Accelerated Aging of Roofing Materials (the “Advanced Surfaces” project) · 2018-06-26 · Accelerated Aging of Roofing Materials (the “Advanced Surfaces” project) Paul Berdahl,

Accelerated Aging of Roofing Materials(the “Advanced Surfaces” project)

Paul Berdahl, Ronnen LevinsonHugo Destaillats, Tom Kirchstetter, Mohamad Sleiman et al.

Heat Island Group, Atmospheric Sciences Department

Building Technologies Program

CRRC Membership MeetingReno NevadaJune 9, 2011

1

Heat Island Group, Lawrence Berkeley National Laboratory2

Hugo Destaillats Ronnen Levinson

Thomas Kirchstetter Paul Berdahl Mohamad Sleiman Haley Gilbert Mike Spears

Hashem Akbari Bill MillerAndre Desjarlais

LBNL team

Concordia University

ORNL

“Advanced Surfaces” Team

George Ban-Weiss


Replacing a dark roof with a cool (highly reflective) roof can

Cool roofs

Reduce annual cooling energy use by 5-20% (Levinson et al. 2005)

Lower the outside air temperature and the rate of smog formation (Rosenfeld et al. 1998; Akbari et al. 2001)

Delay global warming (10 tonnes of CO2 offset by 100 m2 of white roofing)(Menon et al. 2010; Akbari et al. 2009; Oleson et al. 2010)


MOTIVATION• Advance the production and

adoption of high-performance, soiling-resistant roofing products

OBJECTIVES• Create an accelerated soiling

and weathering method for roofs and PVs

• Develop international standards for accelerated exposure

• Learn how to make roofsand PVs stay clean

Overview


Background

• Recent ORNL/LBNL work on soiling of inert PVDF coatings in California– Weak soil adhesion leads to clean materials after rain– Dusty summers are followed by rainy winters– Solar reflectance varies with the season

• Weathering of asphalt shingles– Material changes in first year increase reflectance– Changes thereafter just due to soiling


PVDF white sample at Shafter, CAat 1 year (August)


Soiling reduces reflectance of light surfaces and increases the reflectance of dark surfaces (ORNL / LBNL California study)

Initial reflectance (thousandths)

100 200 300 400 500 600 700

Ref

lect

ance

cha

nge

(thou

sand

ths)

-250

-200

-150

-100

-50

0

50

100

150

Colton, CA, 1 yearPVDFa = 0.14r = 0.165

[Here the parameters a and rare the solar absorptance and solar reflectance of the soil layer.]


Soiling reduces reflectance … continued

• Zero crossing occurs at R* = 0.2 to 0.4– Brightness of local soil– Largest values in southern desert

• PVDF accumulates less soil than tile due to reduced adhesion

• Steeper tilt - less soil• More soil/dust in dry southern California• Seasonal pattern of dusty summers and

wet winters


Close up of unweathered and weathered shingles

Heat Island Group, Lawrence Berkeley National Laboratory

Asphalt on black shingle new (left) and weathered (right)

10


Reflectance of 8 reflective asphalt shingle panels, beginning spring, 2008

Months of exposure (Berkeley)

0 6 12 18 24

Sol

ar re

flect

ance

(tho

usan

dths

)

220

240

260

280

300

320

340

360

C9 cool bright whiteC14 cool light tanC6 cool tanC7 cool siennaC12 whiteC8 cool blue-grayC16 cool weathered woodC1 standard whiteC5 cool chestnut


Effect of aging on solar reflectance (i/ii)

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

Aged

sol

ar re

flect

ance

Initial solar reflectance

FLORIDAno change

CA Title 24running mean

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0Ag

ed s

olar

refle

ctan

ceInitial solar reflectance

ARIZONA no change

CA Title 24

running mean

California Title 24 provisional aged solar reflectance formula:

20.070.020.0 iT24a,

Initial SRSR of an opaque soil layer resistance to soiling


Effect of aging on solar reflectance (ii/ii)

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

Aged

sol

ar re

flect

ance


Factory-appliedcoating

FLORIDA

CA Title 24

running mean

no change

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

Aged

sol

ar re

flect

ance


Field-appliedcoating

FLORIDACA Title 24

no change

running mean

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

Aged

sol

ar re

flect

ance


Metal

FLORIDA

no change

CA Title 24

running mean

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

Aged

sol

ar re

flect

ance


Modifiedbitumen

FLORIDA

no change

CA Title 24

runningmean

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

Aged

sol

ar re

flect

ance


Single-ply membrane

FLORIDA

no change

CA Title 24

running mean

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

Aged

sol

ar re

flect

ance


Tile

FLORIDA

running mean

CA Title 24

no change


Roofing products used in our study

We screened 100 roofing materials from 40 suppliers Selection of different materials:

