NNCA Construction Workshop 2016-02-17
G.Finch - RDH 1
Picking Windows & Glazing Units for Optimal Energy Efficiency in the North
NNCA RESIDENTIAL CONSTRUCTION WORKSHOP, YELLOWKNIFE – FEB 17, 2016
GRAHAM FINCH, MASC, P.ENG – PRINCIPAL, BUILDING SCIENCE RESEARCH SPECIALIST
[email protected] – 604-873-1181
Outline
� Understanding Window
Performance Numbers & What
It All Means
� Energy Regulations and
Available Window Products in
Canada’s North
� Picking Optimal Windows for
Northern Canadian Homes –
Balancing Energy and Comfort
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Why The Focus on Windows?
� Are a focal architectural and
function part of our homes (views,
daylighting, aesthetics)
� Can be one of the biggest
components of heat loss in a
building (20-50% range)
� But they can also gain an
appreciable amount of heat, which
can be good to reduce space-heat
loads – or it can also be bad and
cause overheating and discomfort
� Picking windows is a learned
experience of conflicting priorities
and a fairly technical one at that!
The Simple Solution to Windows?!
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How do YOU Pick a Window?
� Frame & Glazing Considerations
� Aesthetics, Colour, Look & Feel?
� Materials?
� Hardware & Accessories?
� Technical Performance &
Specifications?
� Thermal
� Air-tightness
� Water-resistance
� Security
� Condensation Resistance
� Code Requirements & Other?
Picking Frames
� Frame Material
� Vinyl
� Aluminium
� Wood
� Fiberglass
� Hybrid Combinations
� Dimensions/Thickness
� Structural Performanace
� Aesthetics/Colours/Feel
� Thermal Performance (U-value)
� Hardware Integration
� Installation Method (Flange/Rebate)
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Picking Glass and Glazing
� Insulated Glazing Units (IGUs)
� Double/Triple/Quad Glazing
� Inert Gas Fill (Air, Argon, Xenon,
Krypton)
� Aesthetics
� Colour (Clear, Green, Blue, Grey etc.)
� Clarity (Visible Light Transmission,
VLT)
� Reflection (Inside & Out)
� Technical Specifications
� U-value
� Solar Heat Gain Coefficient (SHGC)
� ER value
� UV Blocking
� Spacer Bars/Edge Seals
Insulating Glazing Units (IGUs)
IGU Components:
1. Surface 1 (exterior)
2. Surface 2 (interior side
of exterior lite)
3. Surface 3 (exterior side
of interior lite)
4. Surface 4 (interior)
5. Low-e coating
6. Edge spacer (separate
glass panes)
7. Desiccant (to dry air)
8. Primary edge seal
(vapor)
9. Secondary edge seal
(structure)
Air/gas filled space(s)With triples – add in surfaces 5&6With quads – add in surfaces 7&8
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Triple & Quad IGUs
� More air/gas spaces = lower (better) IGU
U-values
� Argon minimal cost to add
� Argon does not leak out through dual seal
spacer bars appreciably unless a defect
� More glass = lower SHGC values
� Fundamental law with stacking layers of
glass together, even clear non-low-e glass
� Can get good range of SHGC values from
low to high for available triple units
� Low-e coatings typically put on cavity side
of inner and outer panes of glass within
triples/quads
� Concerns with glass breakage increases
