Afternoon Workshop Sections Best Practices, Inform Design, M&V
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Transcript of Afternoon Workshop Sections Best Practices, Inform Design, M&V
IBPSA - USAAFTERNOON WORKSHOP SECTIONSBEST PRACTICES, INFORM DESIGN, M&V
Modeling Processes• Best Practices• Integrated Design Process
Modeling Procedures• Pre-Design• Schematic Design• Design Development• Construction Documents• Post Occupancy
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BEST PRACTICES
BUILDING SIMULATION MODELING
IBPSA - USA
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Modeling Fundamentals
Performance Rating Method Best Practices Inform Design Measurement &
Verification
IBPSA - USA
OVERVIEW
• Consistency in methods• Reduction in input errors• Generation of reasonable performance values
Modeling best practices are methods incorporated into everyday practice that support:
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Modeling Fundamentals
Performance Rating Method Best Practices Inform Design Measurement &
Verification
IBPSA - USA
DESTINATION
The art in energy modeling is to create a model that is as simple as possible while still providing reasonably accurate results. This requires good judgment and experience.
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Modeling Fundamentals
Performance Rating Method Best Practices Inform Design Measurement &
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IBPSA - USASETTING EXPECTATIONSBLACK BELT ENERGY MODELING
Belt Capabilities
TraineeWhite Collect modeling input dataYellow Perform input data calculationsOrange Develop building geometry and zoning
Tech-nician
Green Create building input file using software wizard
Blue Build minimally-code compliant building model
Core Analyst
Purple Review results for reasonableness Complete calibrations
Brown Perform complex modeling Complete detailed QC Complete system level calibration
Master
Red Understand the algorithms Use supplemental analysis
Black Balance modeling level of detail against accuracy of results needed to support decision making
Concept created and developed by Ellen Franconi, Rocky Mountain Institute,See http://www.ibpsa.us/workshop/ for expanded table 5
Modeling Fundamentals
Performance Rating Method Best Practices Inform Design Measurement &
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IBPSA - USAREAL WORLD CHALLENGES
From Michael Donn. “Quality Assurance – Simulation and the Real World” , 1999 IBPSA Proceedings . See www.ibpsa.org/proceedings/BS1999/BS99_P-05.pdf
• Education of industry• Robust scope of work• Example modeling Statement of
Requirements
Model preparation time limits
• Experience• Sensitivity studies• Published case studies
No clear guidance as to the important features of a
building that should be modeled well
• Available metrics• Systems for making comparisons
Minimum QC systems to help ensure relevance of results/recommendations
• Reduce input errors• Model represents design• Library of similar project results
Lack of quality assurance tools in the simulation
Challenges Strategies
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Modeling Fundamentals
Performance Rating Method Best Practices Inform Design Measurement &
Verification
IBPSA - USA
GENERAL PRINCIPLES
1. Be knowledgeable of the inner workings of the simulation tool
2. Be knowledgeable of the technologies being modeled
3. Prioritize efforts4. Follow modeling procedures that
facilitate quality assurance
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Modeling Fundamentals
Performance Rating Method Best Practices Inform Design Measurement &
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IBPSA - USAGENERAL PRINCIPLESKNOWLEDGE OF INNER WORKINGS – LOAD CALCS
DOE2 EnergyPlus• Envelope gain
– Transfer function• Space loads
– Surface/air heat balance
– Iterative calc
BenefitsProven accurate for most cases.Fast calculations.
BenefitsCalculates surface temperatures, allowing comfort calculations and control.Radiant heating/cooling model.
Envel-ope
RF
WF WF
Solar Lights People/ Equip
WF WF
S
Space Load
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Modeling Fundamentals
Performance Rating Method Best Practices Inform Design Measurement &
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IBPSA - USAGENERAL PRINCIPLESKNOWLEDGE OF INNER WORKINGS
DOE2.2• Sequential Calculations
– Full year loads, then systems• Load calc at constant
temperature
EnergyPlus• Simultaneous Calculations• Temperature can vary each
hour per t-stat setpoint
Loads
Systems
Loads
Systems
Each timestep
BenefitsOutput reports show breakdown of loads by source.
BenefitsProven accurate for most cases.Fast calculations.
