Control Ventilation (DCV) is a mandatory measure in the ASHRAE 90.1 Standards in high density spaces. Zones that meet these criteria must be designated as having DCV controls to regulate the amount of outside air to the zone.

At the Zone level of the Building Tree, Mechanical tab, check the box for DCV, or at the General tab, select a different occupancy type that does not require the use of DCV.


Interior surfaces can either be selected as floors, walls or ceiling/roofs. When inputting an interior floor it is input in the space that is above the other space. For instance on the second floor you would input and interior floor that is over the first floor. As part of this input, the elevation of the floor must be input. We recommend you leave the elevation at zero, the program will use the floor elevation input for the Room.

Many times, a floor is input into the first floor and is designated as being over the second floor. This is not possible. This type of input would be a ceiling/roof, not a floor. A floor must be input as being above another space, a ceiling as being below another space.

Review this input for this surface and be sure you intended to input a floor and not a ceiling/roof. The type of assembly selected determines this definition. Review the floor elevation and the room elevation to be sure they are consistent with the adjacent room.

Note that interior surfaces do not need to be input twice. Thus you would input either the ceiling of the first floor or the floor of the second floor but not both.


When modeling a slab on grade surface it is important to input the area of the slab as well as the exterior perimeter of the slab correctly.  Make sure the exterior perimeter entered is less than the area of the slab.


The DOE-2 engine has a limitation that only allows you to model four central utility plants. The building tree contains more than four so this model cannot be run with DOE-2. You can generally simplify the model and combine plants, there is probably no circumstance where you need more than four independent hydronic chilled water/hot water loops in a building.


When inputting interior surfaces there is a selection at the bottom of the input screen to describe the room that this surface is “Adjacent To”. Without this input, the software does not know what this surface is next to. In the Building Tree, navigate to the interior surface and at the bottom of the input screen, click on the Adjacent To button. Select another room in the list that appears.

Note that inputting interior surfaces between rooms that are in the same zone is not necessary. The only impact you will see from this feature is if you have interior surfaces that are between different zones.


When doing compliance calculations, the software uses an engine developed by the CEC, the Compliance Manager. While the CEC’s published Joint Appendix 4 includes a very detailed list of assemblies as shown in EnergyPro, the CEC Compliance Manager does not implement the entire list.

The CEC recommendation is to open a copy of the Reference Appendices (Help | Title 24 | Reference Appendices), and find the U-factor for your proposed construction assembly in Joint Appendix 4 (also be sure to note the maximum U-factor from Section 150.0 of the standards). With that U-factor known, model a wood-framed assembly with a similar or slightly higher U-factor. Consider naming the construction to match what the builder will be constructing rather than what you modeled (e.g., call the R-30 wood-framed roof/ceiling with 0.032 U-factor that is substituting for your R-38, 0.031 U-factor, roof R-38 metal framed roofin case you use the file for a different job). Lastly, document for the plan checker what you did.

In the Building Tree, navigate to this surface, click on the Construction Assembly and either edit the current assembly by clicking on the green Import button or select another assembly from the library.


The Compliance Manager issued by the CEC has strict requirements on the number of surfaces that must be input into a Zone. Without a minimum of 3 surfaces for Nonresidential or 6 surfaces for Residential, the Compliance Manager will not produce stable results. Also, each Zone will need to have a floor and ceiling/roof to run properly.

Many times the project may not have that many surfaces. One approach you can take is to divide a wall into two pieces and meet the criteria. Also, interior surfaces next to another Zone count towards the six surfaces on both the Zone it is in as well as the Zone it is adjacent to.

When inputting the surface areas, do not try to trick the software by inputting one square foot surfaces.  This will only result in the simulation failing to run.  It is imperative that you input realistic surface sizes for the Zone being modeled.


The mandatory measures require that all heated slab floors must have slab edge insulation. A heated slab floor is a slab-on-grade assembly that has either electric or hydronic heating embedded in the slab. Refer to the Residential Compliance Manual for details on how this would be accomplished, along with insulation details.

In the Building Tree, navigate to the slab floor, and click on the Construction Assembly. You can now either select a different slab floor from the library, or edit the slab floor. To change this to a different selection, click on the green Import button and you will see two different lists of slab floors, Heated and Unheated.

If you select an Unheated Slab, the insulation is no longer required. If you select a Heated Slab, you must choose one from the list with a minimum insulation level that meets the requirements in the mandatory measures section of the code for your climate zone.


When describing surfaces for a Zone, there will generally be four walls, and floor and a ceiling/roof. Looking at the geometry of these inputs, it would not be possible that any individual surface in that zone could be larger than all of the remaining surfaces. This indicates either an input error for the square footages, or there are surfaces that have not been included when describing the Zone, and the CEC Compliance Manager will not run.

Note that interior surfaces are included in this tabulation, so be sure interior surfaces in other zones have the “Adjacent To” set properly so this Zone includes that surface in the tabulation.

Check your inputs for this Zone and verify the correct square footages for each surface and make sure you have both floors and ceiling/roofs input.


