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Building Enclosures for the Future –
Building Tomorrow’s Buildings Today
GRAHAM FINCH, MASC, P.ENG – RDH BUILDING ENGINEERING LTD.
BUILDEX VANCOUVER, FEBRUARY 25, 2015
Outline
Trends and Drivers for Improved Building Enclosures &
Whole Building Energy Efficiency
New BCBC & VBBL Building & Energy Code Updates
Effective R-values & Insulation Behaviour
Highly Insulated Walls – Alternate Assemblies & New
Cladding Attachment Strategies
Highly Insulated Low-Slope Roofs – Insulation
Strategies & New Research into Conventional Roofs
What do you See?
COLD
HOT
What do you see?
The Building Enclosure
The building enclosure separates
indoors from outdoors by controlling:
Water penetration
Condensation
Air flow
Vapor diffusion (wetting & drying)
Heat flow
Light and solar radiation
Noise, fire, and smoke
While at the same time:
Transferring structural loads
Being durable and maintainable
Being economical & constructible
Looking good!
Industry Trends in Building Enclosure Designs
Trend towards more efficiently insulated
building enclosures due to higher energy code
targets and uptake of passive design strategies
At a point where traditional wall/roof designs are
being replaced with new ones
Seeing many new building materials, enclosure
assemblies and construction techniques
Greater attention paid to reducing thermal
bridging & use of effective R-values instead of
nominal insulation R-values
Optimization of cladding attachments for both
structural and thermal performance
More & more insulation is being used
Highly Insulated Building Enclosure Considerations
Highly insulated building enclosures require more
careful design and detailing to ensure durability
More insulation = less heat flow to dry out
incidental moisture
Amount, type & placement of insulation
materials matter for air, vapour and moisture
control
Art of balancing material, cost, and detailing
considerations
Well insulated buildings require balancing thermal
performance of all components & airtightness
No point super-insulating walls or roofs if you
have large thermal bridges - address the
weakest links first
Minimum Building & Energy Codes in BC
BC Building Code (BCBC 2012 w/2014 addenda)
Part 3 Buildings
› ASHRAE 90.1-2010 Reference Energy Standard
› NECB 2011 Reference Energy Code
Part 9 Buildings
› New Part 9.36 Energy Efficiency Measures
Vancouver Building Bylaw (VBBL 2014)
Part 3 Buildings
› ASHRAE 90.1-2010 Reference Energy Standard
› NECB 2011 Reference Energy Code
Part 9 Houses
› New Prescriptive Measures including R-22 effective
insulated walls & U-0.25 windows
Sorting through the Confusion of BC Energy Codes
PART 9 RESIDENTIAL BUILDINGS 3 STOREYS OR LESS
PRESCRIPTIVE PATH
BUILDING ENVELOPE TRADE-OFF
PERFORMANCE PATH
ENERGY COST BUDGET METHOD
PRESCRIPTIVE PATH
BCBC 2012 9.36.
VBBL 20149.25.
BUILDING ENVELOPE TRADE-OFF
VANCOUVER
ASHRAE 90.1-2010NECB 2011
ALL OTHER PART 9 AND PART 3 RESIDENTIAL BUILDLINGS
BUILDING TYPE
Not to be Confused by the Climate Zones
ASHRAE 90.1-2010
Exception Vancouver Climate
Zone 5
NECB 2011 & BCBC Part 9.36
Vancouver Remains
Climate Zone 4
AHJs may also
choose/derive
their own
climate data
which may shift
city climate
zones from
BCBC or
ASHRAE
All BC Codes now require consideration
of Effective R-values
Nominal R-values are the rated
R-values of insulation materials which
do not include impacts of how they are
installed
For example 5.5” R-20 batt insulation or
2” R-10 rigid foam insulation
Effective R-values are the actual
R-values of assemblies which include
for the impacts thermal bridging through
the insulation
For example nominal R-20 batts within
2x6 steel studs 16” o.c. becoming ~R-9
effective, or in wood studs ~R-15
Code Shift to Effective R-values
Thermal Bridging occurs when a conductive
material (e.g. aluminum, steel, concrete, wood
etc.) provides a path for heat to bypass or short-
circuit the installed insulation – reducing overall
effectiveness of the entire system
Heat flow finds the path of least resistance
A disproportionate amount of heat flow occurs
through thermal bridges even if small in area
Often adding more/thicker insulation to
assemblies doesn’t help much as a result
Effective R-values account for the additional
heat loss due to thermal bridges and represent
actual heat flow through enclosure assemblies
and details
Understanding Thermal Bridging
Examples of Thermal Bridges in Buildings:
Wood framing or steel framing (studs, plates) in
insulated wall
Conductive cladding attachments through
insulation (metal girts, clips, anchors, screws etc.)
