Assessment of polycarbonate material as a sustainable substitute for glazing in hot climates

Figures & data

Table 1. Conventional Glass and Polycarbonate (PC) sheets window systems characteristics.

No.	Window system type	Window description	Cavity thickness (mm)	Cavity fill	U-value (w/m^2K)
1	Single glass (6 mm)	6 mm clear glass	-	-	5.70
2	Double Glass 1	2 panes of glass, each 6 mm separated by a cavity	12	-	2.80
3	Double Glass 2	2 panes of glass, each 6 mm separated by a cavity	15	Air	1.40
4	Double Glass 3	2 panes of glass, each 6 mm separated by a cavity	15	Argon	1.20
5	Triple Glass	3 panes of glass, each 6 mm separated by cavities	16	Argon	0.79
	Polycarbonate type name	Polycarbonate Description	Thickness (mm)	R-Value (m^2k/w)	U-Value (w/m^2K)
6	PC10	It consists of two wall panels (layers) sheet	10	0.145	6.80
7	PC20	It consists of seven wall panels (layers) sheet	20	0.376	2.70
8	PC25	It consists of three wall panels (layers) sheet	25	0.357	2.80
9	PC32	It consists of six wall panels (layers), in addition to parallel and diagonal partitions within the sheet	32	0.513	1.90

Note: The U-value in Table 1 includes the cavity and double or triple glass pane. The U-values for the Polycarbonate (No. 6–9) are only for a single PC sheet, not including cavity or double or triple pane.

Figure 1. The Research Approach.

Figure 2. SABIC Multiwall polycarbonate sheets.

Table 2. Boundary conditions set for the simulation.

Characteristics	Description of the Model Building
Location	Dhahran (26.27 N latitude, 50.15 E longitude)
Orientation	Oriented 245° from North
Shape	Square
Floor to Ceiling Height	3.5 m
Floor Area	(10 × 10) 100 m^2
Window-to-Wall Ratio	85%
Infiltration	0.3 ACH
Occupant Density	0.0215 People/m^2
Metabolic rate	117 W/person
Clothing Insulation	0.5clo for Summer and 1clo for winter
Wall U-value	0.351 (W/m^2°C)
Roof U-value	0.346 (W/m^2°C)
Windows U-value	Varies (see Tables 1 & 2)
HVAC System Type	Split with separate mechanical ventilation
Mechanical Ventilation	3 ACH
Supply air temperature	12°C
Operation	Continuous
Setpoint Temperature	Summer 24°C
Lighting Power Density	5 W/m^2–100lux
Type of Lighting	Fluorescent, compact (CFL)
Heating setpoint temperatures
Heating	18°C
Heating setback	12°C
Cooling setpoint temperatures
Cooling	21°C
Cooling setback	28°C

Table 3. U-Values & SHGC of Conventional Glass & Polycarbonate Sheets (SABIC, 2013; 2020; Design Builder, 2020).

Glass and Polycarbonate Alternatives	U-Value (W/m^2k)	SHGC
3 mm single clear glass (Aluminum, No Breaker)	5.8	0.86
3 mm double clear glass/6 mm air (Aluminum, No Breaker)	3.16	0.76
3 mm triple clear glass/6 mm air (Aluminum, No Breaker)	2.2	0.68
10 mm Single 5-wall rectangular polycarbonate (Aluminum, No Breaker)	2.39	0.65
10 mm double 5-wall rectangular polycarbonate/6 mm air (Aluminum, No Breaker)	1.29	0.46
10 mm Triple 5-wall rectangular polycarbonate/6 mm air (Aluminum, No Breaker)	0.87	0.35
16 mm Single 5-wall X-structure polycarbonate (Aluminum, No Breaker)	1.88	0.58
16 mm double 5-wall X-structure polycarbonate/6 mm air (Aluminum, No Breaker)	0.97	0.38
16 mm Triple 5-wall X-structure polycarbonate/6 mm air (Aluminum No Breaker)	0.66	0.28
16 mm Single 9-wall X-structure polycarbonate (Aluminum, No Breaker)	1.77	0.54
16 mm double 9-wall X-structure polycarbonate/6 mm air (Aluminum, No Breaker)	0.91	0.34
16 mm Triple 9-wall X-structure polycarbonate/6 mm air (Aluminum No Breaker)	0.62	0.24

Figure 3. Simulated Building Model (a) Windows opening and (b) Skylight opening.

Figure 4. Cooling Energy (electric) for various single glazing types (kWh) with aluminum frame.

Figure 5. Cooling Energy (electric) for various double glazing types (kWh) with aluminum frame.

Figure 6. Cooling Energy (electric) for various triple glazing types (kWh) with aluminum frame.

Figure 7. Cooling Energy (electric) for single glazing skylight systems (kWh) with aluminum Frames.

Figure 8. Cooling Energy (electric) for double glazing skylight systems (kWh) with aluminum Frames.

Figure 9. Cooling Energy (electric) for triple glazing skylight systems (kWh) with aluminum Frames.

Figure 10. Annual cooling Energy (electric) consumption for various conventional and skylight glazing types (kWh).

Figure 11. Total cooling Energy (electric) savings for various conventional and skylight glazing types (%).

Figure 12. The impacts of window-to-wall (WWR) ratio on cooling energy consumption.

Table 4. Conversion factor from GHG emissions in kg to energy unit of kWh (UK Government 2022, June 22)

Fuel type	Emission type
	kg CO2/kWh	kg CH4/kWh	kg N2O/kWh
Oil	0.28413	0.00042	0.00071
Natural gas	0.20258	0.00028	0.00011
Total in KSA	0.2344	0.00035	0.00034

Figure 13. Total annual GHG emissions of different types of glazings sheet alternatives in windows.

Figure 14. Total annual GHG emissions of different types of glazings sheet alternatives in skylights.

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