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Modeling Fundamentals
Performance Rating Method Best Practices Inform Design Measurement &
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IBPSA - USAGENERAL PRINCIPLESKNOWLEDGE OF INNER WORKINGS
• Perform test runs• Check standard reports• Create and compare hourly output data• Review documentation
Download documentation from DOE-2.2 page • Use Edit-Search of DOE-2.2 Manuals• http://doe2.com/download/DOE-21E/DOE-2EngineersManualVersion2.1A.pdf
Documentation included with engine• InputOutputReference.pdf• EngineeringReference.pdf
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Modeling Fundamentals
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IBPSA - USAGENERAL PRINCIPLESKNOWLEDGE OF TECHNOLOGIES• Colleagues• Manufacturers / Distributors• Technical Journals and Conference Proceedings• DOE Building Technologies Program website
http://www1.eere.energy.gov/buildings/technologies.htmlhttp://www1.eere.energy.gov/buildings/information_resources.html• Energy Design Resources websiteDesign Guidelines: HVAC Simulation GuidelinesDesign Guidelines: Advanced Variable Air Volume (VAV) SystemsDesign Guidelines: CoolTools Chilled Water Plant• List Serve: buildingone.org
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Modeling Fundamentals
Performance Rating Method Best Practices Inform Design Measurement &
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IBPSA - USAGENERAL PRINCIPLESPRIORITIZING EFFORTS
• Climate impact• Building size, massing, process loads, ventilation
Focus on most important building details
• Characterize in detail components that change between runs
Focus on inputs that will affect the evaluation
• Aggregate HVAC zones• Zones may be discontinuous
Minimize number of spaces/zones
• Relevant for daylighting, thermal mass, heat transfer between zones of different temperaturesMinimize interior walls
• SAT, CHW, HW resets• Outside air flow control – occupied/unoccupied• Part-load curves
Properly characterize HVAC and controls
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Modeling Fundamentals
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IBPSA - USAGENERAL PRINCIPLESPRIORITIZING EFFORTS
http://www.aud.ucla.edu/energy-design-tools
Climate analysis and climate-based design strategies
See EERE tool directory - http://apps1.eere.energy.gov/buildings/tools_directory/
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IBPSA - USAGENERAL PRINCIPLESPRIORITIZING EFFORTS
Parameter Low HighEnvelope toVolume Ratio
• Lighting• Process Loads• Mechanical Systems
• Insulation• Windows• Passive Systems
Internal Gains • Insulation• Windows• Passive Systems
• Lighting • Process Loads• Mechanical Systems
Ventilation • Mechanical Systems
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Modeling Fundamentals
Performance Rating Method Best Practices Inform Design Measurement &
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IBPSA - USAGENERAL PRINCIPLESPRIORITIZING EFFORTS
Resources for Gaining InsightsASHRAE High Performing Buildings Magazine• http://www.hpbmagazine.org/
ASHRAE 30% Advanced Energy Design Guides• 30% Better than 90.1-1999• Small offices, retail, K-12, warehouse, lodging, healthcare• http://www.ashrae.org/technology/page/938
ASHRAE 50% Advanced Energy Design Guides• 50% Better than 90.1-2004• Medium box retail, small office, medium office, grocery stores, lodging• http://www.ashrae.org/technology/page/1402
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Modeling Fundamentals
Performance Rating Method Best Practices Inform Design Measurement &
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IBPSA - USAGENERAL PRINCIPLESPRIORITIZING EFFORTS
Resources for Gaining Insights
CIBSE AM11
USGBC• Advanced Energy Modeling for
LEED Technical Manual v 1.0 August 2010 Edition
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Modeling Fundamentals
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IBPSA - USAGENERAL PRINCIPLESFACILITATE QUALITY ASSURANCE
Checking model input• Document assumptions and input values• Use pre-processing tools/spreadsheets to
convert component descriptions into modeling input values
• Import input file segments for complex components modeled often in projects
• Make design changes incrementally in the model
RMI Tool
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IBPSA - USAGENERAL PRINCIPLESFACILITATE QUALITY ASSURANCE
Example Input File Snippets for DOE-2.2
