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2013 Residential compliance Software project Program Advisory Committee (PAC) Meeting

2013 Residential compliance Software project Program Advisory Committee (PAC) Meeting. July 17, 2012 Bruce Wilcox, P. E. Berkeley CA bwilcox@lmi.net. 2013 Residential Software compliance project Goals. Provide public software for 2013 Standards compliance

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2013 Residential compliance Software project Program Advisory Committee (PAC) Meeting

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  1. 2013 Residential compliance Software projectProgram Advisory Committee (PAC) Meeting July 17, 2012 Bruce Wilcox, P. E. Berkeley CA bwilcox@lmi.net

  2. 2013 Residential Software compliance project Goals • Provide public software for 2013 Standards compliance • Improve accuracy, particularly in cooling, to support zero net energy goals • Foster collaborative software environment for the future Wilcox - 2013 Residential Compliance Software Project

  3. Project Technical Team Bruce Wilcox Prime Contractor, Project Manager, Technical Lead Chip Barnaby CSE Lead Programmer Scott Criswell Compliance Manager Lead Programmer Dave KrinkelDevelopment Plan Phil Niles CSE chief scientist Robert Scott Compliance Form Generator Ken NittlerCompliance Ruleset Marc HoescheleDHW Simulation Doug Herr DHW Programmer John Proctor HVAC modeling Wilcox - 2013 Residential Compliance Software Project

  4. Compliance Data Registry Compliance User 3rd Party Tool Compliance Data Repository 3rd Party Tool Building Energy Code Compliance (CBECC) Compliance Report Generator Compliance Manager Software HERS Ruleset 2013 Title-24 Compliance Ruleset & TDV CSE Simulation Engine DHW Engine 2013 Title-24 weather data Diagram key: Transfer of building model (multiple arrows imply transfer of multiple building models) Transfer of compliance reports Inter-process communication of data and/or API calls Possible future modules Pale Blocks

  5. Current Project Schedule Wilcox - 2013 Residential Compliance Software Project

  6. CSE Simulation Engine sTATUS • Energy calculation for “typical” buildings done and testing: • Integrated & improved 2008 attic and duct models • Multiple conditioned and unconditioned zones • Pressure flow inter zone air flow network for infiltration, natural ventilation, mechanical ventilation and duct leakage • State of the art ASHWAT window model • Variable convective films and mass for all surfaces • Sky temperature and radiant heat transfer for all surfaces • Improved air conditioning model with latent load calculation Wilcox - 2013 Residential Compliance Software Project

  7. CSE Simulation Engine sTATUS • Not done yet: • HVAC sizing for the simulation • Central fan cooling ventilation (Nightbreeze etc.) • Other HVAC systems: • Heat pumps • Hydronic and other unducted heating • Evaporative condensers • Multi-segment duct model Wilcox - 2013 Residential Compliance Software Project

  8. Energy Calculation rULES • Will be documented in the 2013 Residential ACM Reference Manual following the Compliance Manager data model organization • Prescribe the user inputs for compliance calculations • Explain how those inputs are used to set up the CSE and DHW calculations for the Proposed and Standard Design • Specify the Reporting and Verification required • For this presentation, focus is on new rules and rules that have changed • To accommodate new and improved algorithms • To respond to changes in the 2013 Standard Wilcox - 2013 Residential Compliance Software Project

  9. rULESCatagories • The Building/Project • Conditioned Zones • Attics • Other unconditioned zones Wilcox - 2013 Residential Compliance Software Project

  10. The Building/Project Rules • Standards Version • Dwelling Units • Solar • Construction Assemblies • Cooling and Heating Subsystems • Fan Subsystems • Distribution Subsystems • HVAC Systems • Ventilation Systems • Zoning • Air Leakage and Infiltration Wilcox - 2013 Residential Compliance Software Project

  11. Standards VeRsion • New Input: Standards Version • Compliance 2014: through December 2014 (with current Federal Air Conditioning efficiency requirements • Compliance 2015: any time (with 2015 Federal Air Conditioning Requirements) • Standard Design: AC efficiency at specified Federal level • Reporting: • Standards Version • SEER & EER if Compliance 2015 Wilcox - 2013 Residential Compliance Software Project

