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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
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
• 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
Window Wall Endorsement
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
Window Wall Endorsement
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
Window Wall Endorsement
11
• 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
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
for Condominium Construction
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
for Condominium Construction
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
for Condominium Construction
15
• 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-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
for Condominium Construction
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
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
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
Total Heat Loss = 8877
36% increase
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
31
10,984
81%
2,592
19%
Ratio = 40%
Glazing U=0.40
Opaque Wall U=0.059
Total Heat Loss = 13576 Btu
208% increase
Area of circle represent total
envelope heat loss
Fenestration heat loss, UA, Btu/hr-F
Opaque wall heat loss UA, Btu/hr-F
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
Total Heat Loss = 8877
36% increase
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
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
Prescriptive Building Envelope Option
[tables]
ComponentPerformance Building
Envelope Option[trade-off]
Systems Analysis[energy modeling]
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
Prescriptive Building Envelope Option
[tables]
ComponentPerformance Building
Envelope Option[trade-off]
Systems Analysis[energy modeling]
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
Component Performance
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
Component Performance
Option
41
81%
19%
Trade-Offs
Fenestration heat loss
Opaque wall heat loss
Area of circle represent total
envelope heat loss
40% Ratio
Glazing U=0.40
Opaque Wall U=0.059 (R17)
42
84%
16%
Trade-Offs
81%
19%
Fenestration heat loss
Opaque wall heat loss
Area of circle represent total
envelope heat loss
50% Ratio
Glazing U=0.33
Opaque Wall U=0.059
40% Ratio
Glazing U=0.40
Opaque Wall U=0.059 (R17)
43
87%
13%
84%
16%
Trade-Offs
81%
19%
Fenestration heat loss
Opaque wall heat loss
Area of circle represent total
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
Opaque Wall U=0.059 (R17)
44
89%
11%
Fenestration heat loss
Opaque wall heat loss
Area of circle represent total
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
Opaque Wall U=0.059 (R17)
Trade-Offs
81%
19%
50% Ratio
Glazing U=0.35
Opaque Wall U=0.037 (R27)
92%
8%
52% Ratio
Glazing U-0.35
Opaque Wall U=0.024 (R41)
89%
11%
50% Ratio
Glazing U=0.35
Opaque Wall U=0.037 (R27)
Fenestration heat loss
Opaque wall heat loss
Area of circle represent total
envelope heat loss
84%
16%
50% Ratio
Glazing U=0.33
Opaque Wall U=0.059
40% Ratio
Glazing U=0.40
Opaque Wall U=0.059 (R17)
87%
13%
60% Ratio
Glazing U=0.28
Opaque Wall U=0.059
Trade-Offs
81%
19%
Compliance Paths
Prescriptive BuildingEnvelope Option
[tables]
ComponentPerformance Building
Envelope Option[trade-off]
Systems Analysis[energy modeling]
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
Continuous Insulation
51
Continuous Insulation
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
ASHRAE Research Project
56
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
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
Glazing Spandrel Areas
Curtain Wall Comparison
Spray Foam
62
Glazing Spandrel Areas
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
Glazing Spandrel Areas
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
Glazing Spandrel Areas
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:
Impact on Design – Case Study
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
Impact on Design – Case Study
74
• With some basic energy efficiency upgrades:
Impact on Design – Case Study
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
Impact on Design – Case Study
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
Source: NSG Group/Pilkington
Apartment House in Kuzaha, Japan
Hospital in Hokkaido, Japan
Library of Amsterdam University
Hermitage Amsterdam
Source: NSG Group/Pilkington
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 Efficiency Glazing
High Performance Curtain Wall using Vacuum Insulated Panel (VIP) Spandrels
Lawrence D. Carbary, Andrew Dunlap, Thomas F. O’Connor
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
Electronically Tintable Glass as an Architectural Enabler Helen Sanders, PhD and Louis Podbelski, AIA.
Electrochromic Glazing
Electronically Tintable Glass as an Architectural Enabler Helen Sanders, PhD and Louis Podbelski, AIA.
Electrochromic Glazing
Electronically Tintable Glass as an Architectural Enabler Helen Sanders, PhD and Louis Podbelski, AIA.
Electrochromic Glazing
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
Glazing Spandrel Areas
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
SHoffman@MorrisonHershfield.com
GTorok@MorrisonHershfield.com
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