Presentation from 2013 SEABEC Conference on Super Insulated Building Enclosures - Balancing Energy, Durability and Economics in the Pacific Northwest

1. May 21, 2013 – SEABEC - Zen and the Art of Building Enclosure Design
Super Insulated Building Enclosures –
Balancing Energy, Durability, and Economics
in the Pacific Northwest
Graham Finch, MASc, P.Eng
RDH Building Sciences Inc.
Vancouver, BC/Seattle, WA

2. Presentation Outline
What are “Super-Insulated”
buildings and what are the
drivers?
Thermal bridging –
problems and solutions
Designing of highly
insulated walls – insulation
placement & durability
considerations
Super-Insulated wood-
frame building enclosure
design guide

3. Energy codes outline minimum thermal
performance criteria based on climate
zone
ASHRAE 90.1, IECC – US
WSEC 2012, SEC 2012– Washington State
& City of Seattle
OEESC 2010 – Oregon State
Energy codes in Pacific Northwest are
some of most stringent but are also the
best implemented in North America
Building enclosure (R-value/U-values)
very important part of compliance
Effective R-values considered
From Energy Codes to Super Insulation

4. Most Energy Codes now consider
effective R-values
Nominal R-values = Rated R-values of
insulation which do not include
impacts of how they are installed
For example R-20 batt insulation or
R-10 foam insulation
Effective R-values include impacts of
insulation installation and thermal
bridges
For example nominal R-20 batts within
steel studs becoming ~R-9 effective, or
in wood studs ~R-15 effective
Effective R-values

5. In Pacific Northwest - minimum energy code R-value
targets generally in range of:
R-15 to R-25 effective for walls
R-25 to R-50 effective for roofs
R-2 to R-4 for windows
Green or more energy efficient building programs
including Passive House - R-value targets in range of:
R-30 to R-50+ effective for walls
R-40 to R-60+ effective for roofs
R-6+ for windows
Other drivers – comfort, passive design, mold-free
What does Super Insulation mean?
From Energy Codes to Super-Insulation

6. Super Insulated?
12” EPS insulation
boards (blocks?) R-54

7. Super Insulated?
8” XPS insulation
below grade R-40
6” mineral fiber (stainless brick ties)
over insulated 2x6 wood frame ~R-38

8. Good to have super insulated walls and roofs – but what
about thermal bridges and poorly insulated windows?
Super Insulated?

9. Thermal bridging occurs when a more conductive
material (e.g. metal, concrete, wood etc.)
bypasses a less conductive material (insulation)
Minimizing thermal bridging is key to energy
code compliance and an energy efficient building
Balance of good window performance and
appropriate window to wall ratio
Use of exterior continuous insulation with
thermally improved cladding attachments
Minimizing the big thermal bridges
Energy codes have historically focused on
assembly R-values – however recently more
attention is being placed on R-values of
interfaces and details
Also impacts comfort, condensation, and mold
Energy Codes and Thermal Bridging – A Balancing Act

10. Whole building airtightness testing
requirements in Seattle and Washington
State building codes are driving
improvements in energy efficiency
Various solutions to achieve higher
degrees of airtightness
Target of 0.40 cfm/ft2 at 75 Pa is
frequently being met – range of 0.10 to
0.20 cfm/ft2 possible with some solutions
Building and Energy Codes and Airtightness

11. Windows significantly
influence overall building
enclosure performance
Think about what R-3
windows do within an R-20
wall – where is the balance?
Tend to see higher window to
wall ratios in multi-family and
commercial buildings
40% to 70%+ is common
vs 15% to 30% in homes
Optimized area and tuned
SHGC, windows can have a
positive impact (passive
design strategies)
Challenges to Energy Efficiency – Windows

12. Impact of Windows on Whole Building R-values

13. Concrete balconies, eyebrows
and exposed slab edges are
one of the most significant
thermal bridges
Essentially ~R-1 component
This reduce overall effective
R-value of the whole wall area
by 40 to 60% (for something
that is just a few % of the
overall wall area)
Adding insulation to
surrounding walls often can’t
make up for the loss
associated with the detail
Challenges to Energy Efficiency – Balcony & Exposed Slabs

