Daylight provides beneficial light for tasks and creates an attractive environment, but too much or too little can be problematic. A study in a London primary school examined the impact of natural and electric light on over 50 pupils aged 7-8 over a school year. Pupils in classrooms with more daylight generally had better mood scores and cortisol levels than those with less daylight. Extra electric lighting helped pupils in rooms with less daylight during winter months, but made no difference in rooms with more natural light. The findings suggest that daylight can improve performance and that we should make good use of this free resource.

1. Daylight
Peter Raynham FILP

2. Daylight: provides
light for tasks

3. Daylight:
attractive
environment

4. Daylight: can go wrong

5. Earth’s Orbit

6. Daily Variation

7. Annual Variation

8. Sun Elevation and Azimuth

9. Daylight Availability

10. Daylight Availability

11. Average Daylight Availability

12. Median Daylight Availability
• The amount of daylight that is available for
half of the time.
• For London 14,100 lux

13. Daylight factor

14. General Requirements
• DF – 2% start of daylight appearance
• DF – 5% daylight provides nearly all of the
light needed
• Median Daylight Illuminance 300 lx

15. Windows
• Contact with outside world
• View in View out
• Let daylight in
• Thermal properties

16. Contact With Outside World

17. View In View Out

18. View In View Out

19. Let Daylight In

20. Energy Savings
• Key factors
– Daylight availability
– Daylight penetration
– Lighting control system
– User satisfaction

21. Is Daylight Beneficial?
• Study in a London School
• Background
• Key points
• Findings

22. Background
Küller, R.; Lindsten, C. (1992). Health and behaviour
of children in classrooms with and without windows. J.
Environ. Psychol. 12, 305-317
Showed:
• Children in classrooms with daylight show
different annual variation in levels of cortisol

23. Background
Hershong, L., Wright, RL. and Okura, S. (2002).
Daylighting impacts on human performance in school. Journal
of the Illuminating Engineering Society
Showed:
• significant effects of daylighting on the
performance of school students

24. Background
Govén, T., Laike, T., Pendse and B. Sjöberg, K.
(2007). The background luminance and colour
temperatures influence on alertness and mental health. CIE
26 Beijing
Showed:
• ambient light is of upmost importance

25. Key Points of the Study
• 4 form entry primary school
(~120 pupils per year)
• Pupils age 7 to 8
• Test of impact of light (natural and electric)
• Variety of pupil impact measures
• Year long study

27. Daylight Factors

28. Electric Lighting

30. Study Dates
Main Dates Supplemental Dates
8th October 2008 5th November 2008
9th December 2008 14th January 2009
10th February 2009 4th March 2009
25th March 2009 29th April 2009
20th May 2009 10th June 2009
Dates of data collection

31. Study Activities
Times Operations
08:00-08:50 Preparations
08:50 The start of school day – Subjective sleep quality reports*
09:50 Subjective mood and sleepiness reports & Saliva samples*
10:15-10:30 Morning break
11:45 Subjective mood and sleepiness reports + Saliva samples
12:00-13:10 Lunch break
14:45 Subjective mood and sleepiness reports + Saliva samples
15:20 The end of School day
Daily routine for the main collection days
* Supplemental collection days

32. Pupils in the Study
Pupil Numbers
Classrooms
Total
C1 E1 E2 C2
The number of participating pupils 14/30 11/29 16/29 15/29 56/117
The number of participating male pupils 7/15 7/14 9/14 7/15 30/58
The number of participating female pupils 7/15 4/15 7/15 8/14 26/59
The number of pupils in the study

33. Overall Avarage Mood Scores
0.00
1.00
2.00
3.00
4.00
5.00
6.00
7.00
8.00
08 Oct. 09 Dec. 10 Feb. 25 Mar. 20 May.
Date
C1
C2
E1
E2

34. Overall Avarage Mood Scores
0.00
1.00
2.00
3.00
4.00
5.00
6.00
7.00
08 Oct. 09 Dec. 10 Feb. 25 Mar. 20 May.
Date
DF ~2%
DF ~5%

35. C1
E1
E2
C2
Prog Jan
Prog May0
0.5
1
1.5
2
2.5
3
Progress in Wrting

36. The analysis of the monthly trend of the cortisol levels at 09.50 revealed a significant
difference between months contrast (F(1,22)=8,087, p=.009) and a significant difference
between the rooms (F(1,22)=4,969, p=.036)

37. Findings Overview
Analysis is being finalised a paper in LR&T should be
published later this year
General findings:
• The pupils with more daylight did better than those
with less
• In the rooms with less daylight the higher level of
electric light helped during the winter
• In rooms with more daylight extra electric light
made no difference

38. Conclusion
• Daylight is a free resource
• We should us it with care
• It can save energy
• It can provide a view
• People like daylight
• Daylight can improve performance