Concrete slab edge (balcony, exposed slab edge)
through a wall
Windows & installation details through insulated
walls
Energy code compliance has historically focused
on assembly R-values – however more
importance is now being placed on details and
interfaces & included thermal bridges
Understanding Thermal Bridging
New Things to Consider: Varying R-values
Recent industry research has re-highlighted the fact that the
R-value of insulation is not always constant (or as published)
Renewed understanding of Aged R-values (Long-term Thermal
Resistance) & Temperature Dependant R-values
Dimensional stability of rigid insulations another issue
Varying Insulation R-value with Temperature
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
6.0
6.5
7.0
-20 -10 0 10 20 30 40 50 60
R-v
alu
e p
er
Inch
of
Insu
lati
on
Mean Temperature of Insulation (°C)
Long-Term R-value per Inch for Various Samples of Insulation vs. Mean Temperature
XPS
EPS
Mineral/ Glass Fiber
Batt Low
Mineral/ Glass Fiber
Batt High
Mineral Fiber Rigid
Board
Cellulose
1/ 2 pcf ocSPF
2 pcf ccSPF
Polyiso
Typical R-value as would be
Published @ 24°C/ 75°F
Published data adapated
f r om BSL - Ther mal
Metr ic Pr oject & Other
Recent Resear ch by BSL
& RDH - data may not
r epr esentat ive of all
insulat ion types
Minimum Effective R-values – Part 3 Buildings
ClimateZone
Wall – Above Grade: Min. R-value (IP)
Roof – Sloped or Flat: Min. R-value (IP)
Window: Max. U-value (IP)
8 31.0 40.0 0.28
7A/7B 27.0 35.0 0.39
6 23.0 31.0 0.39
5 20.4 31.0 0.39
4 & COV 18.6 25.0 0.42
NE
CB
2011
AS
HR
AE
90.1
-2010 –
Res
iden
tial B
uil
din
g ClimateZone
Wall (Mass, Wood, Steel): Min. R-value (IP)
Roof (Attic,Cathedral/Flat): Min. R-value (IP)
Window (Alum, PVC/fiberglass): Max. U-value (IP)
8 19.2, 27.8, 27.0 47.6, 20.8 0.45, 0.35
7A/7B 14.1, 19.6, 23.8 37.0, 20.8 0.45, 0.35
6 12.5, 19.6, 15.6 37.0, 20.8 0.55, 0.35
5 & COV 12.5, 19.6, 15.6 37.0, 20.8 0.55, 0.35
4 11.1, 15.6, 15.6 37.0, 20.8 0.55, 0.40
*7A/7B
combined in
ASHRAE 90.1
COV in ASHRAE
Zone 5, NECB
Zone 4
Minimum Effective R-values – Part 9 Buildings
ClimateZone
Wall - Above Grade: Minimum R-value (IP)
Roof – Flat or Cathedral: Minimum R-value (IP)
Roof – Attic: Minimum R-value (IP)
Window: Max. U-value (IP)
7A 17.5 28.5 59.2 0.28
6 17.5 26.5 49.2 0.28
5 17.5 26.5 49.2 0.32
4 15.8 26.5 39.2 0.32
Wit
ho
ut
a H
RV
Wit
h a
HR
V
ClimateZone
Wall - Above Grade: Minimum R-value (IP)
Roof – Flat or Cathedral: Minimum R-value (IP)
Roof – Attic: Minimum R-value (IP)
Window: Max. U-value (IP)
7A 16.9 28.5 49.2 0.28
6 16.9 26.5 49.2 0.28
5 16.9 26.5 39.2 0.32
4 15.8 26.5 39.2 0.32
COV 21.9 28 nominal 50 nominal 0.25
Resources to Help With New Part 9 Requirements
COV – Guide to R-22+ Effective Walls
in Wood-Frame Construction
BCBC – Illustrated Guides to New Part
9.36 Requirements (Climate Zones 4-8)
Resources to Help With New Part 3 Requirements
Guide to Design of Energy-Efficient
Building Enclosures
Building Enclosure Design Guide –
Currently Being Updated
New HPO Builder Insights –
ASHRAE/NECB – Available Soon!
