Lighting in the workplace is it just about vision?

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1 Lighting in the workplace is it just about vision? Dr Cosmin Ticleanu, BRE

2 General effects of lighting in buildings Visual task performance Safety and visual perception of potential hazards Visual comfort Visual discomfort linked with red, itchy eyes, headaches, and pains associated with poor body posture Mood and wellbeing

3 Lighting for health & safety Reducing negative health symptoms Perceiving potential hazards Adequate lighting (HSG 38): Sufficient task illuminance No glare, flicker or veiling reflections No excessive luminance contrasts Appropriate emergency lighting

Lighting conditions to avoid (HSG 38): Insufficient light on the task Uneven lighting Luminaires too bright Daylight openings too bright (windows or rooflights) Excessive range of brightness Bright

4 Lighting conditions to avoid (HSG 38): Insufficient light on the task Uneven lighting Luminaires too bright Daylight openings too bright (windows or rooflights) Excessive range of brightness Bright reflected images adjacent to the task Reduced contrast of task because of veiling reflections Strong shadows on the task Flicker Stroboscopic effects Tasks difficult to see Lighting for health & safety

5 Minimum lighting for health & safety (HSG 38) Activity Typical examples Average illuminance (lux) General movement Corridors, circulation routes 20 5 Minimum illuminance (lux) Movement in hazardous areas Activity requiring limited perception of detail Activity requiring perception of detail Construction sites, loading bays Kitchens, assembly of large components Offices, bookbinding, sheet metal work Activity requiring perception of fine detail Drawing offices, assembly of electronic components, textile production

6 Lighting standards BS EN :2011 Light and lighting. Lighting of work places. Indoor work places BS EN :2014 Light and lighting. Lighting of work places. Outdoor work places Recommendations for: Maintained illuminance Illuminance uniformity Glare Colour rendering

7 Example for indoor workplaces Source: BS EN :2011

8 Example for outdoor workplaces Source: BS EN :2014

9 Emergency lighting BS EN 1838:2013 Lighting applications. Emergency lighting BS :2016 Emergency lighting. Code of practice for the emergency lighting of premises

10 Example for emergency lighting Minimum horizontal illuminance of: 1 lux at floor level along centre line of escape route 0.5 lux on the empty floor in open areas Maximum luminous intensity for light sources to limit disability glare Minimum CRI of 40 Minimum luminance of safety signs High risk areas: Minimum maintained illuminance on working plane at least 10% of required task illuminance but at least 15 lux Source: BS EN 1838:2013

viewing display boards, shelves For speaking to other people, cylindrical

11 Considering the task Task may be located in one part of the space Task may be vertical e.g. viewing display boards, shelves For speaking to other people, cylindrical illuminance at head height may be more important No need for uniform lighting everywhere Consider task lighting Substantial energy savings from task/ambient lighting

12 Observed Frerquency Occupant preferences Occupants prefer a range of illuminances Use task lighting Give occupants controls, especially dimming controls < Desktop illuminance (lux)

space may still look gloomy if the walls are too dark Additional light

13 Considering the task and the space People judge the brightness of a space by looking at the walls Even if task illuminances are adequate, a space may still look gloomy if the walls are too dark Additional light on the walls and ceiling can make a room look much brighter and more welcoming

occurs when the light source is in the field of view Reflected glare

14 Glare Disability glare affects the ability to see Discomfort glare causes discomfort without affecting the ability to see Direct glare occurs when the light source is in the field of view Reflected glare occurs when the light source is reflected from surfaces in the field of view

15 Too high luminance contrasts causing discomfort glare Examples of glare

16 Too bright light sources causing disability glare for particular view directions Examples of glare

standard recommendation) and too low relative wall

17 Examples of glare Discomfort glare caused by two high desk illuminances (on average 26% higher than standard recommendation) and too low relative wall illuminances (on average 50% of standard recommendation)

Avoiding glare from electric lighting Disability glare: Aiming light towards areas of interest Using suitable shielding Discomfort glare: Using low luminance luminaires Balanced luminance

18 Avoiding glare from electric lighting Disability glare: Aiming light towards areas of interest Using suitable shielding Discomfort glare: Using low luminance luminaires Balanced luminance distribution across space Reflected glare: Correctly arranging VDUs units with respect to luminaires Using matt surfaces rather than glossy finishes Restricting luminaire luminance Using light, high reflectance finishes for ceilings and walls

19 Avoiding direct glare degrees (depending on lamp type) Source: HSG 38

performance Eyestrain Headaches Increased heart rate in agoraphobic individuals Sensitivity to flicker

20 Flicker Critical flicker frequency of human eyes: 60 Hz Flicker of higher frequencies (up to 200 Hz) can still be non-visually detected by the human retina Negative effects include: Visual fatigue Reduced visual performance Eyestrain Headaches Increased heart rate in agoraphobic individuals Sensitivity to flicker varies between individuals; populations more susceptible include children and people suffering from migraine or autism

Flicker Avoiding flicker: Maintaining supply stability Using high-frequency electronic control gear Flicker can still occur when dimming LEDs by means of mains voltage

21 Flicker Avoiding flicker: Maintaining supply stability Using high-frequency electronic control gear Flicker can still occur when dimming LEDs by means of mains voltage dimmers and drivers DC-based LED drivers can dim the light output of LEDs to less than 1% whilst avoiding the risk of flicker Measuring flicker: Percent flicker Flicker index