When modeling HRV or ERV systems, the software requires two ratings, taken from HVI (Heating and Ventilating Institute) Directory.  The ASRE (Adjusted Sensible Heat Recovery) and the SRE (Sensible Heat Recovery) Ratings.  The ASRE must be at least equal to the SRE rating.

At the Zone level of the Building Tree, in the Dwelling Units tab, check your inputs for these two ratings under the IAQ fan heading.


 

When inputting custom curve data points for a Heat Pump HVAC System, as the outdoor drybulb temperature decreases, the output of the heat pump should also decrease since the heat pump will have less capacity at lower temperatures.

Edit the data for the Central System on the Curves tab such that at lower temperatures, the system will have less output than at the higher temperatures.


When inputting custom curve data points for a Heat Pump HVAC System, as the outdoor drybulb temperature decreases, the efficiency of the heat pump should also decrease since the heat pump will operate at lower efficiencies at lower temperatures.

Edit the data for the Central System on the Curves tab such that at lower temperatures, the system will have a higher kW input than at the higher temperatures.


When inputting custom curve data points for a cooling System, as the outdoor drybulb temperature increases, the output of the heat pump should decrease since the cooling system will have less capacity at higher temperatures.

Edit the data for the Central System on the Curves tab such that at higher temperatures, the system will have less output than at the lower temperatures.


When inputting custom curve data points for a cooling System, as the outdoor drybulb temperature increases, the efficiency of the cooling system should also decrease since the cooling system will operate at lower efficiencies at higher temperatures.

Edit the data for the Central System on the Curves tab such that at higher temperatures, the system will have a higher kW input than at the lower temperatures.


When inputting custom curve data points for a cooling System, you must enter data for the cooling system that includes one data point 85F or below, and one point 115F or above.


Modeling of heat pumps requires data be included for the system heating output at both the 47 and 17 degree AHRI outdoor design rating conditions. Manufacturers publish both sets of data in their literature, and this same data is also listed in the AHRI listing and sometimes in the CEC equipment directories.

In the Central System Library, in the Heating Tab, enter the Heating Output for the heat pump based upon both rating conditions.


When a heat pump is input, the software requires that the heating capacity of the unit be given at two rating conditions.  The first rating condition is when the outside ambient drybulb is at 47 degrees F.  The second rating condition is when outside conditions are at 17 degrees F.  At both conditions, the manufacturer’s rated output needs to be input into the Central System Library entry for the heat pump.

At the Central System library, in the Heating tab, enter a value for the Heat Pump heating output at the 17 degree condition.


Variable Refrigerant Flow (VRF) system modeling includes describing both the outdoor condenser unit of the system as well as the indoor evaporator units at each of the zones. Each manufacturer places restrictions on how much indoor unit capacity can be coupled to a particular outdoor unit. EnergyPro will check how much indoor unit capacity has been specified and ensure that this falls within the acceptable limits of the VRF manufacturer.

You should review the VRF modeling guide at www.energysoft.com under the Support section of the website.

Verify the total capacity of each outdoor condenser unit that has been input at the System level of the building tree. Navigate to each Zone under that particular system, and verify the capacities of the indoor units that have been input at the Mechanical tab for the Zone. This total installed capacity of indoor units must fall within the parameters of the manufacturer.


When inputting the efficiency of the HVAC system, ensure the value entered is consistent with the type of system being modeled. If it is small furnace, the value would be an AFUE that is in the range of 0.7 to 1.0, while a small heat pump would have an HSPF in the range of 7 to 12. Double check that you have entered this value correctly by selecting the HVAC system in the System level of the Building Tree and reviewing the inputs in the heating and cooling tabs.


Cooling systems are described with two efficiency metrics, the Energy Efficiency Ratio (EER) and the Seasonal Energy Efficiency Ratio (SEER). Since the SEER represents the seasonal average performance across the cooling season, this value will be higher than the EER.

At the System level of the tree, select the HVAC system. In the Cooling tab, review your inputs for the SEER and the EER and ensure the SEER is higher than the EER.


Each Zone entered into the Building Tree is required to have an Elevation entered for the Zone that describes the distance above the exterior grade of the building. Thus, a ground floor Zone with a slab on grade would have an elevation that is 0.7 feet above the exterior grade. Each floor of the building will require this value be input.

In addition, each Zone is required to have the Floor to Floor height entered that describes the distance from the Zone floor elevation to the Zone above floor elevation. If the Zone that is above another Zone does not have a floor elevation that is at least equal to the lower floor elevation plus the floor to floor height, this is an error.

At the Zone level of the Building Tree, navigate to the Building Story input.  Each unique level of the building (story) should have an entry.  Example, Floor 1, Floor2, etc.

Review the inputs for Floor Elevation and Floor to Floor Height for each Zone in the Building Story, and ensure these values have been input consistently.

Note that it is valid to have a single Zone that encompasses more that one floor of the building, you would simply select the lower story for that Zone.