with more layers of glass
� From experience – durability of glass
triples/quads is better than thin
suspended plastic film systems
Free program by LBNL, called WINDOW allows you to design your own IGUs and get all of the optical properties
Hard Coat vs. Soft Coat Low-e Coatings
� Both thin metal films (silver,
tin, stainless steel etc.) & anti-
reflective metal-oxide films
applied to glass
� Hard coat (pyrolytic) applied
during float process of making
glass
� Tends to result in higher SHGC
but lower thermal performance
(higher U-values)
� Soft coat (sputtered) applied to
glass anytime
� Tends to result in lower SHGC
but better thermal performance
� Newer coatings can get best of
both worlds high SGHC, high
thermal performance Images from PPG
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How Low-e Coatings Work
UV
Images from LBNL
Aesthetics, Colour, & Reflection
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Visible Light Transmission
� Visible Light Transmission (VLT) is the visible light
spectrum that is transmitted through the glazing unit
� Important in day-lighting and glare control
� Typical range of 30-70%, optimum depends on use of
space and window to wall ratio
Solar Heat Gain Coefficient (SHGC)
� SHGC is the % of total solar radiation
transmitted as heat-gain through an
IGU (window)
� SHGC of 0.55 = 55% transferred to
interior (directly by short wave
radiation and indirectly by absorption
and long-wave radiation)
� Remainder is reflected or absorbed
and re-radiated back out
� Too high of SHGC can cause over-
heating within highly glazed spaces
� Not high enough SHGC can limit
amount of potential “free” heat gain
that may be beneficial in heating
climates
SHGC for a window includes the frames, hence why operable windows have lower SHGCs overall
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U-values for IGUs
� U-value for a IGU is driven
by the low-e coating
emissivity, gas fill and gap
width
� Lower emissivity coatings
tend to be soft-coat silver
� Argon gas provides ~25%
improvement in U-value
� Optimal gap is ~1/2” to
5/8” for air/argon - or so
you would think…
U-factor Versus Low-E Coating Emittance
0.2
0.3
0.4
0.04 0.08 0.12 0.16 0.2 0.24
Coating Emittance
U-factor (im
peria
l)
Air U-factor Argon U-factor
U-factor Versus Argon Fill Concentration
0.22
0.24
0.26
0.28
0.30
0.32
0 10 20 30 40 50 60 70 80 90
Argon Fill Concentration (%)
U-facto
r (im
peria
l)
IGU U-values – Gap Widths and NFRC vs ISO
� NFRC (North American) and ISO (European) Standards do not
agree on calculation procedures for center of glass U-values
� Outdoor temperature also matters (i.e. U-values are not fixed)
0.5
0.6
0.7
0.8
0.9
10 12 14 16 18 20 22 24
Ce
ntr
e o
f G
lass
U-V
alu
e,
W/m
2-K
Gap Size, mm
NFRC, -18°C
NFRC, -7°C
NFRC, 0°C
NFRC, 5°C
ISO, -18°C
ISO, -7°C
ISO, 0°C
ISO, 5°C
USI-0.71UIP-0.125 (R-8)
USI-0.52UIP-0.092 (R-10.8)
Triple Glazed IGU 2 Low-e Coatings
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Overall Window U-values
Window U-value =
Frame U-value x
% Frame Area
+
Center of Glass U-value x
