Be Aggressive About the Passive Solutions

Transcription

1 Be Aggressive About the Passive Solutions Integrating Building Envelope Design in Whole Building Energy Goals Daniel Luddy, PE BEMP CPHC LEEP AP Senior Energy Engineer 2015 Building Envelope Forum AIA Seattle Source: Weber Thompson

2 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

3 Whole Building Energy Model ANNUAL ENERGY CONSUMPTION ENERGY (Btu*10 3 ) DATE

4 Whole Building Energy Model HVAC Systems Operating Schedule Weather Lighting Systems Building Envelope Receptacle Equipment Process Equipment Energy Generation

5 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 ANNUAL MBtu BASE BUILDING LIGHTS RESIDENTIAL LIGHTS MISC EQUIP HEATING COOLING FLUID COOLER PUMPS FANS DHW EXTERIOR LIGHTS

6 Whole Building Energy Model Potential Applications CERTIFICATIONS ENERGY CODE COMPLIANCE Local, State and Federal Energy Codes DESIGN GUIDANCE/ FINANCIAL INCENTIVES Conceptual Modeling Net Zero Feasibility Energy Auditing Utility incentives 179D Tax Deduction

7 Typical Modeling Process Design Model CONCEPT DESIGN SCHEMATIC DESIGN DESIGN DEVELOPMENT CONSTRUCTION DOCUMENTS CONSTRUCTION ADMIN BUILDING OPERATION Building Geometry General Program and Function Window Area Envelope Constructions Daylight Penetration Shading Insulation Details Initial HVAC design Initial Lighting design Façade Cladding Final HVAC design Final Lighting design Value Engineering Energy Audits and Retrofits

8 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

9 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

10 Energy Code Limitations Strict Code Limitations Reduced Design Options Cookie cutter Buildings

11 Integrated Modeling Process Conceptual Model Design Model Calibrated Model CONCEPT DESIGN SCHEMATIC DESIGN DESIGN DEVELOPMENT CONSTRUCTION DOCUMENTS CONSTRUCTION ADMIN BUILDING OPERATION Building Geometry General Program and Function Window Area Envelope Constructions Initial HVAC scheme Insulation Details Initial HVAC design Initial Lighting design Façade Cladding Final HVAC design Final Lighting design Value Engineering Energy Audits and Retrofits

12 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

13 Conceptual Model Building Geometry 3 Courthouse Schemes 1 Varying levels of podium vs. tower Source: Ennead Architects

14 Conceptual Model Building Geometry Scheme 1 Scheme 2 Scheme 3 LEED Baseline $503,706 $523,298 $519,069 Proposed Design $357,199 $375,967 $361,404 Energy Cost Savings $146,507 $147,331 $157,665 Cost Savings % 29.09% 28.15% 30.37% LEED Points

15 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

16 Assembly Detailing Identify Critical Components Heat Transfer Analysis Condensation Risk Vapor Migration Computational Fluid Dynamics

17 Assembly Detailing Thermal Bridging R 11 => R 5.5 effective R 21 => R 7.8 effective

18 Assembly Detailing Every connection counts in a high performance envelope Source: Fluke Corp

19 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

20 Assembly Detailing Balcony Integration

21 Assembly Detailing Balcony Integration Uninsulated Interior Exterior THERM results fed into Whole Building Energy Model Wrapped in 2 Mineral Wool Floor Slab Window/Door Sill Balcony solutions all cheaper than further improvements to all wall systems Local thermal comfort effects vs. whole building energy impact Thermal Break System

22 Assembly Detailing - Thermal Mass 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

23 Assembly Detailing Heat Transfer Analysis 1 vapor control option - Interior side of stud 2 vapor control options - Either side of studs CMU w/ Interior Insulation CMU w/ Exterior & Interior Insulation

24 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

25 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

26 Design Model Daylight Fenestration placement and performance critical to daylight penetration

27 Design Model Daylight Harvesting Day light dimming controls can offset thermal loss of fenestration area Source: Ennead Architects

28 Design Model Rightsizing the Load Cooling Equipment 43% Oversized Heating Equipment 80% Oversized Does your mechanical engineer factor in your high performance building envelope? Envelope Design Engineer's Estimates U Value (Btu/h*sqft*F) U Value (Btu/h*sqft*F) CMU Wall Metal framed Wall Roof Storefront Glazing Punched Windows Skylights 0.40 Solar Heat Gain Coefficient 0.40 Solar Heat Gain Coefficient Storefront Glazing Punched Windows Skylights

29 Design Model Triple Pane Windows Energy modeling provides better analysis of the financial impact of high performance building envelopes Source: HLW

30 Design Model Triple Pane Windows Simple Energy Calculation - Spreadsheet Heating and Cooling Load savings through windows = 55 year simple payback Simple Energy Cost Calculation = $3,000 Triple Pane IGU Cost Premium = $165,000

31 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

32 Design Model - Triple Pane Windows Whole Building Energy Model Calculation Integrated Heating and Cooling Savings = 4.8 year simple payback Whole Building Energy Cost Calculation $15,100 + Maintenance Savings $1,500 = $16,600 Total Remaining Triple Pane IGU Cost Premium = $80,400 State Incentive = $9,600 Cooling Tonnage Savings = $35,000 Baseboard Heating Savings = $40,000

33 Design Model Geothermal System Analysis Energy analysis critical for advanced HVAC system design Reductions and balancing of envelope loads can reduce system size and complexity Source: Weiss Manfredi

34 Design Model Geothermal System Analysis Source: EPA 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

35 Design Model Geothermal System Analysis Additional passive solar heating helped balance the loads Analysis of window placement and interior shading controls Source: Weiss Mandredi

36 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

37 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/sqft 90,900 sqft of PV LEED Compliant Design (10% cost savings over ASHRAE ) 166 kbtu/sqft 66,300 sqft of PV Low Energy Alternate 75 kbtu/sqft 29,900 sqft of PV

38 Calibrated Energy Model Based on actual meter and survey data ASHRAE Level III energy audit Peak kw Shaving

39 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

40 Integrated Modeling Process Conceptual Model Design Model Calibrated Model CONCEPT DESIGN SCHEMATIC DESIGN DESIGN DEVELOPMENT CONSTRUCTION DOCUMENTS CONSTRUCTION ADMIN BUILDING OPERATION Building Geometry General Program and Function Window Area Envelope Constructions Initial HVAC scheme Insulation Details Initial HVAC design Initial Lighting design Façade Cladding Final HVAC design Final Lighting design Value Engineering Energy Audits and Retrofits

41 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

42 Whole Building Energy Model - Softwares Many software options available Each have individual strengths and weaknesses

43 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

44 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

45 Integrated Modeling Process Analysis Report Recommended Alternative Energy Efficiency Measures Cost effective Practical Incorporate improvements to all building systems

46 Be Aggressive About the Passive Solutions Integrating Building Envelope Design in Whole Building Energy Goals Daniel Luddy, PE BEMP CPHC LEEP AP Senior Energy Engineer 2015 Building Envelope Forum AIA Seattle Source: Weber Thompson