Daylighting Study Results

Test Description
Times: 7am, 8am, 9am, 10am, 11am, 12pm, 1pm, 2pm, 3pm, 4pm, 5pm, 6pm, 7pm

Dates: March 21st, June 21st, September 21st, December 21st

Sites: Sydney, Australia; Singapore; Hong Kong, China; Phoenix, AZ, US; Barcelona, Spain; Edmonton, AB, Canada

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Result and Analysis

Notations:	N/S – North/South	W/E – West/East	BL – Blind/Louvers
	Vert. – Vertical	Hori – Horizontal	NC – No Covering
	I. Dev. – Illuminance Deviation		NDS – No Direct Sun

Direct Sun Blocking: Lighttex blocks more direct sun than blind/louvers. The following sample charts of skylights in Phoenix, AZ show the percentage of increased direct sun blocking. The x coordinate represents the time when the window was exposed to direct sun. The three curves of Lighttex, horizontal and vertical blind/louvers are the direct sun blocking percentage throughout the day.

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Work Plane Illumination Evenness: The direct sun not only causes visual uncomfortableness and heat gain but affects the evenness of daylighting, another important factor of daylighting quality. We use illuminance deviation to describe the lighting evenness. Lower illuminance deviation means more even daylighting. Blind/louvers do reduce the illuminance deviation. However Lighttex reduces much more so that it is below 50 foot candles in most cases of our six sample cities, which is quite acceptable for most normal activities. The following sample table of a test room with a South Facing Window in Phoenix, AZ shows how much the illuminance is reduced, or the lighting evenness is improved, by both blind/louvers and Lighttex.

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South Facing Room 105.5_Phoenix: Illuminance Deviation Comparison
	Vertical BL	Horizontal BL	Lighttex45
	I. Dev +/-% /NC	I. Dev +/-% /NC	I. Dev	I. Dev +/-% /NC	I. Dev +/-% /Vert.	I. Dev +/-% /Hori.
March 21st
07:00am	-38%	-54%	6	-75%	-60%	-45%
08:00am	-86%	-77%	12	-94%	-59%	-76%
09:00am	-93%	-83%	19	-97%	-57%	-83%
10:00am	-82%	-84%	36	-97%	-82%	-79%
11:00am	-41%	-85%	47	-97%	-94%	-78%
12:00pm	-18%	-85%	52	-97%	-96%	-78%
01:00pm	0%	-85%	52	-97%	-97%	-78%
02:00pm	-15%	-85%	46	-97%	-96%	-79%
03:00pm	-83%	-84%	38	-97%	-81%	-79%
04:00pm	-94%	-83%	20	-97%	-57%	-84%
05:00pm	-89%	-78%	13	-95%	-58%	-79%
06:00pm	-45%	-55%	7	-79%	-61%	-53%
07:00pm	NDS	NDS	NDS	NDS	NDS	NDS
June 21st
07:00am	NDS	NDS	NDS	NDS	NDS	NDS
08:00am	NDS	NDS	NDS	NDS	NDS	NDS
09:00am	NDS	NDS	NDS	NDS	NDS	NDS
10:00am	-93%	-94%	21	-97%	-55%	-48%
11:00am	-90%	-92%	23	-96%	-59%	-49%
12:00pm	0%	-93%	25	-96%	-96%	-47%
01:00pm	0%	-93%	25	-96%	-96%	-47%
02:00pm	-90%	-92%	23	-96%	-59%	-49%
03:00pm	-94%	-94%	36	-95%	-23%	-10%
04:00pm	NDS	NDS	NDS	NDS	NDS	NDS
05:00pm	NDS	NDS	NDS	NDS	NDS	NDS
06:00pm	NDS	NDS	NDS	NDS	NDS	NDS
07:00pm	NDS	NDS	NDS	NDS	NDS	NDS
Sept 21st
07:00am	-46%	-51%	8	-77%	-58%	-53%
08:00am	-89%	-79%	14	-95%	-56%	-77%
09:00am	-93%	-83%	22	-97%	-56%	-83%
10:00am	-83%	-84%	43	-96%	-78%	-76%
11:00am	-36%	-85%	51	-96%	-94%	-77%
12:00pm	-17%	-85%	58	-96%	-95%	-75%
01:00pm	-40%	-85%	40	-97%	-96%	-83%
02:00pm	-41%	-85%	45	-97%	-94%	-78%
03:00pm	-81%	-84%	28	-97%	-86%	-83%
04:00pm	-93%	-82%	18	-97%	-56%	-84%
05:00pm	-84%	-74%	12	-93%	-57%	-74%
06:00pm	-36%	-48%	10	-60%	-38%	-23%
07:00pm	NDS	NDS	NDS	NDS	NDS	NDS
Dec 21st
07:00am	NDS	NDS	NDS	NDS	NDS	NDS
08:00am	-27%	-23%	11	-83%	-77%	-78%
09:00am	-69%	-19%	29	-94%	-81%	-93%
10:00am	-37%	-32%	199	-79%	-67%	-69%
11:00am	-10%	-62%	456	-64%	-60%	-4%
12:00pm	0%	-25%	1019	-28%	-28%	-5%
01:00pm	0%	-33%	894	-37%	-37%	-5%
02:00pm	-15%	-38%	625	-48%	-39%	-17%
03:00pm	-69%	-35%	237	-74%	-16%	-59%
04:00pm	-65%	-16%	27	-93%	-81%	-92%
05:00pm	-26%	-43%	8	-77%	-69%	-60%
06:00pm	NDS	NDS	NDS	NDS	NDS	NDS
07:00pm	NDS	NDS	NDS	NDS	NDS	NDS