% Glass Area
+
Edge of Glass U-value x
% Edge of Glass Area
Overall R-value =
1/U-value
Center of Glazing
U-value
Frame U-value
(Operable & Fixed Frames)
Edge of Glazing
U-value
Window ER Values
� ER Value is a numerical combination of the window U-value,
SHGC and air-leakage rate – for single family homes
� Aimed at consumers, higher number is better
� Used within NBC & Energy Star® to incentivize better energy
performance windows (lower U-value & higher SHGC) favoured)
� Better to use SHGC & U-value in the Far North
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Wading through the Technical Specs of IGUs
Indoor
Trans. UV Tdw
Clear % % Out % In SHGC SC Air Argon WinterSummer Trans ISO/CIE
Clear IG 82% 15% 15% 0.78 0.89 0.48 0.46 45 90 58% 75%
LoE Products - Sputtered
Cardinal LoE²-272 #2 (e=.041) 72% 11% 12% 0.41 0.47 0.30 0.25 56 84 16% 55%
Cardinal LoE²-272 #3 (e=.041) 72% 12% 11% 0.50 0.57 0.30 0.25 56 98 16% 55%
Cardinal LoE²-270 #2 (e=.036) 70% 12% 13% 0.37 0.42 0.29 0.25 56 93 14% 53%
Cardinal LoE²-270 #3 (e=.036) 70% 13% 12% 0.45 0.53 0.29 0.25 56 99 14% 53%
Cardinal LoE3-366 #2 (e=.022) 65% 11% 12% 0.27 0.31 0.29 0.24 56 83 5% 43%
Cardinal LoE3-366 #3 (e=.022) 65% 12% 11% 0.39 0.45 0.29 0.24 56 101 5% 43%
PPG SolarBan 60#2 (e=.043) 71% 12% 13% 0.39 0.45 0.30 0.25 56 95 16% 53%
Viracon VE-2000 #2(e=.040) 72% 11% 12% 0.38 0.44 0.26 0.25 56 84 11% 52%
Guardian Perf. Plus ll #2(e=.044) 69% 19% 17% 0.41 0.47 0.30 0.25 56 65 20% 50%
AFG Comfort TIAC #2(e=.036) 62% 23% 29% 0.40 0.46 0.29 0.25 56 85 30% 51%
AFG Comfort TIR #2(e=.034) 71% 21% 19% 0.47 0.54 0.29 0.25 56 85 30% 57%
AFG Comfort TIPS #3(e=.047) 77% 13% 14% 0.60 0.69 0.30 0.25 56 94 33% 63%
LoE Products - Pyrolytic
AFG Comfort E2 #3 (e=.204) 76% 16% 14% 0.73 0.85 0.35 0.31 53 101 44% 64%
Pilk/LOF Energy Adv. #3,(e=.153) 75% 18% 17% 0.72 0.82 0.33 0.29 54 100 45% 65%
Pilk/LOF Solar E #2(e=.153) 54% 10% 16% 0.48 0.55 0.33 0.29 54 91 40% 52%
PPG Sungate 500 #3,(e=.215) 76% 18% 17% 0.71 0.81 0.35 0.31 52 99 49% 66%
PPG Sungate 300 #3 (e=.324) 76% 18% 18% 0.71 0.82 0.38 0.34 51 96 56% 66%
Glass Temp (F)(Btu/hr/ft²/°F)
Center of Glass
U-Factor
Reflectance
Visible Light
IGU Spacer Bars
� Lots of options – look for
lower conductivity & dual
edge seal technology
� PIB primary seal (vapour),
silicone secondary seal
(structural) works well
� Avoid single seal systems
� Not all created equal
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Conduction through IGU Spacer Bars
Failed IGUs from Bad Spacer Bar Choices
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Condensation & Frost Prevention
� Condensation/frost occurs
when the surface
temperature of the window
drops below the dewpoint
temperature of the
surrounding air
� Causes:
� Inadequate window frames or
IGU spacer bars
� Curtains or blocked interior
airflow
� Poor installation of window
frame
� Too high indoor dew-point
� Poor heating system
configuration
Condensation & Frost due to Hardware Problems
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Frost From Poor Window/Door Selection
And Don’t Forget to Close the Window..
