Transcript Building

Proposed Changes to
Homes and Small Buildings
for
Energy Efficiency
Joan Maisonneuve
CHBA-Alberta
A Tale of Two
NECB – complete document
• Applies to large buildings > 3 stories
• Published by NRC in fall of 2011
• Not yet adopted by the province
• Concerns with window to wall ratios
• CHBA working with builders on this
Part 9 Changes
• Currently out for review by NRC
• Publishing anticipated late 2012
Scope of Part 9 For EE
Housing and small buildings
• Includes secondary suites
• < 600 m2 and 3 storey in height (dwellings)
• Buildings with dwelling units w/common space <
20% of floor area
Building envelope
HVAC
Service water
Early Work by CHBA National
A reasonable step forward not an arbitrary
EnerGuide 80
Elimination of window/door to wall ratios
Reduction of insulation at the attic perimeter
Air tightness is prescriptive areas versus blower
door testing
Opaque & vertical area RSI trade-off
Three Compliance Paths
Prescriptive path
• No specific ENERGUIDE target
• No air leakage target
• No wdw/wall ratios
Trade-off option
Performance Path
• Comparison against a “reference house”
• Energy target = annual energy consumption of
reference house
• Air change rate of 3.2 or 2.5 or tested
Conventions for Units
Effective RSI values for walls, ceiling and
floors
• i.e. transmission through framing combined
with insulated areas
U-value for windows and doors
• Overall window value by A440.2
Calculation of Thermal
Resistance of Assemblies
Includes:
• Studs, joists, lintels, sills, plates (ladders?)
Excludes:
• Minor penetrations (pipes, ducts)
• Areas not intended to be heated
Need to calculate major structural penetrations
• Balcony slabs, beams, columns
• Total area of such penetrations is limited to max 2%
of the gross wall area
• If an area exceeds 2% it must be taken into account
Continuity of Insulation
To prevent a break in the continuity of the
insulation of the building envelope
• Partitions, chimneys, fireplaces, columns beams,
flues
Compensate by insulating for a distance of 4X
the thickness of the penetrating element, inward
and outward
• Also applies where one bldg components meets
another
Requirements for Bldg.
Envelope RSI
Location by Climatic Zones
Climate Zone , Heating Degree Days oC
Zone 4
Zone 5
Zone 6
Zone 7a
Zone 7B
< 3000
3000 to
3999
4000 to
4999
5000 to
5999
6000 to
6999
Lethbridge
Edmonton
Red Deer
Calgary
Grande
Prairie
Depends on HRV or NO HRV
Zone 8
> 7000
Minimum ASSEMBLY RSI
RED = without HRV
Black = with HRV
Assembly
Zone 6
Lethbridge
Zone 7a
Edm, R.D,
Calgary
Zone 7B
G.P.
Ceilings below attics
8.66/8.66
(R-50)
10.43/8.66 (R-60)
10.43/10.43 (R-60)
Cathedral ceilings and
flat roofs
4.75/4.75
(R- 27)
5.07/5.07 (R-30)
5.07/5.07
Walls
3.27/3.16
(R- 18.5)
3.27/3.16 (R-18.5)
4.13/3.27 (R-24)
Floors over unheated
spaces
4.75/4.75
( R-27)
5.07/5.07 (R-30)
5.07/5.07 (R-30)
Rim joists
3.46/ 3.32
(R-20)
3.46/3.32 (R-20)
3.67/3.46
Foundation walls
3.17/3.17
(R-18)
3.57/3.17 (R-20)
3.57/3.17 (R20)
Unheated Floors below
frost line
uninsulated
uninsulated
uninsulated
(R-30)
(R-21)
Examples of Assemblies
Appendix has tables with examples of
assembles and the nominal R-value in
various zones:
Trade-off path available
Table A-9.36.2.6.
Minimum Residual Thermal Resistance Value for Insulation, Sheathing(1) and
other Materials for Walls Above and Not in Contact with the Ground
Assembly description
Description of
base assembly
2x6 wood
framing 12.7mm
gypsum board,
vinyl siding, no
strapping
Stud Spacing
Nominal
insulation
between studs
mm (in.)
m²•K/W
406 (16”)
610 (24”)
2x4 wood
framing 12.7 mm
gypsum board,
vinyl siding, no
strapping
Required Effective Thermal Resistance RSI in m²•K/W (See Article 9.36.2.6.)