$ EXTERIOR WALL"R-eff wall" = MATERIAL TYPE = RESISTANCE RESISTANCE = 7.2 $ASHRAE 4A - 7.2 eff R-value R-13 batt in 4", 24"o.c. steel frame $ Specify with parameter value - {#pa("R Stud Wall")}.."R-ci wall" = MATERIAL TYPE = RESISTANCE RESISTANCE = 7.5 $ASHRAE 4A - 7.5 continuous insulation outside stud wall $ Specify with parameter value - {#pa("R CI Wall")} .."ASHRAE EWall Cons Layers" = LAYERS MATERIAL = ( "GypBd 1/2in (GP01)", "Bldg Paper Felt (BP01)", "R-ci wall", "R-eff wall", "GypBd 1/2in (GP01)" ) THICKNESS = ( 0.042 ) .."E1 EWall Construction" = CONSTRUCTION TYPE = LAYERS ABSORPTANCE = 0.6 ROUGHNESS = 1 LAYERS = "ASHRAE EWall Cons Layers" $ substitute value with parameter name - e.g. ext_wall_layers[]$ {SymIndex(#pa("Exterior Wall Layers"),"CONSTRUCTION","LAYERS")}
http://www.rmi.org/rmi/ModelingTools
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IBPSA - USAGENERAL PRINCIPLESFACILITATE QUALITY ASSURANCE
Checking model output• Develop a review check list• Extract data for evaluating reasonableness of
results– Key output values– Metrics, back-of-the-envelope calculations, hourly data
• Extract results from output files and report side-by-side– Evaluate against rules-of-thumb metrics– Evaluate against performance of actual buildings– Evaluate against each run – is the change as expected?
RMI Tool
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IBPSA - USAGENERAL PRINCIPLESFACILITATE QUALITY ASSURANCE – PARTIAL CHECK LIST
Input OutputASHRAE climate zone Zone and plant loads metWeather data file Building EUIEffective underground R-value Building plugs W/ft2Overall window U-value Building lighting W/ft2Plug loads Building occupant densitySystem type, plant type Cooling - design ft2/ton, kW/ton,
loadingBaseline fan per PRM Cooling loop – GPM/tonVAV - min box turn down, central heating coil
Heating - Btu/ft2, average efficiency, loading
Outside air - fixed, % supply or cfm/person, DCV; off at night
Supply air - design CFM/ft2
Controls – SAT reset, humidity, loop temp resets
Ventilation air - % design flow, CFM/ft2
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IBPSA - USAGENERAL PRINCIPLESFACILITATE QUALITY ASSURANCE – KEY METRICS*
Metric Units Low Medium HighBuilding EUI kBtu/ft2 yr 25 60 95Cooling Design ft2/ton 600 400 250Cooling Design kW/ton 0.6 0.9 1.2Cooling Loop GPM/ton 2.5 2.5 2.5Heating Design Btu/ft2 15 20 30Fans kW/CFM 0.8 1.00 1.2Supply Air CFM/ft2 0.6 1.00 1.4Ventilation Air CFM/ft2 0.1 0.2 0.3Lighting W/ft2 0.7 1.0 1.8Plugs W/ft2 0.5 1.0 1.5
*Typical of office buildings: low–very energy efficient, medium -code, high–existing buildings
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Modeling Fundamentals
Performance Rating Method Best Practices Inform Design Measurement &
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IBPSA - USAGENERAL PRINCIPLESFACILITATE QUALITY ASSURANCE
Reconciliation• Look for careless errors in input• Examine simulation output for explanation• Make sure you understand simulation algorithms• Make sure the model captures actual
process/systems• Increase model detail if needed• Tweak uncertain inputs within a reasonable range
of values• Peer review
RMI Tool
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IBPSA - USAMODELING BEST PRACTICES
PRESENTING RESULTSDocumenting Assumptions, Energy Efficiency Measures, Packages
Activity
Baseline & Proposed Design Baseline Proposed DesignSpace Areas Outside Ventilation LPD EPD LPD EPD
Area % (Ft2/PER) (OA -CFM/PER) (W/ft2) (W/ft2) (W/ft2) (W/ft2)
Lobby 6,642 6 40 11 1.6 0.25 1.0 0.25
Retail 1,902 2 67 16 1.6 0.25 1.0 0.25
Corridor/Storage 38,318 33 1000 0 1.6 0.00 1.0 0.00
Exhibit* 16,321 14 25 9 8.0 4.00 4.0 4.00
Classroom 14,679 13 28 12 1.6 0.50 1.0 0.50
Dining 5,707 5 10 9 1.6 0.10 1.0 0.10
Computer Lab 13,600 12 40 15 1.6 5.00 1.0 5.00
Office 13,315 12 200 17 1.6 0.75 1.0 0.75
Restrooms 5,072 4 150 50 1.6 0.10 1.0 0.10TOTAL
115,556 100
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Modeling Fundamentals
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IBPSA - USAMODELING BEST PRACTICES
PRESENTING RESULTSECM Description 90.1-2004 As-Design 30% Below Description
Envelope Strategies
BASE Envelope and Windows X
Walls: 4" batts in 4" studs 16" o.c. + R-3.8 c.i. (effective R-7 clear wall + R-3.8)Roof: R-15 c.i. above deckGlazing: Thermally broken alum. frames, clear uninsulated (GHs), U-0.57 Btu/hr-ft2-°F and SHGC-0.39 (all other)
1 Roof Insulation X X Roof: R-30 batts between steel joists2 Exterior Wall Insulation X X Walls: 6" batts in 8" studs 16" o.c. + R-3.8 c.i.
