Compliance (NECB 2017) Part (3) Building envelope

Classification: Protected A

Energy CodeCompliance (NECB 2017)Part (3) Building envelope

Prepared & Presented By: Nabil Habashy, Energy Code Specialist, AMA


NECB PresentationsObjectives: NECB intent.

NECB applications.

Part 3 – Building envelope. General requirements:

Above ground Building Envelope /Walls/ Floors/Roofs.

Thermal characteristics of Fenestration.

Thermal characteristics of Doors and Access Hatches.

Thermal characteristics for walls/floors/ Roofs in contact with the ground.

Air Leakage

Trade-off Simple Trade-off


NECB IntentNECB 2017 is an objective based code

NECB 2017 intent:

To limit the negative impact of building design and construction on the environment (OE Environment)

OE1.1 excess use of energy.

Code NECB ABC/NBC

Requirements Power demand of ventilation fan Ventilation flow rates


1.1.1.1. Application of this Code – NECB 20171) Except as provided in Sentence (2), this Code applies to the design and construction of all newbuildings described in Sentence 1.3.3.2.(1) of Division A of the NBC and to additions. (See Note A-1.1.1.1.(1).)2) This Code does not apply to farm buildings.

NECB Application


NECB ApplicationNBC, 2019 (AB edition)1.3.3.2. Application of Parts 3, 4, 5 and 61) Parts 3, 4, 5, and 6 of Division B apply to all buildings described in Article 1.1.1.1.anda) classified as post-disaster buildings,b) used for major occupancies classified asi) Group A, assembly occupancies,ii) Group B, care, treatment or detention occupancies, oriii) Group F, Division 1, high-hazard industrial occupancies.

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Presentation Notes

What is the BTC?


NECB ApplicationSummary Any Building under part 3 Buildings greater than 600m2 or exceeding 3 storeysGroup C, D, E, F2, and F3 All occupancies of (Group A, B, and F1) Buildings Outside the scope of section (9.36) . • Group D, E or F3 whose combined total floor area > 300m2• F2 occupancies

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Presentation Notes

What is the BTC?


Part 3: Building Envelope


Part 3: Building Envelope1.1.2.1. ComplianceCompliance Paths:• Prescriptive path –cookbook• Trade-off path

• Simple trade-off • Detailed trade-off

• Performance path – whole building modeling

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Presentation Notes

The detailed trade-off path is based on the whole building performance compliance path of Part 8 with non-building envelope parameters kept constant or specified as defaults. The detailed-trade off path does not reduce transaction costs for demonstrating compliance compared to the whole building performance compliance path, given that modeling would be required in both cases and modeling is becoming more common place. Trading only building envelope parameters can be done with the modeling rules in the existing performance compliance path and therefore the detailed trade-off path is redundant. Remove the detailed trade-off path. The existing performance compliance path of which the detailed trade-off path is a subset offers more flexibility and can accomplish the same outcome.


Part 3: Building EnvelopeGeneral requirements:

Calculation rules & StandardsProtection of insulation materialsContinuity of insulationSpaces heated to different temperature (>10oc.)Allowable fenestration and door area

Above ground building envelopeVestibuleWalls/Roofs/Floors thermal characteristics. FenestrationDoor and access hatch

Building assemblies in contact with the groundWalls/Roofs/Floors thermal characteristics

Air LeakageOpaque/fenestration/doors/fire place doors.

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Presentation Notes

Protection of insulation materials against degradation of their thermal properties due to: air leakage or convection wetting, or moisture bypassing the plane of thermal resistance. Continuity of insulation At penetrations Keep continuous or overlap 17


Part 3: Building Envelope• Part 3 is concerned with the transfer of heat and

air through the building envelope• The building envelope is the collection of

components that separate conditioned space from unconditioned space, exterior air, or the ground.

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Presentation Notes

SOLAR REFLECTANCE INDEX (SRI): The visible transmittance (VT)


Part 3: Building Envelope3.1.1.5. Thermal Characteristics of Building AssembliesThermal characteristics for MaterialsDetermined through the following standards:

• Product standard listed in NBC• ASTM C 177• ASTM C 518

Calculations shall be carried out • at an average temperature of 24±2°C and under

a temperature difference of 22±2°C.


Part 3: Building Envelope3.1.1.5. Thermal Characteristics of Building AssembliesThermal transmittance of Fenestration & DoorsDetermined through the following standards:

• CSA A440.2/A440.3, “Fenestration Energy performance/User Guide to CSA A440.2-14, Fenestration Energy Performance,” or

• NFRC 100, “Determining Fenestration Product U-factors.”

