Durability and energy savings due to using reflective roofing systems subjected to

different climate conditions

Dr. Saleh Alshehri, Dr. Hamed Saber Research and Applied Studies Center

Jubail University College Jubail Industrial City, KSA

Jubail Energy Management Conference King Abdullah Cultural Center, Jubail Industrial City

December 6, 2017

OUTLINE

NRC’s hygIRC-C Model Objectives Roof System Configuration Hygrothermal Modeling Environmental Conditions

Outdoor Indoor

Results Summary

NRC’s hygIRC-C Model

Full description of hygIRC-C is available in 37 publications (20 journal papers & 17 conference papers)

The hygIRC-C model was recognized by the Canadian industries resulting in Dr. Saber being awarded the NRC’s 2011 George Seaden Innovative Solutions Award for Development of this model.

Mould Risk Assessment

Hygrothermal

Modeling

CFD

2D & 3D hygIRC-C Modules

NRC’s hygIRC-C Model (cont.)

hygIRC-C is the official tool that is currently being used at: National Research Council of Canada (NRC) Canadian Construction Materials Centre (CCMC) Canadian Roofing Contractors Association (CRCA) Canadian Centre for Housing Technology (CCHT)

Being used to certify new construction materials and new building designs to meet the requirements of the National Building Code of Canada (NBCC)

NRC’s hygIRC-C Model (cont.)

Unlike other hygrothermal models, hygIRC-C has the following features:

CFD capability to model drainage cavities, airspaces, cracks, etc…

Aerodynamics on buildings Airflow and heat transfer by radiation through

airspace enclosures of building envelopes (walls and roofs) and fenestration systems (windows, curtain walls and skylight devices)

Runoff due to Wind Driven Rain (WDR) on facades Modeling Phase Change Materials (PCMs)

NRC’s hygIRC-C Model (cont.) Model was extensively validated and used in different building applications:

1. Benchmarking hygIRC-C Versus Data of Full-Scale Tests 2. Wetting and Drying of Cladding Systems 3. Moisture Assessment of Cladding Systems 4. Drying of Ventilated Wall Cavities 5. Wall Energy Rating (WER) 6. Skylight Devices (ASHRAE-RP1415) 7. Wall Systems with Reflective Insulations 8. Insulated Concrete Form (ICF) Wall systems 9. Reflective and non-Reflective Roofing Systems 10. Aerodynamics on Buildings 11. Thermal Performance of Exterior Insulation and Finish Systems (EIFS) of Walls with Drainage

Cavities 12. Predicting Mould Growth in Building 13. Building with Phase Change Materials (PCMs) 14. Retrofitting Wood-Framing Wall Systems Using different Insulations (e.g. VIPs and XPS) 15. Predicting the Performance of Metal Glass Curtain Walls 16. Roof Integrated Photovoltaic Systems 17. Investigate the Risk of Condensation Introduced by Increasing Cavity Insulation of Wall

Systems 18. Certification of New Building Materials, New Systems and New Design (CCMC, CRCA, CCHT) 19. Used in Number of Projects to Address Code Change Requests for the National Building Code

of Canada (NBC) 20. Whole Building Performance 21. Fee-for-Service Projects

Validated in a number of projects using test facilities at Canadian Centre for Housing Technology (CCHT)

Reference House

Test House

NRC’s hygIRC-C Model (cont.)

Objectives

Use hygIRC-C to investigate the hygrothermal performance of reflective and non-reflective roof systems subjected to North American climates

Compare the hygrothermal performance (moisture and energy loss/gain) of reflective and non-reflective roof systems

9

Roofing System Configuration

Steel Deck (From Canam)

P-3615 & P-3606 P-3615

Modified-Bitumen (MOD-BIT) roofing systems

10

Roofing System Configuration (cont.)