  12. Dwelling Units • Inputs • For each dwelling unit type in the building input • Conditioned Floor Area (CFA) • Number of bedrooms • For Multi-Family input the number of each dwelling unit type • Calculate the Indoor Air Quality (IAQ) Ventilation CFM for each unit type • Standard Design: Same Unit Types as Proposed Design • Reporting: Unit Types and minimum IAQ ventilation CFM’s for verification. Wilcox - 2013 Residential Compliance Software Project

  13. Solar • For single family and town houses if • standards version is “Compliance 2015” • and Zone is 9-15 • Then input the kWdc of the proposed Photovoltaic system (minimum 2 kWdc) • Calculate the PV compliance credit as the smaller of: • PV Generation Rate (kTDV/kWdc) * kWdc • Max PV Cooling Credit * Standard Design Cooling Energy (kTDV) Wilcox - 2013 Residential Compliance Software Project

  14. Solar • PV Credit: Wilcox - 2013 Residential Compliance Software Project

  15. Construction Assemblies • Replaces 2008 Joint Appendix 4 U-factor Tables • U-factor calculated in Compliance Manager for Prescriptive compliance and user feedback • U-factor is not an input to the CSE Simulation • Creates Layered constructions for CSE input • Material layers selected from CEC approved library • Flexible R values for insulation layers • Separate frame and cavity surfaces for frame constructions • Reporting: to be determined Wilcox - 2013 Residential Compliance Software Project

  16. Cooling Subsystems • Improved Cooling Algorithm • Adds calculation of indoor humidity and latent load • Evaporator air flow and conditions affect sensible heat ratio • New relationship based on R410 refrigerant • New input for fan motor type: PSC or BPM • Drop cooling size credit • Little used • No consensus on calculation or energy savings • New input, algorithm and report for bypass duct (TBD) Wilcox - 2013 Residential Compliance Software Project

  17. Heating Subsystems • Standard Gas Furnace algorithm unchanged from 2008 RACM (but the Federal minimum efficiency changes) • New air source heat pump algorithm, inputs and reporting to be developed Wilcox - 2013 Residential Compliance Software Project

  18. Fan Subsystems • Component of • Cooling and Heating systems • Ventilation Cooling systems • IAQ Ventilation systems • Inputs • CFM • W/CFM • Type (PSC, BPM) • Model • Fan operates at specified CFM in Airnet • Fan heat added to air stream Wilcox - 2013 Residential Compliance Software Project

  19. Distribution Subsystems • Ducts in unconditioned spaces are an important component: • Cooling and Heating systems • Cooling, Heating and Ventilation systems • Same model as 2008 with added features: • Multiple duct systems located in any zone (attic and crawl for example) • Improved treatment of insulation thickness and conductivity • Duct segments for accuracy and to support input of reduced area, buried ducts etc • Operates in ventilation mode to accurately model CFI IAQ ventilation systems Wilcox - 2013 Residential Compliance Software Project

  20. HVAC Systems • An HVAC system is a collection of one or more of the following components: • cooling subsystem • heating subsystem • fan subsystem • Distribution subsystem • Examples • Split system cooling subsystem, gas furnace, PSC furnace fan, ducts in attic • Whole house fan • Bathroom exhaust for IAQ ventilation • All components of a system use the distribution subsystem Wilcox - 2013 Residential Compliance Software Project

  21. Cooling Ventilation Systems • Natural ventilation through openable windows • Mechanical Cooling Ventilation • Whole House Fan • Integrated Central Fan (Nightbreeze, Smartvent etc) Wilcox - 2013 Residential Compliance Software Project

  22. Window Ventilation Cooling • Same inputs, defaults and reporting as 2008 • Effectiveness reduced by 50% to reflect behavior and experience • Available from dawn to 11 PM • Modeled as envelope holes in airnet Wilcox - 2013 Residential Compliance Software Project

