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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
à Trends and Drivers for Improved Building Enclosures & Whole Building Energy Efficiency
à New BCBC & VBBL Building & Energy Code Updates
à Effective R-values & Insulation Behaviour
à Highly Insulated Walls – Alternate Assemblies & New Cladding Attachment Strategies
à 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
à The building enclosure separates indoors from outdoors by controlling:
à Water penetration
à Condensation
à Air flow
à Vapor diffusion (wetting & drying)
à Heat flow
à Light and solar radiation
à Noise, fire, and smoke
à While at the same time:
à Transferring structural loads
à Being durable and maintainable
à Being economical & constructible
à Looking good!
Industry Trends in Building Enclosure Designs
à Trend towards more efficiently insulated building enclosures due to higher energy code targets and uptake of passive design strategies
à At a point where traditional wall/roof
designs are being replaced with new ones
à Seeing many new building materials,
enclosure assemblies and construction
techniques
à Greater attention paid to reducing thermal
bridging & use of effective R-values instead
of nominal insulation R-values
à Optimization of cladding attachments for
both structural and thermal performance
à More & more insulation is being used
Highly Insulated Building Enclosure Considerations
à Highly insulated building enclosures require more careful design and detailing to ensure durability
à More insulation = less heat flow to dry out incidental moisture
à Amount, type & placement of insulation materials matter for air, vapour and moisture control
à Art of balancing material, cost, and detailing considerations
à Well insulated buildings require balancing thermal performance of all components & airtightness
à No point super-insulating walls or roofs if you have large thermal bridges - address the weakest links first
Minimum Building & Energy Codes in BC
à BC Building Code (BCBC 2012 w/2014 addenda)
à Part 3 Buildings
› ASHRAE 90.1-2010 Reference Energy Standard
› NECB 2011 Reference Energy Code
à Part 9 Buildings
› New Part 9.36 Energy Efficiency Measures
à Vancouver Building Bylaw (VBBL 2014)
à Part 3 Buildings
› ASHRAE 90.1-2010 Reference Energy Standard
› NECB 2011 Reference Energy Code
à 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
à All BC Codes now require consideration of Effective R-values
à Nominal R-values are the rated R-values of insulation materials which do not include impacts of how they are installed
à For example 5.5” R-20 batt insulation or 2” R-10 rigid foam insulation
à Effective R-values are the actual R-values of assemblies which include for the impacts thermal bridging through the insulation
à 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
à 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
à Heat flow finds the path of least resistance
à A disproportionate amount of heat flow occurs through thermal bridges even if small in area
à Often adding more/thicker insulation to assemblies doesn’t help much as a result
à 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
à Examples of Thermal Bridges in Buildings:
à Wood framing or steel framing (studs, plates) in insulated wall
à Conductive cladding attachments through insulation (metal girts, clips, anchors, screws etc.)
à Concrete slab edge (balcony, exposed slab edge) through a wall
à Windows & installation details through insulated walls
à 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
à Recent industry research has re-highlighted the fact that the R-value of insulation is not always constant (or as published)
à Renewed understanding of Aged R-values (Long-term Thermal Resistance) & Temperature Dependant R-values
à 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 FiberBatt Low
Mineral/Glass FiberBatt High
Mineral Fiber RigidBoard
Cellulose
1/2 pcf ocSPF
2 pcf ccSPF
Polyiso
Typical R-value as would be Published @ 24°C/75°F
Published data adapated from BSL - Thermal Metric Project & Other Recent Research by BSL & RDH - data may not representative of all insulation types
Minimum Effective R-values – Part 3 Buildings
Climate Zone
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
NEC
B 2
01
1
ASH
RA
E 9
0.1
-20
10
–
Resi
den
tial
Bu
ild
ing
Climate Zone
Wall (Mass, Wood, Steel): Min. R-‐value (IP)
Roof (AZc, 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
Climate Zone
Wall -‐ Above Grade: Minimum R-‐value (IP)
Roof – Flat or Cathedral: Minimum R-‐value (IP)
Roof – AZc: 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
W
ith
a H
RV
Climate Zone
Wall -‐ Above Grade: Minimum R-‐value (IP)
Roof – Flat or Cathedral: Minimum R-‐value (IP)
Roof – AZc: 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
à In BC, minimum effective R-value targets in energy codes are in range of:
à R-15 to R-30 effective for walls
à R-25 to R-50 effective for roofs
à R-2 to R-4 for windows
à Green or more energy efficient building programs (i.e. Passive House), have more aggressive R-value targets in range of:
à R-25 to R-50+ effective for walls
à R-40 to R-80+ effective for roofs
à R-5 to R-6+ for windows
à 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 details Issues: cladding attachment, material selection
Design Considerations for Super Insulated Walls
à Durability
à Material & Labour Cost
à Ease of Construction
à Wood vs Steel vs Concrete Backup
à Pre-fabrication vs Site-Built
à Thickness & Floor Area
à Air Barrier System & Detailing
à Insulation type(s)
à Water & Vapour control
à Environmental aspects/materials
à Cladding Attachment
à Combustibility
à 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 Wall
Double 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
à Exterior insulation is only as good as the cladding attachment strategy
à What attachment systems work best?
