Durability and energy savings due to using reflective...
Transcript of Durability and energy savings due to using reflective...
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
22
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?