Caltrans District 8 Update for the CalAPA Spring Asphalt Conference 2024
Moving Towards More Energy Efficient Wood Frame Building Enclosures
1. Moving
Towards
More
Energy
Efficient
Wood-‐Frame
Building
Enclosures
Implica(ons
of
the
New
NBC
Sec(on
9.36
! Graham
Finch,
MASc,
P.Eng
Principal,
Building
Science
Research
Engineer
RDH
Building
Engineering
Ltd.
Vancouver,
BC
RCIC
2013
Edmonton
–
April
30,
2013
2. Presenta<on
Outline
! New
Building
Enclosure
Energy
Efficiency
Requirements
Under
New
2012
NBC
Sec(on
9.36
! Highly
Insulated
Wood-‐frame
Enclosure
Assemblies
! Building
Enclosure
Design
Guide
for
Highly-‐
Insulated
Wood-‐frame
Buildings
3. New
NBC
Sec<on
9.36
Energy
Efficiency
Requirements
! New
Sec(on
9.36
-‐
Whole
Building
Energy
Efficiency
Requirements
for
Part
9
houses
! Reference
to
NECB
2011
for
other
buildings
(Part
3)
! Building
Enclosure
(Envelope),
HVAC,
Hot-‐Water
Components
! Prescrip(ve,
Trade-‐off
and
Energy
Modeling
Paths
for
Compliance
! Effec(ve
R-‐values
vs
Nominal
R-‐
values
2010
NBC
Updated
in
December
2012
–
New
Sec8on
9.36.
Energy
Efficiency
4. Nominal
vs
Effec<ve
R-‐values
! Nominal
R-‐values
=
Rated
R-‐values
of
insula(on
which
do
not
include
impacts
of
how
they
are
installed
! For
example
R-‐20
ba
insula(on
or
R-‐10
foam
insula(on
! Effec(ve
R-‐values
or
Real
R-‐values
=
Calculated
R-‐values
of
assemblies/
details
which
include
impacts
of
installa(on
and
thermal
bridges
! For
example
nominal
R-‐20
bas
within
steel
studs
16”
o.c.
becoming
~R-‐9
effec(ve,
or
in
wood
studs
~R-‐15
5. Thermal
Bridging
! Thermal
bridging
occurs
when
a
conduc(ve
material
(e.g.
aluminum,
steel,
concrete,
wood
etc.)
provides
a
path
for
heat
to
flow
around
insula(on
! The
bypassing
“bridging”
of
the
less
conduc(ve
material
significantly
reduces
its
effec(veness
as
an
insulator
! Examples:
! Wood
framing
(studs,
plates)
in
insulated
wall
! Steel
framing
in
insulated
wall
! Conduc(ve
cladding
aachments
through
insula(on
(metal
girts,
clips,
anchors,
screws
etc)
! Concrete
slab
edge
(balcony,
exposed
slab
edge)
through
a
wall
! Window
frames
and
windows
themselves
6. Why
Thermal
Bridging
is
Important
! Effec(ve
R-‐values
account
for
thermal
bridges
and
represent
actual
heat
flow
through
enclosure
assemblies
and
details
! Heat
flow
finds
the
path
of
least
resistance
! Dispropor(onate
amount
of
heat
flow
occurs
through
thermal
bridges
! Ofen
adding
more/thicker
insula(on
can’t
help
! Required
for
almost
all
energy
and
building
code
calcula(ons
! Energy
code
compliance
has
historically
focused
on
assembly
R-‐values
–
however
more
importance
is
being
placed
on
details
and
interfaces
&
thermal
bridges
! Air(ghtness
also
as
important
7. New
NBC
Sec<on
9.36
Energy
Efficiency
Requirements
! Increased
emphasis
on
con(nuous
insula(on,
higher
effec(ve
R-‐values
! Minimum
R-‐value
Tables
for
Above
&
Below
Grade
Enclosures
(Walls,
Roofs,
Floors)
–
dependent
on
whether
HRV
present
in
house
(minor
tradeoff
allowance)
! Maximum
U-‐value
(minimum
R-‐value)
&
Minimum
Energy
Ra(ng
(ER)
Tables
for
Windows,
Doors,
Skylights
! Prescrip(ve
air(ghtness
requirements
(no
blower
door
yet)
! HVAC
duct
sealing/insula(on,
minimum
equipment
efficiency
! Domes(c
Hot
Water,
minimum
equipment
efficiency
! Energy
modeling
op(on
&
Trade-‐off
op(ons
8. New
NBC/NECB
Climate
Zone
Divisions
• >7000 HDD
• 6000 to 6999 HDD
• 5000 to 5999 HDD
• 4000 to 4999 HDD
• 3000 to 3999 HDD
• < 3000 HDD
9. Wall,
Roof
&
Window
Requirements
for
Alberta
(NBC
9.36)
Climate
Zone
Wall
-‐
Above
Grade:
Minimum
R-‐value
(IP)
Roof
–
Flat/
Cathedral:
Minimum
R-‐
value
(IP)
Roof
–
AXc:
Minimum
R-‐value
(IP)
Window:
Max.