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Window Frame Design & Condensation Risk
� Every window has a slightly different condensation
potential & many factors involved
� More conductive frame materials tend to be colder, but also
bring heat from the frame to the edge glass
� Massing of frame material inboard or outboard of thermal
break or IGU matters
� Operable units tend to perform worse than fixed units (frame
profile & air leakage)
� IGU spacer bars matter for edge of glass & frame
temperatures
� Glazing stop material also matters
� Glazing matters – double vs triple glazing, low-e coating
location, and interior surface low-e coatings
� Placement of window in rough opening can be important
Frame Profile/Massing & Condensation Potential
Exterior -18°C Interior 21°C
1.7°C
11.4°C
5.0°C
5.3°C
4.3°C
7.4°C
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Glazing Stops - PVC vs Aluminum with an Aluminum Frame
-0.2°C
2.8°C
PVC Glazing StopAluminum Glazing Stop
14.8°C
3.4°C
3.7°C
3.6°C
Exterior -18°C Interior 21°C
Window Frame Types & Condensation Potential
Thermally Broken Aluminum Reinforced Vinyl Fiberglass
Exterior -18°C Interior 21°C
Edge of IGU slightly warmer with aluminum
Frame colder with aluminum
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Frame Design – Triple Glazed Vinyl
Exterior -34°C Interior 21°C
2.8°C6.9°C
Wood vs Aluminum Curtainwall – Subtle Tradeoffs
-1.9°C
5.1°C
Frame = R-2.6
Frame = R-2.0
Exterior -18°C Interior 21°C
wood Warmer frame
Colder frame
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Double vs. Triple Glazing
8.9°C2.6°C
Exterior -18°C Interior 21°C Exterior -18°C Interior 21°C
Condensation on the Exterior of Windows
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Rating Condensation Resistance of Windows
� Temperature Index (I-value) – CSA A440
� Measured in Lab – coldest location
� Is value that can also be checked in the field - preferred
� Condensation Resistance Factor (CRF) – AAMA
� Measured in Lab – weighted cold location (relative metric)
� Condensation Resistance (CR) – NFRC
� Simulated – weighted factor accounting for range of indoor RH levels (30,50,70%) and fixed outdoor conditions
� All factors are different and cannot be correlated
� In all cases a higher number means a better product with lower potential for condensation
Temperature Index (I-value)
� Measure of a window’s
condensation resistance (higher
better)
� I-value = 100 x (TF - TO)/(TI – TO)
� TF = Frame temperature (worst),
TI and To = inside and outside
temp.
� Can be used to help select
windows based on exterior
design conditions and interior RH
expectations
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Selecting I-values by Winter Design Conditions
0
10
20
30
40
50
60
70
80
90
100
0 -5 -10 -15 -20 -25 -30 -35 -40 -45 -50
Te
mp
era
ture
In
de
x (
I)
January 2.5% Design Temperature
60% Indoor RH
50% Indoor RH
40% Indoor RH
30% Indoor RH
Edmonton WhitehorseYellowknifeResolute
Vancouver
CSA A440.2-2009
Other Considerations - Window Air-Leakage Rates
� Leakage occurs at frame joints/glazing interfaces,
gaskets & operable hardware
� Air leakage ratings in CSA A440-00 and NAFS-08
Window Rating
CSA A440-00 NAFS-08
Max air leakage rate, m3/h/m
Max air leakage rate, converted to L/s/m2
(NFRC Standard Size Window)
Max air leakage rate for R Class,
L/s/m2
A1 2.79 1.86 n/a
A2 1.65 1.10 1.5
A3 0.55 0.37 0.5
Fixed 0.25 0.17 0.2
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Energy Codes & Available Windows in the North
Energy Code Requirements & Regulations for Windows in the North
� NBC Part 9.36 (Houses) Zone 8
� Maximum U-value USI-1.4
(UIP-0.25) or minimum ER of 29
� Is a vinyl, fiberglass or wood
frame window with triple glazing
(air filled non low-e) or argon
filled double glazing with dual
low-e coatings (#2 & #4 surfaces)
� Energy Star® North Zone
� Maximum U-value of USI-1.2
(UIP-0.21) and ER ≥24, OR
minimum ER 34
� NECB 2011 (Larger Buildings)
Zone 8
� Maximum U-value of USI-1.6
(UIP-0.28)
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Additional Requirements Influencing Window Selection
� Yukon
� NBC 9.36 requirements adopted in April 2013
� Whitehorse Green Building Standard – Energuide 82 or better
� Whitehorse building bylaw – maximum window U-value USI-
1.4 (UIP-0.25)
� Northwest Territories
� Yellowknife Building Bylaw – Energuide 80 or better home
� Typically see triple pane vinyl with argon and one low-e
coating
� Nunavut
� Nunavut Housing Corporation – minimum Energy Star®
Northern Zone, maximum USI-1.2 (UIP-0.21)
� Local supply is more challenging that YT and NT with limited
options and replacement parts etc.
