From Rendering To Reality:Principles of Glass Selection for Facades
International Conference on Green Buildings & Built Environment
Sourabh Kankar
Glass Selection Criterion
Solar Spectrum vis Performance and Design
Architectural Glass Developments.
Smart Windows Emerging Technologies
Agenda
Delaware Welcome CenterWilmington, DE
SN 654 on GreenEnvironetics (Cubellis)
Glass Selection Criterion
Rendering To Reality
AllureLas Vegas, NVNU 40 on Clear
EDI ArchitecturePhoto: KHS&S
Manufacturer, Processor, & Fabricator
Performances of Glass
* Design : Visual aspect
Color
* Functions : Security
Acoustic
Thermal insulation
Solar control
Glare …………………
Light Transmission
Higher Transmission
68%
1331 L StreetWashington, DCSN 68 on Clear
SmithGroup
Lower Transmission
18%
Ivy Hotel + ResidencesMinneapolis, MNSilver 20 on ClearWalsh Bishop ArchitectsPhoto: Blue Photography
Reflectivity
Lower Reflectivity
11%
Lofts @ 655 Sixth AvenueSan Diego, CASN 68 on Clear
Public ArchitecturePhoto: Loopnet.com
Higher Reflectivity
31%
Reckson Executive ParkMelville, NY
Silver 20 on ClearReckson Associates
Guardian Proprietary
Aesthetics - Color Perception
Perception depends on:
1) Light (outside and inside)
2) Object (and background)
3) Observer (angular dependence)
SN54-CrystalGray outboard
Color Rendering Index (CRI)
Guardian Proprietary
• The color rendering index defines the spectral quality of glasses in transmission.
• Examples– Tungsten bulb & Sunlight/Blue Sky = 100– High Quality Fluorescent = 90– Green Glass = 80
• Between 80-90 -> Good• 90-100 -> Very Good• Museums typically specify 95 or higher.
100
100
32
15
Clear Insulating 97Clear Insulating Low-E 95Blue Insulating 85Bronze Insulating 95Gray Insulating 95Green Insulating 88Light Gray Insulating 93
CRIProduct
Color Rendering Index
Colored Magnetron Sputtered coatings on clear glass
View from inside
Color Rendering Index
Example
View through body tinted blue glass
View through Guardian blue reflective glass, coated on clear glass
Performances of Glass
* Design : Visual aspect
Color
* Functions : Security
Acoustic
Thermal insulation
Solar control
Glare …………………
Performances of Glass
One of the most important function is the :
Energy saving
Internal comfort Solar control
What is Solar Control Glass?
• Solar control glass protects the facade interior from solar heat gain (SC-value ,g-value or solar factor) and provides thermal insulation (U-value)
• Two effects are responsible for the reduction of energy transmission through glazings:
Energy Absorption
Energy Reflection
RAT Equation
R
A
T
E
R- Reflection
A- Absorption
T- Transmission
E- Emissivity
Solar Spectrum vis Performance and Design
Guardian Proprietary
Solar Performance and Common Terminology Solar Radiation Total Energy
UV VIS Near (Solar) IR Thermal IR →→→→
20 C ~ 10,000 nm
What can we see?
How energy efficient will it be?
Solar Energy and Visible Light
• One important issue for modern architecture is transparency in order to provide the end user maximum comfort while increasing natural daylighting.
• Solar control glass must be evaluated for energy transmission (SF, SC, SHGC) and daylighting (visible light transmission).
• The ratio of light and energy transmission is the Spectral Selectivity (S) of a glazing also LSG
Visible Light transmission
Total energy transmission
Higher is better
Clear float glass: S ~ 1
Physical maximum: S = 2.4
S =
Performances of Glass
How do I recognize a performant solar control glass ?
Check out performances of the coated glass by reading the light transmission and total energy transmission (SF , SC or SHGC).
The higher the LSG , the better the performances of the glass.
LT% SF% LSG
Clear float glass 80 80 1
Reflective coating 20 18 1,1
Single silver layer 50 30 1,6
Double silver layer 50 28 1,8
Triple silver layer 60 28 2,1
LSG (Selectivity): Visible Transmission vs. SHGC
20
Single Silver (LSG=1.4) HighPerformance, Climaguard
No Silver (LSG=1.0) Solar
Double Silver (LSG=1.9) Super Neutral, DS, ClimaGuard
LSG = L ight to S olar G ain ratio = Visible Transmission (Tvis) / SHGC
Triple Silver (LSG=2.3) SNX, ClimaGuard
(Monolithic Data)
Solar Spectrum
THERMAL INFRARED (IR)
2500-50,000 nm
UV
Guardian Proprietary
Performance Cool to Moderate Climates (Commercial and Some Residential)
Cooling and heating dominates building energy costs
– High Tvis and Low SHGC = High LSG– Low-E (U-value) for good thermal insulation
Single, double, or triple silver applied to Surface #2 of a dual glaze IG
Commercial applications (all climates) – Residential (warmer climates)
Guardian Proprietary
Performance Warm Climates(Commercial and Some Residential)
Cooling dominates building energy costs
– Low SHGC, Low LSG– Ok with Low Tvis (reducing glare)
No or Single silver coating applied to Surface #2 of a dual glaze IG
Commercial and residential applications
Architectural Glass Developments
Architectural Glass Development
Coated Glass Technologies
PYROLYTIC
– On line method applies metallic coatings during the float glass making process.