U-‐
value
(IP)
/
Min.
ER
8
21.9
28.5
59.2
0.25
/
29
7B
21.9
28.5
59.2
0.25
/
29
7A
17.5
28.5
59.2
0.28
/
25
6
17.5
26.5
49.2
0.28
/
25
Without
a
HRV
Climate
Zone
Wall
-‐
Above
Grade:
Minimum
R-‐value
(IP)
Roof
–
Flat/
Cathedral:
Minimum
R-‐
value
(IP)
Roof
–
AXc:
Minimum
R-‐value
(IP)
Window:
Max.
U-‐
value
(IP)
/
Min.
ER
8
17.5
28.5
59.2
0.25
/
29
7B
17.5
28.5
59.2
0.25
/
29
7A
16.9
28.5
49.2
0.28
/
25
6
16.9
26.5
49.2
0.28
/
25
With
a
HRV
11. Guidance:
Effec<ve
R-‐values
within
NBC
9.36
! Some
guidance
(Table
A-‐9.36.2.6.(1)A
provided
for
calcula(on
of
effec(ve
R-‐values
of
some
assemblies
(to
help
transi(on
from
nominal
R-‐values)
! Sufficient
for
most
wood-‐frame
/ICF
wall
assemblies
! No
provisions
for
cladding
aachment/
thermal
bridging
12. Typical
Wood-‐frame
Wall
Assemblies
–
Effec<ve
R-‐values
Wall
Assembly
/
Insula<on
Rated
R-‐
value
Effec<ve
Wall
R-‐value
**
Studs
at
16”,
25%
F.F.*
Studs
at
24”,
22%
F.F.*
2x4
w/
R-‐12
baes
10.7
-‐
2x4
w/
R-‐14
baes
11.5
-‐
2x6
w/
R-‐19
baes
15.5
16.1
2x6
w/
R-‐22
baes
16.6
17.4
2x6
w/
2pcf
18.3
19.3
sprayfoam
(R-‐5/in,
R-‐27.5)
2x6
w/
2pcf
sprayfoam
(R-‐6/in,
R-‐33)
18.6
19.8
*Studs at 16” o.c.=25% total Framing Factor (F.F.) and Studs at 24” o.c. =22% total framing factor. This
includes typical framing arrangements of studs, sill and top plates, window headers, corners, built-up
studs etc.
** All values calculated using three-dimensional thermal modeling calibrated to hot-box testing
13. Beyond
2x6
Framed
Walls
! Effec(ve
R-‐value
targets
above
~R-‐17
essen(ally
means
that
standard
prac(ce
of
ba
insula(on
in
2x6
stud
frame
wall
is
inadequate
! Shifs
code
minimum
baseline
wall
assembly
to:
! Insulated/Foam
Sheathing
! Sprayfoam?