3 Window Performance X X Glazing: Thermally broken alum. frames, Low-e IGU w/gray exterior lite, U-0.4 Btu/hr-ft2-°F and SHGC-0.32 (all other)
Lighting
BASE ASHRAE 2004 LPDs X Maximum allowable LPDs per ASHRAE 90.1-2004, corresponds with LEED Baseline lighting
AD As Designed LPDs X LPDs as designed
4 15% Lower than ASHRAE 90.1-2004 X LPDs are 15% lower than those allowable per ASHRAE 90.1-2004
Heating, Cooling, and VentilationBASE Baseline HVAC Systems X Packaged VAV with hot Water Reheat
AD As-Designed HVAC Systems X VAV with Hot Water Reheat + DirectEvaporative
5 Indirect/Direct Evaporative Cooling XAdd blow-through Indirect/Direct Evaporative cooling section to AHU
6 Condensing Boiler XHot Water Boilers (Forced draft, sealed combustion)93% (Std Rating @ 80F HWRT). Terminal boxes set to 10% and baseboard used for perimeter heating
7 High-Efficiency Fans X Premium efficiency motors on fans. Evaporative section in AHU may increase static pressure and required fan BHP.
Documenting Assumptions, Energy Efficiency Measures, Packages
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IBPSA - USAMODELING BEST PRACTICES
PRESENTING RESULTS
Area Light-ing
22%
Process Loads24%
Heating: Natural Gas16%
Cooling21%
Pumps: Electricity
2%
Pumps: Natural Gas
5%
Fans8%
DHW1% Ext. Equipment
1%
LEEDBaseTotal Cost: $60,650/yr
Normalized Cost: $1.36/sf/yr
Area Light-ing
19%
Process Loads23%
Heating: Natural Gas6%
Heating: Electricity0%
Cooling4%
Pumps: Electricity2%
Pumps: Natural Gas0%
Fans7%
DHW1%
Ext. Equipment
1%
Savings35%
Proposed_30pctTotal Cost: $39,416/yr
Normalized Cost: $0.88/sf/yr
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IBPSA - USAMODELING BEST PRACTICES
PRESENTING RESULTSRoof_Ins
Ext-Wall_Ins
GlazingAs-De-
signedfan ef-fi-
ciencyLDP
Daylight
DCV
Base-boards
30% Be-low
$0 $5,000 $10,000 $15,000 $20,000 $25,000
$1,855
$2,066
$3,825
$8,118
$8,231
$10,409
$10,667
$11,219
$20,381
$21,234
Annual Energy Cost Savings, $ 26
Modeling Fundamentals
Performance Rating Method Best Practices Inform Design Measurement &
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IBPSA - USAMODELING BEST PRACTICES
PRESENTING RESULTS
LEEDBase
Roof_Ins Ext-Wall_Ins
Glazing DIEvap-CHW-Bak
fan ef-fi-
ciency
LDP Daylight DCV Base-boards
Pro-posed_3
0pct
$0
$10,000
$20,000
$30,000
$40,000
$50,000
$60,000
$70,000
Annu
al E
nerg
y Co
st, $
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