Implications for Sustainable Design of Glass Facades Facade Consultant Staying... · Implications for Sustainable Design of Glass Facades How New Energy Codes Will Impact Glazing

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

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

Learning Objectives

2

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

• 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

Challenge for Glass Buildings

4

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

Building Envelope Design

Under the New Energy Codes

5

Insurance Requirements

• Design requirements:

• ‘Rainscreen’ design:

• Primary and secondary planes of protection

• Ventilated air spaces between planes

• Positive drainage to the exterior

• 3rd 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

OAA Pro-Demnity

Window Wall Endorsement

7

OAA Pro-Demnity


• 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

• 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.

OAA Pro-Demnity


9

• 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.

OAA Pro-Demnity


10

• 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

OAA Pro-Demnity


11


• 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

Tarion Bulletin 19

for Condominium Construction

12

• 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

Tarion Bulletin 19


13

• 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

Tarion Bulletin 19


14

• 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

Tarion Bulletin 19


15

• Window wall is an identified risk area, specific

requirements include:


• Review of details and shop drawings ensuring compliance

with the OAA and Pro-Demnity design 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

Tarion Bulletin 19


16

• 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-10

• 2014 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

Unintended Consequences

17

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

Min.I-value

W/m2K W/m2K W/m2K

Windows and Doors

2.5 54 2.0 68 1.7 77

Skylights 3.5 None 3.0 None 2.7 None

Unintended Consequences

Minimum U-value and Condensation Resistancefor Windows, Doors and Skylights

NBCC 2010, OBC 2014 Part 9 Table 9.7.3.3

Note: these requirements are for low indoor humidity. Requirements for high indoor humidity are not defined

OR OR OR

18

Energy Codes

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-10

2. ≥ 5% over ANSI/ASHRAE/IESNA 90.1

3. ≥ 25% over 1997 Model National

Energy Code for Buildings

20

SB-10 Compliance Paths

21

• 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

SB-10 & ASHRAE 90.1 - 2010

22

SB-10 & ASHRAE 90.1 - 2010

23

SB-10 & ASHRAE 90.1 - 2010

R2.9

R2.2

24

Glazing Ratio

Glazing Ratios

26

• Current North American energy code prescriptive path

code requirements:

• ASHRAE 90.1 - 2010: 40%

• IECC - 2009: 40%

• IECC – 2012: 30%

• OBC SB-10: 40%

A step backward to earlier designs?

Glazing Ratios

27

28

Glazing Ratios

A building can still be all glass

with a 40% glazing ratio

2,764

42%

3,764

58%

Ratio 10%,

Glazing U=0.40

Opaque Wall U=0.059 (R=17)

Total Heat Loss = 6528 Btu

Thermal Impact of Glazing

Area of circle represent total

envelope heat loss

Fenestration heat loss, UA, Btu/hr-F

Opaque wall heat loss UA, Btu/hr-F

29

5,504

62%

3,373

38%

Ration = 20%

Glazing U=0.40

Opaque Wall U=0.059

Total Heat Loss = 8877

36% increase

2,764

42%

3,764

58%

Ratio 10%,

Glazing U=0.40





envelope heat loss



30

8,244

73%

2,983

27%

Ratio = 30%

Glazing U=0.40

Opaque Wall U=0.059

Total Heat Loss 11227 Btu

72% increase

5,504

62%

3,373

38%

Ration = 20%

Glazing U=0.40

Opaque Wall U=0.059


36% increase

2,764

42%

3,764

58%

Ratio 10%,

Glazing U=0.40





envelope heat loss



31

10,984

81%

2,592

19%

Ratio = 40%

Glazing U=0.40

Opaque Wall U=0.059


208% increase


envelope heat loss



8,244

73%

2,983

27%

Ratio = 30%

Glazing U=0.40

Opaque Wall U=0.059

Total Heat Loss 11227 Btu

72% increase

5,504

62%

3,373

38%

Ration = 20%

Glazing U=0.40

Opaque Wall U=0.059


36% increase

2,764

42%

3,764

58%

Ratio 10%,

Glazing U=0.40




32

• Sustainability Standards raise the bar further:

• LEED 2009

• ASHRAE 189.1 High Performance Green Buildings

• International Green Construction Code

All require performance over and above

baseline energy code

Sustainability Standards

33

• 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

Sustainability Standards

34

Compliance Paths

Prescriptive Building Envelope Option

[tables]

ComponentPerformance Building

Envelope Option[trade-off]

Systems Analysis[energy modeling]

35

Compliance Paths


[tables]




36

• PRESCRIPTIVE BUILDING ENVELOPE OPTION

• Must meet or exceed code specified values

• Glazing: Vertical Fenestration max U-0.40*

• Area: 40% max.