From Code Minimum to Super Insulation
In BC, minimum effective R-value targets in
energy codes are in range of:
R-15 to R-30 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 (i.e. Passive House), have more
aggressive R-value targets in range of:
R-25 to R-50+ effective for walls
R-40 to R-80+ effective for roofs
R-5 to R-6+ for windows
Plus other drivers – air-tight, thermal comfort,
passive design, mould-free
Super Insulated Walls
Where to Add More Insulation in Walls?
Stuff It?
Wrap It?
Getting to Super Insulation Levels in Walls
Base 2x6
Framed
Wall <R-16
Exterior Insulation
R-20 to R-60+
Deep
Stud,
Double
Stud,
SIPS
R-20 –
R-80+
Split Insulation R-
20 to R-60+
Interior Insulation
R-20 to R-30+
Issues: cladding attachment, thickness
Issues: thermal bridging, thickness, durability
Issues: thickness, durability, interior detailsIssues: cladding attachment, material selection
Design Considerations for Super Insulated Walls
Durability
Material & Labour Cost
Ease of Construction
Wood vs Steel vs Concrete Backup
Pre-fabrication vs Site-Built
Thickness & Floor Area
Air Barrier System & Detailing
Insulation type(s)
Water & Vapour control
Environmental aspects/materials
Cladding Attachment
Combustibility
and Others…
Deep Stud & Double Stud Wall Considerations
Double Stud TJI Stud
2x8 to 2x12 Deep
Stud w/ Interior
Service Wall
Double Stud w/
Interior Service
WallDouble Stud w/ or w/o interior
service wall
Key design
considerations:
air barrier details,
vapour control,
overall thickness,
reducing potential
for wetting
Interior Insulated Wall Considerations
2x6 w/ x-strapped 2x4s on
interior and filled with fibrous or
sprayfoam insulation
2x6 w/ interior
rigid foam insulation
2x6 wall w/ 2x4 X-framing or
rigid insulation at interior
Key design
considerations:
air & vapour barrier
selection, interior
services details
Structurally Insulated Panels (SIPs) Considerations
SIPs Panel w/
EPS insulation
SIPs wall panel
SIPs wall panel w/ interior
service wall
Key design
considerations:
detailing & sealing
of joints &
interfaces,
protection of
panels from
wetting
Exterior Insulated Wall Considerations
Fully exterior insulated 2x4 wall
with rigid insulation
CLT wall panel with semi-rigid
exterior Insulation
2x4 frame wall with rigid exterior
insulation
Key design
considerations:
attachment of
cladding through
exterior insulation,
air barrier/WRB
details
Split Insulated Wall Considerations
Semi-rigid or sprayfoam insulation with
intermittent thermally improved
cladding attachments
Larsen truss
over 2x4 wall
12” EPS over
2x4 wall
Key design
considerations:
type of exterior
insulation, cladding
attachment through
exterior insulation,
air/vapour barrier
placement
Split insulated 2x4 wall with rigid or
semi-rigid insulation
Cladding Attachment & Exterior Insulation
Exterior insulation is only as good as the
cladding attachment strategy
What attachment systems work best?
What is and how to achieve true
continuous insulation (ci) performance?
What type of insulation?
Exterior Insulation & Cladding Attachment Considerations
Cladding weight & gravity loads
Wind loads
Seismic loads
Back-up wall construction (wood, concrete, steel)
Attachment from clip/girt back into structure (studs, sheathing, or slab
edge)
Exterior insulation thickness
Rigid vs semi-rigid insulation
R-value target, tolerable thermal loss?
