be aggressive about the passive solutions · 2016. 6. 16. · 179d tax deduction energy code...
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Be Aggressive About the Passive SolutionsIntegrating Building Envelope Design in Whole Building Energy Goals
Daniel Luddy, PE BEMP CPHC LEEP APSenior Energy Engineer
2015 Building Envelope ForumAIA Seattle
Source: Weber Thompson
Learning Objectives
• When to engage energy modeling in the design process
• Where integrated energy modeling can assist in envelope design
• How to use energy analysis results effectively balance cross-discipline design decisions
• How envelope design software can be integrated into the whole building model
Whole Building Energy Model
DATE
ENER
GY (B
tu*103)
ANNUAL ENERGY CONSUMPTION
Whole Building Energy Model
Process Equipment
HVAC Systems
Lighting Systems
Energy Generation
Receptacle EquipmentBuilding Envelope
Weather
Operating Schedule
Whole Building Energy Model
• Proposed design is compared to a baseline standard
• Individual energy efficiency measures can be evaluated in broader context
ENERGY USE COMPARISON
ANNUA
L MBtu
BASE BUILDING LIGHTS RESIDENTIAL LIGHTS MISC EQUIP HEATING COOLING FLUID COOLER PUMPS FANS DHW EXTERIOR LIGHTS
DESIGN GUIDANCE/FINANCIAL INCENTIVES
Conceptual Modeling
Net Zero Feasibility
Energy Auditing
Utility incentives
179D Tax Deduction
ENERGY CODE COMPLIANCE
Local, State and Federal Energy Codes
CERTIFICATIONS
Whole Building Energy Model – Potential Applications
Typical Modeling Process
CONCEPT DESIGN
• Building Geometry• General Program and Function
SCHEMATIC DESIGN
• Window Area• Envelope Constructions• Daylight Penetration• Shading
DESIGN DEVELOPMENT
• Insulation Details• Initial HVAC design• Initial Lighting design
CONSTRUCTION DOCUMENTS
• Façade Cladding• Final HVAC design• Final Lighting design
CONSTRUCTION ADMIN
• Value Engineering
BUILDING OPERATION
• Energy Audits and Retrofits
Design Model
Limitations of Late Energy Modeling
IT’S TOO LATE!
• Building envelope has been detailed and finalized
• Equipment has already been bought
• Energy efficiency improvements are extremely limited
• Who wants more change orders?
• Can’t be used for energy code compliance
Energy Code Limitations
• Prescriptive requirements are one size fits all
• Thermal envelope is not optimized for your project
• Amount of window and skylight areas are limited
• Requirements may hurt building performance (i.e. over-insulating, reducing solar heating in winter)
• Only energy modeling allows tradeoffs of building envelope performance with mechanical and electrical systems
Energy Code Limitations
Strict Code Limitations
Reduced Design Options
Cookie‐cutter Buildings
Calibrated Model
Calibrated Model
Conceptual Model
Conceptual Model
Design ModelDesign Model
Integrated Modeling Process
CONCEPT DESIGN
• Building Geometry• General Program and Function
SCHEMATIC DESIGN
• Window Area• Envelope Constructions• Initial HVAC scheme
DESIGN DEVELOPMENT
• Insulation Details• Initial HVAC design• Initial Lighting design
CONSTRUCTION DOCUMENTS
• Façade Cladding• Final HVAC design• Final Lighting design
CONSTRUCTION ADMIN
• Value Engineering
BUILDING OPERATION
• Energy Audits and Retrofits
Integrated Modeling Process
• Early design guidance
• Identify key components of energy consumption
• Understand the effect of the envelope on other building systems
• Evaluate energy efficiency alternatives
• Optimize building envelope performance to save:
– Design time and effort
– Construction costs
– Energy costs over time
11
Conceptual Model – Building Geometry
• 3 Courthouse Schemes
• Varying levels of podium vs. tower
Source: Ennead Architects
Conceptual Model – Building Geometry
Scheme 1 Scheme 2 Scheme 3LEED Baseline $503,706 $523,298 $519,069Proposed Design $357,199 $375,967 $361,404
Energy Cost Savings $146,507 $147,331 $157,665Cost Savings % 29.09% 28.15% 30.37%LEED Points 9 9 10
Conceptual Model – Glazing Area & Placement
• Determine window U-factor and SHGC necessary for 30%-50% glazing
• Provide energy guidance for consideration with aesthetics, tint, cost, etc.