406 (16”)
610 (24”)
2.93
3.16
3.27
4.13
Minimum required residual nominal thermal resistance (1) (3) (5)
(RSI) in m²•K/W
3.34 (R19) (2) RSI 0.11 (R 0.6) RSI 0.36 (R2) RSI 0.47 (R2.7) RSI 1.33 (R7.5)
3.87 (R22)
—
4.23 (R24)
—
3.34 (R19) (2)
RSI 0.04 (R
0.2)3
3.87 (R22)
—
4.23 (R24)
—
—
—
RSI 0.84 (R4.7)
2.11 (R12)
RSI 1.01 (R5.7)
RSI 1.24 (R7)
RSI 1.35 (R7.7)
RSI 2.20
(R12.6)
2.46 (R14)
RSI 0.85 (R4.9) RSI 1.08 (R6.1) RSI 1.19 (R6.8)
2.11 (R12)
RSI 0.95 (R5.4) RSI 1.18 (R6.7) RSI 1.29 (R7.4)
2.46 (R14)
RSI 0.82 (R4.6)
RSI 2.05
(R11.7)
RSI 2.15
(R12.2)
RSI 2.02
(R11.5)
RSI 0.14 (R0.8) RSI 0.25 (R1.4) RSI 1.11 (R6.3)
—
RSI 0.11 (R 0.6) RSI 0.97 (R5.5)
RSI 0.27 (R1.5) RSI 0.38 (R2.2)
RSI 1.24 (R7)
RSI 0.02 (R 0.1) RSI 0.13 (R 0.7) RSI 0.99 (R5.6)
RSI 1.05 (R6)
RSI 1.16 (R6.6)
Allowable Reduction In Attic
Reduction in required insulation level at
perimeter of attics under sloped roofs
• Minimum nominal RSI 3.52 (R20) at exterior of wall
• Maximum 1200 mm from interior/ exterior of wall
Minimum height at outside surface of exterior of
wall depends on:
• Minimum 1” vent clearance
• Roof slope and location of top-bottom chord junction
Issue for scissor trusses?
Foundations
Heating Degree-Days(HDD) of Building Location, in Celsius
Degree-Days
Zone 4
Zone 5
Zone 6
Zone 7a
Zone 7b
Zone 8
<3000
≥7000
Building Assembly Below or
in Contact With the Ground
Foundation Walls
3000 to
3999
4000 to
4999
5000 to
5999
6000 to 6999
Minimum Effective thermal resistance (RSI) in m²•K/W
2.05
3.17
3.17
3.57
3.57
4.17
Unheated Basement Floors
– below frost line
uninsulated
uninsulated
uninsulated
uninsulated
uninsulated
uninsulated
– above frost line
1.96
1.96
1.96
1.96
1.96
1.96
Floors on Permafrost
2.32
2.32
2.85
4.44
4.44
Heated Basement Floors )
2.32
2.85
2.85
Structural Slab on grade
1.96
1.96
1.96
3.72
3.72
4.59
Windows & Doors
No prescriptive area limits
• U-values for doors and windows of 1.6 or 1.4
• OR Energy Rating values of 25 & 29
17% to 22% FDWR used as references in
building envelope trade-off option 3
• Used in performance compliance path
Trade-Off Option
Above ground opaque – Above-ground opaque
• Decreased insulation in a wall area compensated by
increased insulation in an equal area of ceiling or
another wall
• Limits placed on maximum permitted reduction in
performance
• i.e. Tall wall areas
Windows – Windows
• increased U-value (decreased R-value) of one
window area compensated by decreased U-value
(increased R-value) for another equal window area
Air tightness
Prescriptive details
• Materials, properties, joints, penetrations
• NO testing required in prescriptive path
• Testing may be used in the performance path
Assembly Specification
• Qualified Assemblies plus junctions
Air Tightness
Properties specified for materials intended to
provide air tightness
Construction details described for joints and
junctions in the airtight material
• Service penetrations including chimneys, ducts, vent
stacks, wiring and electrical boxes
• Foundations and sill plates, sill plates and rim joists
• Windows/doors/skylights and walls/ceilings
• Interior walls and exterior walls/ceilings
HVAC
Equipment sized to Can/CSA F-280
HVAC Ducts - generally
• Sizing to good practice
Ducts outside the plane of insulation
• Sealed joints
• Insulated to same level as required for above-grade walls
Ducts – under insulated floors over unheated spaces
• Sealed
• Insulated to wall RSI
• Sides can be insulated to compensate for reduction on top &
bottom
• Round ducts? At rim joist area?
HVAC
Intakes and Outlets
• Dampers in most cases
Temperature controlled within 1C
Eliminate conflicts with cooling
Zone adjustment capability required
Automatic humidity control required
HVAC Efficiencies
Table of minimum efficiencies
• Gas-fired boilers
90% AFUE
• Gas-fired furnaces 92% AFUE
• Gas-fired fireplaces 62.4% FE
• Air conditioners, air cooled 14 or 14.5 SEER
Concern:
• Table includes equipment even where there is no
specified minimum efficiency
Ventilation
HRV’s optional
• Reduced level of insulation may be installed
in the building envelope
Where used must have:
• Sensible heat recovery efficiency of 60%
Service Water
Service water = domestic water heating
equipment
• Gas-fired storage tanks
EF> 0.62
• Electric
Et > 98%
• Gas-fired tankless < 117kW
EF > 0.8
Heat traps above water heaters NOT required
Performance Path
No EnerGuide specified
Comparison between “Reference House” and
Proposed House
Reference house = prescriptive requirements
Top Issues From Review
Variation in degree-days
Fireplaces as heating appliances
Overlap of insulation to foundation
HRV installation
Tall walls/trade-off
Guidance for plans examiners
Calculating walk-out basements
Costing
Dave
Questions
Additional Information:
• www.nationalcodes.nrc.gc.ca
• www.chba.ca