Envelope Design Training

Energy Trust New Buildings Envelope Design Training October 27th, 2015

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Trainings & Education Site

Energy Trust of Oregon Envelope Design Training AIA Portland October 2015 Marty Houston, AIA, CSI, LEED AP Walsh Construction Co.

Enclosure Design Training

• The Role of the Building Enclosure in the Creation of Low Energy Buildings…

• Critical Barriers

• The Thermal Barrier

• The Air Barrier

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Definition: Water Vapor

Water in it’s gaseous state

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Definition: Water Vapor

Water in it’s gaseous state

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Definition: Water Vapor Diffusion

The process by which water vapor spreads or

moves through permeable materials caused by a difference in water vapor pressure.

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Definition: Vapor Permeability

Permeability, rated in Perms, is a measure of

the rate of transfer of water vapor through a material.

The higher the number, the easier it is to pass

water vapor through a material.

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Vapor Permeability of

Standard Building Materials

1. Polyethylene .06 2. XPS Rigid 1 3. OSB 2 4. Plywood 3.5 5. EPS Rigid 3.5 6. 15# Felt 6 7. 2 PSJTX 11 8. Tyvek CW 23 9. Cat5 18 10. Vaproshield 50/212

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Definition: Condensation

Condensation is the change in the phase of

water from the gaseous phase into liquid droplets or solid grains .

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Definition: Dew Point

• The dew point is the temperature to which a given parcel of air must be cooled, at constant barometric pressure, for water vapor to condense into water.

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Pop Quiz

1. How many of you know the difference between an air barrier, a weather resistive barrier and a vapor barrier?

2. How many materials do you need to have all

three in one wall?

The Path to Low Energy Buildings

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Basic Building Design

Enclosure

MEP

On-site Renewable Energy


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Enclosure

MEP


Load Reduction


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Enclosure

MEP


Load Reduction

Meeting loads as efficiently and cleanly as possible…


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Enclosure

MEP


Load Reduction

Enclosure – Key Attributes • Insulation

• Airtightness

• Optimized Glazing

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Basic Building Design (BBD)

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• Low energy building design should focus first on a few basic building design concepts:

– Building size & shape

• As small as possible for the given program • As compact as possible for the given program, relative to

climatic factors

– Building orientation – Optimized glazing design

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E-W Orientation = 5%-6% Reduction in Annual Energy Use

Dwg: Building Shape

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20 24 26

26 All contain 8 volume units- what about

surface area?

Enclosure Area to Volume Ratio

BBD

• Optimized Glazing Design – i.e. windows sized, configured and oriented to optimize daylighting, views and solar gain – Window-to-wall ratio managed to avoid excessive

heat loss while allowing for daylighting and views – Glazing systems designed to avoid excessive solar

gain – i.e. glass coatings, shadings, etc. – Use well-insulated & airtight glazing systems

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Window-to-Wall Ratio: 50%

Window to Wall Ratio

Critical Barriers • Water-Shedding Surface Rain Penetration Control

• Water-Resistive Barrier Rain Penetration Control

• Thermal Barrier Thermal Control

• Air Barrier Air Leakage Control

• Vapor Barrier Vapor Diffusion Control

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Critical Barriers • Water-Shedding Surface Rain Penetration Control • Water-Resistive Barrier Rain Penetration Control • Thermal Barrier Thermal Control

– Controls conductive and radiant heat flow

• Air Barrier Air Leakage Control – Controls air flow / convective heat flow

• Vapor Barrier Vapor Diffusion Control

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Critical Barriers

Thermal Barrier

Exterior

Stucco Cladding Air Space Sheathing Paper Exterior Sheathing Insulated Stud Space Polyethylene Sheet Interior Gypsum Board

Interior

Critical Barriers:

Vapor Barrier Air Barrier Water Resistive Barrier Water Shedding Surface

Exterior Interior

Continuity – A Key Principle

• Continuous barriers are required to achieve effective thermal and moisture control

• Continuity of critical barriers must be

provided, not just at field areas, but also at interface details – Transitions – Penetrations – Terminations

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Continuity – A Key Principle

