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
May 21, 2013 – SEABEC - Zen and the Art of Building Enclosure Design

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

From Energy Codes to Super Insulation
! 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

Effective R-values
! 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

From Energy Codes to Super-Insulation
! 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?

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

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

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

Energy Codes and Thermal Bridging – A Balancing Act
! 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

Building and Energy Codes and Airtightness
! 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

Challenges to Energy Efficiency – Windows
! 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)

Impact of Windows on Whole Building R-values

Challenges to Energy Efficiency – Balcony & Exposed Slabs
! 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

Impact of Concrete Balconies and Exposed Slab Edges
! 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
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%

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

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

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

Effective R-values of Various Cladding Attachments
Good Bad Ugly

Strategies: Thermally Improved Cladding Attachments

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

Challenges to True Energy Efficiency – R-value Claims
! 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

Real Insulation R-values – Old Science
Various N.A. Polyiso Samples
& Ages - Names Removed
From:
Canadian
Building Digest
#149, 1972
Older and higher density
Room
Temperature
winter summer

Challenges to True Energy Efficiency – To Good to be True!
! 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

New and Upcoming Challenges to Energy Efficiency?
! 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?

Moving Towards Super Insulated Enclosures
! 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

Energy Efficient Building Enclosure Design Fundamentals
! 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

What about the Pacific Northwest

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

Definitely Not Super Insulated.. But Still Failed

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

What Have We Learned from Past Enclosure Failures?
! 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

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

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

Exterior Insulated Walls
! 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
Steel Stud Concrete Heavy Timber (CLT)

Key Considerations - Exterior Insulation Assemblies
! 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 - 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

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

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

Case Study: Bullitt Center – Split Insulation Wall Assembly
! 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

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

The Need to Go Higher – Reduce the Thermal Bridging

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

Bullitt Center – Exterior Wall Assembly
! 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

Double/Deep Stud Insulated Walls
! 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

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.

Deep/Double Stud and Moisture Risk Assessment

Further Guidance on Highly Insulated Walls & Details
! 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)

Final Thoughts – Super-Insulation Retrofit Case Study
! 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 – “The Art and Balance”
! 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

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