14. Example of slab/balcony impact:
Slab edge typically occupies ~8% of the
gross wall area (8” slab in 8’8” high wall)
Balconies may occupy 1-2% of the gross
wall area
Window to wall ratio affects opaque wall
area
Impact of Concrete Balconies and Exposed Slab Edges
Exposed Slab Edge
Percentage for Different
WWR
100% wall: 0%
windows
60% wall: 40%
windows
50% wall: 50%
windows
40% wall: 60%
windows
20% wall: 80%
windows
8” slab, 8’ floor to
ceiling
7.7% 12.8% 15.4% 19.2% 38.5%
Exposed Slab Edge Percentage for
Different WWR
100% wall: 0%
windows
60% wall: 40%
windows
50% wall: 50%
windows
40% wall: 60%
windows
20% wall: 80%
windows
8” slab, 8’ floor to ceiling 7.7% 12.8% 15.4% 19.2% 38.5%

15. Cast-in thermal breaks
Standard in Europe – becoming
more available in North America
Pre-cast and discretely attached
concrete balconies (bolt on)
Solutions for Balconies

16. Exterior insulation is only as good
as the cladding attachment
strategy
How to achieve continuous
insulation performance?
Flashings and other details also
important
Challenges to Energy Efficiency – Cladding Attachment

17. Many Possible Strategies – Wide Range of Performance
Cladding Attachment through Exterior Insulation

18. Effective R-values of Various Cladding Attachments
GoodBadUgly

19. Strategies: Thermally Improved Cladding Attachments

20. Strategies Wood-frame: Screws through Exterior Insulation
Longer cladding
Fasteners directly
through rigid
insulation (up to 2”
for light claddings)
Long screws through
vertical strapping and rigid
insulation creates truss
(8”+) – short cladding
fasteners into vertical
strapping Rigid shear block type connection
through insulation, cladding to
vertical strapping

21. Wide range of R-values marketed with
polyisocyanurate (polyiso) and closed-cell
(2 pcf) sprayfoam insulation
Polyiso – reports of R-5 up to R-7.5
Closed cell sprayfoam – reports of R-5 to 6.5
Both influenced by age (off-gassing of
blowing gases, replaced with air makes
worse with time)
R-value changes with temperature
Higher density equals lower R-values
This isn’t new science or information
Real long-term thermal resistance (LTTR)
values for both products in the
R-4.5 to R-5.5 range when you need them
Challenges to True Energy Efficiency – R-value Claims

22. Real Insulation R-values – Old Science
From:
Canadian
Building Digest
#149, 1972
VariousN.A.PolyisoSamples
&Ages-NamesRemoved
Olderandhigherdensity
winter summer
Room
Temperature

23. Wide range of aluminum foil
radiant barrier products on
market (paints too)
Varying marketing claims –
anything from R-1 all the way up
to R-15+
Realistically may achieve R-1 to
R-3 (very still air) if product
faces a dead air cavity (ref.
testing by many institutes)
Be very wary of false claims &
suspicious test results
Why care? Often cheaper to use
real insulation
Challenges to True Energy Efficiency – To Good to be True!

24. Wood-framed buildings generally provide good R-values, but…
Taller wood-frame buildings – higher stud framing factors
Solid wood buildings – Cross Laminated Timber (CLT)
Where to insulate & air-seal - what assemblies to use?
New and Upcoming Challenges to Energy Efficiency?

25. Trend towards more highly insulated building enclosures
due to higher energy code targets and uptake of passive
design strategies
Often means new enclosure assemblies (mainly walls) and
construction techniques
Higher R-value windows (triple glazing and less conductive
window frames)
Reduction of thermal bridging, more structural analysis of
façade components, balconies etc.
Super insulation achieved with proper balance!
Long-term performance of new assemblies (particularly
wood frame) can be a challenge in our wet environment
Moving Towards Super Insulated Enclosures

26. Thermal insulation continuity & effectiveness – energy
code driven
Airflow control/airtightness – energy code and building
code driven
Control of condensation and vapor diffusion – building
code driven
Control of exterior moisture/rainwater & detailing –
building code driven
More insulation = less heat flow to dry out moisture
Amount, type and placement of insulations matters
Greater need to more robust and better detailed assemblies
Potentially more sensitive to vapor, air & moisture issues
Energy Efficient Building Enclosure Design Fundamentals