• Lack of continuity at critical barriers may lead to: – Water leakage – Air leakage – Thermal bridging – Condensation

• Resulting in:

– Poor energy performance – Durability problems

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Design of Critical Barriers

• Designer of the building enclosure should be able to trace the continuity of each critical barrier through the enclosure system

• Begin with building sections / wall sections • Continue with foundation, wall and roof details • Establish lines of continuity of all five barriers

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Tracing the Barriers

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Thermal Barrier (TB)

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Water-shedding Surface (WSS)

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Water-resistive Barrier (WRB)

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Air Barrier (AB)

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Vapor Barrier (VB)

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RDH

Window: Aluminum Rebate (Box) FrameWall Assembly: Non Combustible - Exterior InsulationCladding: Brick Veneer

WINDOW SILL – JAMBSteel Stud FramingDens-Glass Wall SheathingBeveled Wood Sub-SillSelf Adhered MembraneMetal AngleSill MembraneCorner MembraneJamb MembraneShimsSealant

Self Adhered Membrane

Interior Gypsum BoardWood Stool

Exterior Rigid InsulationBrick Veneer and TiesMetal Drip EdgeBacker Rod & Exterior SealantBacker Rod & Interior Sealant at jamb

Window

VAPOUR BARRIERVAPOUR BARRIER

AIR BARRIERAIR BARRIER

EXT. MOISTURE BARRIER

VAPOUR BARRIER

AIR BARRIER

WATER SHEDDING SURFACE

EXT. MOISTURE BARRIER

VAPOUR BARRIER

END

48 Source: RDH Building Sciences

THERMAL BARRIER

Durability - A Key Principle

• Durable = sustainable • Selection and use of durable materials - suited

to the application / exposure - is critical • Effective design and detailing of the enclosure

for watertightness, airtightness and thermal resistance is essential for achieving both energy performance and long term durability

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The Air Barrier

• The air barrier is the system of materials that controls air leakage / convective heat flow through the building enclosure

• The air barrier is not one material but instead is an integrated system of many different materials/components

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The Problem of Air Leakage

• Air leakage accounts for 20-40% of the heat loss through building enclosures…

• Air leakage = higher energy costs • Air leakage = larger carbon footprint • Air leakage = reduced water penetration control • Air leakage = increased condensation risk • Air leakage = poor airflow control

– Impacts reliability of ventilation system design 51

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Source: State of Wisconsin Minimium Requirements for the Building Envelope

Air Barrier - Definitions • Air barriers are defined by their air permeance • Air Barrier Association of America (ABAA) has

taken lead position in developing and promulgating standards

• Now incorporated in many codes - including WSEC

• “Materials” – ≤ 0.04 cfm/sf @ 1.57 psf pressure differential – ASTM E 2178, Standard Test Method for Air

Permeance of Building Materials 53

Air Barrier - Definitions • “Assemblies”

– A collection of air barrier materials and air barrier components assembled together in a specific manner to create continuity (ABAA)

– ≤ 0.04 cfm/sf @ 1.57 psf – ASTM E 2357, Standard Test Method for

Determining Air Leakage of Air Barrier Assemblies

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Air Barrier - Definitions • “System”

– An air barrier system is a system of building assemblies within the building enclosure designed, installed, and integrated in such a manner as to stop the uncontrolled flow of air into and out of the building enclosure (ABAA)

– A whole building air barrier is a system – ≤ 0.40 cfm/sf @ 1.57 psf – ASTM E 779, Standard Test Method for Determining

Air Leakage Rates by Fan Pressurization – Alternate standard: ≤ 0.25 cfm/sf @ 1.57 psf (USACE)

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Air Barrier - Materials • Exterior cladding • Sealants • Flashings (membrane flashing, metal flashing) • Windows • Doors (poor AB) • Housewraps (e.g. Tyvek) • Wall membranes (e.g. “peel & stick”) • Roof membranes • Drywall • Polyethylene sheet

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Photo - Air Barrier

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Air Barrier - Materials

• Material selection criteria includes: – Air permeance – Vapor permeance – Water resistance (if serving as WRB also) – Cost – Constructability – Availability

