Lecture 6: Building Envelope Description (Part II) Material prepared by GARD Analytics, Inc. and University of Illinois at Urbana-Champaign under contract to the National Renewable Energy Laboratory. All material Copyright U.S.D.O.E. - All rights reserved

2 Importance of this Lecture to the Simulation of Buildings  Every building is different in many ways: Location/exterior environment Construction/building envelope HVAC system  Building envelope/construction determines how a building will respond to the exterior environment  Thermal simulation requires information about the physical make-up of the building, where various constructions are located and how they are oriented, how the building is subdivided into zones, etc.  Thermal simulation requires information on the building envelope to properly analyze the building from an energy perspective

3 Purpose of this Lecture  Gain an understanding of how to specify the building construction Groups of Surfaces (Zones) and Overall Building Characteristics Walls, Roofs, Ceilings, Floors, Partitions, etc. Materials and Groups of Materials (Constructions)

4 Keywords Covered in this Lecture  Zone  SurfaceGeometry  Surface (all types)  Construction  Material:Regular  Material:Regular-R  Material:Air

5 Review of Envelope Hierarchy Building Zone … more zones Surface … more surfaces Construction Material … more materials only one construction per surface

6 Keyword: Zone  IDD Description (shortened)  Purpose: to define basic properties about a thermal zone ZONE, A1, \field Zone Name N1, \field Relative North (to building) N2, \field X Origin N3, \field Y Origin N4, \field Z Origin N5, \field Type N6, \field Multiplier N7, \field Ceiling Height N8, \field Volume A2 ; \field Zone Inside Convection Algorithm

7 Keyword: Zone  IDD Description (detailed) ZONE, \required-object A1, \field Zone Name \required-field \type alpha \reference ZoneNames N1, \field Relative North (to building) \units deg \type real \default 0 Keyword User defined zone name Allows rotation of the zone with respect to the building; see north axis for building description

8 Keyword: Zone  IDD Description (detailed, continued) N2, \field X Origin \units m \type real \default 0 N3, \field Y Origin \units m \type real \default 0 N4, \field Z Origin \units m \type real \default 0 Origin for the “lower southwest corner” of the zone in Cartesian coordinates

9 Keyword: Zone  IDD Description (detailed, continued) N5, \field Type \maximum 1 \minimum 1 \default 1 N6, \field Multiplier \type integer \minimum 1 \default 1 N7, \field Ceiling Height \units m \type real \default 0 N8, \field Volume \units m3 \type real \default 0 Used to represent similar zone without having to input all of the data multiple times This is a placeholder for a future feature of the program Volume is used to calculate the amount of thermal capacitance in the zone air and has an impact on how quickly the zone air temperature changes

10 Keyword: Zone  IDD Description (detailed, continued) A2 ; \field Zone Inside Convection Algorithm \type choice \key Simple \key Detailed \key CeilingDiffuser \key TrombeWall \note Simple = constant natural convection (ASHRAE) \note Detailed = variable natural convection based \note on temperature difference (ASHRAE) \note CeilingDiffuser = ACH based forced and mixed \note convection correlations for ceiling diffuser \note configuration with simple natural convection \note limit \note TrombeWall = variable natural convection in an \note enclosed rectangular cavity Determines the interior convection correlation used by the program; optional parameter

11 Keyword Example: Zone  IDF Example or ZONE,ZONE ONE, 0.0, 6.096, 0.0, 0.0, 1, 1, 0.0, 0.0, Detailed; ZONE, ZONE ONE, !- Zone Name 0.0, !- Relative North (to building) {deg} 6.096, !- X Origin {m} 0.0, !- Y Origin {m} 0.0, !- Z Origin {m} 1, !- Type 1, !- Multiplier 0.0, !- Ceiling Height {m} 0.0, !- Volume {m3} Detailed; !- Zone Inside Convection Algorithm

12 Keyword: SurfaceGeometry  Three dimensional (3D) Cartesian coordinate system  Right hand coordinate system X-axis points east Y-axis points north Z-axis points up Y Axis X Axis Z Axis Building and/or Zone North Axis

13 Keyword: SurfaceGeometry (cont’d)  Vertex-based Specify 3D coordinates of each corner of a surface  World Coordinates All coordinates refer to global origin Building and Zone north axes ignored Zone origins ignored (except for daylighting)  Relative Coordinates Zones relative to building Surfaces relative to zones Subsurfaces relative to zones