At the Zone level of the Building Tree, a Zone Terminal box has been input as well as the Heating and Cooling Airflow values.  The heating flowrate for this zone is lower than what is needed to provide the minimum code required ventilation for the zone.

At the Zone level of the Building Tree, in the Mechanical tab, compare the Heating Airflow input to the code required airflow reported in this message.  Note that while you may have chosen to input lower ventilation rates in the Room Occupancy tab, the code minimum specified by the CEC in the CBECC ACM manual tables will always be used as the minimum so you cannot go below this number.


When modeling Zones, each surface in the Zone must have a unique name. This is a rule enforced by the CEC Compliance Manager. Note that when inputting names, only the first 25 characters that you input are considered, so ensure the names are reasonably short, and unique.

At the Building Level of the Tree, navigate to the surface and edit the name so that is it unique.


 

Under the Distribution tab at the System level of the tree, you are given the option of selecting the location of the ductwork. When the location has been set to Attic, the CEC Compliance Manager requires that the total size of the attic must be at least 10% of the total square footage of the home. Without an attic of at least this size, there is insufficient space for the model to include the total volume of ductwork.

You have the option of changing the location of the ductwork by editing this input and selecting another location if your attic area does not meet this criteria.

If you think you have attic area that is 10% or more, navigate to each roof in the building tree. Review the area input for each roof. Also, click on the construction assembly and verify that you have selected a roof construction that includes an attic, and not a cathedral roof type construction.


The Light Fixture you have selected has included an input below the fixture for a Control for Credit Lighting Power Density adjustment per Table 140.6-A in the Title 24 Standards. The control referenced is not valid for the type of occupancy selected for this Zone.

Please review the valid applications of this control in Standards Table 140.6-A and make sure you have selected a valid control. You can either change the control or change the occupancy at the Zone level of the tree.


Under the Distribution tab at the System level of the tree, you are given the option of selecting the location of the ductwork. When the location has been set to Garage, the CEC Compliance Manager requires that you must have a Zone in the building tree input that has the Zone Type set to “Res Garage”.

You have the option of changing the location of the ductwork by editing this input and selecting another location if you don’t have a garage.

If you think you have input a garage, navigate to each Zone in the building tree. Review the Zone Type input for each Zone, one should be “Res Garage”.


Under the Distribution tab at the System level of the tree, you are given the option of selecting the location of the ductwork. When the location has been set to Crawlspace, the CEC Compliance Manager requires that the total size of the crawlspace must be at least 15% of the total square footage of the home. Without a crawlspace of at least this size, there is insufficient space for the model to include the total volume of ductwork.

You have the option of changing the location of the ductwork by editing this input and selecting another location if your attic area does not meet this criteria.

If you think you have crawlspace area that is 15% or more, navigate to each exterior floor in the building tree. Review the area input for each floor. Also, click on the construction assembly and verify that you have selected a floor construction that includes a crawlspace.


The Light Fixture you have selected has included an input below the fixture for an Additional Allowance as described in Table 140.6-C in the Title 24 Standards. The Additional Lighting Allowance referenced cannot be used on the type of occupancy selected for this Zone.

Please review the Additional Lighting Allowances in Standards Table 140.6-C and make sure you have selected a valid selection per this table. You can either change the Additional Allowance selection for the light fixture or change the occupancy at the Zone level of the tree.


The Lighting Elements in the building tree have an entry for the Fixture Reference Code, as well as the Luminaire listed in the library.  When entering a Reference Code, it has to match the Luminaire in the library throughout the tree.

In other words, using Reference Code F-1 for fixture A, and then using Reference Code F-1 for fixture B would not be valid {0}.  Fixture B would require a different reference code, this is required to build the fixture list as part of the documentation on the forms.
Check your Luminaire Selection and Reference Code to ensure they are correct at each entry in the Building Tree.


The HVAC System has been input with an Evaporatively Cooled Condenser, but the EER rating at 95 degrees for the unit has been input as being higher than the EER rating at 84 degrees. Since the EER84 rating is at 84 degrees and the EER95 rating is at 95 degrees, the EER84 rating should always be higher than the EER95 rating.

Either change the EER84 or EER95 rating so that the EER84 is higher than the EER95 rating.


In the location listings, you have the option of selecting a location, and also you have the option of editing the location using the User Defined option. You have edited the location and you have not selected a valid DOE Climate Zone. In the Location Selection you must edit your Location and select a valid DOE Climate Zone. We suggest not using the User Defined feature, but rather that you select a stock location from the listings.


Your HVAC System is marked as either New or Altered, but you do not have a New Mechanical System selected at the system level of the tree. An HVAC system is REQUIRED for the type of calculations you are performing.

In the System menu of the Building Tree, select a System from the Central Library.


You have selected an HVAC System that is a Combined Hydronic System, which can only be modeled by the CEC CBECC engine if the heating boiler is not a Heat Pump. In this case you are using a Heat Pump for the boiler and this cannot be modeled.

