Presentation given at ACI California Regional Conference, June 2012. A look at lessons learned from a few local Passive House projects.

1. High Performance Details
Lessons Learned
• Wall assembly challenges
• Window choices
• Foundations simplified
Bronwyn Barry, Assoc. AIA, CPHC
One Sky Homes & Passive House BB Consulting
PHCA Co-President
2012
Bronwyn Barry ACI California 2012

2. Challenging walls
Envelope Results kBTU/ft2.yr heating energy
Preliminary Aug 3, 2009 Max. allowed = 4.75 kBTU/ft2.yr
SIP wall system** Prefab Stud wall Site built
5.5" w/ rigid 7.25" w/ 9.5" TJI
5.5" 7.25" 5.5" insul. 7.25" rigid insul. studs
Window Est. Cost ($K) 49 52 47 53 49 55 79
Sierra Pacific* 4.52 4.01 5.11 4.58 4.54 4.19 3.91
37 86 89 84 90 86 92 116
**assuming $4k for interior furring
using Recoup 200DX HRV w/ 3' OA duct runs
4" EPS under slab
11-7/8" TJI roof
4" EPS slab edge
Source: Performance analysis from Dan Johnson, Arkin Tilt Architects and cost estimates from Quantum Builders
Bronwyn Barry ACI California 2012

3. Conflicting details
Beware of architectural and structural details not agreeing!
Bronwyn Barry ACI California 2012

4. Complicated junctions
Floor to floor assembly with open web hanging floor truss
Bronwyn Barry ACI California 2012

5. (With solutions)
Floor to floor assembly with open web hanging floor truss,
With 2” of spray foam
Bronwyn Barry ACI California 2012

6. Window choices
Marin Remodel Window Cost Benefit Analysis
Brand Existing US- Av. Euro Av. PH Certified US -good US-best Canadian
R-value W#5 0.99 2.69 5.73 8.68 6.09 8.64 5.9
Heat Dem #
(kBTU/ft2yr) 13.7 7.63 6.97 5.71 6.05 8.01 6.75
Price / $29,400.00 $45,344.50 $50,830.00 $35,507.42 $92,297.79 $39,852.10
Heat Dem delta 0 6.07 6.73 7.99 7.65 5.69 6.95
$ Saving/a** 0 1,736.02 1,924.78 2,285.14 2,187.90 1,627.34 1,987.70
30yr $saving 0 182.10 57,743.40 68,554.20 65,637.00 48,820.20 59,631.00
40yr $saving 0 69,440.80 76,991.20 91,405.60 87,516.00 65,093.60 79,508.00
yrs to paybk 0 16.94 23.56 22.24 16.23 56.72 20.05
30 yr CO2
savings (lbs) *** 0 20.03 22.21 26.37 25.25 18.78 22.94
(Highest/Best rating shown in orange field.)
* The above revised Sorpetaler cost & rating # reflects the following changes:
New TF Design window profile (rated at R8 value.) with triple glazing
Double glazed wood Accordian-Sliding door at Dining Room
Bug screen for 10 side window units only (no doors.)
** Assuming $0.13 per kBTU/ft2yr (1 Therm = 100,000 BTUs = $1.30 @ 2,200sf =$286.00)
*** 11 lbs of CO2 saved for each Therm saved
Source: Cost Benefit Analysis by Bronwyn Barry, CPHC, for Quantum Builders, 2009
Bronwyn Barry ACI California 2012

7. 2-pane vs 3-pane comfort
Triple
Pane
(Bathroom)
vs
Dual
Pane
(Laundry)
W indow
C omfort
C omparison
95
90
85
80
75
Temperature
(°F)
70
65
60
55
50
45
5/6
-­‐ 00:00 5/7
-­‐ 00:00 5/8
-­‐ 00:00 5/9
-­‐ 00:00 5/10
-­‐ 00:00 5/11
-­‐ 00:00 5/12
-­‐ 00:00 5/13
-­‐ 00:00 5/14
-­‐ 00:00 5/15
-­‐ 00:00
Outdoor
Temp Temp,
air,
Bathroom,
3-­‐pane Temp,
air,
Laundry,
2 -­‐pane
Temp,
Globe,
Bathroom,
3-­‐pane Temp,
Globe,
Laundry,
2 -­‐pane, Temp,
Int.
Surface,
Bathroom,
3-­‐pane
Temp,
Int.
Surface,
L aundry,
2 -­‐pane
Source: Monitoring data from Building America (DOE), PG&E and Davis Energy at Cottle Residence,
San Jose by One Sky Homes
Bronwyn Barry ACI California 2012

8. Select good spacers
(at the correct width)
Image Source: Greenbuildingadvisor post by Alex Wilson credited to: www.windownation.com
Bronwyn Barry ACI California 2012

