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CAHP Master Builder Modeling GuidelinesMaster Builder1.2.1Insulated Roof Tiles (continuous rigid foam exterior alternate)These roof tiles are specifically manufactured to contain insulation to increase the thermal performanceof the roofing material. These tiles function similar to continuous insulation above the roof deck.CBECC-ResCBECC-Res 2013 4 adds an insulated roof tile system into the Construction library (i.e. Roofing types). Itprovides the ability of modeling an insulated roof tile system.1. Under Envelope tab, create or edit a Construction Assembly that “Can Assign to” the Attic Roof.2. Select “steep slope roof tile, metal tile, or wood shakes” as Roof Type.3. Under “Roofing” dropdown selection, three available options for insulated roof tile systems areGreen Hybrid Roofing Tile, GHR Tile with ENSOPRO, and GHR Tile with ENSOPRO Plus (detailedmaterial characteristics can be found in Table 5: Materials List, 2016 Residential ACM ReferenceManual).Figure 7: CBECC-Res insulated roof tileEnergyProAs of August 2016, EnergyPro does not have the ability to model insulated roof tiles. This capability maybe available in future software releases.1.2.2Wedge-It Insulation (rigid foam external alternate)Wedge-It insulation are wedge-shaped extruded polystyrene blocks that are installed between battensunderneath the concrete tiles. Although Wedge-It blocks are not continuous, this insulation option cancomply with Master Builder requirements, and can meet Title 24 prescriptive requirements.CBECC-Res and EnergyPro1. Assign a weighted area average R-value as a continuous exterior insulation layer on the roofdeck to represent the Wedge-It insulation.The weighted area average R-value must consider the air-gaps between Wedge-It blocks (for waterdrainage), the gaps for battens, and the tapered-wedge geometry of the Wedge-It cross section itself.

Master BuilderCAHP Master Builder Modeling Guidelines1.3 Ducts in Conditioned SpaceDucts in conditioned space credit can only be taken if all ducts, and air handling equipment is entirelycontained within finished, habitable, and directly conditioned spaces. Credit can be taken with orwithout HERS verification. HERS verification credit will lead to higher compliance. Qualifying designsinclude ducts in a conditioned plenum space, ducts in a dropped ceiling within the conditioned space,ducts in interstitial spaces between floors, and ducts under a finished cathedral ceiling. When ducts arelocated in an unventilated attic (sealed attics), they are not considered to be in in conditioned space andcredit should not be taken. For sealed attics, see section 1.4.1 Unventilated Attic (UVA) a.k.a. SealedAttic1.3.1Ducts in Conditioned Plenum Space (Box or Scissor)Figure 8: Diagrams of ducts in a conditioned plenumSource: Adapted from www.ductsinside.org and CEC2003This design creates a plenum space made within the attic that is insulated to ceiling insulation levels,sealed off from the attic, and is intentionally conditioned from the conditioned space. In the case ofscissor or box plenum trusses, the existence of an unconditioned attic zone external to the plenumspace is assumed and a critical component of the thermal pathways that determine the modelingresults.CBECC-Res1. The plenum boundary must be modeled. For a box-truss, this includes building the vertical kneewall components of the box, and accounting for the top of the box. For a scissor truss, thissimply means accounting for the extra surface area of the angled plenum top. All plenum

Master BuilderCAHP Master Builder Modeling Guidelinescomponents should be modeled either as an interior wall (i.e. knee-walls for the vertical side ofa box plenum) or a Ceiling (below attic) element.A knee wall is a sidewall separating conditionedspace from attic space under a pitched roof. Kneewalls are modeled in CBECC-Res as an interior wall(although actually a demising surface) and areinsulated as an exterior wall. (CBECC-Res 2013 UserManual 6.6.4)2. To model a knee wall (side of the box plenum):a. Create an interior wall component within the zone adjacent to the atticb. Assign the wall areac. Select the “Zone on Other Side” as Atticd. Create or edit a Construction Assembly that “Can Assign to” the Interior Walli. Set insulation to match insulation levels being used.e. Assign this assembly to the interior wall component representing the knee wallFigure 9: CBECC-Res creating knee walls for plenum spaceFigure 10: CBECC-Res creating construction assembly for knee wall

