Implications for Sustainable Design of Glass Facades

Transcription

1 Implications for Sustainable Design of Glass Facades How New Energy Codes Will Impact Glazing Design Stéphane Hoffman, M. Eng., M. Arch., PE VP Façade Engineering Group George Torok, C.E.T., BSSO Building Science Specialist

2 Learning Objectives 1. Review new energy code requirements with a focus on glazing ratios and their impact on the design of glass buildings 2. Review the implication of glazing ratios when evaluating the code compliant baseline building against proposed glass building designs for compliance to sustainability standards 3. Understand the impact of thermal bridging on effective R-value for spandrel and opaque wall assemblies. 4. Learn about new technologies that can increase the performance of glazed assemblies 2

3 Changing Focus on Envelope Last Decade s Focus: Durability WRB & Rainscreen Design Reviews Field Review & Testing Next Decade s Focus: Energy Air & Thermal Barriers Whole Building Energy Modeling Whole Building Commissioning 3

4 Challenge for Glass Buildings Recent Energy Codes have raised performance requirements for ALL systems: This makes Baseline Building REALLY efficient HVAC efficiencies can no longer be expected to make up for shortfall in envelope performance Glazing Ratio restriction define performance of the Baseline Building Increasing the Glazing Ratio significantly impacts Energy Performance Spandrel Assemblies challenged to meet increasing performance for opaque walls 4

5 Building Envelope Design Under the New Energy Codes 1. Introduction 2. Insurance Requirements 3. Energy Codes 4. Glazing Ratios 5. Continuous Insulation and Spandrel Design 6. Case Studies 7. Technical Innovation 8. Expectation versus Reality 9. Future Trends 5

6 Insurance Requirements

7 OAA Pro-Demnity Window Wall Endorsement Design requirements: Rainscreen design: Primary and secondary planes of protection Ventilated air spaces between planes Positive drainage to the exterior 3 rd Party review: Independent consultant (architect or professional engineer) with expertise in design and installation of Window Wall systems must review, recommendations must be incorporated into design 7

8 OAA Pro-Demnity Window Wall Endorsement During design: Manufacturer must submit shop drawings and calculations, sealed by a professional engineer for structural integrity, air barrier continuity and water ingress management Manufacturer must submit air and water leakage resistance test reports Shop drawings and test reports must be reviewed and approved by design architect and independent consultant 8

9 OAA Pro-Demnity Window Wall Endorsement Before construction: Construct full-scale mock-up including framing, fixed and operable glazing, doors, anchorage, slab edge covers, and transitions to adjoining assemblies Test for air and water leakage and environmental separation to recognized industry standards Construction and testing must be reviewed and approved by the Independent Consultant. 9

10 OAA Pro-Demnity Window Wall Endorsement During construction: Window wall must be installed in accordance with the approved design, including recommendations of the independent consultant Window wall must be successfully field tested for air and water infiltration to recognized industry standards to the satisfaction of the independent consultant. 10

11 OAA Pro-Demnity Window Wall Endorsement After construction: 5 year minimum warranty from manufacturer against air and water leakage Includes all labour and materials required to repair or replace if failure occurs during the warranty period 11

12 Tarion Bulletin 19 for Condominium Construction Before construction: Scope of work: Design and field review services including schedule of site visits -must be proposed and approved by Tarion, to address risk areas, appropriate for the type and size of building to be constructed Design review: Review design documents, mark-up, submit, track resolution Design must comply with OBC and with good architectural and engineering practice 12

13 Tarion Bulletin 19 for Condominium Construction During Construction: Field review: Throughout construction as outlined in the Scope of Work, nominally: Generally, every 60 days At 75% complete stage At building watertight stage Identify construction deficiencies found, track resolution 13

14 Tarion Bulletin 19 for Condominium Construction During Construction: Construction submittals: Review, identify deficiencies and changes to design, track resolution, including: Lab test reports for windows and patio doors Field tests: Throughout construction as outlined in the Scope of Work, including: Water leakage resistance tests for windows and patio doors 14

15 Tarion Bulletin 19 for Condominium Construction After construction: Final Report including: All submitted reports Condominium Declaration and Description (including as-built drawings, specifications, etc.) Designer of Record final clearance letters Field Review Declaration, including: Outstanding deficiencies or unfinished work Cost to correct deficiencies 15