• If outside the scope of the above standards:• ASHRAE Handbook – Fundamentals or• Tested to ASTM C 1363


Part 3: Building Envelope3.1.1.5. Thermal Characteristics of Building AssembliesR-Effective calculations for Building AssembliesNECB lists 3 methods1. Calculations

• ASHRAE Fundamentals • ISO 14683 • BC Hydro - Notes• ASHRAE Research Project RP-1365 - Notes

2. 2D or 3D thermal modeling or3. Laboratory testing ASTM C 1363


Part 3: Building Envelope3.1.1.6. Fenestration/Door Calculations • Calculation includes rough opening in the walls• Gross wall area doesn’t include parapets,

projected fins, ornamentation and appendages.• For allowable Skylight area, gross roof area shall

be the insulated roof area including skylights.


Part 3: Building EnvelopeCalculation of Overall Thermal TransmittanceArticle 3.1.1.7.Added more clarity; the effect of thermal bridging should be accounted for in RSI effective calculations.1. Repetitive structural members.

Secondary Structural Members 2. Major structure penetrations.3. Junctions in components and assemblies.4. Secondary structure members.5. Fasteners need not be taken into account.

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Presentation Notes

Key considerations” Cladding attachments and wall thickness.


THERMAL BRIDGING SOLUTIONSFOR CLADDING ATTACHMENTS

Secondary Structural Members


Secondary Structural Members

THIRD PARTY CALCULATIONS


Secondary Structural Members THIRD PARTY CALCULATIONS


Part 3: Building Envelope3.1.1.7. Overall Calculations • Calculations to include the effect of thermal bridging

• Studs, joists, lintels, sills and plates, etc.• Beam, girders, curbs, balconies, floor, etc.• Roof to wall junctions, corners, spandrels, etc.• Girts, purlins, hat channels, U-channels, shelf

angles, etc.

• Enclosed unconditioned spaces, e.g. sun porch, enclosed veranda, enclosure considered to have U-Value of 6.25 W/(m2·K).

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Presentation Notes

A-3.1.1.7.(5) Effect of an Unconditioned Space. The conservative overall thermal transmittance allowed in Sentence 3.1.1.7.(4), which is equivalent to that of a layer of glass, is intended to provide an easy credit under the prescriptive path for any unconditioned space that may be protecting a component of the building envelope. The value given does not take into account the construction of the enclosure surrounding the unconditioned space; the construction of this enclosure being uncontrolled by this Code, too many variables, such as its size or airtightness, may negate any higher credit that could be allowed. There may be simulation tools under the performance path that can provide a better assessment of the effect of an indirectly heated space, which may be used to advantage when an unheated space is designed to provide significantly better protection than the worst-case scenario assumed here. Vented spaces, such as attic and roof spaces or crawl spaces, are considered to be part of the exterior space; therefore, Sentence 3.1.1.7.(4) does not apply when calculating the overall thermal transmittance of their building envelope components.


Part 3: Building Envelope3.1.1.7. Overall Thermal TransmittancePipes, ducts, equipment with through-the-wall venting, packaged terminal air conditioners or heat pumps need not be taken into account.• The impact of penetrations described in Sentence

3.1.1.7.(2) on the overall thermal transmittance is difficult to assess but is considered to be negligible if the insulation is installed tight to the penetration.


Part 3: Building Envelope3.1.1.7. Overall Calculations The effect of thermal bridging shall be considered for• The junctions between the following building

envelope materials, components, and assemblies:• i) glazing assemblies,• ii) spandrels,• iii) parapets,• iv) roof-to-wall junctions,• v) corners, and• vi) edges of walls or floors, and


Part 3: Building Envelope3.2.1.1 Protection of Insulation MaterialsThe building envelope shall be designed to avoidincreasing the overall thermal transmittance of the insulation material due toa) air leakage or convection,b) wetting, orc) moisture bypassing the plane of thermal resistance.

Where any of the above conditions occur, their effecton the overall thermal transmittance of the insulation material shall be calculated in accordance with Article 3.1.1.5.(options include lab test)


Part 3: Building Envelope3.2.1.2 Continuity of InsulationPipes, ducts, conduits, cabinets, panels, or recessed heaters, parallel to the building envelope.

• The overall thermal transmittance of the building envelope shall not be increased.

Joints such as expansion or construction joints or joints between walls and doors or fenestration.

• Insulated in a manner that provides continuity across such joints. (See Note A-3.2.1.2.(2).)

This means that there should be no gap in the insulation between the two components. An obvious application is insulating the space between a window or door frame and the rough framing members.