Asphalt shinglesConcrete tilesClay tilesSingle-ply membraneMetal roofingFactory applied coatings

Field applied coatings

Selection criteria included diversity of products & colors, market presence, sample uniformity and availability of aged samples

coatings

shingles concrete tiles metal roofing

clay tiles single-ply membrane


Natural weathering of roofing products

hot and dry(Arizona)

hot and humid(Florida)

temperate(Ohio)

Samples naturally aged at 3 weathering sites

Samples collected and characterized quarterly

JANUARY APRIL JULY OCTOBER

2011

2012

2013

Florida


Laboratory accelerated soiling tests

Outline:

1. Develop spraying system for application of soiling agents

2. Test with soot, salts, organic matter and dust surrogates

3. Compare deposition of soiling constituents on roofing materials

4. Validate by comparing with naturally aged samples

5. Validate by comparing with roadway tunnel-soiled samples

Dust28 – 66%

Soot4 – 12%

POM8 – 36 %

Salts18 – 27%

Dust53%

Salts23%

POM18%

Soot6%

Average composition (in mass) of soiling components from atmospheric deposition

POM: Particulate Organic Matter

Favez et al, 2006 – Atmos. Environ


Soiling surrogates prepared in our lab

Soot hydrosolSalts Organics Dust

Ozone


Accelerated aging at LBNL

spray nozzleCompressed spraying vessel

samples

Prototype system for application of soiling agents to roofing samples

Unsoiled Soiled

soiling mixture

IR lamp (drying)

Weatherometer


Effect of each soiling constituent on SR

Humic acid

Soot

0,0

0,1

0,2

0,3

0,4

0,5

0,6

0,7

0,8

0,9

1,0

250 500 750 1000 1250 1500 1750 2000 2250 2500

Ref

lect

ance

Wavelength (nm)

UnsoiledSoiled with SaltsSoiled with DustSoiled with humic acidSoiled with soot

1.0

0.9

0.8

0.7

0.6

0.5

0.4

0.3

0.2

0.1

0.0

UnsoiledLab soiled with saltsLab soiled with dustLab soiled with humic acidLab soiled with soot

Organicsorganics


Optimization of soiling mixture to mimic soilingof roofing products in hot & humid climate

Can organics mimic microbiological growth?

Very good match between our lab soiled (1 min) and 3 years aged roofing membrane in Florida

organics


Summary

Developing reliable approach for accelerated soilingof roofing materials

Good correlation between the loading of soiling constituents and the loss of solar reflectance (ρa/ρi)

Tunable to mimic soiling in dry, temperate, hot & humid climates

Validated with naturally aged and tunnel-soiled samples in preliminary tests (further validation underway)

Straightforward method that can be readily adopted by industry

Established a large network of industrial collaborators and other stakeholders to support implementation


Ongoing work

– Integrate laboratory weathering and soiling

– Examine seasonal effects in natural weathering

– Validate our laboratory process with naturally aged samples

– Form new ASTM, ISO task groups

– Convene summer 2011 workshop at LBNL to build momentum for soiling standard

– CRADA with Dow Chemical


Thursday, July 28 –Friday, July 29, 2011

Berkeley, California USA

http://coolroofs2011.lbl.gov

Agenda

• Accelerated soiling and weathering of roofing materials

• Incorporation of accelerated aged ratings into policies, standards and rating systems

• Benefits of soiling- and weathering-resistant cool urban surfaces

• Development of next generation cool roofing (and pavement)

• Marketplace trends in cool roofing

Intended audience

• Roofing industry • Weathering firms • US DOE, US EPA, CEC, CARB• US CRRC, EU Cool Roof Council,

international rating bodies (e.g., China, India, Japan)

• ASTM, ASHRAE, ISO, US Green Building Council

• Utilities and other stakeholders


CRADA with ORNL and Dow Chemical

Goal: facilitate development of advanced elastomeric coating technology

Target: 75% aged solar reflectance, boosting energy savings by 50%

DOW will develop new polymers and coating formulations

ORNL/LBNL will evaluate retention of solar reflectance in natural and accelerated aging tests


Acknowledgments

• Funding: – U.S. Department of Energy (DOE)

• Program Manager: Marc LaFrance

• Our industrial partners• Experiments and measurements

– David Francois– Tosh Hotchi– Amandine Montalbano– Chelsea Preble – Mike Spears – Vasileia Zormpa

Documents

Accelerated Aging of Roofing Materials (the “Advanced Surfaces” project) · 2018-06-26 · Accelerated Aging of Roofing Materials (the “Advanced Surfaces” project) Paul Berdahl,