16 Tarion Bulletin 19 for Condominium Construction Window wall is an identified risk area, specific requirements include: Before construction: Review of details and shop drawings ensuring compliance with the OAA and Pro-Demnitydesign principles and requirements During construction: Factory manufacture review Field mock-up installation prior to installation Field review of adhesives, fasteners, surface preparation, reinforcing, detailing, joint details, finish materials, application, frequency varies with building size 16

17 Unintended Consequences Pro-Demnity Window Wall Endorsement and Tarion Bulletin 19 are not intended to address energy but 2006 OBC and 2014 OBC include energy performance requirements in Supplementary Standard SB OBC will also include general thermal performance requirements in Parts 5 and 9 to minimize surface condensation on the warm side of the component or assembly including windows, doors and skylights: Performance requirements are not defined in Part 5 Part 9 includes requirements, use as guideline? Must coordinate with SB-10 requirements 17

18 Unintended Consequences Minimum U-value and Condensation Resistance for Windows, Doors and Skylights NBCC 2010, OBC 2014 Part 9 Table Windows and Doors 2 ½% January Design Temperature Warmer than -15 C -15 C to -30 C Colder than -30 C Max. U-value Min. I-value Max. U-value Min. I-value Max. U-value OR OR OR W/m 2 K W/m 2 K W/m 2 K Min. I-value Skylights 3.5 None 3.0 None 2.7 None Note: these requirements are for low indoor humidity. Requirements for high indoor humidity are not defined 18

19 Energy Codes

20 SB-10 Compliance Paths One of three total building energy consumption performance paths: 1. = ANSI/ASHRAE/IESNA 90.1, Energy Standard for Buildings Except Low-Rise Residential Buildings, with modifications given in SB % over ANSI/ASHRAE/IESNA % over 1997 Model National Energy Code for Buildings 20

21 SB-10 Compliance Paths 21

22 SB-10 & ASHRAE Outlines minimum performance parameters for: Maximum fenestration-to-wall ratio (40%) Wall, Roofs, Windows elements etc. Prescriptive and performance paths for insulation Weighted U-value allowed for some trade-offs within element type Envelope Trade-off calculations required for trade-offs across element types HVAC and Electrical requirements 22

23 SB-10 & ASHRAE

24 SB-10 & ASHRAE R2.9 R2.2 24

25 Glazing Ratio

26 Glazing Ratios 26

27 Glazing Ratios Current North American energy code prescriptive path code requirements: ASHRAE : 40% IECC -2009: 40% IECC 2012: 30% OBC SB-10: 40% A step backward to earlier designs? 27

28 Glazing Ratios A building can still be all glass with a 40% glazing ratio 28

29 Thermal Impact of Glazing 3,764 58% 2,764 42% Ratio 10%, Glazing U=0.40 Opaque Wall U=0.059 (R=17) Total Heat Loss = 6528 Btu Area of circle represent total envelope heat loss Fenestration heat loss, UA, Btu/hr-F Opaque wall heat loss UA, Btu/hr-F 29

30 Thermal Impact of Glazing 3,373 38% 5,504 62% 3,764 58% 2,764 42% Ration = 20% Ratio 10%, Glazing U=0.40 Glazing U=0.40 Opaque Wall U=0.059 Opaque Wall U=0.059 (R=17) Total Heat Loss = 8877 Total Heat Loss = 6528 Btu 36% increase Area of circle represent total envelope heat loss Fenestration heat loss, UA, Btu/hr-F Opaque wall heat loss UA, Btu/hr-F 30

31 Thermal Impact of Glazing 2,983 27% 8,244 73% 3,373 38% 5,504 62% 3,764 58% 2,764 42% Ratio = 30% Glazing U=0.40 Opaque Wall U=0.059 Total Heat Loss Btu 72% increase Ration = 20% Ratio 10%, Glazing U=0.40 Glazing U=0.40 Opaque Wall U=0.059 Opaque Wall U=0.059 (R=17) Total Heat Loss = 8877 Total Heat Loss = 6528 Btu 36% increase Area of circle represent total envelope heat loss Fenestration heat loss, UA, Btu/hr-F Opaque wall heat loss UA, Btu/hr-F 31