The approach to model an Electric boiler or Heat Pump Water Heater that provides space heating is to treat it as an electric space heater, and indicate no ducts.  This is a CEC rule, not a program limitation, so you should consider an alternative system.


The current CEC CBECC engine will not allow you to set the fan CFM at zero (such as when modeling a radiant system).  You must enter a CFM for the Supply Fan on all HVAC Systems.


All fans that are input into EnergyPro require a valid motor power rating (either input as the Brake Horsepower (BHP), the Nameplate Horsepower, or the Input Wattage).  This applies to any fans in which you have input a flow rate (CFM) in order for the CBECC Com engine to simulate the fan.

In the Central System Library, check the Fan tab for valid inputs for the Supply Fan and optionally the Return Fan.

In the Zonal System Library, check the Fan tab for any fan powered terminal boxes and equipment.

At the Zone level of the tree, check the Mechanical tab for valid inputs for the Exhaust Fan.


When defining an HVAC system, it is a requirement of the CBECC Com calculation engine that ALL HVAC system must have a capacity entered for the system.  The software will not auto-size capacities, it is your responsibility to define this number.

At the Central System Library, edit the HVAC system and add a Heating and/or Cooling output for the HVAC system identified in this message.


The Title 24 Standards mandate that any Nonresidential buildings with more than 200 sqft of Site Built Vertical fenestration cannot use the Center of Glass inputs in the fenestration description.

In the Fenestration Library, edit your inputs for the fenestration ratings and either use a Manufactured product, or use Defaults or NRFC rated values in the energy model.


You have left the Floor Area for the room set to zero.  A Floor Area entry is required for all Rooms in the building tree.  If you double click on the Error this will take you to the Room in the Building Tree where you should enter a valid value greater than zero.


When defining openings in a wall that include shading features (Overhangs or Sidefins) you must define the geometry of the Wall (Width and Height) as well as the geometry of the Windows and Doors (Width, Height) as well as the location of the opening on the Wall (XPos, YPos).  The XPos and YPos are the position of the bottom left corner of the Window or Door on the Wall.

If the Window/Door Height + the YPos exceeds the total wall height, the surface is located out of the boundary of the Wall.

If the Window/Door Width + the XPos exceeds the total wall width, the surface is located out of the boundary of the Wall.

Check your inputs for the wall dimensions, as well as your inputs for the Window/Door dimensions as well as the relative X/Y positions for validity.


At the Zone level of the Building Tree, an input is provided for the Story of the building the Zone is assigned to.  In that list, each Story is required to have a unique name that describes the particular Story.  As an example, Floor 2 could be used to describe the second story of the building.

Each name in this list must be unique, duplicate names are not permitted.  Check this list and ensure each Story is assigned a unique name.


The Floor to Floor Height for the Zone can never be less than the Ceiling Height. This Ceiling Height must always be less than the floor to floor height.

At the Zone level of the tree, in the Building Story input, either increase the Floor to Floor Height, or decrease the Ceiling Height.


You are analyzing an Addition alone, and the Existing Floor Area is set to 0.  In the case of an Addition, the Existing Floor Area of the building must be entered.

Navigate to the top level of the Building Tree and enter the Existing Building Floor Area.

If you are not modeling an Addition alone, navigate to the top level of the tree, and change the Building Type.


At the System level of the Building Tree, you have an HVAC system input with the “Outside Air From” setting configured to receive outside air from another HVAC system.  That other HVAC system has not been defined and must be properly configured for the simulation to run.

Select a valid HVAC system for your DOAS system from the Central System library.


At the Zone level of the Building Tree, a Zone Terminal box has been input as well as the Heating and Cooling Airflow values.  The cooling flowrate for this zone is lower than what is needed to provide the minimum code required ventilation for the zone.

At the Zone level of the Building Tree, in the Mechanical tab, compare the Cooling Airflow input to the code required airflow reported in this message.  Note that while you may have chosen to input lower ventilation rates in the Room Occupancy tab, the code minimum specified by the CEC in the CBECC ACM manual tables will always be used as the minimum so you cannot go below this number.


At the Zone level of the Building Tree, a Zone Terminal box has been input as well as the Heating and Cooling Airflow values, and the Minimum CFM Ratio for the Zone Terminal Box.  The Minimum turndown for this zone is lower than what is needed to provide the minimum code required ventilation for the zone.  The minimum turndown airflow rate is equal to the Cooling Airflow times the Minimum CFM Ratio input for the Zone Terminal Box.

At the Zone level of the Building Tree, in the Mechanical tab, compare the Cooling Airflow input and the Minimum CFM Ratio to the code required airflow reported in this message.  Note that while you may have chosen to input lower ventilation rates in the Room Occupancy tab, the code minimum specified by the CEC in the CBECC ACM manual tables will always be used as the minimum so you cannot go below this number.

Note that if you have checked the box for Demand Control Ventilation (DCV) your terminal box is allowed to turndown the airflow to 0.15 cfm/sqft and thus the minimum ventilation rate will be reduced in this case.