SPUTTER COATINGS
– Coatings applied in a vacuum allowing multiple thin metallic coatings to be applied to glass in a very uniform manner.
POST TEMPERABLE COATINGS
– Sputter coated glass which can be further fabricated after coating.
Guardian Proprietary
Post-Temperable Sputter Coatings
Post-temperable coatings are the latest development in high performance coatings:
– Local/regional supply– Quick delivery on replacements– Performance equal to traditional sputter coats– Design flexibility – bent, laminated, etc.
Guardian Proprietary
Summary of Coated Glass Trends
− Large increase in sputter low-E used in commercial projects
− Continued growth in double-silver and triple-silver low-E coating
− Also significant growth in “hybrid” coatings
− Declines in reflective sputter and pyrolytic’s growth
− Increased use of laminated glass
− Very little use of monolithic vision glass in facades
− Significant growth in “post- temperable” coatings
Smart Windows Emerging Technologies
Emerging Innovation
� Glass for Environmental & Energy Applications
� Advanced & Dynamic Glazing� Advanced Insulating Glass Units
� Infinite Edge Technology Spacer� Vacuum Insulating Glass (VIG)
� Building Integrated Photovoltaic (BIPV)
� Glass for Electronic Applications
Guardian Confidential
Printed Glass Technology Platform
�Annealed and HT silkscreen versions of SunGuard products.
�Generic and Digital Patterns
�Full Color Palette
Low-ESilkscreen
SunGuard Print
Thermochromic
Laminate Platforms:�Laminate Film
�Liquid Laminate
morning
noonWavelength (nm)
% T
rans
mis
sion
23ºC
40ºC
60ºC
80ºC
NO WIRES
Electrochromic
Technology Platforms:�Sputtered coatings
�Laminated devices
60%
40%
20%
4%
Adjustable Solar Control
Wavelength (nm)
% T
rans
mis
sion
IET Spacer vs Metal Spacers�Exceeds thermal properties of metal spacers.
�Enhanced durability and structural properties vs. non-metal spacers.
�Favorable cost / performance
Infinite Edge Technology
Primary sealant increased path length reduces moisture vapor transmission and impedes in-fill gas loss.
Primary sealant
Energy Standard Trends
Energy standards / requirements are driving change.
More energy efficient IG & Window designs are required.
Double-pane technology is giving way to triple-pane.
Guardian Confidential
Whole Window U-Factor
Vacuum Insulating Glass
Vacuum Insulating Glass
How does it works?�Uses two layers of glass separated by a very thin gap.
�Between the two lite is an array of nearly invisible pillars.
�The pillars keep the two panes of glass from drawing together as the vacuum is applied.
�Creates a thermos bottle-like environment in which convective and conductive heat transfer are virtually eliminated.
�Low-E coatings are used to reduce radiative heat transfer.
�Performance losses are eliminated by the truly hermetic seal.
IGU Performance Comparison
How does it perform?�Vacuum in the cavity is 10-4 torr.
�After a vacuum is applied, the unit is hermetically sealed.
�This method of construction achieves a center-of-glass insulating factor of R-10 or higher.
Vacuum Insulating Glass
Pillar
Vacuum Tube
Frit Edge Seal
Vacuum Cavity
Pillars
Configuration R Value Avg Cost
Double Pane w/Argon 5 to7 Rs 130/ Ft2
Triple Pane w/Argon 7 to 8 Rs 260/Ft2
Triple Pane w/ Krypton 8 to 10 Rs 520/Ft2
Vacuum Insulated Glass (VIG) 10+ Rs 455/Ft2
BIPV�A PV component that replaces the look and function of a primary building material, such as vision and spandrel glass, or skylights.
Building Integrated Photovoltaics
One challenge for BIPV has been a difficult trade-off between opacity and high efficiency versus transparency and low efficiency
� Desired benefits:
� Leveraging building surface areas for power generation and combining costs.
� Coordination of supply and installation with other glass products for the façade
� Customized sizes, shapes and colors.
Building Integrated Photovoltaics
TodayToday TomorrowTomorrow
Building Integrated Photovoltaics
Energy Generating SkylightValue proposition PV Skylight� Dynamic Solar Heat Gain (up to 5x)
� Daylighting without glare
� Five-fold possible increase in SRR (Skylight to Roof Ratio)
� PV power output
� Net Zero Building
� Cash Flow from Grid
Cover glass
3D substrate
LCD glass
Cover & sensor glass
Solid-state lighting substrate
Copier/scanner cover
STN substrate Electrochromic Mirror
Guardian Confidential
Applications for Glass in Electronics
Thank You!
The Evolution of Glass And High Performance Coatings