32 Thermal Impact of Glazing 2,592 19% 10,984 81% 2,983 27% 8,244 73% 3,373 38% 5,504 62% 3,764 58% 2,764 42% Ratio = 40% Glazing U=0.40 Opaque Wall U=0.059 Total Heat Loss = Btu 208% increase Ratio = 30% Glazing U=0.40 Opaque Wall U=0.059 Total Heat Loss Btu 72% increase Ration = 20% Ratio 10%, Glazing U=0.40 Glazing U=0.40 Opaque Wall U=0.059 Opaque Wall U=0.059 (R=17) Total Heat Loss = 8877 Total Heat Loss = 6528 Btu 36% increase Area of circle represent total envelope heat loss Fenestration heat loss, UA, Btu/hr-F Opaque wall heat loss UA, Btu/hr-F 32

33 Sustainability Standards Sustainability Standards raise the bar further: LEED 2009 ASHRAE High Performance Green Buildings International Green Construction Code All require performance over and above baseline energy code 33

34 Sustainability Standards LEED for New Construction and Major Renovation Energy and Atmosphere Prerequisite No. 2 : Option 1: demonstrate 10% improvement EA Credit 1 (EAc1): Optimize Energy Performance: Option 1: whole building energy simulation: 1 to 19 points for 12% to 48% improvement 34

35 Compliance Paths Prescriptive Building Envelope Option [tables] Component Performance Building Envelope Option [trade-off] Systems Analysis [energy modeling] 35

36 Compliance Paths Prescriptive Building Envelope Option [tables] Component Performance Building Envelope Option [trade-off] Systems Analysis [energy modeling] 36

37 Prescriptive Option PRESCRIPTIVE BUILDING ENVELOPE OPTION Must meet or exceed code specified values Glazing: Vertical Fenestration max U-0.40* Area: 40% max. *metal framing 37

38 Compliance Paths Prescriptive Building Envelope Option [tables] Component Performance Building Envelope Option [trade-off] Systems Analysis [energy modeling] 38

39 Component Performance Option COMPONENT PERFORMANCE Design heat loss rate for the proposed envelope assemblies less than target heat loss rate UA p UA t Limited to envelope assemblies Over performance in some assemblies can be traded off for underperformance in others 39

40 Component Performance Option UA p = U mr A mr + U ad A ad + U rs A rs + U ra A ra + U ogc A ogc + U og A og + U mw A mw + U mbw A mbw + U sfw A sfw + U wfow A wfow + U d A d + U vg A vg + U vgm A vgm + U vgd A vgd + U fm A fm + U fs A fs + U fwo A fwo + F s P s + F sr P sr Don t worry= UA t = U radt A radt + U mrt A mrt + U rst A rst + U ort A ort + U ogcort A ogcort + U ogort A ogort + U mwt A mwt + U mbwt A mbwt + U sfwt A sfwt + U wt A wt + U vgt A vgt + U vgmt A vgmt + U vgdt A vgdt + U dt A dt + U fmt A fmt + U fst A fst + U ft A ft + F st P st + F rst P rst 40

41 Component Performance Option 41

42 Trade-Offs 19% 81% 40% Ratio Glazing U=0.40 Opaque Wall U=0.059 (R17) Area of circle represent total envelope heat loss Fenestration heat loss Opaque wall heat loss 42

43 Trade-Offs 19% 16% 81% 84% 40% Ratio Glazing U=0.40 Opaque Wall U=0.059 (R17) 50% Ratio Glazing U=0.33 Opaque Wall U=0.059 Area of circle represent total envelope heat loss Fenestration heat loss Opaque wall heat loss 43

44 Trade-Offs 19% 16% 13% 81% 84% 87% 40% Ratio Glazing U=0.40 Opaque Wall U=0.059 (R17) 50% Ratio Glazing U=0.33 Opaque Wall U= % Ratio Glazing U=0.28 Opaque Wall U=0.059 Area of circle represent total envelope heat loss Fenestration heat loss Opaque wall heat loss 44