à What is and how to achieve true continuous insulation (ci) performance?
à What type of insulation?
Exterior Insulation & Cladding Attachment Considerations
à Cladding weight & gravity loads
à Wind loads
à Seismic loads
à Back-up wall construction (wood, concrete, steel)
à Attachment from clip/girt back into structure (studs, sheathing, or slab edge)
à Exterior insulation thickness
à Rigid vs semi-rigid insulation
à R-value target, tolerable thermal loss?
à Ease of attachment of cladding – returns, corners
à Combustibility requirements
Many Cladding Attachment Options & Counting
Vertical Z-girts Horizontal Z-girts Crossing Z-girts Galvanized/Stainless Clip & Rail
Thermally Improved Clip & Rail
Aluminum 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
à 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
à 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 steel
Shelf 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
Effe
ctiv
e R
-Val
ue o
f Who
le W
all A
ssem
bly
(ft2 ·
°F·h
r/BTU
)
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
Per
cent
The
rmal
Deg
reda
tion
of E
xter
ior I
nsul
atio
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
à Ongoing field monitoring study being performed in Lower Mainland over past 2.5 years to:
à Quantify performance of different roof membrane colors (reflective white, neutral grey, & black) in combination with different insulation strategies (polyiso, stone wool, & hybrid)
à Better understand impacts of insulation movement, membrane soiling and moisture movement within conventional roofs
Why We Did It?
à To resolve the great debate as to selection of a dark vs a light coloured roof membrane in Lower Mainland of BC
à To understand how reasonably long light coloured roofs stay white
à To better understand insulation movement & how it impacts roofing durability
à 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
à 9 unique roof test areas, each 40’ x 40’ and each behaving independently
à 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
à Temperature
à Heat Flux
à Relative Humidity
à Moisture Detection
à Displacement
à Solar Radiation
Heat Flux
Relative Humidity & Moisture Detection
Displacement
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
Tempe
rature [°F]
Tempe
rature [°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
à Increased temperatures affect:
à Membrane degradation/durability
à 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
Effective Assembly R-‐value -‐IP Units
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
Meta
l D
eck
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
Heat Flux [W
/m²]
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
Degree
Days [°C·∙da
ys]
Daily Ene
rgy Tran
sfer [W
·∙hr/m² p
er day]
Monthly Average Daily Energy Transfer by Insulation Arrangement
ISO ISO-‐SW SW Heating Degree Days (18°C)
OutwardHe
at Flow
InwardHe
at Flow
Ou
tward
H
eat
Flo
w
Inw
ard
H
eat
Flo
w
Energy Consumption and Membrane/ Insulation Design
à Energy modeling performed for a commercial retail building (ASHRAE
building prototype template) to compare
roof membrane colour & insulation strategy
à Included more realistic thermal performance of
insulation into energy models
à Stone wool: Lower R-value/inch
Higher heat capacity and mass
à Polyiso: Higher R-value/inch
(varies with temperature a lot)
Lower heat capacity
Lower mass
à 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
Annu
al Heatin
g En
ergy, kWh/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
Annu
al Coo
ling En
ergy, kWh/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
à Rated R-values of insulation do not tell the whole story about actual heat flow through roofs (and walls)
à Surface colour (solar absorptivity, long-wave emissivity), insulation type, thermal mass, latent energy transfer all impact this
à Durability & whole building energy consumption impacts
à Monitoring of long term movement, aged R-values, membrane degradation, moisture movement and more ongoing