Ease of attachment of cladding – returns, corners
Combustibility requirements
Many Cladding Attachment Options & Counting
Vertical Z-girts Horizontal Z-girts Crossing Z-girts Galvanized/Stainless
Clip & Rail
Thermally Improved
Clip & RailAluminum Clip & Rail Non-Conductive
Clip & Rail
Long Screws through
Insulation
Cladding Attachment: Continuous Wood Framing
~15-30% loss in R-value
Cladding Attachment: Vertical Steel Z-Girts
~65-75%+ loss in R-value
Cladding Attachment: Horizontal Steel Z-Girts
~45-65%+ loss in R-value
Cladding Attachment: Horizontal Steel Z-Girts
Cladding Attachment: Crossing Steel Z-Girts
~45-55%+ loss in R-value
Cladding Attachment: Clip & Rail, Steel
~30-50% loss in R-value for galvanized, 20-30% for stainless
Cladding Attachment: Clip & Rail, Steel
Cladding Attachment: Clip & Rail, Stainless Steel
Cladding Attachment: Clips w/ Diagonal Z-Girts
Cladding Attachment: Metal Panel Clips (Steel)
Cladding Attachment: Metal Panel Clips (Aluminum)
Cladding Attachment: Steel Clip & Rail
Cladding Attachment: Steel Clip & Rail
Cladding Attachment: Aluminum Clip & Rail
~15-30% loss in R-value (spacing dependant)
Cladding Attachment: Clip & Rail, Isolated Galvanized
Isolate the metal, improve the
performance
~10-25% loss in R-value (spacing dependant)
Cladding Attachment: Clip & Rail, Isolated Galvanized
Cladding Attachment: Clip & Rail, Non-Conductive
Remove the metal –
maximize the
performance
~5-25% loss in R-value (spacing & fastener type dependant)
Cladding Attachment: Clip & Rail, Non Conductive
Cladding Attachment: Improved Metal Panel
Cladding Attachment: Other Discrete Engineered
12’
10’
Cladding Attachment: Screws through Insulation
Longer cladding
Fasteners directly
through rigid
insulation (up to 2”
for light claddings)Long screws through
vertical strapping and rigid
insulation creates truss –
short cladding fasteners
into vertical strapping
Rigid shear block type connection
through insulation, short cladding
fasteners into vertical strapping
Cladding Attachment: Screws Through Insulation
Cladding Attachment: Screws through Insulation
Really Thick Insulation = Really Long Screws
10” Exterior Insulation
In Other Areas of the World: Adhered EIFS
12” EPS insulation
boards (blocks?) R-54
Cladding Attachment: Masonry Ties & Shelf Angles
Continuous shelf angles
~50% R-value loss
Brick ties – 10-30% loss for
galvanized ties, 5-10% loss for
stainless steelShelf angle on stand-offs
only ~15% R-value loss
Cladding Attachment: Masonry Ties & Shelf Angles
Insulation Attachment Fasteners
Cladding Attachment Matters – Effective R-values
20
30
40
50
60
70
80
16.8 33.6 50.4
Effective R
-Valu
e o
f W
hole
Wall
Assem
bly
(f
t2·
F·h
r/B
TU
)
Nominal R-Value of Exterior Insulation (ft2· F·hr/BTU)
NO PENETRATIONS
NO PENETRATIONS
NO PENETRATIONS
Nominal R-Value of Exterior Insulation (ft2·°F·hr/BTU)
4” – R-16.8 8” – R-33.6 12” – R-50.4
20
30
40
50
60
70
16.8
33.6
50.4
Continuous Vertical Z-Girt - 16" OC
Continuous Horizontal Z-Girt - 24" OC
Aluminium T-Clip - 16" x 48"
Aluminium T-Clip - 16" x 24"
Intermittent Galvanized Z-Girt - 16" x 48"
Intermittent Galvanized Z-Girt - 16"x 24"
Isolated Galvanized Clip - 16" x 48"
Isolated Galvanized Clip - 16" x 24"
Intermittent SS Z-Girt - 16" 48"
Intermittent SS Z-Girt - 16" x 24"