45 Trade-Offs 19% 16% 13% 81% 84% 87% 40% Ratio Glazing U=0.40 Opaque Wall U=0.059 (R17) 50% Ratio Glazing U=0.33 Opaque Wall U= % 60% Ratio Glazing U=0.28 Opaque Wall U=0.059 Area of circle represent total envelope heat loss Fenestration heat loss Opaque wall heat loss 89% 50% Ratio Glazing U=0.35 Opaque Wall U=0.037 (R27)

46 Trade-Offs 19% 16% 13% 81% 84% 87% 40% Ratio Glazing U=0.40 Opaque Wall U=0.059 (R17) 50% Ratio Glazing U=0.33 Opaque Wall U= % 8% 60% Ratio Glazing U=0.28 Opaque Wall U=0.059 Area of circle represent total envelope heat loss Fenestration heat loss Opaque wall heat loss 89% 50% Ratio Glazing U=0.35 Opaque Wall U=0.037 (R27) 92% 52% Ratio Glazing U-0.35 Opaque Wall U=0.024 (R41)

47 Compliance Paths Prescriptive Building Envelope Option [tables] Component Performance Building Envelope Option [trade-off] Systems Analysis [energy modeling] 47

48 Systems Analysis Systems Analysis Approach for Entire Building: Proposed building shall provide equal or better conservation of energy than the standard design. Accounts for performance of all systems impacting energy performance: HVAC, Lighting, Envelope, etc. Over performance in some systems can be traded off for underperformance in others 48

49 Challenge with Systems Analysis The baseline building is a hypothetical code-matching building: The bar has been raised for ALL systems Baseline building already REALLY efficient Unless you are planning on installing highly efficient energy using systems (mechanical, lights, etc.) or incorporating some aspect of on-site renewable energy don t expect to be able to make up for shortfall in envelope performance 49

50 Continuous Insulation and Spandrel Design

51 Continuous Insulation Most Energy Codes have enacted continuous insulation requirements to address thermal bridging These codes create specific challenges with respect to spandrel design 51

52 Continuous Insulation 52

53 Alternate Means of Compliance Performance based approach provides alternative to these prescriptive requirement: Must demonstrate that proposed assembly meets or exceeds the specified Maximum U-Value 53

54 Glazing Spandrel Spandrel area interrupted by framing creating a thermal bridge Truly continuous insulation must be provided either inboard or outboard of frame Must demonstrate that proposed assembly meets or exceeds the specified Maximum U-Value 54

55 ASHRAE Research Project Goals and Objectives of the Project: Calculate thermal performance data for common building envelope details for mid- and high-rise construction Develop procedures and a catalogue that will allow designers quick and straightforward access to information Provide information to answer the fundamental questions of how overall geometry and materials affect the overall thermal performance 55

56 ASHRAE Research Project Calibrated 3D Modeling Software: Heat transfer software by Siemens PLM Software, FEMAP & Nx Model and techniques calibrated and validated against measured and analytical solutions Guarded hot box test measurements, 29 in total 56

57 ASHRAE Research Project Details Catalogue: 40 building assemblies and details common to North American construction Focus on opaque assemblies, but also includes some glazing transitions Details not already addressed in ASHRAE publications Highest priority on details with thermal bridges in 3D 57

58 Applying Results ASHRAE Data Sheets 58

59 ASHRAE Research Project on 3D Heat Loss ASHRAE Data Sheets 59

60 Contribution of Thermal Performance of Wall Assembly to Energy Use(GJ/m 2 of Floor Area) U0.26 R-3.9 Clear Wall Only Including Poor Details Including Efficient Details R-4.5 R-5.2 R-5.0 R-5.3 U0.10 R-10.2 R-14.3 R-16.7 Additional building energy use based on thermal performance of the building wall assembly for varying amounts of nominal exterior insulation for a mid-rise MURB in Edmonton (overall assembly thermal resistance in ft 2 ºF h/btu also given) 60

61 Glazing Spandrel Areas Curtain Wall Comparison No Spray Foam 61

62 Glazing Spandrel Areas Curtain Wall Comparison Spray Foam 62

63 Glazing Spandrel Areas Spandrel Section R Value Back Pan Insulation Detail 22 (Air in Stud Cavity) Detail 23 (Spray Foam in Stud Cavity) 63