Part 3: Building Envelope3.2.1.3 Spaces Heated to Different Temperatures

The building envelope also includes the separation between separate interior spaces that are intended to be conditioned at temperatures differing by >10oC at design conditions, such as:

• Cold storage warehouses to an office • Swimming pools to ice rinks • Offices to warehouses with minimal heat

Ice Rink14oC

Swimming Pool25oC

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Presentation Notes

t1 = indoor heating design temperature of the colder conditioned space, in °C, t2 = indoor heating design temperature of the warmer conditioned space, in °C, t0 = outdoor 2.5% January design temperature as specified in Article 1.1.4.1., in °C, and U =overall thermal transmittance required in Sentences 3.2.2.2.(1), 3.2.2.3.(2) and 3.2.2.4.(1), in W/(m2·K).


Part 3: Building EnvelopeAllowable fenestration and door area.Varies from 20% to 40%, based on HDD of location•FDWR = 0.40 for HDD < 4000•FDWR ≤ (2000 - 0.2HDD)/3000 for 4000 ≤ HDD ≤ 7000•FDWR = 0.20 for HDD > 7000

•FDWR = 0.40 for HDD ≤ 4000•FDWR =(2000 - 0.2 HDD)/3000 for 4000 < HDD <7000•FDWR = 0.20 for HDD ≥ 7000

Skylights – maximum 5% 2% of gross roof areaEdmonton -approx. 32.5%Calgary -approx. 33.3%

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Presentation Notes

Edmonton 5120 Calgary 5000


Part 3: Building EnvelopeVestibules:Required at all “main” entries (some exceptions)

A vestibule is not required for an exterior door :• Revolving door,• Vehicular movement or material handling,• Service, emergency exit, or stairwell exit door,• Seasonal use door, such as a door leading to a patio,• Dwelling units,• Retail space less than 200 m2 in area or • Space less than 150 m2 for other uses, or• Building less than 5 storeys in building height & fewer

than 3500 HDD


Part 3: Building EnvelopeAbove-ground Opaque Building Assemblies Thermal Transmittance

NECB 2011/2015 Roofs are U 0.162 (R-35)NECB 2017 Roofs are U 0.138 (R-41)


Part 3: Building EnvelopeAbove-ground Opaque Building Assemblies Semi-heated buildings:(1.2.1.2.) A semi-heated building is considered to be a building with a design set-point temperature of less than 15°C.

Zone 7A : R-27 Zone 6: R-24


Part 3: Building EnvelopeAbove-ground Opaque Building Assemblies Considerations:

Where the top of a foundation wall is less than 0.4 m aboveground level, Table 3.2.3.1. (below ground/contact with ground) is to be used.

Where radiant heating cables or heating or cooling pipes or membranes are embedded in the surface of an above-ground opaque building assembly, thermal transmittance shall not be greater than 80%

Example: Roofs 7B : U-Value = 0.162 (R35)Roofs with Embedded pipes 7B: Maximum U-Value = 0.162x 80/100 = 0.1296 (R43.7)

To counteract the increased heat loss that occurs due to the increased temperature difference between the interior and exterior surfaces


Part 3: Building EnvelopeFenestration thermal transmittance:

NECB 2011/2015 Zone 7B are 2.2


Part 3: Building EnvelopeDoors and Access Hatches Doors thermal transmittance:

Doors of area less then 2% and U-Value is not greater than U(4.4) are exemptedAccess Hatches U-Value (nominal insulation) not more than U(1.3)

Following doors are exempted:Storm doors, automatic sliding glass doors, revolving doors, and fire shuttersBut these glazed areas must be factored in as part of the area of fenestration


Part 3: Building EnvelopeWalls in Contact with the Ground Thermal transmittance:

• Insulation on walls to extend 2.4 m or bottom of wall whichever is less.

• Embedded radiant heating cables or heating or cooling pipes or membrane, thermal transmittance shall not be greater than 80% ( means more insulation is required)

• Where the top of the footing is less than 0.6 m below ground level, insulation shall be placed on the top or bottom surface of the floor not less than 1.2 m from the perimeter


Part 3: Building EnvelopeWalls in Contact with the Ground Thermal transmittance:

If Footing is less than 0.6 m below ground level

Not less than 1.2 mfrom the perimeter(top or bottom of the floor)

Insulation on walls to extend 2.4 m or bottom of wall


Part 3: Building EnvelopeRoofs in Contact with the Ground Thermal transmittance:

• Roofs that are part of the building envelope and are less than 1.2 m below the exterior ground level shall be not greater than that shown in Table 3.2.3.1

3.2.3.1. Thermal Transmittance of Building Assemblies in Contact with the Ground


Part 3: Building EnvelopeFloors in Contact with the Ground:

If no insulation required U-values for floors separating conditioned space from the ground that are less than 0.6 m below grade shall be not greater than that shown in Table 3.2.3.1. ( 0.757 for 1.2 meters)• *Extend vertically around the perimeter of the floor.If insulation required

(No embedded heating/cooling ):• On their top or bottom surface for a distance of not less than

1.2 m from their perimeter or over their full area.• *Extend vertically around the perimeter of the floor.