Northern Canada Window Suppliers and Local Preferences
� Vinyl framed triple glazed windows common for homes
� Apparently not a lot of U-value labelling happening - though
understood that triple glazed vinyl or fiberglass meets code
� Seeing mix of argon filled non low-e triple glazing and argon
filled dual low-e triple glazing
� Anecdotes of medium low solar heat gain being preferred and
both northern and southern suppliers expressed doubt of merits
for passive solar gains in the North – concerns of overheating
discomfort
� Anecdotes that sliding windows easier to maintain than crank
operated casements (from remote communities)
� Interestingly quad-pane makes up 20-25% of local sales for one
northern supplier
� Northern Suppliers
� Northerm (Whitehorse) and Arctic Front Windows (Hay River)
� Several Southern Supplies actively providing products
� Ply Gem, All Weather, Kohltech, JeldWen, Gentek, Cascadia
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Available Glazing Units
� Four major suppliers of low-e coated glass to the residential
window industry: Cardinal, Guardian, PPG and AGC
� All make double and triple glazed units, harder to get quads
made from major suppliers
� Each supplier has products available that can be categorized as
having low, medium and high solar heat gain properties
� Minor costs differences between coatings and manufacturers
� Glazing cost is minor (~$5/sqft) compared to the overall cost of a
window (avg $50/sqft in Yellowknife)
� Argon gas fill is fairly standard and often available at minimal
cost
� Note about Hot2000 – enter actual window properties from
manufacturer – do not let H2K calculate it
Selecting Optimal Windows for Energy Efficiency
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Window Selection for Energy & Thermal Comfort
� Winter Goals
� Minimize heating energy
� Improve thermal comfort by
reducing cold surfaces
� Low U-values, High SHGC
� Summer & Swing Season Goals
� Minimize overheating to
prevent or reduce cooling
needs
� Improve thermal comfort by
reducing surface temperatures
and indoor gains
� U-values not as important,
Lower SHGC more valuable
Optimal Window for Northern Housing
� Study performed by RDH
with CMHC to look at optimal
window selection for a
representative northern
housing archetype
� Above permafrost
construction, single storey
with heated “crawlspace” for
services
� 1000 sq.ft house with 10%
window to wall ratio
� While one archetype chosen
here, the findings can be
readily extrapolated to other
and larger housing designs
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Energy Modeling Assumptions
� 4 occupants
� Standard NBC/NECB set-point and
appliance/plug load assumptions
unless more detailed northern
modifications mde
� R-40 effective walls, R-60 roof,
R-40 floor, 1.5ACH airtightness
� Oil heat & hot water (80% efficient)
in NT/NU, electric in YT
� Ducted HRV, 60% efficient
� Starting window assumption,
USI-1.4 (UIP-0.25), SHGC 0.26
� Modeling compared to NRCan
benchmarks for similar homes
Room Electricity
5%Lighting4%
System Fans0%
Heating (Oil)71%
DHW (Oil)20%
Room Electricity12%
Lighting8%
System Fans0%
Heating (Electricity)
46%
DHW (Electricity)
34%
Whitehorse$2400
Yellowknife$4800
Optimal Window Study – Study Locations
2010 NBC CLIMATIC INFORMATION FOR NORTHERN LOCATIONS.
Whitehorse Yellowknife Resolute
Latitude 60.7 ͦN 62.4 ͦN 74.7 ͦN
Climate Zone 7B 8 8
Heating Degree Days (HDDs) 6580 8170 12360
January 2.5% Design Temperature -41 ͦC -41 ͦC -42 ͦC
Assumptions for modeling (2015):• Electric heat in Whitehorse at $0.16/kWh
• Fuel oil in Yellowknife and Resolute at $1.17/L ($0.128/kWh)
• Easily scalable for other regions & fluctuating prices
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Impact of Window U-value as Only Variable
� Archetype home heating cost savings for various window U-values
compared to the NBC 9.36 maximum U-value of 1.40 SI (0.25 IP)
-$100
-$50
$-
$50
$100
$150
$200
$250
$300
0.8 0.9 1 1.1 1.2 1.3 1.4 1.5 1.6
Annual Home Heating Cost Savings
Window U-Value (W/m2-K)
Whitehorse Yellowknife Resolute NBC 9.36 Maximum U-Value
(0.14) (0.18) (0.21) (0.25) (0.28)
Impact of SHGC as Only Variable
� Archetype house heating cost savings for various window
SHGC values compared to a baseline value of 0.26.