! Exterior/Split
Rigid
Insula(on
! Double/Deep
Stud
! Structurally
Insulated
Panels
(SIPs)
! Insulated
Concrete
Forms
(ICFs)
15. GeXng
to
Higher
R-‐values
–
Insula<on
Placement
Baseline
2x6
w/
R-‐22
bas
=
R-‐16
effec<ve
Exterior
Insula(on
–
R-‐20
to
R-‐40+
effec<ve
• Constraints:
cladding
aachment,
wall
thickness
• Good
for
wood/steel/concrete
Deep/Double
Stud–
R-‐20
to
R-‐40+
effec<ve
• Constraints
wall
thickness
• Good
for
wood,
wasted
for
steel
Split
Insula(on–
R-‐20
to
R-‐40+
effec<ve
• Constraints:
cladding
aachment
• Good
for
wood,
palatable
for
steel
16. Exterior
Insulated
Walls
! Insula(on
outboard
of
structure
and
control
layers
(air/vapor/water)
! Thermal
mass
at
interior
where
useful
! Excellent
performance
in
all
climate
zones
! Cladding
Aachment
biggest
source
of
thermal
loss/bridging
! Not
the
panacea,
can
s(ll
mess
it
up
Steel Stud Concrete Heavy Timber (CLT)
17. Exterior
Insula<on
Assemblies
! Key
Considera(ons:
! Cladding
Aachment
! Wall
Thickness
! Heat
Control:
Exterior
Insula(on
! Air
Control:
Membrane
on
exterior
of
structure
! Vapor
Control:
Membrane
on
exterior
of
structure
! Water
Control:
Membrane
on
exterior
of
structure
(possibly
surface
of
insula(on)
19. Minimizing
Thermal
Bridging
through
Exterior
Insula<on
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
20. Key
Considera<ons
-‐
Split
Insula<on
Assemblies
! Key
Considera(ons:
! Exterior
insula(on
type
! Cladding
aachment
! Sequencing
&
detailing
! Heat
Control:
Exterior
and
stud
space
Insula(on
! Air
Control:
House-‐wrap
adhered/sheet/
liquid
membrane
on
sheathing,
sealants/
tapes
etc.
Ofen
vapor
permeable
! Vapor
Control:
Poly
or
VB
paint
at
interior,
plywood/OSB
sheathing
! Water
Control:
Rainscreen
cladding*,
WRB
membrane,
surface
of
insula(on
21. Split
Insula<on
Assemblies
–
Exterior
Insula<on
Selec<on
! Foam
insula(ons
(XPS,
EPS,
Polyiso,
ccSPF)
are
vapor
impermeable
! Is
the
vapor
barrier
on
the
wrong
side?
! Does
your
wall
have
two
vapor
barriers?
! How
much
insula(on
should
be
put
outside
of
the
sheathing?
–
More
the
beer,
but
room?
! Rigid
mineral
or
glass
fiber
insula(on
are
vapor
permeable
which
can
address
these
concerns
! Vapor
permeability
of
WRB
and
air-‐barrier
also
important
! Risk
is
dependant
on
interior
condi(ons
(RH)
and
poten(al
for
air-‐leakage,
and
on
exterior
condi(ons
(rain/RH)
and
poten(al
for
water
leaks
22. Double/Deep
Stud
Insulated
! Double
2x4/2x6
stud,
Single
Deep
2x10,
2x10,
I-‐Joist
etc…
! Common
wood-‐frame
wall
assembly
in
many
passive
houses
! Lends
itself
well
to
pre-‐fabricated
wall/roof
assemblies
! Interior
service
wall
–
greater
control
over
interior
air(ghtness
! Higher
risk
for
damage
if
sheathing
gets
wet
(rainwater,
air
leakage,
vapor
diffusion)
23. Key
Considera<ons
–
Double
Stud/Deep
Stud
! Key
Considera(ons:
! Air-‐sealing
! Rainwater
management/detailing
! Heat
Control:
Double
stud
cavity
fill
insula(on(s)
! Air
Control:
House-‐wrap/membrane
on
sheathing,
poly,
air(ght
drywall
on
interior,
OSB/plywood
at
interior,
tapes,
sealants,
sprayfoam.