• Location / placement of air barrier relative to

insulation location is major determinant

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Air Barrier - Approaches • Interior Side

– Airtight Drywall Approach – Sealed Polyethylene Approach

• Exterior Side

– Exterior Sheathing Approach – Sheathing Membrane Approach (“housewrap”)

• Where cavity insulation approach is used • Vapor permeable

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Air Barrier - Approaches • Exterior Side



– Sheathing Membrane Approach (“peel & stick”) • Where exterior insulation approach is used • Vapor impermeable

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Air Barrier - Approaches • Exterior Side



– Sheathing Membrane Approach (“peel & stick”) • Where exterior insulation approach is used • Vapor impermeable

– Sheathing Membrane Approach (fluid-applied) • Vapor permeability dependent on whether cavity

insulation or exterior insulation approach is used

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Air Barrier - Continuity • To design and construct a complete air

barrier system for the building, continuity must be provided at interfaces between all materials and components…

• Easier said than done!

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Air Barrier - Continuity • Key Details for Air Barrier Continuity:

– Wall to foundation – Roof to wall – Floor lines – Window and door perimeters – Other penetrations – Transitions between wall types – Transitions between cladding materials

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Airtightness & IAQ • Mechanical ventilation becomes increasingly

important as building airtightness increases • Effectiveness - and efficiency - of ventilation

system becomes more highly critical to ensuring overall building performance, including indoor air quality… – Dedicated fresh air delivery to each space – Controlled air flow between spaces – Controlled ventilation rates – Heat recovery from exhaust air – IF YOU BUILD IT TIGHT- VENTILATE RIGHT! 69

KEN

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The Thermal Barrier

• The thermal barrier is the system of materials that controls conductive and radiant heat flow through the building enclosure

• Insulation - yes - but many other materials and components serve as part of the thermal barrier

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Thermal Barrier Problems

• Thermal Bridges

• Insulation Material Selection

• Insulation Installation “Defects”

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Get Your Thermal Bridge On

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Thermal Bridging


• Thermal Bridges • Insulation Material Selection • Insulation Installation Defects • Glazing Assemblies

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• Thermal Bridges

• Insulation Material Selection

• Insulation Installation Defects • Glazing Assemblies?

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Thermal Bridges

• Exterior Wall Framing Members – Light gauge steel framing – Wood framing

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R-Value Comparison

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Photo - Light Steel Frame Walls

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Thermal Bridges

• Exterior Wall Framing Members – Light gauge steel framing – Wood framing

• Regions of Framing “Build-up” – Exterior Wall Openings (e.g. headers, posts) – Exterior Wall Corners – Exterior Wall to Floor Intersections – Exterior Wall to Roof Intersections

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Photo: Not so advanced framing…

Other Thermal Bridges

• Window Frames (Aluminum & Steel) • Metal Subframing at Cladding Systems • Steel Ledger Angles at Cladding Systems • Projecting Slab Edges (Concrete) • Large Structural Framing Members (Steel)

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Drawing – Straube report

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89 Image courtesy of Mike Williams

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Thermal Bridging

Condensation Risk

• Thermal bridges not only cause problems with poor thermal performance but can also lead to significantly increased risk of condensation problems

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PERFECT WALL

Source: philipluo.com

PERFECT WALL

Source: Building Science Corporation

PERFECT WALL

PERFECT WALL

Source: philipluo.com

INSULATION STRATEGIES

Interior Insulation (wall) • Advantages

• easier to install • Material costs low

• Disadvantages • Allows dewpoint interior to weather barrier • May require fire separation from habitable space • Does not protect weather barrier from thermal

movements • Thermal bridging at framing members reduces

effective R-value


Interior Insulation (wall) • Product Types

• Fiberglass batts (3.1 to 4.3/in) • Mineral wool (3.7 to 4.5/in) • Cotton batts (3.5/in) • Sprayed-in cellulose (3.6 to 3.8/in) • Sprayed-in fiberglass (3.7 to 4.2/in) • Closed cell spray foam (6/in) • Open cell spray foam (3.5/in)