-$100
-$50
$-
$50
$100
$150
$200
$250
0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 0.55
Annual Home Heating Cost Savings
Window Solar Heat Gain Coefficient (SHGC)
Whitehorse Yellowknife Resolute NBC 9.36 Baseline SHGC
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Selecting Windows in the North Based on ER?
� Typical house heating cost savings for various window ER
values compared to the NBC 9.36 baseline value of ER 29.
Note two different products with the same ER of 34 yield different heating energy consumption due to the differences in U-value and SHGC.
-$200
-$100
$-
$100
$200
$300
$400
25 30 35 40 45 50
Annual Home Heating Cost Savings
Energy Rating (ER)
Whitehorse Yellowknife Resolute NBC 9.36 Baseline ER
Typical Northern Housing Window Combinations
SAMPLE WINDOW PRODUCTS AVAILABLE & SUITABLE FOR CANADAS NORTH
Configuration*Low-E
Coatings**
Operable Unit Performance***
USI (W/m2-K)U-Value
(Btu/hr-ft2-F)SHGC
Triple Glazed, Vinyl Frame, 1 Low-e Coating
LoE 180 1.25 0.22 0.38
LoE 366 1.25 0.22 0.17
LoE 270 1.25 0.22 0.22
Triple Glazed, Vinyl Frame, 2 Low-e Coatings
LoE 180/180 1.08 0.19 0.36
LoE 366/180 1.02 0.18 0.16
Triple Glazed, Fibreglass Frame, 2 Low-e Coatings
LoE 180/180 1.19 0.21 0.28
LoE 366/180 1.17 0.21 0.13
LoE 270/180 1.19 0.21 0.17
Triple Glazed, Passive House Frame, 2 Low-e Coatings
LoE 180/180 0.86 0.15 0.37
LoE 366/180 0.84 0.15 0.17
Quad Glazed, Vinyl Frame, 2 Low-e Coatings
LoE 270/270 0.73 0.13 0.24
*All configurations include argon gas fill and warm edge spacers.**Low-emissivity glass from Cardinal line of products shown as an example; other glass manufacturer’s products are available with similar performance characteristics.*** Performance characteristics shown are values calculated in accordance with NFRC 100 and 200 for operable configurations of actual products. All products’ operable units are casements, except Passive House units are tilt and turn.
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Archetypical House Heating Cost Differences
� Typical house heating cost savings relative to the highest U-value
product (Vinyl frame with Cardinal LoE 366, U-0.22, SHGC 0.17).
-$50
$-
$50
$100
$150
$200
$250
$300
$350
Vinyl 366 Vinyl 180 Vinyl 270 Vinyl180/180
Vinyl366/180
Fibreglass180/180
Fibreglass366/180
Fibreglass270/180
VinylPassiveHouse180/180
VinylPassiveHouse366/180
Quad Vinyl270/270
Annual Home Heating Cost Savings
Whitehorse Yellowknife Resolute
Influence of Window to Wall Ratio
� Typical change in home heating energy costs for various WWRs
compared to a baseline value of 10% (USI-1.40, SHGC-0.26).
-$700
-$600
-$500
-$400
-$300
-$200
-$100
$-
$100
$200
5% 10% 15% 20% 25% 30%
Annual Home Heating Cost Savings
Window to Wall Ratio
Whitehorse Yellowknife Resolute
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Influence of Window Orientation
� Typical change in home heating energy costs for windows
facing various cardinal directions compared to a house with
equal window area in all directions.
