12TH GREEN ARCHITECTURE CONFERENCE "GREEN APARTMENT" April 15, 2017
Low-E Glass for Green Apartment AGC Asia Pacific Pte Ltd Strategic Planning and Business Development Division Global Technology Network Yusuke Mori, Ph.D
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Façade Considerations A Façade is any side of a building that faces the public
Basic Considerations • • • •
Safety Aesthetics Strength (Wind Load, etc. ) Thermal performance (U-Value, SHGC)
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Façade Considerations Modern Urban Considerations • • • • •
Life Cycle Costs Functionality Weatherability Comfort (Sound, Daylight, etc.) Renewable Energy
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Glass Product Parameters • SHGC : Solar Heat Gain Coefficient • U : U-value
• LT : Light Transmission • LR: Light Reflection
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Light Transmittance and Reflection
Visible Light (VL) 100%
Light Transmission (LT) about 90 %
Light Reflection (LR) about 8 % Light Absorption
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Solar Heat Gain Coefficient (SHGC) Solar Factor = DET + Re-emitted Heat = 0.87 Total Solar Energy =1.00
Direct Energy Transmission (DET) = 0.85
Energy Reflection (ER) = 0.08 Re-emitted Heat = 0.05
Re-emitted Heat = 0.02 Energy Absorption (EA) = 0.07
<calculated factors are based on a 3mm clear float glass>
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U Value Indoor temperature : Tin
Outdoor temperature : Tout
Radiation
Radiation Conduction
Convection
Convection
(and conduction)
(and conduction)
U-value =
Heat transfer Temperature difference
(W/m².K)
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U Value Amount of heat transfer through the glass (per m2) per Degree Celsius difference between outdoor and indoor temperature Example : if the U-value of the glass was 4.0 w/m2 K, thenâ&#x20AC;Ś Outdoor Temperature
Indoor Temperature
Temperature diff
Heat transfer W/m2
25
25
0
0
26
25
1
4
27
25
2
8
28
25
3
12
30
25
5
20
The lower the U-Value, the better performance the glass.
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AGC Range of Solar Control (Low E) Glazing Stopsol (On Line) Good SC Easy handling
Sunergy (On Line) Versatile pyrotic Easy handling
Stopray (off Line) Excellent selectivity Neutral color Low U
Wide range products for various requests.
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STOPRAY (Silver based low-E) â&#x2014;?Improved solar shielding performance (SC: Shading coefficient) Solar energy 100%
Reflection 8% Re-radiation 4%
SC:1.0 Transmittanc e 86%
Solar energy 100%
Reflection
14% Absorption6% Re-radiation Re-radiation 7% 2%
Single pane
SC:0.90
Solar energy 100%
Transmittanc e 74%
Reflectio 35% Absorption12% n Re-radiation Re-radiation 5% 40%
Double glazing
This is the key point
SC:0.28 Transmittanc e 21% Absorption44% Re-radiation 4%
Special Metal Film
Low-E double glazing
Glass facing interior
â&#x2014;?Improved thermal insulation (U value) U value:
U value:
U value:
5.8 W/(m2K)
3.0 W/(m2K)
1.6
W/(m2K)
Glass facing exterior Spacer Desiccant
Single pane
Double glazing
Low-E double glazing
Structure of Low-E double glazing
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The Secret of Heat Shielding 100
The optical interference effect is used to enable visible light to pass through and infra-red light to be reflected
Transmittance (%)
90
Double-glazing
80 70 60 50 40
Low-E double-glazing
30 20 10
Ag
ZnO
Optimal design of multilayered film structure
0 紫外線 可視光線 UV Visible light -10 200 400 600 800
Spectroscopic transmittance 100
Cross section TEM Photograph
ZnO Glass
Layered structure of Low-E Film
90 80
Reflectance (%)
Ag
1000 1200 1400 1600 1800 2000
Wavelength (nm)
~250nm
ZnO
近赤外線 Near-infrared light
Low-E double-glazing
70 60 50 40 30
Double-glazing
20 10 0 紫外線 可視光線 light UV Visible 紫外線 可視光線 -10 200 400 600 800
近赤外線 Near-infrared light 近赤外線 1000 1200 1400 1600 1800 2000
Wavelength (nm)
Spectroscopic reflectance
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The Secret of Thermal Insulation The low emissivity of silver suppresses heat transfer by radiation
Uses low emissivity of silver Emissivity: 0.9
Ag
Heat dissipation by radiation reduced to 1/10 Emissivity: below 0.1
ZnO ~250nm
ZnO Ag
ZnO Glass Layered structure of Low-E Film
Conventional glass
Low-E glass
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AGC Range of Solar Control (Low E) Glazing Stopsol (On Line) Good SC Easy handling
Sunergy (On Line) Versatile pyrotic Easy handling
Stopray (off Line) Excellent selectivity Neutral color Low U
Wide range products for various requests.
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Pyrolytic (On Line) Coating – CVD Stopsol, Sunergy Float Online Production Raw material
Under coater – layer #1
burner
Top coater – layer #2
Metal bath FURNACE molten glass
Glass Temp. 600oC ~ 700oC
Strength of Online Coating
High Durability & Resistances : Scratch, Chemical, etc…
Easy Handling for Glass Processing
Versatile : Can be used Single or double glazed.