*metal framing

Prescriptive Option

37

Compliance Paths


[tables]




38

• COMPONENT PERFORMANCE

• Design heat loss rate for the proposed envelope

assemblies less than target heat loss rate

• UAp ≤ UAt

• Limited to envelope assemblies

• Over performance in some assemblies can be traded off

for underperformance in others

Component Performance

Option

39


Option

UAp = UmrAmr + UadAad + UrsArs + UraAra + UogcAogc

+ UogAog + UmwAmw + UmbwAmbw + UsfwAsfw +

UwfowAwfow + UdAd + UvgAvg + UvgmAvgm + UvgdAvgd +

UfmAfm + UfsAfs + UfwoAfwo + FsPs + FsrPsr

UAt = UradtAradt + UmrtAmrt + UrstArst + UortAort +

UogcortAogcort + UogortAogort + UmwtAmwt + UmbwtAmbwt +

UsfwtAsfwt + UwtAwt + UvgtAvgt + UvgmtAvgmt +

UvgdtAvgdt + UdtAdt + UfmtAfmt + UfstAfst + UftAft +

FstPst + FrstPrst

Don’t worry=

40


Option

41

81%

19%

Trade-Offs

Fenestration heat loss

Opaque wall heat loss


envelope heat loss

40% Ratio

Glazing U=0.40

Opaque Wall U=0.059 (R17)

42

84%

16%

Trade-Offs

81%

19%




envelope heat loss

50% Ratio

Glazing U=0.33

Opaque Wall U=0.059

40% Ratio

Glazing U=0.40


43

87%

13%

84%

16%

Trade-Offs

81%

19%




envelope heat loss

60% Ratio

Glazing U=0.28

Opaque Wall U=0.059

50% Ratio

Glazing U=0.33

Opaque Wall U=0.059

40% Ratio

Glazing U=0.40


44

89%

11%




envelope heat loss

87%

13%

60% Ratio

Glazing U=0.28

Opaque Wall U=0.059

84%

16%

50% Ratio

Glazing U=0.33

Opaque Wall U=0.059

40% Ratio

Glazing U=0.40


Trade-Offs

81%

19%

50% Ratio

Glazing U=0.35


92%

8%

52% Ratio

Glazing U-0.35


89%

11%

50% Ratio

Glazing U=0.35





envelope heat loss

84%

16%

50% Ratio

Glazing U=0.33

Opaque Wall U=0.059

40% Ratio

Glazing U=0.40


87%

13%

60% Ratio

Glazing U=0.28

Opaque Wall U=0.059

Trade-Offs

81%

19%

Compliance Paths

Prescriptive BuildingEnvelope Option

[tables]




47

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

• 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

Challenge with Systems

Analysis

49

Continuous Insulation

and Spandrel Design

• Most Energy Codes have enacted

continuous insulation

requirements to address thermal

bridging

• These codes create specific

challenges with respect to

spandrel design


51


52

• Performance based approach provides alternative to

these prescriptive requirement:

• Must demonstrate that proposed assembly meets or

exceeds the specified Maximum U-Value

Alternate Means of Compliance

53

• 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

Glazing Spandrel

54

• 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

ASHRAE Research Project

55

• 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


• 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

Applying Results

ASHRAE Data Sheets

58

ASHRAE Data Sheets

ASHRAE Research Project on

3D Heat Loss

59

0.00

0.02

0.04

0.06

0.08

0.10

0.12

0.14

0.16

R-3.9

R-4.5

R-5.0R-5.3R-5.2

R-10.2

R-14.3R-16.7

Co

ntr

ibu

tio

n o

f T

her

ma

l P

erfo

rma

nce

of

Wa

ll A

ssem

bly

to

En

erg

y U

se(G

J/m

2o

f F

loo

r

Are

a)

Clear Wall Only Including Poor Details Including Efficient Details

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 ft2·ºF·h/Btu also given)

U0.26

U0.10

60

Glazing Spandrel Areas

No Spray Foam

Curtain Wall Comparison

61


Curtain Wall Comparison

Spray Foam

62


3.4

4.24.8 5.0

7.4

8.2

8.8 9.1

0

1

2

3

4

5

6

7

8

9

10

0 5 10 15 20 25 30

Sp

an

dre

l S

ecti

on

R V

alu

e

Back Pan Insulation

Detail 22 (Air in Stud Cavity) Detail 23 (Spray Foam in Stud Cavity)

63

No Spray Foam Spray Foam


64

• 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

Case Studies

• 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

Case Study

67

If Fenestration U = 0.35

If effective R-value

is equal to

Then vision glass

area % can be up to

18* 46.2

20 47.0

22 47.9

24 48.7

26 48.7

28 49.6

30 49.6

32 50.5

34 50.5

40 51.3

50 51.3

60 52.2

100 53.0

*Code minimum is R-19 cavity insulation + R-8.5 continuous insulation, which is 1/0.057 = R-18 effective [Table 10-5A(1)]