9. Imported and local 3-pane
Source: Analysis of Heat Loss Reduction through window edges by E. isevieius, V. Staponkus,
& A. Jurelionis; Kaunas University of Technology, Lithuania. 2005
Image: Lorna Fear IR images Bronwyn Barry ACI California 2012

10. The case for triple pane
Approx.
US Min. Min. max. UW max. RW
Climate Outdoor Outdoor max. UW (BTU/ (hr.ft2.°F/
Zone Temp (C) Temp (F) (W/m2-C) hr.ft2.°F) BTU)
Zone 2 10 50 2.1 0.37 2.70
Zone 3 0 32 1.05 0.18 5.56
Zone 4 -5 23 0.84 0.14 7.14
Zone 5 -10 14 0.7 0.12 8.33
Zone 6 -15 5 0.6 0.1 10.00
Zone 7 -20 -4 0.53 0.09 11.11
Data Source: Dariush Arasteh– LBNL, private email, 2009.
Map Source: http://resourcecenter.pnl.gov/cocoon/morf/ResourceCenter/dbimages/full/973.jpg
Bronwyn Barry ACI California 2012

11. Don’t assume perfect translation
cold regions: quadruple or vacuum
hot regions: solar control first
moderate: triple or sometimes double
Map Source: Passive House Institute, Darmstadt, Germany
Bronwyn Barry ACI California 2012

12. The Rating Systems
National Fenestration
Rating Council (NFRC)
• U.S. based
• No minimum standards
• Simulation and product test
Passive House Institute:
• German based
• Set performance standards
• Simulation only
From presentation: ‘A Tale of Two Rating Systems’ by B. Barry, October 2011
Bronwyn Barry ACI California 2012

13. How the NFRC rates windows
Uf Ucog = U-value glass
Uedge Ucog Acog = Area glass
Uf = U-value frame
Af = Area frame
Uedge = U-value edge of
Aedge Acog glass
Af Aedge = Area edge of glass
Aw = Area Window
(Ucog*Acog) + (Uf*Af) + (Uedge*Aedge)
Uw =
Aw
From presentation: ‘A Tale of Two Rating Systems’ by B. Barry, October 2011
Bronwyn Barry ACI California 2012

14. How the PHI rates windows
Lf
Uf
Ug Lg
ψspacer
Ag
ψinstall Af
(Ug*Ag) + (Uf*Af) + (ψspacer*Lg) + (ψinstall*Lf)
Uw-installed =
Aw
Bronwyn Barry ACI California 2012

15. Generates different results
Component NFRC PHI
Window size 1.8 m2 1.82 m2
Width of frame * 0.15 m 0.1 m
Delta T in Therm Boundary condition 39 deg C 30 deg C
U-glass 0.73 W/m2K 0.7 W/m2K
Spacer vs edge of glass 0.22 W/K 0.15 W/K
Final U-window value (metric) 0.79 W/m2K 0.77 W/m2K
Final U-window value (IP) 0.139 BTU/hr.ft2.°F 0.135 BTU/hr.ft2.°F
Final R-value 7.18 hr.ft2.°F/BTU 7.37 hr.ft2.°F/BTU
* Frame size variation is due to different profile options submitted by manufacturer’s representative
to the two testing agencies and is not a protocol difference.
Bronwyn Barry ACI California 2012

16. Climate specific details
Option 1 Option 2 Option 3
Spread footing, 8” ICF stem wall, floating slab floor.
Bronwyn Barry ACI California 2012

17. Cost and simplicity still matter
Perimeter Foundation Study
Opt. Psi fRsi Assembly
# (BTU/hrfF) (%) Assembly Description benefits/negatives
1 0.136 0.86 Spread Ftg, ICF stem wall: 8" conc. w/ 2" EPS sides, 5" slab w/ 4" HD EPS blw Easy to build
not
2 0.103 calc'd Same as #1 + 1 3/4" Foamglas below ICF stem wall Foamglas expensive
3 0.042 0.88 Same as #1 + 1 3/4" HD EPS at top of ICF stem wall Best performance
!
But this is ONLY appropriate in very specific climates!
Bronwyn Barry ACI California 2012

18. My lessons learned:
• ‘Outsulate’ your walls for best forgiveness
factor and performance results
• Stick with triple-pane windows (for now)
• Foundation perimeter insulation is crucial
• Continuous sub-slab insulation is climate
specific
• Don’t assume perfect translations
• Religion relies on faith, everyone else
bring data! (With thanks to Danny Parker)
Bronwyn Barry ACI California 2012

19. Thank you
Bronwyn Barry, Assoc. AIA, CPHC
One Sky Homes & Passive House BB Consulting
PHCA Co-President
2012
Bronwyn Barry ACI California 2012