64 Glazing Spandrel Areas No Spray Foam Spray Foam 64

65 Glazing Spandrel Areas Provide R-15 insulation in the back pan Provide continuous insulation inboard of the back pan in an airtight fashion Maximize area with floor to ceiling spandrel to further improve performance 65

66 Case Studies

67 Case Study Goal to maximize vision glass 2 levels commercial 19 floors residential Gross wall area = 76,000 sq. ft. All glass envelope Washington State Energy Code prescribes 40% glazing ratio 67

68 If Fenestration U = 0.35 If effective R-value is equal to Then vision glass area % can be up to 18* Vision glazing area, % Thermal performance of opaque wall (1/U), h ft2 F/Btu *Code minimum is R-19 cavity insulation + R-8.5 continuous insulation, which is 1/0.057 = R-18 effective [Table 10-5A(1)] 68

69 For a range of fenestration U-factors Opaque glazing effective R-value and Vision glazing area for a given vision glazing U-factor (colored lines) Vision glazing area maximum, % Opaque glazing effective R-value, h ft2 F/Btu

70 What does R-33 code compliant wall look like? 5.3 backpan insulation + Insulated knee wall Min. wool R-4.1/in. = R-11.3 eff + R-22.0 eff XPS R-5/in. = R-12.6 eff + R-20.7 eff SPF R-6/in. = R-14.4 eff + R-18.9 eff 70

71 Horizontal versus Vertical Opaque Areas 51% (vision) glazing R-33 code-compliant opaque wall Maximized floor-to-ceiling opaque panels

72 Impact on Design Case Study 40-Storey High-rise Condo in Toronto Envelope: Window wall, 70% window-to-wall ratio (therefore Compliance Paths 2 or 3) Vision panels double glazed, thermally broken aluminum frame, R1.9 Spandrel panels single glazed, mineral wool insulation, steel backpan R5.3 Mechanical: Four-pipe fan coil system Forced-draft, 80% efficiency boiler and mid-efficiency chiller Corridor make-up air 72

73 Impact on Design Case Study Energy performance as designed: End-Use Design (GJ) MNECB Reference (GJ) % Savings Lighting 2,799 2, % Receptacles 1,376 1, % Heating 15,539 12, % Cooling 1,542 1, % Pumps 1,923 2, % Fans 1,545 2, % DHW 5,163 5, % Exterior Lighting % Elevators % % Savings Relative to MNECB -7.4% 73

74 Impact on Design Case Study With some basic energy efficiency upgrades: Envelope: 5% reduction in window-to-wall ratio Mechanical: Variable speed water pumps Mid-efficiency domestic hot water equipment 15% reduction in hot water usage (low-flow fixtures) High-efficiency condensing boiler Occupancy sensors for underground parking garage lights 74

75 Impact on Design Case Study With some basic energy efficiency upgrades: End-Use Design (GJ) MNECB Reference (GJ) % Savings Lighting 2,649 2, % Receptacles 1,376 1, % Heating 9,122 12, % Cooling 1,524 1, % Pumps 1,617 2, % Fans 1,814 2, % DHW 3,869 5, % Exterior Lighting % Elevators % % Savings Relative to MNECB 20.1 % 75

76 Impact on Design Case Study With some additional energy efficiency upgrades: Individual suite ERV = 25% over 1997 MNECB (becoming common in high-rise MURBs targeting LEED) Individual suite heat recovery 25% over 1997 MNECB 76

77 Mechanical is part of the answer= 77

78 =but the Envelope is the Key! Path of least resistance = window-to-wall ratio reduction Glass building envelopew get ready for innovation Better details (address thermal bridges) 78

79 The Time is now for a Paradigm Shift Shiftfrom nominal R-value thinking to effective R-value Lookto building envelope to achieve energy gains Movebeyond adding insulation. Efficiency through better details? Be prepared to evaluate new products 79

80 Technological Innovation

81 Evolving Technology 81

82 Evolving Technology 82

83 Improved Thermal Breaks 83

84 Alternate Framing Material Pultrudedstranded glass fibers thermally fused with polyurethane 700 times less thermal conductivity than aluminum 84

