james a. d’aloisio, p.e., secb, leed ap bd+c, gpro: o&m

9th Annual CNY Engineering Expo

Holiday Inn, Liverpool, NY Monday 12 November 2012

James A. D’Aloisio, P.E., SECB, LEED AP BD+C, GPRO: O&M

BUILDING STRUCTURES & THERMAL BRIDGING

Klepper, Hahn & Hyatt Structural Engineering

315.446.9201 Landscape [email protected] Building Envelope Systems

BUILDING STRUCTURES & THERMAL BRIDGING 2 OF 48

FOR THE NEXT HOUR….

Journey to the Thermal Bridge

Why consider thermal bridging?

Basics of heat transfer and thermal bridging

Thermal Bridging Solution Strategies

Geometric Separation

Intermittent Bridging Elements

Stainless Steel Bridging Elements

Nonconductive Thermal Shims

Manufactured Structural Thermal Break Assemblies

Summary, Recommendations and Questions


WHY CONSIDER THERMAL BRIDGING?


COMPARISON OF COSTS BETWEEN BUILDINGS

Cu

mu

lati

ve C

ost

(Cu

rre

nt

$)

Building Life (Years) 0 25 50 75 100

Conventional building

Energy efficient building

Sustainable building

Sustainable building with

revenue from excess power generation


MY JOURNEY TO THE THERMAL BRIDGE

Wall Detail ca. 1960

The area of the steel

that is bridging the

insulation is about

1% of the wall area.

What’s the reduction

in the insulation’s

R- value?


THERMAL BRIDGING….

Is conductive heat transfer through thermally

conductive materials across a building envelope

Is responsible for energy loss as well as potential

for condensation and reduced occupant comfort

Occurs with structural steel, cold formed steel,

concrete, masonry, wood, and other materials

Has not commonly been addressed by structural

engineers in the U.S. - until recently

Can be minimized if properly detailed


BASICS OF HEAT TRANSFER

Types of Heat Transfer

Conduction

Convection

Radiation


MATERIAL

(per inch)

R-Value

ft²·°F·h/Btu

U-Factor

Btu/ft²·°F·h

Silica Aerogel R-10 0.1

Expanded Polystyrene R-3.8 to R-4.2 0.26 to 0.29

Cellulose R-3.0 to 3.8 0.33 to 0.26

Hardwood (most) R-0.71 1.4

Concrete, normal weight R-0.08 12

Stainless Steel R-0.009 110

Carbon Steel R-0.0031 320

CONDUCTIVE HEAT TRANSFER

U–Factor – A material’s thermal transmission

R-Value – A material’s resistance to heat flow

R = 1 U

http://en.wikipedia.org/wiki/Foot_(length)

http://en.wikipedia.org/wiki/Fahrenheit


http://en.wikipedia.org/wiki/Hour

http://en.wikipedia.org/wiki/British_thermal_unit

http://en.wikipedia.org/wiki/British_thermal_unit

http://en.wikipedia.org/wiki/Foot_(length)



http://en.wikipedia.org/wiki/Hour


CONDUCTIVE HEAT TRANSFER PATHS

Series

Add up R-values along

the path of heat flow

Parallel

Heat chooses path of

least resistance


INFRARED BUILDING IMAGES


THERMAL BRIDGING AND CONDENSATION

Steel Beam

Concrete Balcony


OTHER COUNTRIES AND THERMAL BRIDGING

All European Union countries

have new energy codes

Based on limiting carbon

emissions of buildings for

Kyoto Protocol

Set limits of thermal bridging,

varying with building types


MODERN STEEL CONSTRUCTION INSERT -

THERMAL STEEL BRIDGING

Thermal Steel Bridging

Task Committee

A joint venture between ASCE’s

Structural Engineering Institute

and AISC


COLD-FORMED STEEL FRAMING

Use continuous rigid

insulation past studs

THERMAL BRIDGING SOLUTION STRATEGIES



GEOMETRIC SEPARATION

Original Detail Modified Detail



Reduce or eliminate

penetrations through

insulated building

envelope


INTERMITTENT BUILDING ELEMENTS

Original Detail:

Continuous angle

supporting wood

roof blocking

Modified Detail:

Clip angle, 6”

long, 24” o.c.

supporting wood

roof blocking



New concept

for brick shelf

angle support


STAINLESS STEEL BRIDGING ELEMENTS




Proprietary

system for

brick shelf

angle support

Comes in both

galvanized &

stainless steel


NONCONDUCTIVE THERMAL SHIMS

Original Detail:

Base plate of

steel post in

contact with

interior steel

support beam

Modified Detail:

½” thermoplastic

shim plate

between base

plate and beam



High School, Upstate NY

Only supporting 24

inches of brick


MANUFACTURED STRUCTURAL

THERMAL BREAK ASSEMBLIES (MSTBA’S)

Original Detail:

Steel cantilever

beam attached

directly to interior

steel support

Modified Detail:

MSTBA between

cantilever beam

and interior steel

support




Outside

Temperature

-10°C

+14°F

Outside

Temperature

-10°C

+14 F

+20°C

+68 ° F

+20°C

+68 °F

Room

Temperature

+15.1°C

+59.2° F

Room

Temperature

+10.6°C

+51.9°F

BELOW

DEW

POINT!

Without Thermal Break Thermal Break Technology

68

61

54

46

40

32

25

18

10

3

-4

Grad F

Dew point < 55°F

13°C




Concrete

to Concrete

Steel to Steel


CONCRETE-TO-CONCRETE MSTBA’S

Balcony Slab


CONCRETE CORBEL MSTBA’S


STEEL-TO-STEEL MSTBA’S



Tension

Insulation Spacer

Compression + Shear


NORTH AMERICAN CASE STUDIES - MSTBA’S

UNIVERSITY OF CALGARY STUDENT RESIDENCE



INDIANAPOLIS

MUSEUM OF

ART - PAVILION



SYRACUSE UNIVERSITY

MANLEY FIELDHOUSE

ICE STORAGE ADDITION - 2012

SUMMARY



RECOMMENDATIONS

Minimize cross-sectional area of bridging elements, where structurally possible

Minimize conditions of continuous bridging, substituting intermittent bridges

Use stainless steel when feasible

Work with architects to develop envelope details

Consider currently available and reliable products

Look for upcoming new information and research

Consider thermal bridging in your design practice


WHAT’S AHEAD?

Research on steel connection assemblies with FRP “shims” – sponsored by Pankow Foundation, AISC, FRP manufacturers

More product info from MSTBA manufacturers

Improved energy modeling and envelope requirements in building codes, including IgCC

Awareness of carbon emissions and GWP gases?

More practitioner info - Thermal Bridging Task Committee to develop detailing guidebook

Increased practitioner awareness and experience


QUIZ

1 - Name three strategies to minimize thermal

bridging in buildings.

2 - Put in order of decreasing thermal

conductivity the following three materials:

Carbon steel, aluminum, stainless steel.

3 - Name three problems that thermal

bridging in buildings can cause.

Thank you for listening! Questions?

BUILDING STRUCTURES & THERMAL BRIDGING

Klepper, Hahn & Hyatt Structural Engineering

315.446.9201 Landscape [email protected] Building Envelope Systems

CNY Engineering Expo Monday 12 November 2012

James A. D’Aloisio, P.E., SECB, LEED AP BD+C, GPRO: O&M

james a. d’aloisio, p.e., secb, leed ap bd+c, gpro: o&m

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