Non-visual effects of light Body clock and exposure to artificial light at night Intrinsically photosensitive retinal ganglion cells in the retina

melatonin varies with spectral irradiance: peak at 446-477nm Blue wavelengths (400-500nm) appear to affect alertness, body temperature and heart rate

22 Non-visual effects of light Body clock and exposure to artificial light at night Intrinsically photosensitive retinal ganglion cells in the retina (iprgcs) most sensitive to blue light Ongoing research on minimum light level resulting in changes in melatonin level Threshold for suppressing melatonin varies with spectral irradiance: peak at nm Blue wavelengths ( nm) appear to affect alertness, body temperature and heart rate Common cool white LEDs produce significant light output in the nm range Night-time exposure to any type of cool white light source can be disruptive, not just LEDs

Circadian lighting WELL Building Standard Equivalent Melanopic Lux (EML), a proposed alternative metric weighted to the iprgcs instead of to the cones, which is the case with traditional lux WELL v1

23 Circadian lighting WELL Building Standard Equivalent Melanopic Lux (EML), a proposed alternative metric weighted to the iprgcs instead of to the cones, which is the case with traditional lux WELL v1 & v2 Electric lighting: At least 150EML for all workstations vertically facing forward at 1.2m above floor level DIN SPEC & DIN SPEC Daytime: At least 250lux / 8000K at the eye for several hours preferably in the morning Evening: At most 50lux / 2700K at the eye Illuminance adjustments at other colour temperatures / light spectra

Potential health benefits of special types of lighting LEDs can be manufactured

appears white to the naked eye Blue enriched LEDs during daytime can be used to

Short wavelength visible light (450-500nm) can also help to reduce symptoms of

24 Potential health benefits of special types of lighting LEDs can be manufactured to generate light in very specific areas of the spectrum, even in a light that appears white to the naked eye Blue enriched LEDs during daytime can be used to correct disrupted sleep, resynchronize circadian rhythms or increase alertness Short wavelength visible light ( nm) can also help to reduce symptoms of SAD Integration with smart controls to create advanced circadian lighting systems

Example of BRE work: Office POE study Problem: too much bright

situ measurements (luminaire luminance; surface luminance; desk

Computer modelling (UGR) Solution proposed: additional perimeter

25 Example of BRE work: Office POE study Problem: too much bright light coming from above Sore eyes and headaches BRE study: In situ measurements (luminaire luminance; surface luminance; desk illuminance; walls and ceiling illuminance; surface reflectance) Computer modelling (UGR) Solution proposed: additional perimeter wall lighting; dimmable lighting; zoned / grouped lighting controls

Example of BRE work: Classroom POE studies T8 direct lighting (magnetic ballasts) or CFL directindirect lighting (electronic ballasts), sometimes dimmable /

BB90 for 300 lux on horizontal working plane]; 0.3-0.6 of average working plane illuminance [0.5-0.

26 Example of BRE work: Classroom POE studies T8 direct lighting (magnetic ballasts) or CFL directindirect lighting (electronic ballasts), sometimes dimmable / K Average working plane illuminance: lux [300 lux in BS EN ] Average wall illuminance: lux / 345 lux in one case [200 lux in BB90 for 300 lux on horizontal working plane]; of average working plane illuminance [ in SLL Code for Lighting] Average whiteboard illuminance: lux / 330 lux in one case [320 lux in BS EN ] Cylindrical illuminance: lux / 215 lux in one case [150 lux in SLL LG5 at 1.2m above floor level]

Example of BRE work: Research on circadian lighting 23 participants in open plan office Variable lighting administered over several weeks in winter Site measurements, monitoring and computer

27 Example of BRE work: Research on circadian lighting 23 participants in open plan office Variable lighting administered over several weeks in winter Site measurements, monitoring and computer modelling of lighting Subjective and objective measures of occupant reaction (questionnaires, regular questions and performance tests) Monitoring of level of activity using activity tracking watches Determine how variable lighting impacts on health and wellbeing are linked with control schedules Identify optimal control strategies for circadian lighting and produce associated guidance so that health and wellbeing benefits are maximised

28 Example of BRE work: Research on biophilic office design Monitoring of light levels Computer modelling of existing electric lighting and daylight distribution Annual profiles of daylight illuminance and total illuminance at eye level Levels of circadian stimulation Liaising with BRE Social Research on occupant surveys BRE Wellness and Biophilia Symposium 6-7 June 2019, BRE Watford

Conclusion Electric lighting should: Meet minimum recommendations for health and safety Meet relevant standard recommendations Provide adequate

29 Conclusion Electric lighting should: Meet minimum recommendations for health and safety Meet relevant standard recommendations Provide adequate illumination both for the task and the space Not cause glare and flicker Provide adequate levels of emergency lighting Also consider the non-visual effects of light

30 bregroup.com Thank you Dr Cosmin Ticleanu WELL AP MSLL Principal Consultant, Lighting Fire & Building Technology Group BRE Watford, UK WD25 9XX +44 (0) bregroup.com

The SLL Lighting Handbook

The SLL Lighting Handbook The Society of Light and Lighting 222 Balham High Road, London SW12 9BS +44(0)20 8675 5211 www.cibse.org CONTENTS PART 1: FUNDAMENTALS Chapter 1: Light 1.1 The nature of light