  23. Whole House Fan Ventilation Cooling • New measure for 2008 • Input is total CFM of fans and W/CFM • Effectiveness reduced by 75% to reflect average behavior • Available from dawn to 11 PM (requires windows to be opened) • Modeled as exhaust fan from conditioned zone to attic in airnet • CFM and W/CFM from CEC fan listing • Standard Design and default: • 2 CFM/CFA at 0.1 W/CFM in single family in Zones 8-14 • Reporting: Proposed CFM and W/CFM Wilcox - 2013 Residential Compliance Software Project

  24. Integrated Central Fan Ventilation Cooling • New measure for 2013 • Available any hour of the day • Modeled as supply fan from outdoors to zones with relief to attic in airnet • Controlled on current vent setpoints and indoor-to-outdoor delta T • Fixed speed systems (Smartvent etc) input fixed CFM and fan W • Variable speed systems (Nightbreeze, etc) use manufacturer certified max CFM, W/CFM and off max functions • Reporting: Type, CFM, W/CFM • Verification: • Type, CFM & W/CFM at max flow • Duct leakage in air conditioning mode with damper normally closed (but not specially sealed) Wilcox - 2013 Residential Compliance Software Project

  25. Indoor Air Quality Ventilation Systems • Same functional requirements as 2008 • New 2013 requirement to verify whole house outdoor ventilation CFM for each dwelling unit. • Reporting: • Type, CFM for each dwelling unit, W/CFM • Verification: • Type, CFM of outdoor air, and W/CFM if not default. Wilcox - 2013 Residential Compliance Software Project

  26. Zoning the Building • Zoning the spaces in the building is optional (recommended for added accuracy even for single zone systems) • A 40 ft2 opening will be assumed between adjacent zones • Building components such as ceilings, floors, walls, windows and point source internal gains (such as the kitchen) must be assigned to the correct zone • Heating and cooling, up to the CSE sized capacity of the system assigned to the zone, are assumed to be delivered to each zone as required to meet the scheduled set points. • The location of duct system return grills must be input • The Standard Design building has the same zoning as the proposed design. Wilcox - 2013 Residential Compliance Software Project

  27. Zonal Systems • The cooling system zonal thermostats are deleted and all spaces operate in cooling at the conditioned zone set points • The heating system zonal thermostats and schedule are maintained for systems that meet the current requirements for that credit • An algorithm will be developed to model the impact of bypass ducts on cooling system performance Wilcox - 2013 Residential Compliance Software Project

  28. Air Leakage and Infiltration • Envelope air leakage is a building level characteristic • Input is Air Changes at 50 Pascals (ACH50) measured according to the CEC approved method (copied from Resnet). • Default and Standard Design is • 5 ACH50 for single family and multi-family homes • 7 ACH50 for Townhouse leakage measured as a single unit • A lower value may be used for single family and townhouses if verified • Reporting: ACH50 if other than default Wilcox - 2013 Residential Compliance Software Project

  29. Envelope Air Leakage (ACH50)

  30. Air Leakage Distribution • Envelope air leakage is located at the building surfaces Wilcox - 2013 Residential Compliance Software Project

  31. Leakage Location Single Family

  32. Airnet Holes • The leakage in a surface isrepresented by 2 holes spaced vertically at 25% and 75% of the height of the surface • If the air in the space is warmer than air outside, air density (stack effect) causes air to flow in the bottom hole and out the top hole. • If the air in the space is colder the flow goes the other way Wilcox - 2013 Residential Compliance Software Project

  33. Wind and Mechanical Effects • Holes are needed on each side because wind pressure is different on each side of the building (upwind, downwind and parallel sides assumed, wind is not orientation specific). • Fans and duct leaks change the pressure uniformly on the whole space • The combined pressure on each hole is the sum of the wind, stack and fan pressure (which may add or cancel each other) Wilcox - 2013 Residential Compliance Software Project

  34. Multi-Zone • Gets pretty complicated… • There is also a hole between each pair of zones (door or stair) • Then we add Windows.. • The Compliance Manager calculates the size and location of each hole • The Airnet calculation finds the air pressure in each zone that makes the air flows in the entire network balance Wilcox - 2013 Residential Compliance Software Project

  35. Conditioned Zones • Dimensions and Location • Internal Gains • Exterior Surfaces • Ceilings below Attics • Exterior Walls • Surfaces between Zones • Interior walls, ceilings and floors • Slab on grade floors • Raised Floors Wilcox - 2013 Residential Compliance Software Project