When modeling an Underground Surface, the Depth below Grade is a required input and cannot be set to Zero.

At the Underground Surface, edit this value to match the depth below grade for the Basement Zone.


The surface you have input has an area of zero which is not a valid surface and the simulation will not run.  You either need to edit the surface in the Building Tree and input a valid surface area, or you need to delete the surface from the Building Tree.


At the system level of the tree, you have input one or more HVAC systems with an identical name.  The CEC CBECC engine uses the system name in the simulation and reports and requires that all systems in the building have a unique name.

Navigate to the System level of the Building Tree and edit the name shown.  Note that you do not need to edit the name in the Central System library, that name does not have to be unique.  Only the name shown in the Building Tree at the system level will need to be edited.


You have input either a window or a skylight into the Building Tree.  In that entry, you have selected a Fenestration product from the Fenestration Library.  The fenestration selected is the wrong type.

Click on the Fenestration item in the building tree, this will take you into the Fenestration Library.  Review the entry for Fenestration Type, if this is a skylight, it needs to be set accordingly.  If it is a Vertical Fenestration product, ensure the appropriate selection is made.

Note that if you have both windows and skylights using the same fenestration entry, you will need to create two entries in the library, one for windows, another for skylights.


You are modeling a Highrise Residential project and have failed to input the correct number of stories for this occupancy type.  Highrise residential projects are considered four stories or more.

At the Zone level of the tree, review each entry for the Floor Number input.  You must ensure that this is set to four or more.  If your project is in fact less than four floors, you need to change the Zone Occupancy input to Multi-Family and run the Res T24 Performance calculation instead.


At each Zone is an input for the Number of Floors which determines how many stories for this particular zone.  So if a zone being modeled included both the second and third floors of a building, it would be set to two since that zone included two floors.  Normally you would set this to one and model each floor as a zone. The CEC CBECC engine will not allow this number to be greater than 3, which means the zone you are modeling consists of all three floors of a building.  While you might have a zone that exceeds 3 floors this particular input cannot be greater than 3.

To correct this, go to the Zone and change this number to no more than 3.


At the Zone level of the Building Tree there is an input for the Accessory Dwelling Unit (ADU) that includes the choices of No, Attached or Detached.  You have designated more than one Zone as being an ADU and this is not permitted by the modeling tools.

You must either change the setting in the Zone to no, or you must combine the various Zones designated as being ADU into a single Zone.


The area of this surface is greater than half the total surface area of this zone, which includes both child surfaces and Interior walls and floors which are next to this zone.

This is not physically possible to have a single surface that is larger than half of all other surfaces in a zone, since that zone as a minimum will have ceilings and floors that will prevent this circumstance.

You have either made a mistake in the area of this surface or you have forgotten to input all of the other surfaces in the Zone.

Either reduce the size of this surface, or increase the areas of other surfaces in the Zone.


The total area of Interior walls which are adjacent to your Zone is greater than half the total surface area of this zone, which includes both child surfaces and Interior walls and floors which are next to this zone.

This is not physically possible to have a single surface that is larger than half of all other surfaces in a zone, since that zone as a minimum will have ceilings and floors that will prevent this circumstance.

You have either made a mistake in the area of this surface or you have forgotten to input all of the other surfaces in the Zone.

Either reduce the size of this surface, or increase the areas of other surfaces in the Zone.


The total area of Interior floors which are adjacent to your Zone is greater than half the total surface area of this zone, which includes both child surfaces and Interior walls and floors which are next to this zone.

This is not physically possible to have a single surface that is larger than half of all other surfaces in a zone, since that zone as a minimum will have ceilings and floors that will prevent this circumstance.

You have either made a mistake in the area of this surface or you have forgotten to input all of the other surfaces in the Zone.

Either reduce the size of this surface, or increase the areas of other surfaces in the Zone.


You have entered a Zone as unconditioned but the current CEC CBECC engine does not support modeling of unconditioned zones. You have the option of inputting spaces as Residential garages. This input is handled at the Zone level of the tree under Zone Type.

Either change the Zone Type to Conditioned or Res Garage, or remove this zone from the model.


You have selected an HVAC system that is a multiple zone Variable Air Volume (VAV) system.  This type of system requires that you input the Zone Terminal Boxes for each zone served by the system.  If a zone does not have any terminal boxes, simply input a terminal box that is Constant Volume for the modeling.

To input the terminal box, go to the Zone level of the Building Tree, in the Mechanical tab you will select an appropriate Zonal System for the zone.


The HVAC System you have selected is not a system type currently supported by the CEC CBECC engine. The CEC does not currently have this type of system implemented in the Compliance Manager but will be implementing it in an upcoming version.

For now, please select a different system type or just input a smaller system.