Master BuilderCAHP Master Builder Modeling GuidelinesNOTE: When creating the Ceiling (below attic) for a box plenum, ceiling area will remain the same toaccount for the insulation on top of the plenum space. If the insulation on top of the box-plenummatches the insulation used elsewhere in the attic. No separate modeling is required. If it differs, modelthis area similar to modeling an FAU platform used; build a new Ceiling below attic component andassign the surface area and a construction assembly representing the R-value of the top of the plenum.If modeling a scissor truss, model a Ceiling below attic component. The surface area should account forthe extra surface that is the result of an angled attic floor.Distribution System modeling1. Under Mechanical Tab, create or edit a Distribution System to place ducts in one of thefollowing, depending on plan:a. Duct located within conditioned space (except 12 lineal feet)b. Ducts located entirely in conditioned spacec. Verified low-leakage ducts entirely in conditioned space (NOTE: Requires HERSVerification)NOTE: For option a., the 12 linear feet limit includes the air-handler length itself. For options b. and c.,the air-handler must also be located in conditioned space. For all three options, the modeling algorithmseliminates conduction losses from internally located ducts, but will only eliminate losses due to airleakage if the user selects the verified low leakage ducts in conditioned space credit, which requiresHERS verification.Figure 11: CBECC-Res create a distribution system

CAHP Master Builder Modeling GuidelinesMaster BuilderFigure 12: CBECC-Res ducts in conditioned space optionsEnergyPro1. Create one interior wall (knee wall) in the Conditioned Zone that is adjacent to the attica. The interior wall should have the square footage of all vertical plenum surfacescombined. For example, if a plenum has two 50 sf. Surfaces, and two 25 sf. surfaces, theinterior wall would have a total of 150 sf.2. Input the appropriate information for the wall (for example, wall area and floor elevation)3. Check the Next to Residential Attic checkbox4. Click on the New Assembly field5. Select or create a wall assembly with the insulation R-value being used on the plenumDistribution systems1. Create or edit an existing HVAC system2. Click on the distribution tab at the top of the HVAC system page, and then select “Conditioned”in the Duct Location dropdown menu3. If the low-leakage ducts test will be verified by a HERS Rater, select the option of ‘Ducts inConditioned Space with Leakage Verified’ (NOTE: Requires HERS Verification)Figure 13: EnergyPro interior knee wall

CAHP Master Builder Modeling GuidelinesMaster BuilderFigure 14: EnergyPro duct location for within conditioned space1.3.2Ducts in Dropped CeilingFigure 15: Diagram of ducts in a dropped ceilingSource: www.ductsinside.orgA dropped ceiling is a space made within the building envelope under the insulated ceiling (attic floor)that is sealed from the attic and uses the Ceiling (below attic) insulation.CBECC-ResThe only modeling action is to place the ducts and equipment in conditioned space. The thermal envelopwill be at the ceiling (attic floor) and no additional insulation or modeling requirements are necessary.NOTE: CBECC-Res will assume that HVAC equipment is also located in conditioned space. This optioneliminates conduction losses, but will only eliminate losses due to leakage if the user selects verified lowleakage ducts in conditioned space, which requires HERS verification.1. Under the Mechanical tab, create or edit the Distribution Systems for a ducts located in conditionedspace scenario. Choose one of the three options:o Ducts located Ducts located within conditioned space (except 12 ft)o Ducts located entirely in conditioned spaceo Verified low-leakage ducts entirely in conditioned space. NOTE: Requires HERSverification.