Fiberglass Clip - 16" x 48"
Fiberglass Clip - 16" x 24"
Galvanized Screws - 16" x 16"
Galvanized Screws - 16" x 12"
SS Screws - 16" x 16"
SS Screws - 16" x 12"
20
30
40
50
60
70
16.8
33.6
50.4
Continuous Vertical Z-Girt - 16" OC
Continuous Horizontal Z-Girt - 24" OC
Aluminium T-Clip - 16" x 48"
Aluminium T-Clip - 16" x 24"
Intermittent Galvanized Z-Girt - 16" x 48"
Intermittent Galvanized Z-Girt - 16"x 24"
Isolated Galvanized Clip - 16" x 48"
Isolated Galvanized Clip - 16" x 24"
Intermittent SS Z-Girt - 16" 48"
Intermittent SS Z-Girt - 16" x 24"
Fiberglass Clip - 16" x 48"
Fiberglass Clip - 16" x 24"
Galvanized Screws - 16" x 16"
Galvanized Screws - 16" x 12"
SS Screws - 16" x 16"
SS Screws - 16" x 12"
20
30
40
50
60
70
16.8
33.6
50.4
Continuous Vertical Z-Girt - 16" OC
Continuous Horizontal Z-Girt - 24" OC
Aluminium T-Clip - 16" x 48"
Aluminium T-Clip - 16" x 24"
Intermittent Galvanized Z-Girt - 16" x 48"
Intermittent Galvanized Z-Girt - 16"x 24"
Isolated Galvanized Clip - 16" x 48"
Isolated Galvanized Clip - 16" x 24"
Intermittent SS Z-Girt - 16" 48"
Intermittent SS Z-Girt - 16" x 24"
Fiberglass Clip - 16" x 48"
Fiberglass Clip - 16" x 24"
Galvanized Screws - 16" x 16"
Galvanized Screws - 16" x 12"
SS Screws - 16" x 16"
SS Screws - 16" x 12"
Effective R-Value of 2x6 Wall (R-20 batt) + Exterior Insulation as Indicated
0%
20%
40%
60%
80%
16.8 33.6 50.4
Perc
ent T
herm
al D
egre
da
tion
of E
xte
rior
Insula
tio
n
Nominal R-Value of Exterior Insulation (ft2· F·hr/BTU)
Cladding Attachment R-values – It Matters!
20
30
40
50
60
70
16.8
33.6
50.4
Continuous Vertical Z-Girt - 16" OC
Continuous Horizontal Z-Girt - 24" OC
Aluminium T-Clip - 16" x 48"
Aluminium T-Clip - 16" x 24"
Intermittent Galvanized Z-Girt - 16" x 48"
Intermittent Galvanized Z-Girt - 16"x 24"
Isolated Galvanized Clip - 16" x 48"
Isolated Galvanized Clip - 16" x 24"
Intermittent SS Z-Girt - 16" 48"
Intermittent SS Z-Girt - 16" x 24"
Fiberglass Clip - 16" x 48"
Fiberglass Clip - 16" x 24"
Galvanized Screws - 16" x 16"
Galvanized Screws - 16" x 12"
SS Screws - 16" x 16"
SS Screws - 16" x 12"
20
30
40
50
60
70
16.8
33.6
50.4
Continuous Vertical Z-Girt - 16" OC
Continuous Horizontal Z-Girt - 24" OC
Aluminium T-Clip - 16" x 48"
Aluminium T-Clip - 16" x 24"
Intermittent Galvanized Z-Girt - 16" x 48"
Intermittent Galvanized Z-Girt - 16"x 24"
Isolated Galvanized Clip - 16" x 48"
Isolated Galvanized Clip - 16" x 24"
Intermittent SS Z-Girt - 16" 48"
Intermittent SS Z-Girt - 16" x 24"
Fiberglass Clip - 16" x 48"
Fiberglass Clip - 16" x 24"
Galvanized Screws - 16" x 16"
Galvanized Screws - 16" x 12"
SS Screws - 16" x 16"
SS Screws - 16" x 12"
20
30
40
50
60
70
16.8
33.6
50.4
Continuous Vertical Z-Girt - 16" OC
Continuous Horizontal Z-Girt - 24" OC
Aluminium T-Clip - 16" x 48"
Aluminium T-Clip - 16" x 24"
Intermittent Galvanized Z-Girt - 16" x 48"
Intermittent Galvanized Z-Girt - 16"x 24"
Isolated Galvanized Clip - 16" x 48"
Isolated Galvanized Clip - 16" x 24"
Intermittent SS Z-Girt - 16" 48"
Intermittent SS Z-Girt - 16" x 24"
Fiberglass Clip - 16" x 48"
Fiberglass Clip - 16" x 24"
Galvanized Screws - 16" x 16"
Galvanized Screws - 16" x 12"
SS Screws - 16" x 16"
SS Screws - 16" x 12"
Percent Thermal Degradation of Exterior Insulation