• Tradeoff envelope performance with HVAC and lighting
Assembly Detailing
• Identify Critical Components
• Heat Transfer Analysis
• Condensation Risk
• Vapor Migration
• Computational Fluid Dynamics
Assembly Detailing
R‐11 => R‐5.5 effective R‐21 => R‐7.8 effectiveThermal Bridging
Assembly Detailing
Every connection counts in a high performance envelope
Source: Fluke Corp
Assembly Detailing – Balcony Integration
• Minor assemblies can have an outsized impact on performance
• Thermal bridging effect magnified as other components are improved
Source: Fogarty Finger
Assembly Detailing – Balcony Integration
Uninsulated
Wrapped in 2” Mineral Wool
Thermal Break System
Interior Exterior
Floor Slab Window/Door Sill
Assembly Detailing – Balcony Integration
• THERM results fed into Whole Building Energy Model
• Balcony solutions all cheaper than further improvements to all wall systems
• Local thermal comfort effects vs. whole building energy impact
• Thermal mass can slow of heating and cooling cycles
• Additional insulation can reduce the thermal mass effect
• Early analysis can save money spent on unnecessary or detrimental construction costs
Assembly Detailing - Thermal Mass
Assembly Detailing – Heat Transfer Analysis
CMU w/ Interior Insulation CMU w/ Exterior & Interior Insulation
1 vapor control option -Interior side of stud
2 vapor control options -Either side of studs
Assembly Detailing – Vapor Migration
• WUFI
• Analyzes vapor migration and accumulation across seasons over multi-year period
• Software is constantly improving but vapor movement is incredibly complex
Design Model – Whole Building Integration
• Building Envelope drives mechanical and lighting design
• Mechanical load accuracy improved
• Energy savings is compounded
• Code and certification issues mitigated early in the design process
Design Model – Daylight
• Fenestration placement and performance critical to daylight penetration
Design Model – Daylight Harvesting
• Day light dimming controls can offset thermal loss of fenestration area
Source: Ennead Architects
Envelope Design
U‐Value (Btu/h*sqft*F)CMU Wall 0.051Metal‐framed Wall 0.061Roof 0.032Storefront Glazing 0.35Punched Windows 0.38Skylights 0.40
Solar Heat Gain Coefficient
Storefront Glazing 0.35Punched Windows 0.33Skylights 0.35
Envelope Design Engineer's Estimates
U‐Value (Btu/h*sqft*F) U‐Value (Btu/h*sqft*F)CMU Wall 0.051 0.104Metal‐framed Wall 0.061 0.104Roof 0.032 0.048Storefront Glazing 0.35 0.40Punched Windows 0.38 0.40Skylights 0.40 0.40
Solar Heat Gain Coefficient
Solar Heat Gain Coefficient
Storefront Glazing 0.35 0.40Punched Windows 0.33 0.40Skylights 0.35 0.40
Design Model – Rightsizing the Load
Does your mechanical engineer factor in your high performance building envelope?