(with embedded heating/cooling):• Over their full area.• *Extend vertically around the perimeter of the floor.

*Or external insulation extends down to the bottom ofThe floor


New in NECB 2017

Lowered U value for Roofs (increased R values); for all Zones

e.g. Zone 7A

NECB 2011 NECB 2015 NECB 2017

Walls 0.21 0.21 0.21

Roofs 0.162 0.162 RSI 6.17 (R35) 0.138 RSI 7.24 (R41)

Floors 0.162 0.162 0.162


No change for Below ground assemblies.


New in NECB 2017

Lowered U value for Fenestration and Doors; (increased R values) for all Zones

Zone 7ANECB 2011 NECB 2015 NECB 2017

ALL 2.2 2.2 (RSI 0.45 –R 2.56 ) 1.9 (RSI 0.52 – R 2.95)

Doors 2.2 2.2 (RSI 0.45 –R 2.56 ) 1.9 (RSI 0.52 – R 2.95)



Part 3: Building Envelope3.2.4. Air LeakageAir Barrier for Building assemblies :An air leakage rate no greater than 0.2 L/(s·m2) at a pressure differential of 75 Pa.Tested to:CAN/ULC-S742, “Air Barrier Assemblies – Specification,”

OrASTM E 2357, “Determining Air Leakage of Air Barrier Assemblies,”Note:If tested under ASTM E 23571-in-50 hourly wind pressures do not exceed 0.65 kPa,andThe air barrier assembly is installed on the warm side.


Part 3: Building Envelope3.2.4. Air LeakageAir Barrier for Fenestration:

Metal & Glass curtain walls:An air leakage rate no greater than 0.2 L/(s·m2) when tested in accordance with ASTM E 283, at a pressure differential of 75 Pa.

Fixed windows and skylights:An air leakage rate no greater than 0.2 L/(s·m2) at a pressure differential of 75 Pa.when tested in accordance with AAMA/WDMA/CSA 101/I.S.2/A440, “NAFS – North American Fenestration Standard/Specification for Windows, Doors, and Skylights,”


Part 3: Building Envelope3.2.4. Air LeakageAir Barrier for Fenestration:

Operable windows and skylightsAir leakage rate not greater than 0.5 L/(s·m2) when tested in accordance with AAMA/WDMA/CSA 101/I.S.2/A440, “NAFS – North American Fenestration Standard/Specification for Windows, Doors, and Skylights,” at a pressure differential of 75 Pa.


Part 3: Building Envelope3.2.4. Air LeakageAir Barrier for Doors:Exterior Doors:Air leakage rate not greater than 0.50 L/(s·m2) when tested inaccordance with ASTM E 283, at a pressure differential of 75 Pa.

Revolving doors, automatic commercial sliding doors (including theirrespective fixed sections), overhead doors.Air leakage rate not greater than 5.0 L/(s·m2) when tested as a complete assembly in accordance with ASTM E 283 at a pressure differential of 75 Pa.


Part 3: Building Envelope3.2.4. Air LeakageAir Barrier for Doors:Main entry exterior doors Are permitted to have an air leakage rate not greater than 5.0 L/(s·m²) when tested as a complete assembly in accordance with ASTM E 283, at a pressure differential of 75 Pa, providedThe total area of such doors does not exceed 2% of the gross wall area

Loading docks that interface with truck boxes Shall have weather seals that seal the truck box to the building.

Fireplace Doors Shall be equipped with doors or enclosures to restrict air movement through the chimney when the fireplace is not in use.


Part 3: Building EnvelopeTrade-off rules:• For above-ground assemblies and to the allowable fenestration

and door areas.• Doesn’t apply to addition or semi-heated buildings.• Vertical portions are only permitted to be traded off against

vertical portions.• Horizontal portions are only permitted to be traded off against

Horizontal portions.

Make Sure:• For embedded assemblies that have radiant heating, cooling

pipes, membrane, shall have an overall thermal transmittance no greater than 80%

• Other high performance construction technique are not permitted to be included in trade-off calculation.


Thank you

QuestionsE-mail : [email protected]

Phone :1.866.421.6929

PLEASE VISIT https://www.alberta.ca/energy-codes.aspx

mailto:[email protected]

https://www.alberta.ca/energy-codes.aspx

https://www.alberta.ca/energy-codes.aspx

Documents

Compliance (NECB 2017) Part (3) Building envelope