Nominal R-Value of Exterior Insulation (ft2·°F·hr/BTU)
4” – R-16.8 8” – R-33.6 12” – R-50.4
Super Insulated Roofs
Getting to Super Insulation Levels in Low-Slope Roofs
Code Minimum
Insulated Roofs
Exterior Insulated+
(conventional or
inverted/PMR)• Best durability but most
expensive
• Some challenges with
more layers of
insulation & detailing
• Simple design
Deeper Joist/Truss –
(vented or unvented) Least durable but least
expensive
• Simple design
• Standard details with
deeper structure
Split Insulated
(unvented)• Decent durability
• Moderate cost
• More complex design
Conventional
Inverted/PMR
Vented
Considerations for Vented/Unvented Roofs
To vent or not to vent? That is
the question…
Considerations for Inverted/PMR Roofs
How to keep
insulation from
becoming
saturated below
pavers, ballast or
soil/green roofs
Considerations for Conventional Insulated Roofs
-4” stone wool
-4” polyiso
-2-8” EPS
(R-50+)8” of polyiso (R-44)
Unique drain connections/details
How much more insulation can
be added, what type(s)?
Conventional Roofing Research Study
Ongoing field monitoring study being
performed in Lower Mainland over past
2.5 years to:
Quantify performance of different roof
membrane colors (reflective white, neutral
grey, & black) in combination with different
insulation strategies (polyiso, stone wool,
& hybrid)
Better understand impacts of insulation
movement, membrane soiling and
moisture movement within conventional
roofs
Why We Did It?
To resolve the great debate as to
selection of a dark vs a light
coloured roof membrane in
Lower Mainland of BC
To understand how reasonably
long light coloured roofs stay
white
To better understand insulation
movement & how it impacts
roofing durability
To monitor the performance of
hybrid insulation approaches &
alternate protection boards
Confused owner?
New 5 Years Old
What We Have Been Monitoring
Stone wool - R-21.4
(2.5” + 3.25”, adhered)
Weight: 26.7 kg/m2
Heat Capacity: 22.7 kJ/K/m2
Polyiso - R-21.5
(2.0” + 1.5”, adhered)
Weight: 4.6 kg/m2
Heat Capacity: 6.8 kJ/K/m2
Hybrid - R-21.3
(2.5” Stone wool over 2.0” Polyiso, adhered)
Weight 14.3 kg/m2, Heat Capacity – 13.7 kJ/K/m2
Design target: Each Assembly the same ~R-21.5 nominal
Where We Have Been Monitoring
9 unique roof test areas, each 40’ x 40’ and each behaving
independently
Similar indoor conditions (room temperature) and building use
(warehouse storage)
Figure 1 Study Building and Layout of Roof Membrane Cap Sheet Color and Insulation Strategy
Polyiso
Hybrid
Stone wool
120’ 120’
Grey
White
Black
Polyiso
Hybrid
Stonewool
How We Have Been Monitoring
Temperature
Heat Flux
Relative Humidity
Moisture Detection
Displacement
Solar Radiation
Heat Flux Relative Humidity &
Moisture DetectionDisplacement
Temperature Solar Radiation
Study Findings: What is the
Impact of Membrane Colour?
32
50
68
86
104
122
140
158
176
194
0
10
20
30
40
50
60
70
80
90
May Jun Jul Aug Sept Oct Nov Dec Jan Feb Mar Apr
Tem
pe
ratu
re [
°F]
Tem
pe
ratu
re [
°C]
Monthly Average of Daily Maximum Membrane Temperatures and Maximum Membrane Temperature for Each Month by Membrane Colour
White Grey Black White - Maximum Grey - Maximum Black - Maximum
* *
*W-ISO-SW had significant data loss in August and September and is removed from the average for those months.