14 Keyword: SurfaceGeometry (cont’d)  Surface starting position, looking from outside UpperLeft, UpperRight, LowerLeft, LowerRight  Order of vertex entry Clockwise, Counterclockwise  Coordinate system WorldCoordinateSystem, RelativeCoordinateSystem  IDF Example: SurfaceGeometry, UpperLeftCorner, !- SurfaceStartingPosition CounterClockWise, !- VertexEntry WorldCoordinateSystem; !- SurfaceGeometryKey

15 Relative Coordinate Options  Building North Axis Relative to true north Rotates about bldg origin  Zone North Axis Relative to building north Rotates about zone origin  Zone Origin Relative to building origin (0,0,0)  Surface vertices in zone coordinates True North Building North Axis +30 degrees Zone North Axis (0,0,0) Building Origin Zone Origin (x, y, z)

16 Types of Surfaces  Surface:HeatTransfer Surface:HeatTransfer:Sub Surface:HeatTransfer:InternalMass  Surface:Shading:Detached Surface:Shading:Detached:Fixed Surface:Shading:Detached:Building  Surface:Shading:Attached

17 Heat Transfer Surface  Surface:HeatTransfer  Walls, Roofs, Floors, Ceilings  Inside environment is always a zone  Outside environment Exterior with or without wind and sun Another zone surface (interzone heat transfer) Adiabatic (internal mass with geometry) Other Side Coefficients (user control of exterior surface temperature, ignores solar and sky radiant)

18 Heat Transfer Surface (cont’d)  Exterior surfaces cast shadows Shadows only cast in the direction of the outward facing normal A roof extended beyond the walls will not cast shadows downward  Interior surfaces do not cast shadows  All surfaces reflect solar as diffuse inside zone

19 Heat Transfer Surface (cont’d)  IDD Description (shortened) Surface:HeatTransfer, A1, \field User Supplied Surface Name A2, \field Surface Type (FLOOR|WALL|CEILING|ROOF) A3, \field Construction Name of the Surface A4, \field InsideFaceEnvironment A5, \field OutsideFaceEnvironment \note (OtherZoneSurface|ExteriorEnvironment|Ground| \note OtherSideCoeff) A6, \field OutsideFaceEnvironment Object \note Used only if OutsideFaceEnvironment is \note OtherZoneSurface or OtherSideCoeff \note If OtherZoneSurface, specify name of \note corresponding surface in adjacent zone or \note specify current surface name for internal \note partition separating like zones

20 Heat Transfer Surface (cont’d)  IDD Description (shortened, continued) A7, \field Sun Exposure (SunExposed|NoSun) A8, \field Wind Exposure (WindExposed|NoWind) N1, \field View Factor to Ground N2, \field Number of Surface Vertex Groups N3, \field Vertex 1 X-coordinate N4, \field Vertex 1 Y-coordinate N5, \field Vertex 1 Z-coordinate N6, \field Vertex 2 X-coordinate N7, \field Vertex 2 Y-coordinate N8, \field Vertex 2 Z-coordinate N9, \field Vertex 3 X-coordinate N10, \field Vertex 3 Y-coordinate N11, \field Vertex 3 Z-coordinate N12, \field Vertex 4 X-coordinate N13, \field Vertex 4 Y-coordinate N14; \field Vertex 4 Z-coordinate

21 Heat Transfer Subsurface  Surface:HeatTransfer:Sub  Windows, Doors, Glass Doors Only windows and glass doors transmit sunlight Can have interior windows  Must be placed on a base surface  Cannot completely cover base surface

22 Door and Window Details  Outside reveal defined by window vertices  WindowFrame AndDivider specifies details of frame, sill, inside reveal, etc.

23 Heat Transfer Subsurface (cont’d)  IDD Description (shortened) Surface:HeatTransfer:Sub, A1, \field User Supplied Surface Name A2, \field Surface Type (WINDOW|DOOR|GLASSDOOR) A3, \field Construction Name of the Surface \note To be matched with a construction \object-list ConstructionNames A4, \field Base Surface Name (that subsurface attached to) A5, \field OutsideFaceEnvironment Object \note Used only if Base OutsideFaceEnvironment is \note OtherZone or OtherSideCoeff \note If OtherZone, specify name of corresponding \note subsurface in adjacent zone or specify current \note subsurface name for internal partition \note separating like zones N1, \field View Factor to Ground