You are modeling a VRF system in Version 6 or 7 (this FAQ does not apply to version 8), and since the VRF modeling is not approved by the CEC for Title 24 permit application, you cannot use the VRF system type in EnergyPro.  For Title 24 permit submittals, you must model the units as a series of minimum efficiency split system heat pumps.  Model all of the ‘indoor units’ as their own outdoor unit (in the Central System Library, and at the System level of the Tree) and the outdoor unit does not get modeled. The heating and cooling capacity, fan airflow and design power should all come from the indoor unit specs. Don’t model an outside air economizer in the outside tab. You can use the System Multiplier in the Building Tree if any of the units are identical.  The heating and cooling efficiencies would be the standard code minimum efficiencies.

3 Phase – 13 SEER, 11 EER, 7.7 HSPF

1 Phase – 14 SEER, 11.7 or 12.2 EER, 8.2 HSPF

Please also reference the Appliance Efficiency Standards for the standard efficiencies.


You have input an Interior Surface that has a very large surface area. In this case, the interior surface are is larger than the sum of all other surfaces in the Zone it is adjacent to. This is not physically possible to have a single surface that is larger than all other surfaces in a zone, since that zone as a minimum will have ceilings and floors that will prevent this circumstance.

You have either made a mistake in the area of this surface or you have forgotten to input all of the other surfaces in the Zone.

Either reduce the size of this surface, or increase the areas of other surfaces in the adjacent Zone.


You have selected an HVAC System that is a Hydronic Heating System, which can only be modeled by the CEC CBECC engine if the heating boiler is Gas Fired (not a Heat Pump or Electric Resistance boiler). In this case you are using are not using a Gas Fired unit for the boiler and this cannot be modeled.

Either change your system type to a Non-Hydronic system at the System level of the Tree, General tab, or at the Plant level of the tree, Heating Hot Water Tab, select a Boiler that is Gas Fired.

The approach to model an Electric boiler or Heat Pump Water Heater that provides space heating is to treat it as an electric space heater, and indicate no ducts.  This is a CEC rule, not a program limitation, so you should consider an alternative system.


The project has been identified at the Top level of the Building Tree as a Addition Alone.  When analyzing this type of project, the HVAC system must either be defined as Existing or New.  You cannot select Altered.

If you wish to analyze the HVAC system as being Altered, you must input the entire Existing portion of the building into the building tree.  At the top level of the Building Tree, change the Building Type to Existing + Addition/Alteration.

Your other option is to go to the System level of the Building Tree and change the System Type to New or Existing.


At the System level of the Building Tree, you have specified HVAC systems that include chilled water coils.  You have not input a chiller to serve these coils at the Plant level of the Building Tree.

Go to the Plant level of the Building Tree, and in the Chilled Water Tab, input the chiller and associated chilled water pumps for the HVAC system.


You have defined equipment in this building that requires a boiler.  This could include hot water coils at the air handler, zone terminal box heating coils, or in the case of a water source heat pump, a condenser water loop that requires a boiler.  You are required to input a boiler and hot water pumps.

Go to the Plant level of the Building Tree, and in the Heating Hot Water Tab, input the boiler and associated hot water pumps for the HVAC system.


When equipment is defined at the central plant such as Boilers, Chillers and Cooling Towers (including those used for Hydronic Heat Pumps) you must be sure to define the pump associated with that piece of equipment.

To correct this problem, go to the Plant Level of the Building Tree, and go into either the Heating Hot Water, Chilled Water or Hydronic tab and define the flow rate and horsepower for pumps associated with all equipment that has been input.


When inputting Interior Surfaces, you have the ability to indicate the Zone that the surface is Adjacent To as part of the inputs.  Since different Zones can have different Floor Multipliers, the CBECC engine requires that the Zones on each side of the interior surface must have the same Floor Multiplier.

If you wish to change the Floor Multiplier, go to the Zone level of the Building Tree and click on the Building Story.  From there you can edit the Floor Multiplier.

Another option is to edit the Interior Surface and change the Adjacent To setting to be another Zone that has the same Floor Multiplier, or you could even set the surface as Adjacent To itself.


You have defined equipment in this building that requires a cooling tower.  This could include water cooled chillers or in the case of a water source heat pump, a condenser water loop that requires a cooling tower.  You are required to input a cooling tower and condenser water pumps.

Go to the Plant level of the Building Tree, and in the Chilled Water tab (for chillers) or in the Hydronic tab (for water source heat pumps), input the cooling tower and associated condenser water pumps for the HVAC system.


When inputting Underground Walls, the CBECC Res engine will only allow a wall construction assembly which is either Concrete, Insulated Concrete Form (ICF) or Brick.  For Underground Walls, you must select a construction assembly from the library which is one of these types, you cannot use conventional frame walls, and CMU walls are also not supported currently.

In the Building Tree, you must either select a different construction assembly that fits this description, or edit the construction assembly you have selected, hit the green Import button and import either a Concrete, ICF or Brick wall from the JA4 selections.

It is acceptable to add framing and insulation to the concrete wall once selected, however, in the Res T24 Perf tab.