Master BuilderCAHP Master Builder Modeling GuidelinesEnergy Pro1.2.3.4.1.3.3Create or edit an existing HVAC systemSelect the distribution tab at the top of the HVAC system windowSelect “Conditioned” in the Duct Location dropdown menuIf the low-leakage ducts test will be verified by a HERS Rater, select the option of ‘Ducts inConditioned Space with Leakage Verified’ (NOTE: Requires HERS Verification)Ducts within a Cathedral Ceiling (finished attic)A cathedral ceiling is a roof that is finished on the interior and meant to be used as a habitable space. Acathedral ceiling (finished attic) is not considered an unventilated attic (UVA); the difference is that thespace below the roof deck of a cathedral ceiling is fully finished, habitable and intentionally conditioned.This design may add additional conditioned square footage to the home if it creates a loft-type space.The temperature in the space below the roof fluctuates with the rest of the conditioned space, whereasthe temperature in an unventilated attic may fluctuate separately from the conditioned space.CBECC-Res1. Create a cathedral ceiling: Delete both the Ceiling (below attic) and the Attic (if they are currently present inmodel) Create a Cathedral Ceiling for the conditioned zone. Edit or create a Construction Assembly for insulation that “Can Assign to” the CathedralCeiling (minimum R-22 insulation).i. NOTE: an Inside Finish, such as gypsum board, must be used for a habitablespace.2. Creating conditioned space below the cathedral ceiling (e.g. a loft): Option 1: If the cathedral ceiling will be in a separate conditioned zone (e.g. a loft),create a separate conditioned zone (similar to creating a second story zone)i. Omit the Ceiling (below attic)ii. Add any necessary floor over garage3. Under the Mechanical tab, create or edit the Distribution Systems for a ducts located inconditioned space scenario. Choose one of the three options:o Ducts located Ducts located within conditioned space (except 12 ft)o Ducts located entirely in conditioned spaceo Verified low-leakage ducts entirely in conditioned space. NOTE: Requires HERSverification.

CAHP Master Builder Modeling GuidelinesMaster BuilderFigure 16: CBECC-Res building tree for a cathedral ceiling– Option 1 separate zone (Left)Figure 17: CBECC-Res building tree for a cathedral ceiling – Option 2 main zone (Right)EnergyProIf the cathedral ceiling will be over the conditioned floor area of the house and does not create aseparate zone (e.g. a loft):1. Delete or edit existing roof space in the zone (if necessary) If the cathedral ceiling will only cover part of the conditioned zone, then edit theexisting roof to only reflect the portion of the roof that is not a cathedral ceiling.2. Create a cathedral ceiling for the conditioned zone(s) that it will cover Click on the New Assembly field and select a cathedral ceiling from the roof library orimport a cathedral ceiling with the appropriate insulation R-value from the JA4 Library.If the cathedral ceiling will be over conditioned space that is part of a separate zone (e.g. loft):1. Delete or edit existing roof space in the zone (if necessary) If the cathedral ceiling will only cover part of the conditioned area, then edit the existingroof to reflect only the portion of the roof that is not a cathedral ceiling.2. Create a new conditioned zone in the building tree3. Create a new room/floor in the conditioned zone In the General tab, enter the square footage and average ceiling height of the cathedralceiling4. Create a cathedral ceiling for the new room Add a roof (cathedral ceiling) to the new room/floori. The roof area should equal the floor area of the sealed attic space Click on the New Assembly field and select a cathedral ceiling from the roof library orimport a cathedral ceiling with the appropriate R-value from the JA4 Library. EnergyProuses the term ‘Rafter’ ceiling in the JA4 library to represent cathedral ceiling assemblies.

Master BuilderCAHP Master Builder Modeling GuidelinesFigure 18: Creating a Rafter/Cathedral assembly from the JA4 Library5. Add an Interior Floor to the room (e.g. loft) (this represents the floor between the new room(e.g. loft)and the floor below) If the floor of the new room (e.g. loft) is only over conditioned spacei. Add an internal floor beneath the roomii. Enter the appropriate area (should be the floor area of the sealed attic)iii. Click on the New Assembly field and enter the appropriate R-Value and detailsfor the interior surfaceiv. In the Adjacent To field, select the appropriate room If the floor of the new room (e.g. loft) is over both conditioned and unconditioned space(i.e. over living space and garage space)i. Create two separate floor surfaces; one for the area over conditioned space(interior floor), and one for the area over unconditioned space (exposed floor).ii. Enter the appropriate area for each interior surface (both surfaces should havea total area equal to that of the sealed attic floor area)iii. Click on the New Assembly field for each interior surface, and enter theappropriate R-Values and details for each interior surfaceiv. I

Master Builder CAHP Master Builder Modeling Guidelines 2016 Prescriptive roof assembly and distribution systems. Applicable in climate Zones 4, & 8-16. For Climate zones 1-3 and 5-7, prescriptive requirements remain similar to the 2013 Code, using standard attic assemblies. Some nuanced diff