Colour – Impact on Surface Temperatures
Increased temperatures affect:
Membrane degradation/durability
Heat/Energy Flow through assembly
Study Findings: What is the impact
of the insulation strategy?
Varying R-value of Field Study Roofs
14
15
16
17
18
19
20
21
22
23
24
10 20 30 40 50 60 70 80 90 100 110 120 130 140
Effe
ctiv
e A
ssem
bly
R-v
alu
e -
IP U
nit
s
Outdoor Membrane Surface Temperature (Indoor, 72°F)
Effective Roof Insulation R-value - Based on Roof Membrane Temperature
Stone Wool (Initial or Aged)
Hybrid (Initial Average)
Hybrid (Aged)
Polyiso (Initial Average)
Polyiso (Aged)
Based on laboratory measurements of actual insulation samples removed from site (and 4 year old aged polyiso from prior
research study)
Insulation Impact on Peak & Lagging Membrane &
Metal Deck Temperatures
Ro
of
Mem
bra
ne
Me
tal
Deck
Heat Flow – Variation with Insulation Strategy
SENSOR CODING:
SW - stone wool, ISO – polyiso, ISO-SW - hybrid
-25
-20
-15
-10
-5
0
5
10
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
He
at F
lux
[W/m
²]
Heat Flux Sensors
G-ISO HF
G-ISO-SW HF
G-SW HF
Net Annual Impact of Insulation Strategy
0
100
200
300
400
500
600
-150
-100
-50
0
50
100
May Jun Jul Aug Sept Oct Nov Dec Jan Feb Mar Apr Annual
De
gre
e D
ays
[°C
·day
s]
Dai
ly E
ne
rgy
Tran
sfe
r [W
·hr/
m²
pe
r d
ay]
Monthly Average Daily Energy Transfer by Insulation Arrangement
ISO ISO-SW SW Heating Degree Days (18°C)
Ou
twar
dH
eat
Flo
wIn
war
dH
eat
Flo
w
Ou
tward
Heat
Flo
w
Inw
ard
Heat
Flo
w
Energy Consumption and Membrane/
Insulation Design
Energy modeling performed for a
commercial retail building (ASHRAE
building prototype template) to compare
roof membrane colour & insulation strategy
Included more realistic thermal performance of
insulation into energy models
Stone wool: Lower R-value/inch
Higher heat capacity and mass
Polyiso: Higher R-value/inch
(varies with temperature a lot)
Lower heat capacity
Lower mass
Hybrid: Stone wool on top moderates
temperature extremes of polyiso –
makes polyiso perform better
Most Energy Efficient Roofing Combination?
0
20
40
60
80
100
120
1 - Miami 2 - Houston 3 - San Francisco 4 - Baltimore 5 - Vancouver 6 - Burlington VT 7 - Duluth 8 - Fairbanks
An
nu
al H
eat
ing
Ene
rgy,
kW
h/m
2
Climate Zone
Black - Aged Polyiso
Black - Stonewool
Black - Aged Hybrid
White - Aged Polyiso
White - Stonewool
White - Aged Hybrid
0
20
40
60
80
100
120
1 - Miami 2 - Houston 3 - San Francisco 4 - Baltimore 5 - Vancouver 6 - Burlington VT 7 - Duluth 8 - Fairbanks
An
nu
al C
oo
ling
Ene
rgy,
kW
h/m
2
Climate Zone
Black - Aged Polyiso
Black - Stonewool
Black - Aged Hybrid
White - Aged Polyiso
White - Stonewool
White - Aged Hybrid
Commercial Retail Building Heating Energy – kWh/m2/yr
Commercial Retail Building Cooling Energy – kWh/m2/yr
Most Energy Efficient Roofing Combination?
Lighter membrane, stone
wool or hybrid is better for
same design R-value
Darker membrane, stone
wool or hybrid is better for
same design R-value
Conclusions & Ongoing Research
Rated R-values of insulation do not tell the whole story
about actual heat flow through roofs (and walls)
Surface colour (solar absorptivity, long-wave
emissivity), insulation type, thermal mass, latent
energy transfer all impact this
Durability & whole building energy consumption
impacts
Monitoring of long term movement, aged R-values,
membrane degradation, moisture movement and more
ongoing