Cooling Equipment 43% OversizedHeating Equipment 80% Oversized
Design Model – Triple Pane Windows
Energy modeling provides better analysis of the financial impact of high performance building envelopes
Source: HLW
Design Model – Triple Pane Windows
Simple Energy Calculation - Spreadsheet
Heating and Cooling Load savings through windows = 55 year simple payback
Triple Pane IGU Cost Premium = $165,000
Simple Energy Cost Calculation = $3,000
Design Model – Triple Pane Windows
First Costs
Cost premium of triple pane IGUs vs. code compliant double pane IGUs
- 35 ton reduction in rooftop unit size
- Removal of perimeter electric baseboard radiation
+ State incentive for electricity savings
Annual Savings
Heating and cooling savings through windows
+ Heating and cooling savings from smaller, optimized HVAC system
- Annual maintenance costs for baseboard radiation and additional cooling capacity
Design Model - Triple Pane Windows
Whole Building Energy Model Calculation
Integrated Heating and Cooling Savings = 4.8 year simple payback
Remaining Triple Pane IGU Cost Premium = $80,400
Whole Building Energy Cost Calculation $15,100 + Maintenance Savings $1,500 = $16,600 Total
State Incentive = $9,600 Cooling Tonnage Savings = $35,000
Baseboard Heating Savings = $40,000
Design Model – Geothermal System Analysis
Source: Weiss Manfredi
• Energy analysis critical for advanced HVAC system design
• Reductions and balancing of envelope loads can reduce system size and complexity
Design Model – Geothermal System Analysis
• HVAC sizing usually only considers peak conditions (worst point in the year)
• Geothermal heat pumps require relative balance of annual heating and cooling loads
• Adding electric heating increases source EUI from 80 kBtu/sqft to 103 kBtu/sqft
Source: EPA
Design Model – Geothermal System Analysis
• Additional passive solar heating helped balance the loads
• Analysis of window placement and interior shading controls
Source: Weiss Mandredi
Design Model – Computational Fluid Dynamics
• Flovent, Autodesk CFD
• Studies air movement, including forced air distribution and convective loops
• Temperature-critical features (i.e. artwork, feature walls)
• Natural ventilation
• Effects of prevailing winds on infiltration or exhaust
Design Model – Integrating Renewables
• 19,000 sqft restaurant
• How large of a PV system is needed to reach net zero site energy?
Typical Restaurant (2003 CBECS data)
235 kBtu/sqft90,900 sqft of PV
Typical Restaurant (2003 CBECS data)
235 kBtu/sqft90,900 sqft of PV
LEED Compliant Design (10% cost
savings over ASHRAE 90.1-2007)
166 kBtu/sqft66,300 sqft of PV
LEED Compliant Design (10% cost
savings over ASHRAE 90.1-2007)
166 kBtu/sqft66,300 sqft of PV
Low Energy Alternate
75 kBtu/sqft29,900 sqft of
PV
Low Energy Alternate
75 kBtu/sqft29,900 sqft of
PV
Calibrated Energy Model
• Based on actual meter and survey data
• ASHRAE Level III energy audit
• Peak kW Shaving
Calibrated Model – Resiliency and the Future
Evaluate building operation with internal and external changes:
• Future climate conditions
• Changes in operation schedule
• Projected utility rates
• Integration with renewables, backup generation and energy storage
Calibrated Model
Calibrated Model
Conceptual Model
Conceptual Model
Design ModelDesign Model
Integrated Modeling Process
CONCEPT DESIGN
• Building Geometry• General Program and Function
SCHEMATIC DESIGN
• Window Area• Envelope Constructions• Initial HVAC scheme
DESIGN DEVELOPMENT
• Insulation Details• Initial HVAC design• Initial Lighting design
CONSTRUCTION DOCUMENTS
• Façade Cladding• Final HVAC design• Final Lighting design
CONSTRUCTION ADMIN
• Value Engineering
BUILDING OPERATION
• Energy Audits and Retrofits
Integrated Modeling Process – Modeler Requirements
Energy modeler should have:
• Multi-disciplinary knowledge
• BEMP certification
• Understanding of current codes and certification requirements
• Experience modeling similar types of buildings
• Knowledge of available incentives and tax credits
• Third party independence is preferable
Whole Building Energy Model - Softwares• Many software options available
• Each have individual strengths and weaknesses
Integrated Modeling Process
Energy Kickoff Meeting
• Establish Energy Goals (EUI, LEED points, energy code, etc.)
• Discuss initial building design and proposed systems
• Establish specific questions/issues
• Determine schedule and deliverables
Preliminary Info
• Early drawings/BIM model
• MEP narrative• Energy targets for
undesigned systems• Anticipated
operation
Integrated Modeling Process – Analysis Report
Full Energy Analysis Report
• Side by side of model inputs
• Analysis of energy options
• Identification of key energy metric
• Schedule information
• Utility rates
• Energy Model Outputs
Integrated Modeling Process – Analysis Report
Recommended Alternative Energy Efficiency Measures
• Cost effective
• Practical
• Incorporate improvements to all building systems
Be Aggressive About the Passive SolutionsIntegrating Building Envelope Design in Whole Building Energy Goals
Daniel Luddy, PE BEMP CPHC LEEP APSenior Energy Engineer
2015 Building Envelope ForumAIA Seattle
Source: Weber Thompson