Proposed Changes to Homes and Small Buildings for Energy Efficiency Joan Maisonneuve CHBA-Alberta.
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Transcript of Proposed Changes to Homes and Small Buildings for Energy Efficiency Joan Maisonneuve CHBA-Alberta.
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 envelopeHVAC
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 AssembliesIncludes:
• 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
Depends on HRV or NO HRV
Climate Zone , Heating Degree Days oC
Zone 4 Zone 5 Zone 6 Zone 7a Zone 7B Zone 8
< 3000 3000 to 3999
4000 to 4999
5000 to 5999
6000 to 6999
> 7000
Lethbridge EdmontonRed DeerCalgary
Grande Prairie
Minimum ASSEMBLY RSIRED = without HRVBlack = with HRV
Assembly Zone 6Lethbridge
Zone 7aEdm, R.D, Calgary
Zone 7BG.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 (R-30)
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 (R-21)
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
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 Required Effective Thermal Resistance RSI in m²•K/W (See Article 9.36.2.6.)
Description of base assembly
Stud Spacing Nominal insulation
between studs
2.93 3.16 3.27 4.13
mm (in.) m²•K/W Minimum required residual nominal thermal resistance (1) (3) (5) (RSI) in m²•K/W
2x6 wood framing 12.7mm gypsum board, vinyl siding, no
strapping
406 (16”) 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) — RSI 0.14 (R0.8) RSI 0.25 (R1.4) RSI 1.11 (R6.3)
4.23 (R24) — — RSI 0.11 (R 0.6) RSI 0.97 (R5.5)
610 (24”) 3.34 (R19) (2) RSI 0.04 (R 0.2)3
RSI 0.27 (R1.5) RSI 0.38 (R2.2) RSI 1.24 (R7)
3.87 (R22) — RSI 0.02 (R 0.1) RSI 0.13 (R 0.7) RSI 0.99 (R5.6)
4.23 (R24) — — — RSI 0.84 (R4.7)
2x4 wood framing 12.7 mm gypsum board, vinyl siding, no
strapping
406 (16”) 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) RSI 2.05 (R11.7)
610 (24”) 2.11 (R12) RSI 0.95 (R5.4) RSI 1.18 (R6.7) RSI 1.29 (R7.4) RSI 2.15 (R12.2)
2.46 (R14) RSI 0.82 (R4.6) RSI 1.05 (R6) RSI 1.16 (R6.6) RSI 2.02 (R11.5)
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
Building Assembly Below or in Contact With the Ground
Heating Degree-Days(HDD) of Building Location, in Celsius Degree-Days
Zone 4 Zone 5 Zone 6 Zone 7a Zone 7b Zone 8
<3000 3000 to 3999
4000 to 4999
5000 to 5999
6000 to 6999 ≥7000
Minimum Effective thermal resistance (RSI) in m²•K/W
Foundation Walls 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 - - - - 4.44 4.44
Heated Basement Floors ) 2.32 2.32 2.32 2.85 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