Air(ghtness
on
both
sides
of
cavity
recommended
! Vapor
Control:
Poly,
VB
paint
or
OSB/
plywood
at
interior
! Water
Control:
Rainscreen
cladding*,
WRB
at
house-‐wrap/membrane,
flashings
etc.
24. Building
Enclosure
Design
Guidance
! Energy-‐Efficient
Building
Enclosure
Design
Guide
for
Wood-‐frame
Mul(-‐Unit
Residen(al
Buildings
in
Marine
to
Cold
Climates
! Builds
off
of
Previous
Building
Enclosure
Design
Guides
&
CMHC
Best
Prac(ce
Guides
! Focus
on
durable
and
highly
insulated
wood-‐frame
assemblies
to
meet
current
and
upcoming
energy
codes
! Guidance
for
taller
and
alternate
wood-‐frame
structures
(ie
post
&
beam,
CLT)
up
to
6
stories
25. What
is
in
the
Guide?
! Chapter
1:
Introduc(on
! Context
! Chapter
2:
Building
and
Energy
Codes
across
North
America
! Canadian
Building
and
Energy
Code
Summaries
&
R-‐value
requirements
! US
Building
and
Energy
Code
Summaries
&
R-‐value
requirements
! Performance
Ra(ng
Systems
&
Green
Building
Programs
26. What
is
in
the
Guide?
! Chapter
3:
Moisture,
Air
and
Thermal
Control
! Building
as
a
System
! Climate
Zones
! Interior
Climate,
HVAC
Interac(on
! Cri(cal
Barriers
! Control
of
Rainwater
Penetra(on
! Control
of
Air
Flow
! Controlling
Condensa(on
! Construc(on
Moisture
! Controlling
Heat
Flow
and
Insula(on
! Whole
Building
Energy
Efficiency
! Computer
Simula(on
Considera(ons
for
Wood-‐frame
Enclosures
27. What
is
in
the
Guide?
! Chapter
4:
Energy
Efficient
Wall
and
Roof
Assemblies
! Above
Grade
Wall
Assemblies
• Split
Insulated,
Double
Stud/Deep
Stud,
Exterior
Insulated
• Infill
Walls
for
Concrete
Frame
! Below
Grade
Wall
Assemblies
• Interior
and
Exterior
Insulated
! Roof
Assemblies
• Steep
Slope
&
Low
Slope
! Chapter
5:
Detailing
! 2D
CAD
(colored)
and
3D
build-‐sequences
for
various
typical
enclosure
details
! Chapter
6:
Further
Reading
&
References
28. Air
Flow
Control
–
Air
Barrier
Strategies
! Air
Barrier
Systems
(Fundamentals,
Materials,
Performance,
tes(ng)
! Sealed
Poly/Sheet
Membranes
! Air(ght
drywall
! Sprayfoam
! Sealed-‐Sheathing
Approaches
› Unsupported
sheet
membranes
› Supported
sheet
membranes
with
ver(cal
strapping
› Sandwiched
membranes
behind
exterior
insula(on
› Self-‐Adhered
and
liquid
applied
membranes
29. Heat
Flow
Control
&
Insula<on
! Control
of
Heat
Flow
! Minimizing
Conduc(ve
Losses,
Minimizing
Air
Leakage
! Placement
of
Insula(on
within
assemblies
! Wood
framing
factors
! Types
of
insula(on,
R-‐values
and
typical
uses
! Thermal
bridging
and
effec(ve
R-‐values
34. Detailing
! 2D
CAD
details
(colored)
provided
for
typical
details
for
each
wall
assembly
type
(split
insulated,
double
stud,
exterior
insulated)
plus
some
for
infill
walls
! 3D
sequence
details
provided
for
window
interfacing
(split
insulated,
double
stud,
exterior
insulated)