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Updated and enhanced version of an oldie, with added info on responsibility of manufacturers and then that of the designer. High performance windows now a local reality.
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Sills and Thresholds for High Performance Windows
Bronwyn Barry, Assoc.AIACertified Passive House Designer
Director, One Sky Homes
COPYRIGHT ONE SKY HOMES 2013
• All about the Edge• Overthinking it: losing your Balance• Your responsibility: Size and Location• Don’t forget the basics: water management• A FREE install example for paying attention
Passive House Recipe" Buildings heated with hair dryers"
Overview:
Consider your Edge
Sum of the Whole is GREATER than sum of the Parts?
• Glass > spacer• Spacer > Sash• Sash > Frame• Frame > Wall
Source: ARCHnews Green Column, June 2009. Dan Johnson, [email protected]
Scrutinize the Sill:
• Can it Drip?• Will it Drain?• Can you set it
back into the wall?
Specify good glass
Image Source: Breweryreviewery.com. Scanned graphic from: Residential Windows by John Carmody et al
(Adjust according to your own taste preference.)
But don’t over-think the SHGC
Source: B.Barry – One Sky Homes. Moore Residence Retrofit PHPP outputs, 2012
• Exterior shading is better than lower SHGC
• Changing SHGC per orientation is overrated!
(Only try this in Heating Dominated climates)
Try exterior shades: a better SHGC
Image source: Hella.info, Balance Project (www.needsbased.com) and author’s own photo of project Berkeley, CA (right)
Remember Your Balance
* Varies with climate, site and season* Goal: optimize passive energy flows across seasons
GAINS LOSSES
Solar Heat Gains (Qs)
+Internal Heat Gains (QI)
+Annual Heat Demand (QH)
=
Transmission Heat Losses (QT) +Ventilation Heat Losses (QV)
+Useful Cooling Demand (QK)
70 °F
( QS + QI ) – ( QT + QV ) = QH*
COPYRIGHT ONE SKY HOMES 2013
Learn to adjust your ‘levers’
• Location• Shape• Orientation• Glazing• SHGC• Shading
• Occupants• Lighting• Electronics• Appliances• Mechanicals• HW storage
• Insulation• Thermal Bridging• Windows/Doors
• Glass U-value• Frames• Install
• Air Sealing• HRV
GAINS LOSSES
( QS + QI ) – ( QT + QV ) = QH
COPYRIGHT ONE SKY HOMES 2013
A quick Retrofit example:
BEFORE AFTER COPYRIGHT ONE SKY HOMES 2013
Finding the Balance:
Window Area
OrientationSHGC
Reduction Factor for
Solar Radiation
WindowArea
WindowU-Value
WindowR-Value
GlazingArea
Glazing Area as
% of Gross Floor Area
Average Global Radiati
on
Transmission Losses
Heat Gains Solar Radiation
maximum: ft2 BTU/hr.ft2.F hr.ft2.F/BTUft2
kBTU/ft²yr
kBTU/yr kBTU/yr
North 0.49 0.51 19.6 0.27 3.7 15.2 0.9% 48 314 238
East 0.37 0.51 59.5 0.23 4.4 45.1 2.7% 142 806 1601
South 0.55 0.11 105.5 0.23 4.3 86.3 5.2% 144 1462 938
West 0.48 0.27 155.7 0.22 4.5 127.1 7.7% 49 2053 997
Horizontal 0.00 0.00 0.0 0.00 0.0 0.0 0.0% 150 0 0
0.49 0.28 340.2 0.23 4.4 273.8 4635 3773
• Did you Look at your Pluses and Minuses?• Retrofits are challenging… but still Passive House Possible
Source: IR Images: Lorna Fear IR images
Edgy: Frames & Spacers
Find your biggest LOSERS and ELIMINATE THEM!
Why certification matters: • Health• Comfort• Durability
Info from PHI component Certification Criteria document: http://www.passiv.de/downloads/03_certification_criteria_transparent_components_en.pdf
Ever seen moldy glass?
PHI Certification requires: Uw, installed and fRsi,
(which check for interior cold spots and interior surface condensation.)
This ensures a high level of occupant comfort due to the elimination drafts and mold growth.
The Frame is the interesting part:
Image 1: SmartWin(Propassivhausfenster.net) 2.Enersign.de, Image 3: passivehausfenster.at , Image 4: walchfenster.at
Good Frame Design Includes:• Strength • Durability • Insulation, • Drainage • and various options for installation.
Understand Frame efficiency
Source: Protokollbund Nr. 37, Passive House Institute, Darmstadt, Nov. 2008
(Less frame, more glazing can lower your Heating Demand)
Cold Climate Forecast
Big moves in thin glass
Source: SuperWindows.eu & http://www.passiv.de/komponentendatenbank/files/pdf/zertifikate/zd_pazen_enersign-plus-arctis_en.pdf
Invis 160 = Ug 0.15 W/m2K ENERsign Arctis = Uw 0.57 W/m2K
A B
CD
Your Design choices
Window Width Ht Total
U-installed
Cost/sf
(") (") SF BTU/hr.ft2.F $
A-1 26 3/8 46 5/8
24.1
0.14
$143.12A-2 29 5/8 46 5/8 0.14
A-3 56 15 3/8 0.15
B-1 26 3/8 62 24.1
0.14$121.23
B-2 29 5/8 62 0.14
C 49 3/5 70 24.1 0.13 $83.56
D 45 5/7 76 24.1 0.13 $83.31
Better Design Choices:
• Large openings• Taller or vertical• Fixed windows• Casement only for operable• No muntins• No mullions
Design and Image Source: zanderroth architekten, with thanks to bruteforcecollaborative.com for all vent panel image sourcing
Why put glass in it?
Images: Left and bottom right: Wicona thermally broken ventilation flap for Wicline, Top right unknown. Source BFC
Explore a DESIGN opportunity
Source: Protokollbund Nr. 37, Passive House Institute, Darmstadt, Nov. 2008
POOR: Uw(installed) = 0.85 W/m2K/m2KPsi-install = 0.033 W/m2K
BETTER: Uw(installed) = 0.83 W/m2K0 W/m2
Psi-install = 0.028 W/m2K
BEST: Uw(installed) = 0.83 W/m2KW/m2
Psi-install = 0.027 W/m2K
EXTERIOR
INSET
CENTERED
Location, location, location
A Sample Install
SILL & JAMB (CASEMENT)
Air-sealing RO to plywood sheathing
Window buck with dropped sill
Prosoco liquid flashing over RO and exterior insulation
Alu drip edge added to base of window
Exterior sills and jamb trim added
COPYRIGHT ONE SKY HOMES 2013
Interior Close-up
WINDOW BUILDUP AT SILL WINDOW INSTALL SEQUENCE COPYRIGHT ONE SKY HOMES 2013
Now with local options:
Good luck
(And Thank You)
Vision
(Northwin)
PHI Certification Documents: www.passivehouse.com
CaliPassiv
(Wooden Window Inc.)
Synergist (Casagrande)
Bronwyn Barry, Assoc. AIA, CPHCDirector, One Sky Homes
PHCA Co-President2012