85 Improving Insulating Glass 85

86 Improving Insulating Glass Single vs. Double Glazed Vacuum Insulating Glass IG Clear vs. IG Low-e Warm Edge 86

87 Vacuum Insulating Glazing 2 plies of 3 mm (1/8 in.) clear glass with low-e Small, 0.7 mm (0.03 in.) dia. pillars spaced on 25 mm (1 in.) centers Vacuum sealed in the gap Low melting temperature solder glass around the edges (one possible method) Resulting glass is just less than 7 mm (9/32 in.) Source: Guardian 87

88 Vacuum Insulating Glazing Multi-Layer Very High Performance Glazing (HVIG) U-Factor = 0.15 (R 6.7) Passive solar gain low-e: SHGC = 0.57 Tvis= 62% Solar control low-e, green tint: SHGC = Tvis= 33% Source: NSG Group/Pilkington 88

89 Vacuum Insulating Glazing New Construction Hospital in Hokkaido, Japan Apartment House in Kuzaha, Japan Source: NSG Group/Pilkington

90 Vacuum Insulating Glazing Retrofit & Replacement Hermitage Amsterdam Library of Amsterdam University Source: NSG Group/Pilkington

91 Vacuum Insulated Panels 91

92 Vacuum Insulated Panels 92

93 Making the Most of High Efficiency Glazing Vision Glass Insulating Glass Unit VIG or HVIG Curtain Wall Frame Vision and spandrel panel adhered (SSG) Spandrel Panel Vacuum insulated panel 93

94 Making the Most of High Efficiency Glazing High Performance Curtain Wall using Vacuum Insulated Panel (VIP) Spandrels Lawrence D. Carbary, Andrew Dunlap, Thomas F. O Connor

95 Making the Most of High Efficiency Glazing High Performance Curtain Wall using Vacuum Insulated Panel (VIP) Spandrels Lawrence D. Carbary, Andrew Dunlap, Thomas F. O Connor

96 Electrochromic Glazing Electronically TintableGlass as an Architectural Enabler Helen Sanders, PhD and Louis Podbelski, AIA.

97 Electrochromic Glazing Electronically TintableGlass as an Architectural Enabler Helen Sanders, PhD and Louis Podbelski, AIA.

98 Electrochromic Glazing Electronically TintableGlass as an Architectural Enabler Helen Sanders, PhD and Louis Podbelski, AIA.

99 Electrochromic Glazing Electronically TintableGlass as an Architectural Enabler Helen Sanders, PhD and Louis Podbelski, AIA.

100 Integrated Photovoltaic 100

101 Alternate Glazing Material Aerogel Translucent Panels 101

102 Expectation vs. Reality

103 Expectations vs. Reality Code compliance does not guarantee energy efficiency: There are many factors that are not currently accounted for Increasingly sophisticated modeling is available to more accurately predict thermal performance 103

104 Glazing Spandrel Areas Spandrel Section R Value Back Pan Insulation Detail 22 (Air in Stud Cavity) Detail 23 (Spray Foam in Stud Cavity) 104

105 Future Trends

106 The Future of Energy Codes Different approaches can be employed in codes to account for thermal bridging using the same data Performance based Prescriptive based Solutions based The procedures and data provided by 3D modeling promise to enable more development and enforcement 106

107 The Future It will likely become increasingly more difficult to ignore thermal bridging at intersections of assemblies Move beyond simply adding more insulation Better able to evaluate condensation resistance to improve building durability and occupant comfort 107

108 The Future Whole Building Energy Efficiency Analysis Input values that account for all thermal bridging More accurate load analysis for sizing Determine cost effectiveness of insulating the building envelope through better details Efficient use of materials Change how sustainable rating programs reward good design for energy efficiency and material use 108

109 Façade Engineering vs Building Envelope Review vs Manufacturer Consultations Involvement earlier in the design process with initial focus on assemblies over details Focused on performance optimization of envelope assemblies Relies on performance analysis to guide design decisions More holistic approach balancing impact of envelope with other energy systems (HVAC, lighting, etc.) Impartial approach 109

110 Thank You