Steel Deck (P-3615)

Air

Insulation: Polyisocyanurate 2” (50 mm) 72 ASHRAE Polyisocyanurate Insulation

1” Fibreboard 54 ASHRAE Fibreboard

Cap Sheet with Base Sheet 0.30” 7.34 mm total thickness 92 PERD Torch applied asphalt based membrane

Steel deck vapor permeance 3.3 m (5 US perms)

Felt-II (Bituminous) 0.65 mm

3”

Hygrothermal Modeling

Initial Conditions: Moisture Content in all layers corresponding to 50% RH and T = 10oC

Indoor Conditions: ASHRAE EN15026

Outdoor Conditions: Weather data of North America NRC weather database

Time for simulation: 5 years Up to 11 years

11

Solar short-wave absorption coefficient:

0.2 (white roof) 0.88 (black roof)

Long-wave emissivity: 0.9 for black & white roofs

Material Properties: NRC material database

12

Environmental Conditions

Outdoor Conditions: North American Climates

US Cities: Seattle (HDD = 2564) Wilmington (HDD = 1349) Phoenix (HDD = 578)

Canadian Cities: Toronto (HDD = 3650) Montreal (HHD = 4200) St. John’s (HDD = 4800) Saskatoon (HDD = 5950)

13 Time = 0 Jan 1st

Results (cont.) Effect of Indoor Conditions: ASHRAE vs EN15026

Toronto

Results

(a) time = 4356 h (July 1st at noon) (b) time = 8760 h (end of the year)

Toronto, EN15026 (black roof) Temperature contours (in oC)

Toutdoor > Tindoor Toutdoor < Tindoor

(a) T

empe

ratu

re (o C

)(Ju

ly 1

stat

noo

n)

(b) R

H (%

)(Ju

ly 1

stat

noo

n)

(c) V

ertic

al v

eloc

ity (m

m/s

)(Ju

ly 1

stat

noo

n)

(d) T

empe

ratu

re (o C

)(a

t end

of t

he y

ear)

(e) R

H (%

)(a

t end

of t

he y

ear)

(f) V

ertic

al v

eloc

ity (m

m/s

)(a

t end

of t

he y

ear)

Results (cont.) Toronto, EN15026 (black roof)

Toutdoor > Tindoor

Toutdoor < Tindoor

Results (cont.)

Toronto, EN15026

Results (cont.)

EN15026

City

Maximum Surface Temperature (oC)

Hourly Monthly Average

Black Roof White Roof Black Roof White Roof

Toronto 67 39 29 23

Montreal 75 39 29 23

St John's 51 32 19 15

Saskatoon 65 39 26 20

Seattle 68 39 30 23

Wilmington 78 42 35 28

Phoenix 81 52 47 38

Results (cont.)

City Yearly Accumulation Energy Gain (Wd/m) Ratio

Black Roof White Roof Black/White

Toronto 26.2 4.9 5.3

Montreal 25.7 3.8 6.7

St John's 6.8 0.5 13.0

Saskatoon 15.4 2.1 7.4

Seattle 30.7 4.5 6.9

Wilmington 61.8 14.9 4.2

Phoenix 126.5 53.2 2.4

City Yearly Accumulation Energy Loss (Wd/m) Ratio

Black Roof White Roof Black/White

Toronto -116 -132 0.9

Montreal -131 -151 0.9

St John's -146 -163 0.9

Saskatoon -168 -188 0.9

Seattle -82 -98 0.8

Wilmington -44 -56 0.8

Phoenix -26 -33 0.8

Cooling Load (Summer) Heating Load (Winter)

19 Time = 0 Jan 1st

Results (cont.)

Black Roof, EN15026

20 Time = 0 Jan 1st

Results (cont.)

White Roof, EN15026

Simulation time: up to 11 years

21

Summary hygIRC-C was used to predict the hygrothermal performance

of white and black MOD-BIT roofs subjected to different climates of North America

The EN15026 indoor condition resulted in higher Moisture Content (MC) in the roof compared to ASHRAE indoor condition

White roofs require less cooling load in summer compared to black roofs

White roofs require more heating load in winter compared to black roofs

White roofs run with low risk of moisture accumulation in all cities investigated in this paper except in St. John’s and Saskatoon

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https://www.hpo.bc.ca/sites/www.hpo.bc.ca/files/download/Report/Properties%20of%20Materials%20in%20Building%20Envelopes%20.pdf

Changes in Part 9 in the 2105 National Building Codes of Canada The methodology that was developed in this project was recently considered by the TG of ASHRAE to modify ASHRAE-160 Standard

Thank You!

Questions?