Exterior Insulation (wall) • Advantages

• Mitigates thermal bridging • Protects weather barrier from thermal movements • Pushes dewpoint exterior of weather barrier

• Disadvantages • Installation requires more coordination • Higher material cost • Drying time of wall may lengthen depending on

material choices


Exterior Insulation (wall) • Product Types

• Extruded polystyrene (XPS) (4.5 to 5.0/in) • Expanded polystyrene (EPS) (3.6 to 4.0/in) • Polyisocyanurate (5.6/in) • Closed cell spray foam (6/in) • Mineral wool (3.7 to 4.5/in)


Split Insulation (wall) • Advantages

• Mitigates thermal bridging • Protects weather barrier from most thermal

movements • Sometimes cost effective

• Disadvantages • Installation still requires more coordination • Drying time of wall may lengthen depending on

material choices • Weather barrier material choices narrow • Dewpoint will reside in stud cavity….but for how long?


Interior Insulation (roof) • Advantages

• Easier to install • Material costs low

• Disadvantages • Allows dewpoint interior to roof membrane • Does not protect roof membrane from thermal

movements and weathering • Susceptible to moisture during construction • Thermal bridging at fasteners reduces effective R-

value mildly


Infrared Scan of EPDM Roof

THERM model w/ fasteners thru all insulation

THERM model w/ fasteners thru first layer of insulation


Exterior Insulation (roof) • Advantages

• Mitigates thermal bridging • Protects roof membrane from thermal movements • Pushes dewpoint exterior of roof membrane • Quicker “dry-in” of building

• Disadvantages • Installation requires more coordination • Insulation needs to be covered (pavers, ballast,

vegetation, etc.) to protect from exposure


Source: Roxul


Source: Roxul

Source: Roxul


Figure source: Roxul

Why is CONTINUITY important?

PORTLAND AIR INFILTRATION

WATER VAPOR DIFFUSION

1” SQUARE HOLE

10000 1000 100 10 1 0.1

# GRAINS PER HOUR

INTERIOR 68°F 50%RH

EXTERIOR 41°F 80%RH

SOURCE: WBDG


MIAMI AIR INFILTRATION

INTERIOR 70°F 50%RH

WATER VAPOR DIFFUSION

1” SQUARE HOLE

EXTERIOR 91°F 56%RH

0.1 1 10 100 1000 10000 # GRAINS PER HOUR

SOURCE: WBDG


Solve the air and water first……..then worry about insulation!

Case Study 1 – Exterior infiltration

Case Study – Exterior infiltration

Case Study 2 – Interior infiltration

• Case Study - Interior


???


Temperature = 20°F Relative Humidity = 93%

Vapor Pressure Force = 7.2psf

Temperature = 70°F Relative Humidity = 53%

Vapor Pressure Force = 15.7psf

PENCIL TEST – plans and sections

UNCONDITIONED CONDITIONED


UNCONDITIONED

CONDITIONED

DETAILS

THE OTHER “C” WORD - COMPATIBILITY

COMPATIBILITY

Energy Trust of Oregon The Quality Process- You Don’t Get Something for Nothing AIA Portland October 2015 Marty Houston, AIA, CSI, LEED AP Walsh Construction Co.

Program for Quality 172

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Program for Quality

174 Design for Quality

176 Build for Quality

178 Maintain for Quality

W. Edwards Deming 179

Quality= Results of Work Efforts

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Total Costs

“Cost of Quality Versus Cost of Non-Quality in Construction: the Crucial

Balance”

Yehiel Rosenfeld Published November 2008

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Key Ideas and Definitions

• All Buildings are Prototypes • ISO9000: Quality is a Managerial Issue • Focus on Proactive Measures • Internal Failures • External Failures • Total Cost of Quality

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Total Costs of Quality

• Prevention • Appraisal

• Internal Failures • External Failures

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Hidden Costs of Non- Quality

• Exposure to Future Liabilities • Failure to Retain Existing Customers (tenants)

• Loss of New Customers (tenants) • Short and Long-Term Damage to Reputation

• Increased Insurance Costs

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You get what you pay for

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You get what you pay for

Envelope Design Training

Environment

Transcript of Envelope Design Training