 


You are trying to perform a Prescriptive Calculation on a project specified as New Construction (New Home).  The Prescriptive calculation is only valid for Additions and Alterations and can produce the CF1R-ADD and the CF1R-ALT.  For a new home, the CF1R-NCB must be produced and registered with a HERS provider, we have no way to upload that information to the HERS provider.

This project should be run under the Performance approach instead.


In the Assembly Library, you have forgotten to define the Layers for your construction assembly.  At least one layer must be defined.

Go to the Assembly Library on the bottom left of the screen under Libraries, select this assembly and navigate to the Layers tab on the right.  Double click on a blank layer and select an appropriate material from the list.


The CEC CBECC modeling engine requires you to input any interior surfaces in the House (conditioned zone) not into a space marked as Zone Type = Residential Garage.  Drag and drop this surface from the Garage into the House, and then re-assign the Adjacent To setting for the surface.


When modeling conditioned spaces under Title 24, all spaces are required to be ventilated per the code.  At the Zone level of the tree, in the Mechanical tab, you have set the Ventilation to None.  This is not a valid choice, so either choose that it comes from the HVAC system, from an Exhaust Fan, or it is Naturally Ventilated.  Note that the Natural Ventilation choice is only valid for Residential spaces and cannot be used for Commercial spaces.


When modeling conditioned spaces under Title 24, all spaces are required to be ventilated per the code.  At the Zone level of the tree, in the Mechanical tab, you have set the source of ventilation as being provided by the HVAC system.  The HVAC system is specified as having the fans cycle with the load, which will not provide continuous ventilation, or it has no ducts.

You have a number of choices here:

At the Zone level of the Building Tree, in the Mechanical tab, choose another source of ventilation, such as a local exhaust ventilation fan.  Note that the Natural Ventilation choice is only valid for Hotel/Motel Guest Rooms and cannot be used for other spaces.

If this is a VRF system, change the Indoor Unit fan specification and remove the option for Fan Cycles with Load.

For other systems, change the Central System option in the Controls tab to have the fan run continuously.

Add a Dedicated Outside Air System (DOAS) to provide the ventilation.


When modeling conditioned spaces under Title 24, all spaces are required to be ventilated per the code.  At the Zone level of the tree, in the Mechanical tab, you have set the Ventilation to Natural Ventilation.  The Natural Ventilation choice is only valid in the software for Hotel/Motel Guestrooms (2016 Title 24 also allows it in Highrise Res) and cannot be used for other occupancies.  This setting needs to be change to either a  Ducted HVAC System, or to an Exhaust Fan.


In the Title 24 Standards section 120.1, the code mandates a minimum exhaust rate based upon the occupancy of the space.  When you select the Zone Occupancy and Ventilation function in the General tab, this information is determined.

One choice is to select a different Ventilation function for the Zone.  Go to the Zone and click on the General tab and click the Select button to change the Ventilation function.

The other choice is to go to the Zone and click on the Mechanical tab and specify an exhaust fan that will provide the exhaust rate shown on that tab.


Title 24 Standards section 140.9 regulates Kitchen Hoods, and contains a table that specifies the maximum exhaust flow for a hood.  Hoods that are Eyebrow style may not be used in Heavy Duty or Extra Heavy Duty applications.  Hoods that are Backshelf / Passover style may not be used in Extra Heavy Duty applications.

To correct this, go to the Zone level of the Tree, Mechanical tab and select a lower duty rating for the hood.


Central Hot Water systems used in Multi-Family applications cannot have the Distribution entry set, other than to choose either Standard or (HERS Req’d) Pipe Insulation, All Lines.  The other choices are not valid in this application.  You can either uncheck the box indicating this is a Central system, or change your selection under Distribution.


At the Zone level of the Building Tree you have set the Occupancy Type to a Nonresidential Occupancy selection.  Since you are doing a Lowrise Residential calculation (Residential Title 24 Performance), all occupancies must either be Single Family or Multi-Family.  Any other selections in that list fall under Nonresidential occupancies.
Go to the Zone level of the Building Tree and designate the Zone Occupancy selection as either Single Family or Multi-Family.


At the Zone level of the Building Tree you have set the Occupancy Type to either a Single Family or Multi-Family selection.  Since you are doing a Nonresidential calculation (Nonresidential Title 24 Performance), no occupancy can be set to Single Family or Multi-Family.

Note that a Zone Type of Res Garage is also considered a Lowrise Residential occupancy.

Go to the Zone level of the Building Tree and designate the Zone Occupancy selection as any selection in the list other than Single Family or Multi-Family and ensure the Zone Type is not set to Res Garage.


When defining a Variable Refrigerant Flow (VRF) system, two components must be defined in the Building Tree.  The Outdoor Condenser is defined at the System level of the tree, and each Indoor Evaporator unit is defined at the Zone level of the tree.  Each Zone is required to have an Indoor unit defined.

To define the indoor unit, go to the Zone level of the Building Tree, and in the Mechanical tab, click on the Zonal unit.  Select an Indoor unit that has the type specified as Variable Refrigerant Flow.