-$120
-$100
-$80
-$60
-$40
-$20
$-
$20
$40
$60
$80
0 45 90 135 180 225 270 315 360
Annual Home Heating Cost Savings
Window Orientation (Degrees) Measured from South
Whitehorse Yellowknife Resolute
NorthWest East
Benefits of Insulated Shutters
� Typical heating energy savings for a house with various exterior
shutter configurations compared to a house without exterior
shutters
Insulated shutters (R-11) versus uninsulated (R-1) are shown. “Tight” installation refers to shutters that are installed as airtight as possible against the wall or window; “loose” installation refers to cases where outdoor air bypasses the shutters.
$-
$10
$20
$30
$40
$50
$60
$70
$80
$90
Closed at Night,Loose Installation
Closed at Night,Tight Installation
Closed Below -10 C,Loose Installation
Closed below -10 C,Tight Installation
Annual Home Heating Cost Savings
Shutter Operation
Insulated Whitehorse Uninsulated Whitehorse
Insulated Yellowknife Uninsulated Yellowknife
Insulated Resolute Uninsulated Resolute
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Selection of Windows for Comfort in the North
� Lower U-value windows will always be more comfortable
and have less drafts than high U-value windows during
the cold winter months
� Challenge is balancing the SHGC for the potential
wintertime gain vs swing season/summer overheating
� Comfort can be difficult to quantify, however can look
at window surface temperatures, air temperatures and
“operative temperatures”
Comfort Analysis & Glazing SHGC Selection
� Archetype Northern Home, West Zone Operative Temperature, June 21st –
Example with windows closed/poor ventilation – extreme case
Whitehorse
SHGC 0.26, No Shutters
SHGC 0.1, No Shutters
SHGC 0.55, No Shutters
SHGC 0.26, Shutter closed when direct sun
SHGC 0.26, Shutters closed when indoor air temp is greater than 21
24
26
28
30
32
34
36
38
40
1:0
0
3:0
0
5:0
0
7:0
0
9:0
0
11
:00
13
:00
15
:00
17
:00
19
:00
21
:00
23
:00
Tem
pe
ratu
re (
°C)
24
26
28
30
32
34
36
38
40
1:0
0
3:0
0
5:0
0
7:0
0
9:0
0
11
:00
13
:00
15
:00
17
:00
19
:00
21
:00
23
:00
Tem
pe
ratu
re (
°C)
Yellowknife
NNCA Construction Workshop 2016-02-17
G.Finch - RDH 30
Comfort Analysis – Window Surface Temperature & Operative Temperatures (Yellowknife)
SHGC Selection for Comfort
� Optimal SHGC & risk for discomfort depends on
number of factors:
� Window to wall ratio
› Higher window area = greater chance of overheating
� Window orientation
› West-facing windows pose greatest risk to overheating
followed by east- and south-facing
� Potential for shading, type/operation of shading
devices
› Overhangs, shutters, near-by trees or buildings reduce
overheating potential
� If risk of overheating is high then suggest a
lower SHGC window of 0.2 to 0.3 (will pay more
for heating)
� If risk of overheating is low then suggest a
higher SHGC window 0.4 or higher to reduce
heating
NNCA Construction Workshop 2016-02-17
G.Finch - RDH 31
Summary: Window Design in Northern Canada
� Window design (amount and orientation) and product
selection has significant impact on energy consumption
& thermal comfort in Northern Homes
� Design a house with reasonable window to wall ratios
(less than 15%), orient glazing primarily to south if
possible and include exterior shading (overhangs,
shutters, trees)
� Ask manufacturers for their product’s U-value & SHGC
� Select the lowest possible U-value available, at least lower
than USI-1.4 (UIP-0.25)
� Assess risk of overheating and choose glazing with
appropriate SHGC
› Low risk choose high SHGC >0.4
› High risk choose lower SHGC 0.15 to 0.3
� rdh.com | buildingsciencelabs.com
Discussion + Questions
[email protected] – 604.873.1181
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