27. What about the Pacific Northwest

28. Continue to repair moisture damaged
buildings in the Pacific Northwest
Not Super Insulated.. Lower Risk But Still Failed

29. Definitely Not Super Insulated.. But Still Failed

30. “Super Insulated” Glazing Systems .. Failed
Systemic Failure of proprietary triple glazing units

31. Rainwater penetration causes most problems –poor details
(e.g. lack of, poorly implemented, bad materials)
Air leakage condensation can cause problems
Vapor diffusion contributes but doesn’t cause most problems
– unless within a sensitive assembly
Many windows leak and sub-sill drainage and flashings are
critical, other details and interfaces also important
Insulation inboard of structural elements decreases
temperatures which increases risk for moisture damage
Durability of building materials is very important
Watch over-use of impermeable materials in wet locations
Drained & ventilated rainscreen walls & details work well
Unproven materials/systems can be risky
What Have We Learned from Past Enclosure Failures?

32. Insulation Placement and Assembly Design Considerations
Interior
Insulation
Exterior
Insulation
Split
Insulation

33. Getting to Higher R-values – Placement of Insulation
Baseline
2x6 w/ R-22
batts = R-16
effective
Exterior Insulation – R-20 to R-40+ effective
• Constraints: cladding attachment, wall thickness
• Good for wood/steel/concrete
Deep/Double Stud–
R-20 to R-40+
effective
• Constraints wall
thickness
• Good for wood,
wasted for steel
Split Insulation–
R-20 to R-40+ effective
• Constraints: cladding
attachment
• Good for wood, palatable for
steel
New vs Retrofit
Considerations

34. Insulation outboard of structure and control layers (air/vapor/water)
Thermal mass at interior where useful
Cladding attachment biggest source of thermal loss/bridging
Excellent performance in all climate zones – But is not the panacea,
can still mess it up
Exterior Insulated Walls
Steel Stud Concrete Heavy Timber (CLT)

35. Key Considerations:
Cladding attachment
Wall thickness
Heat Control: Exterior
insulation (any type)
Air Control: Membrane on
exterior of structure
Vapor Control: Membrane on
exterior of structure
Water Control: Rainscreen
cladding, membrane on exterior
of structure, surface of
insulation
Key Considerations - Exterior Insulation Assemblies

36. Key Considerations - Split Insulation Assemblies
Key Considerations:
Exterior insulation type
Cladding attachment
Sequencing & detailing
Heat Control: Exterior and stud space
Insulation (designed)
Air Control: House-wrap
adhered/sheet/liquid membrane on
sheathing, sealants/tapes etc. Often
vapor permeable
Vapor Control: Poly or VB paint at
interior, plywood/OSB sheathing
Water Control: Rainscreen cladding,
WRB membrane, surface of insulation

37. Split Insulation Assemblies – Exterior Insulation Selection
Rigid exterior foam insulations (XPS, EPS,
Polyiso, closed cell SPF) are vapor impermeable
(in thicknesses, 2”+)
Is the vapor barrier on the wrong side?
Does the wall have two vapor barriers?
How much insulation should be put outside
of the sheathing? – More is always better, but
is there room? Cost?
Semi-rigid or rigid mineral or glass fiber
insulations are vapor permeable and
address these concerns
Vapor permeance properties of sheathing
membrane (WRB)/air-barrier is also important

38. Split Insulation and Moisture Risk Assessment
Insulation Ratio Here is over 2/3 to the exterior of
the sheathing
Careful with lower ratios with foam

39. R-value design target up to R-25 for
steel framed wall assembly. Energy
modeling showed could trade-off a
bit but no lower than R-18.2 (code)
6” steel stud frame wall structure
(supported outboard of slab edge,
and perimeter beams)
Expectation to be cost effective,
buildable and minimize wall
thickness
Tasked with the evaluation of a
number of potential options
Lack of performance from standard
practices helped innovate a new
solution
Case Study: Bullitt Center – Split Insulation Wall Assembly