  36. Zone Location and dimensions • Location and dimensions added for Airnet • Floor to floor height • Elevation of the bottom of the Zone • Window head height of the top windows • Zone types and thermostats are unchanged except • The zonal cooling thermostats are deleted Wilcox - 2013 Residential Compliance Software Project

  37. Surfaces • Surface inputs unchanged except for Construction instead of U-factor • Airnet holes automatically created in each wall, floor and ceiling. Hole size proportional to area as fraction of total area of surface type in building • Ceilings below Attics • Defined in the conditioned space zone below • Air net hole to attic automatically created in each surface • Floors, roofs and ceilings between zones • Dimensions and constructions must be entered in one zone • Openings defaulted to 40 square feet between conditioned zones in the same dwelling unit • Air net holes to unconditioned zone automatically created in each surface Wilcox - 2013 Residential Compliance Software Project

  38. Windows • Window and skylight inputs and reporting unchanged • Shade operation for windows • Interior shades half open during day, 80% closed at night • Automatically operated exterior shades closed when air conditioning. Rules to be developed. Wilcox - 2013 Residential Compliance Software Project

  39. Thermal Mass • Inside the zone light mass and surfaces are fixed: • Light mass (Cair) is 2 BTU/CFA • Interior wall with one side area equal to CFA • Interior floor if multi-story zone • Furniture made of 2.5” wood with one side are equal to 2 times the CFA • No change to slab floors (default 80% carpet, 20% bare) Wilcox - 2013 Residential Compliance Software Project

  40. HERS II Internal Gain • Internal gains according to HERS II formulas and schedule • Appliance efficiency and fuel types default in both Proposed and Standard Design • If multi-zone, specify the zone where point sources (such as kitchen) are located • Added latent fraction to HERS II gains: Wilcox - 2013 Residential Compliance Software Project

  41. Sensible Internal Gain Comparison Wilcox - 2013 Residential Compliance Software Project

  42. Unconditioned Zones • Attic • Floor Area • Ventilation • Attic Edge • Other zones (optional) • Crawl Spaces • Basements • Garages Wilcox - 2013 Residential Compliance Software Project

  43. Attic • Attic floor area defined by ceiling areas of zones below • Attic ventilation is no longer a compliance variable • 1/300 soffit ventilation assumed • Vent area increased if needed to provide a minimum of CFM/375 ft2 free area for cooling ventilation fan relief • Insulation in the attic • Input is R value • Insulation type (cellulose, fiberglass, foam, etc) is not a variable • Assume R = 2.6/inch (light blown fiberglass) Wilcox - 2013 Residential Compliance Software Project

  44. Attic Edge - Not Part of the Attic Wilcox - 2013 Residential Compliance Software Project

  45. Attic Edge • Solution is to treat the attic edge area as a cathedral ceiling • No heat flow to the attic from this area • Attic floor area (and volume) reduced by the edge area • Tapered insulation cross section (and truss path) on left above can be approximated by 2 rectangular sections on the right that provide nearly the same steady state heat flow and can be simulated as a 1 dimensional surfaces in CSE Wilcox - 2013 Residential Compliance Software Project

  46. Attic Edge • Inputs • Roof Pitch • Distance from top plate to roof deck, default 3.5” • Ceiling Insulation and Below deck insulation R • Length of attic edge • For simplicity not an input • Assume 3 times the square root of Attic Floor Area • Compliance Manager generates the cathedral surfaces • Standard Design: default geometry with Prescriptive R • Reporting: Heel height for verification if not defaulted Wilcox - 2013 Residential Compliance Software Project

  47. Other Unconditioned Spaces • Modeling (optional) for improved accuracy and flexibility • Crawl Spaces • Basements • Garages • Rules to be developed • Default: Current rules (not modeled as zones) • Standard Design: Same modeling as proposed • Reporting: to be developed Wilcox - 2013 Residential Compliance Software Project

  48. Other RACM Topics To Be Developed • Domestic Hot Water • Additions/Alterations • Testing Wilcox - 2013 Residential Compliance Software Project

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