The definition of a "Super-Insulated" building, with a problem and solution based look at thermal bridging. The energy codes in the Pacific Northwest are some of the most stringent, but are also the best implemented in North America. Effective R-values are considered in the Energy codes and include the impacts of insulation installation and thermal bridges. A look into the other drivers behind Super-insulation such as comfort, passive design and mold-free enclosures.

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 wallsR-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 wallsR-40 to R-60+ effective for roofsR-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/ft2at 75 Pa is frequently being met –range of 0.10 to 0.20 cfm/ft2possible 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
Good
Bad
Ugly

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
Various N.A. Polyiso Samples & Ages -Names Removed
Older and higher density
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
Baseline2x6 w/ R-22 batts = R-16effective
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 StudConcreteHeavy 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: BullittCenter –Split Insulation Wall Assembly

40. BullittCenter –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)
14.1 Crossing Z-girts also evaluated <R-16 effective
Intermittent Metal Clips
17.1 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
BullittCenter –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 (googlethe 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