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Pyrolytic (On Line) Coating â&#x20AC;&#x201C; CVD
Visual light
Visual light ~35%
Solar energy
Stopsol High light reflection
~8%
Solar energy
Sunergy Low light reflection
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Results: Comparison of Simulation & Measurement Data for 02 Aug 2015 (AGC Collaboration with Research Institution in SG)
Clear float
IWEC SG 02 Aug
Sunergy Clear Sunergy Green/ Grey
Stopray Ace 42T
ipasol Ultraselect 62/29
• • •
Experimental results show similar trends to simulation results, but different absolute values Averaging to minute-based data to obtain hourly mean solar irradiance Simulated results are greatly affected by variety of factors (weather condition)
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Comparison: Clear vs Solar Control Low-E
Clear Float 6mm monolithic High temperature of 41.5 deg for the area near the glass
Sunergy Cool 6mm monolithic Warm temperature of 32.5 deg for the area near the glass
Solar Control Low-E glass can reduce the temperature.
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REF1) Vinhomes Central Park Ho Chi Minh AGC Solar Control Low-E Glass used in Vinhomes Apartment AGC Product: Sunergy Cool Advantages Improve thermal comfort resulting energy saving due to better heat gain mitigation by the Low-E glass. Reduced sunlight and glare from the sun into the apartment, increase privacy for owner Reduced UV light which can caused decolouration of furniture over a period of time. Disadvantages Incremental increase in initial investment Reduction in daylighting into the apartment
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REF2) 76 Shenton Apartment Singapore AGC Solar Control Low-E Glass used in 76 Shenton Apartment AGC Product Sunergy Green Advantages Improve thermal comfort resulting energy saving due to better heat gain mitigation by the Low-E glass. Reduced sunlight and glare from the sun into the apartment, increase privacy for owner Reduced UV light which can caused decolouration of furniture over a period of time. Disadvantages Incremental increase in initial investment Reduction in daylighting into the apartment
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Required SHGC and VLT vs Glass on BEEC Vietnam QCVN09-2013 6mm 1.00
▲ AGC Clear and Tinted ● AGC Solar Control Low-E ■ AGC Solar Control Reflective AGC Low-E DGU
0.90
▲ Other Clear and Tinted ● Other Solar Control Low-E ■ Other Solar Control Reflective Other Low-E DGU
WWR Clear
0.80
0.70
Solar Control Low-E (Single)
SHGC
0.60
0.50
20
Green
30
40
0.40 50
Solar Control Reflective (Single)
0.30
0.20
Low E DGU
0.10 100
90
80
70
60
0.00 0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
VLT
Most of solar control glasses (Single) from most glass suppliers including AGC cannot be used.
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Minimum VLT on QCVN09 2013 (BEEC) 2.1.2 Requirements for building exterior walls and roofs Table 2.3. WWR-related SHGC for glazing
WWR, %
N
SHGCmax on 8 main orientations NE, NW or SE, E or W SW
S
VLTmin 0.70 0.70 0.60 0.55 0.50 0.45 0.40 0.35 0.30
20
0.90
0.80
0.86
0.90
30
0.64
0.58
0.63
0.70
40
0.50
0.46
0.49
0.56
50
0.40
0.38
0.40
0.45
60
0.33
0.32
0.34
0.39
70
0.27
0.27
0.29
0.33
80
0.23
0.23
0.25
0.28
90
0.20
0.20
0.21
0.25
100
0.17
0.18
0.19
0.22
[Minimum VLT] Requirements of Minimum VLT are NOT preferable for the following reasons: A. High VLT may reduce Lighting cost, but affected areas are limited near window. B. For buildings in general, lighting costs are much less than air-conditioning costs. High VLT results in increasing electricity of air conditioning because half of the solar energy is transferred via visual wavelength light. C. Products which satisfy the VLTmin are only clear glass, green tinted glass and low-E double-glazed units (DGU). Owners/ architects and constructors cannot choose from all reflective and solar control glasses and must pay twice expense, and the creativity of the architects will be severely limited as they design new buildings
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Summary Glass can connect the occupants to its surrounding environment through its transparency. This can improve the occupant’s well being. Glass can contribute to Green Apartment by reducing the gain heat resulting reduction in air conditioning consumption. Correct selection of glass is importance to meet the design intend, thermal comfort and cost optimization. 22
Appendix(s)
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Thermal performance Thermal performance
Heat (Solar) Shielding Heat (Solar) Shielding performance is mainly decided by Solar Heat Gain Coefficient (SHGC).
Thermal insulation Thermal insulation performance is mainly decided by U-value.
Solar Heat Gain Coefficient (SHGC) Solar Heat Gain Coefficient: Think of it as the glasses ability to block the heat we feel from the sun
SHGC (g-value) = τe + qi
= τe + αe
hi he + hi
Solar Factor is decided by τe, αe and εi. Heat (Solar) Shielding property cannot be decided by VLT Total Solar Energy =1.00
Based on ISO9050:2003 (3.5), TCVN7737:2016 (4.3.3), TCVN7737:2007(4.5), TCVN7528:2005 (6.3.4), TCVN8260:2009 (5.5.2)
Solar Direct Reflectance (ρe)
Solar Direct Transmittance (τe) Solar Direct Absorptance (αe)
Secondary heat transfer factor toward OUT (qe)
Secondary heat transfer factor toward IN (qi)
U Value Based on TCVN8260:2009 (5.5.1), JISR3209:1998 (Chapter 5)
5.5.1. Full insulation level of insulating glass box (Overall heat transfer resistance), 1/U
1/U [k m2/W] = Re + R + Ri R≤12(mm)
R
1 25,0 5,14 s s 1
1
1 1
2
1
d 1000
R: the insulation of the air layer; Re: the thermal insulation of the outer glass Ri: the thermal insulation of the inside glass 1 Re = 4,9 16,3 1
1 Ri = 5,4 2 4,1
ε 1 and ε 2 is the emission coefficient of the glass on the outside and the inside of the glass S: Layer thickness, d: Glass thickness
Thermal insulation property cannot be also determined by VLT