When entering a light fixture in the Building Tree, it is a requirement that you input the Reference Code for that fixture.  Typically, this will be indicated on the lighting fixture schedule on the plans.


The DOE-2 simulation used for the ASHRAE 90.1, Savings By Design and Nonresidential Performance calculations is not able to simulate an exhaust fan with variable flow at the zone.  The solution is to model this as part of the return fan for the HVAC system, and this may also mean that the system is marked as being 100% outside air.

This edit would be made by removing the exhaust fan from the Zone level of the Tree, and inputting it as part of the HVAC system, which is one level up in the building tree.


The VRF Indoor Unit you have entered in the Zonal Library does not have a Heating and/or Cooling capacity entered.  The current simulation requires both and Heating and Cooling Capacity for VRF Indoor Units.

Navigate to the Zone level of the Building Tree, in the Mechanical Tab, click on and edit the Indoor Unit and enter the capacities.


At the Zone level of the tree, Mechanical tab you have specified that the ventilation will come from the HVAC system under the input for Ventilation Type.  The code does not permit the use of the HVAC system as a source of ventilation, you must provide a dedicated ventilation system to ventilate a Hirise Residential Occupancy.

This could be an exhaust fan input at the Zone Mechanical Tab under Ventilation, a Supply Fan, or a DOAS system.

At the Zone level of the Building Tree, in the Mechanical tab, choose Zone Ventilation Fan as the source of ventilation and input the Airflow and motor watts for the Exhaust Fan under Ventilation, or include a DOAS system to provide the ventilation.


You have chosen to use an Exhaust Fan to provided the mandated Outside Air Ventilation for your zone.  You are required to define the Airflow for the exhaust fan, as well as the motor fan power.

At the Zone level of the Building Tree, Mechanical tab, input a valid exhaust fan that will be large enough to meet the ventilation required for this zone.


The HVAC System is input as a ducted Gas Fired system with Cooling.  This type of system has a maximum fan power limitation of 0.45 w/cfm in cooling mode.

You can either change your system type to something other than a ducted Gas Furnace, or you must go to the System level of the Building Tree and in the HERS tab set this value to 0.45 w/cfm or less.


When modeling a space designated as a Parking Garage area, you are required to set the Occupancy to Unconditioned.  Go to the Zone level of the Building Tree, and in the General tab, set the Occupancy to Unconditioned.


When defining Lighting elements in the Building Tree, you must select either an Existing or New Luminaire (or both for Alterations) from the Luminaire Library.


When modeling Closed Circuit Cooling Towers, the setpoint on the tower must be at least 10 degrees higher than the outdoor summer drybulb temperature to ensure a stable simulation.  This is a requirement of the CBECC engine.

To solve this problem, edit your Cooling Tower, and change the Setpoint Temperature input to a value that is at least 10 degrees above the Summer OADB.


When modeling Closed Circuit Cooling Towers, the simulation requires a maximum Delta T of 15 degrees F across the air side of the tower.  To accomplish this the fan CFM must be kept to a minimum level to prevent the Delta T going above 15 degrees.

Edit the Cooling Tower, and on the Fan tab, increase the CFM of the fan.


When modeling multiple zones on a single zone system, EnergyPro will “combine” the zones for the purposes of reducing the unmet load hours.  Basically, the program puts all the zones onto a single thermostat.  However, the CBECC simulation does not allow these zones to reference different Stories.

At the Zone level of the Building Tree, change the Building Story entry to be the same.  You can input an average ceiling height if necessary.


When modeling multiple zones on a single zone system, EnergyPro will “combine” the zones for the purposes of reducing the unmet load hours.  Basically, the program puts all the zones onto a single thermostat.  However, the CBECC simulation does not allow these zones to have multiple exhaust fans, and they must all be on the first zone.

At the Zone level of the Building Tree, you can put all of the exhaust fans into a combined exhaust fan on the first Zone listed under the HVAC System.


You have indicated that you have an Energy Recovery system, as the Zone level of the Tree, Mechanical or Dwelling Units tab.  However, the Adjusted Sensible Heat Recovery (ASRE) rating, taken from the Heating and Ventilating Institute (HVI) listing shows that this number is LESS than the Sensible Recovery Efficiency (SRE) from the same listing.  This number must be greater than the SRE rating.

At the Zone level of the Building Tree, Mechanical or Dwelling Units tab, please review your inputs for the ASRE and SRE ratings.


When performing Tax Credit calculations, the ResNet rules dictate that an Envelope Leakage Test (Blower Door Test) be performed.

At the Top level of the Building Tree, Residential Tab, check the box for Envelope Leakage Testing, and indicate the tested Air Changes per/hour at 50 Pascals pressurization


At the system level of the building tree, in the residential tab, you have input a Whole House (the CEC uses the term Ventilation Cooling), the CFM rate for this fan exceeds a simulation limit of 3.5 cfm/sqft, which is an internal CBECC limit.  You must lower this airflow rate to simulate this home.  A typical value would be in the range of 1.0 – 2.0 cfm/sqft.


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