24 Heat Transfer Subsurface (cont’d)  IDD Description (shortened, continued) A6, \field Name of shading control \note used for windows and glass doors only \note If not specified, window or glass door has \note no shading (blind, roller shade, etc.) A7, \field WindowFrameAndDivider Name \note Used only for exterior windows (rectangular) \note and glass doors. \note Unused for triangular windows. \note If not specified (blank), window or glass door \note has no frame or divider and no beam solar \note reflection from reveal surfaces. N2, \field Multiplier

25 Heat Transfer Subsurface (cont’d)  IDD Description (shortened, continued) N3, \field Number of Surface Vertex Groups N4, \field Vertex 1 X-coordinate N5, \field Vertex 1 Y-coordinate N6, \field Vertex 1 Z-coordinate N7, \field Vertex 2 X-coordinate N8, \field Vertex 2 Y-coordinate N9, \field Vertex 2 Z-coordinate N10, \field Vertex 3 X-coordinate N11, \field Vertex 3 Y-coordinate N12, \field Vertex 3 Z-coordinate N13, \field Vertex 4 X-coordinate N14, \field Vertex 4 Y-coordinate N15; \field Vertex 4 Z-coordinate

26 Shading Surface  Three types  Transmittance schedule (default is always opaque)  Automatically mirrored to cast shadows in both directions  Must specify vertices A (0,0,0) Upper Left Corner Vertex for Overhang C B D

27 Shading Surface (cont’d)  IDD Description (shortened) Similar for all three shading surface types:  Surface:Shading:Detached:Fixed  Surface:Shading:Detached:Building  Surface:Shading:Attached Surface:Shading:Attached, A1, \field User Supplied Surface Name A2, \field Base Surface Name A3, \field Transmittance schedule for shading device N1, \field Number of Surface Vertex Groups N2, N3, N4, \field Vertex 1 X, Y, Z-coordinates N5, N6, N7, \field Vertex 2 X, Y, Z-coordinates N8, N9, N10, \field Vertex 3 X, Y, Z-coordinates N11, N12, N13; \field Vertex 4 X, Y, Z-coordinates Detached shading surfaces are not associated with a base surface

28 Construction  List material layers from outside to inside  Convection coefficients (film layers) are added automatically  IDF Example: CONSTRUCTION, CEILING39, !- User Defined Name C5 - 4 IN HW CONCRETE, !- Outside Layer E4 - CEILING AIRSPACE, !- Layer #2 E5 - ACOUSTIC TILE; !- Inside Layer

29 Materials for Opaque Surfaces  Material:Regular Has thermal mass Thickness, conductivity, density, and specific heat  Material:Regular-R Has no thermal mass Specify only thermal resistance  Material:Air Also no thermal mass, just resistance Cannot be an outside layer, no absorptances Otherwise, modeled same as Material:Regular-R

30 Material Example MATERIAL:REGULAR, PLASTERBOARD-2, !- Name Rough, !- Roughness 0.01, !- Thickness {m} 0.16, !- Conductivity {W/m-K} 950.0, !- Density {kg/m3} 840.0, !- Specific Heat {J/kg-K} 0.9, !- Thermal Absorptance 0.6, !- Solar Absorptance 0.6; !- Visible Absorptance Options: VeryRough, MediumRough, Rough, Smooth, MediumSmooth, VerySmooth  Parameters Affecting: Convection—Roughness Conduction—Thickness, Conductivity, Density, Specific Heat Radiation—Absorptances  Material:Regular-R and Material:Air contain a subset of the above information (see IDD for more details)

31 DataSets for Materials and Constructions  EnergyPlus\DataSets\ BLASTMaterials.idfBLASTConstructs.idf DOE-2Materials.idfDOE-2Constructs.idf WindowGlassMaterials.idf WindowGasMaterials.idf WindowShadeMaterials.idf WindowConstructs.idf WindowBlindMaterials.idf

32 Materials for Moisture Transfer  MaterialProperty:Moisture:MTF Moisture Transfer Function model  MaterialProperty:Moisture:EMPD Effective Mean Penetration Depth model  \DataSets\MoistureMaterials.idf

33 Summary  In EnergyPlus… Buildings are made up of one or more Zones Zones are made up of one or more Surfaces Zones are “thermal zones”—basis of the heat balance solution Surfaces are defined by a Construction Constructions are made up of one or more Material layers  Accuracy of simulation results directly related to accuracy of input data