40. Bullitt Center – Exterior Wall Assembly Evaluation
Baseline: R-19 batts
within 2x6 steel stud with
exposed slab edges = R-
6.4 effective
Considered 2x8 and 2x10
studs - still less than R-8
Target R-value up to R-25
Vertical Z-Girts (16” oc)
5” (R-20) exterior
insulation plus R-19 batts
within 2x6 steel stud
= R-11.0 effective
Horiz. Z-Girts (24” oc)
5” (R-20) exterior
insulation plus R-19 batts
within 2x6 steel stud
= R-14.1 effective
Crossing Z-girts also
evaluated <R-16 effective
Intermittent Metal Clips
5” (R-20) exterior
insulation plus R-19 batts
within 2x6 steel stud
= R-17.1 effective
up to R-21 with some
modifications

41. The Need to Go Higher – Reduce the Thermal Bridging

42. The Need to Go Higher – Reduce the Thermal Bridging
Intermittent Fiberglass
Spacers, 3½” to 6”
(R-14 to R-24) exterior
insulation
= R-19.1 to R-26.3 +
effective

43. Metal panel
1” horizontal metal hat tracks
3 ½” semi-rigid mineral fiber (R-14.7)
between 3 ½” fiberglass clips
Fluid applied vapor permeable
WRB/Air barrier on gypsum sheathing
6” mineral fiber batts (R-19) between
6” steel studs
Gypsum drywall
Supported outboard slab edge
(reduce thermal bridging)
Effective R-value R-26.6
Bullitt Center – Exterior Wall Assembly

44. Double 2x4/2x6 stud, single deep 2x10, 2x12, I-Joist etc.
Common wood-frame wall assembly in many passive houses (and
prefabricated highly insulated walls)
Often add interior service wall – greater control over airtightness
Inherently at a higher risk for damage if sheathing gets wet (rainwater,
air leakage, vapor diffusion) – due to more interior insulation
Double/Deep Stud Insulated Walls

45. Key Considerations – Double Stud/Deep Stud
Key Considerations:
Air-sealing
Rainwater management/detailing
Heat Control: Double stud cavity fill
insulation(s) – dense-pack cellulose,
fiberglass, sprayfoam
Air Control: House-wrap/membrane on
sheathing, poly, airtight drywall on interior,
OSB/plywood at interior, tapes, sealants,
sprayfoam. Airtightness on both sides good
Vapor Control: Poly, VB paint or
OSB/plywood at interior
Water Control: Rainscreen cladding, WRB
at house-wrap/membrane, flashings etc.

46. Deep/Double Stud and Moisture Risk Assessment

47. Guide to the Design of Energy
Efficient Building Enclosures – for
Wood Multi-Unit Residential
Buildings
Provides design and detailing
guidance for highly insulated
wood-frame wall & roof assemblies
Contains North American energy
code guidance, building science
fundamentals
Insulation placement, air barrier
systems, cladding attachment
Available as a free download direct
from FP Innovations (google the
title above)
Further Guidance on Highly Insulated Walls & Details

48. Deep energy retrofit of 1980s vintage
concrete frame multi-unit residential
building – owners decision to renew
aesthetic (old concrete, leaky windows)
Original overall effective R-value R-2.8
Exterior insulate and over-clad existing
exposed concrete walls (R-18 eff.)
Install new triple glazed fiberglass frame
windows (R-6 eff.) – triple glazing
incremental upgrade <5 year payback
Retrofitted effective R-9.1 (super-
insulated for a building of this type)
55% reduction in air leakage measured
Enclosure improvements 20% overall
savings (87% space-heating)
Actual savings being monitored –
seeing higher than predicted savings
Final Thoughts – Super-Insulation Retrofit Case Study

49. Super-Insulated building enclosures require careful
design and detailing to ensure durability
Balancing materials, cost, and detailing considerations
Cladding attachment detailing – minimize loss of R-value of
exterior insulation
Shifting insulation to the outside the structure improves
performance and durability – balance is often cost
Super-Insulated buildings require balancing thermal
performance of all components & airtightness
No point super-insulating walls/roofs if you have large thermal
bridges or poor performing windows - address the weakest
links first
Opportunities for both new and existing buildings
Final Thoughts – “The Art and Balance”

50. Questions
Graham Finch – gfinch@rdhbe.com
Highly Insulated Wood-frame Enclosure Guide
– FP Innovations