44

46

48

50

52

54

56

58

60

10 20 30 40 50 60V

isio

n g

lazin

g a

rea,

%Thermal performance of opaque wall

(1/U), h·ft2·°F/Btu

0.35

68

For a range of fenestration

U-factors

44

46

48

50

52

54

56

58

60

10 20 30 40 50 60 70 80

Vis

ion

gla

zin

g a

rea

ma

xim

um

, %

Opaque glazing effective R-value, h·ft2·F/Btu

Opaque glazing effective R-value and Vision glazing area for a given

vision glazing U-factor (colored lines)

0.31

0.32

0.33

0.34

0.35

69

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

Horizontal versus

Vertical Opaque Areas

• 51% (vision) glazing

• R-33 “code-compliant”

opaque wall

• Maximized floor-to-ceiling

opaque panels

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

• Energy performance as designed:


End-Use Design (GJ)MNECB

Reference (GJ)% Savings

Lighting 2,799 2,886 3.0 %

Receptacles 1,376 1,372 -0.3 %

Heating 15,539 12,585 -23.4 %

Cooling 1,542 1,220 -26.4 %

Pumps 1,923 2,342 17.9 %

Fans 1,545 2,332 33.8 %

DHW 5,163 5,014 -3.0 %

Exterior Lighting 38 38 0.0 %

Elevators 900 900 0.0 %

% Savings Relative to MNECB -7.4%

73

• 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

• With some basic energy efficiency upgrades:


End-Use Design (GJ)MNECB

Reference (GJ)% Savings

Lighting 2,649 2,886 8.2 %

Receptacles 1,376 1,372 -0.3 %

Heating 9,122 12,585 27.5 %

Cooling 1,524 1,220 -24.9 %

Pumps 1,617 2,342 31.0 %

Fans 1,814 2,332 22.2 %

DHW 3,869 5,014 22.8 %

Exterior Lighting 38 38 0.0 %

Elevators 900 900 0.0 %

% Savings Relative to MNECB 20.1 %

75

• 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

Mechanical is part of the

answer=

77

� Path of least resistance =

window-to-wall ratio

reduction

� Glass building envelopeW

get ready for innovation

� Better details

(address thermal bridges)

=but the Envelope is the Key!

78

• Shift from nominal R-value

thinking to effective R-value

• Look to building envelope to

achieve energy gains

• Move beyond adding insulation.

Efficiency through better details?

• Be prepared to evaluate new

products

The Time is now for a

Paradigm Shift

79

Technological Innovation

81

Evolving Technology

Evolving Technology

82

Improved Thermal Breaks

83

• Pultruded stranded glass fibers

thermally fused with

polyurethane

• 700 times less thermal

conductivity than aluminum

Alternate Framing Material

84

Improving Insulating Glass

85

Improving Insulating Glass

IG Clear vs. IG Low-e Warm Edge

Vacuum Insulating

GlassSingle vs. Double Glazed

86

• 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.)

Vacuum Insulating Glazing

Source: Guardian

87

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 = 0.195

Tvis = 33%

Source: NSG Group/Pilkington

88

Vacuum Insulating Glazing –

New Construction


Apartment House in Kuzaha, Japan

Hospital in Hokkaido, Japan

Library of Amsterdam University

Hermitage Amsterdam


Vacuum Insulating Glazing –

Retrofit & Replacement

Vacuum Insulated Panels

91

Vacuum Insulated Panels

92

Vision Glass

• Insulating Glass Unit

• VIG or HVIG

Curtain Wall Frame

• Vision and spandrel

panel adhered (SSG)

Spandrel Panel

• Vacuum insulated panel

Making the Most of

High Efficiency Glazing

93

Making the Most of


High Performance Curtain Wall using Vacuum Insulated Panel (VIP) Spandrels

Lawrence D. Carbary, Andrew Dunlap, Thomas F. O’Connor

Making the Most of


High Performance Curtain Wall using Vacuum Insulated Panel (VIP) Spandrels

Lawrence D. Carbary, Andrew Dunlap, Thomas F. O’Connor

Electronically Tintable Glass as an Architectural Enabler Helen Sanders, PhD and Louis Podbelski, AIA.

Electrochromic Glazing







Integrated Photovoltaic

100

Alternate Glazing Material

101

Aerogel Translucent Panels

Expectation 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

Expectations vs. Reality

103


3.4

4.24.8 5.0

7.4

8.2

8.8 9.1

0

1

2

3

4

5

6

7

8

9

10

0 5 10 15 20 25 30

Sp

an

dre

l S

ecti

on

R V

alu

e

Back Pan Insulation

Detail 22 (Air in Stud Cavity) Detail 23 (Spray Foam in Stud Cavity)

40

9.1

104

Future Trends

• 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

The Future of Energy Codes

106

• 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

The Future

107

• 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

Whole Building Energy

Efficiency Analysis

The Future

108

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

Thank You

[email protected]

[email protected]

Documents

Implications for Sustainable Design of Glass Facades Facade Consultant Staying... · Implications for Sustainable Design of Glass Facades How New Energy Codes Will Impact Glazing