Impact case study database

Summary LED lighting is energy efficient but potential flicker and associated discomfort and health risks may deter or slow its adoption. Essex research determined parameters for the speed and amount of flicker in lighting that is required to prevent harmful effects on health. Wilkins’ function was the foundation for the development of a global industry standard for mitigating health risks from LED lighting developed by the Institute of Electrical and Electronic Engineers (IEEE) in 2015 (IEEE1789™[ S1]). The standard subsequently became an Approved American National Standard (ANS) in 2016. The standard drove innovation in the design of lighting and electrical components that enable flicker frequency and depth to be set to safe and comfortable limits. With companies trading in over 100 countries applying safer technologies and billions of compliant LED products now sold worldwide, IEEE 1789 has significantly mitigated individual ill health and consequent reduced economic productivity, and accelerated worldwide adoption of energy efficient LED lighting.

Development of IEEE Standard 1789TM [S1]

In 2008, Wilkins was invited as a recognised expert in visual stress from flicker [ R1- R6], to join an international working group established by the IEEE, a worldwide technical professional organisation based in the USA, to consider the impact of flicker in LEDs. The working group comprised of visual scientists, lighting experts, environmental psychologists, lamp designers, LED driver designers, medical experts, and LED lamp users, and developed IEEE Standard 1789: “Recommended Practices for Modulating Current in High Brightness LEDs for Mitigating Health Risks to Viewers” [ S1]. Essex research [ R4] produced the function linking risk to both flicker frequency and modulation depth, which forms the core of IEEE 1789. Wilkins was co-editor of Clauses 6 and 8 of IEEE 1789 [ S1]. Essex research [ R1, R2, R4, R6] is listed in the bibliography. The report was approved by the IEEE Standards Board on 26 March 2015 [ S1].

A testimonial from the founder and chair of the IEEE Standards Group, IEEE PAR 1789, emphasises the importance of Wilkins’s work in defining this standard [ S2]: “ Professor Wilkins’s research was a foundation for the recommended practices that were contained in the IEEE PAR 1789 document. The standard relied heavily on his published work that explained the levels of flicker that can lead to fatigue and headaches. This led to the IEEE standards group creating low risk regions for flicker. From these regions, it is not too difficult for a power electronics designer to create an electronic driver to keep the flicker below the risk regions. However , these safe operating regions were unknown prior to Professor Wilkins’s work.*”

Adoption of IEEE 1789 Recommendations Internationally

IEEE 1789 has been embedded in regulatory frameworks worldwide. For example, The American National Standards Institute (ANSI), which coordinates the US voluntary standardization system, accepts IEEE 1789 as satisfying ANSI requirements for openness, committee balance, public review and appeals process; IEEE 1789 became an approved ‘American National Standard’ on September 7, 2016 [ S3, p. 517]. The ANSI/IEEE1789 Standard has enabled regulatory bodies to promote the adoption of energy efficient LED lighting by ensuring that it is also safe and comfortable:

The USA Environmental Protection Agency (EPA) has a mission to protect human health and the environment. The EPA promotes ‘greener’ product choice by endorsing a product label known as ‘ Energy Star’ [ S4a, b] with which manufacturers certify that their electrical products, including light bulbs and fixtures, conform to established standards. In 2018, Energy Star updated their lighting (luminaires) specification (V2.1 [S4c], updated from v2 effective 2016) to include a section on flicker that requires compliance with product testing and metrics described by IEEE Recommended Practices [ S1]. Compliance with ANSI/IEEE 1789 is required in order for the product label ‘Energy Star’ to be used [ S4c, section 7, p.11; section 11.6, p. 21 and section 11.7, p.22] ensuring safe and comfortable green product choice.

The State of California USA has an Energy Commission whose code is to reduce wasteful energy consumption. ANSI/IEEE 1789 formed part of the evidence presented during the three-yearly open stakeholder consultation on the State of California’s “Building Energy Efficiency Standards for Residential and Non-residential Building (Title 24)” [ S5a]. California now has established standards regarding product testing for flicker, and mandatory reporting of test results to the California Energy Commission. The California Title 24 2019 [ S5b] mandated requirement that “light output has an amplitude modulation of less than 30 percent for frequencies less than 200Hz” ( S5b, p. 125) conforms to the ANSI/IEEE 1789 standard. Specifically, the identified limit is below the threshold specified by the IEEE 1789 Recommended Practice ( S1, p.44 and Figure 20), so as to limit the adverse biological effects of flicker.

Industry and governmental agencies worldwide recommend compliance with IEEE 1789 to minimise risks to health and promote energy efficiency [ S1]. For example, the International Energy Agency (IEA), a consortium of 13 countries whose aim is to reduce electricity consumption via energy efficient products, specifies criteria for flicker modulation to protect health based upon [ S1] (p. 6 footnote 6 [ S6a]). The Alliance for Solid State Illumination Systems and Technologies (ASSIST) [ S6b] recommendations cite [ R4 and R6]. The Design Lights Consortium [ S6c] is dedicated to accelerating the widespread adoption of high-performing commercial lighting solutions and in 2018 adopted the requirement to test in accordance with IEEE Recommended Practices ( S6c p.8 refers to [ S1]). The International WELL Building Institute (IWBI) sets standards for buildings, interior spaces and communities seeking to support health and wellness. The IWBI [ S6d] electric light quality part 2 requires that electric lighting in regularly occupied spaces conforms to low risk LED as defined by IEEE standard 1789 [ S1].

Driving Innovation in Lighting Design and LED Products

The testimonial from the IEEE 1789 Chair [ S2] notes the extensive impact of the IEEE Standard resulting from Wilkins’ research on the LED industry worldwide: “ companies have made a decision to add the extra components to the power electronic drivers to minimize flicker”. He further states that “ the research Professor Wilkins has performed at Essex has strongly influenced the design specifications of widespread LED lighting technologies (probably millions of bulbs) on the commercial market today. Because of this, there will be fewer negative biological effects upon photosensitive populations”.* [ S2]

Evidence of lighting design innovation driven by IEEE 1789 is provided by USA patents for driver design (e.g. 2017, [S7] citing [ R1] and [ R6], and evidence that companies trading in over 100 countries worldwide have changed their product design to conform to IEEE 1789, to mitigate health risks. For example, Signify (formerly Philips Lighting), a global leader in lighting, trading commercially in more than 70 countries, created their EyeComfort trademark [ S8] based on research presented in [ R1] and the IEEE Recommended Practices [ S1]. Dyson [ S9], a global consumer technology company trading in more than 100 countries worldwide has developed a trademarked task light CSYS, that is described as a “ powerful light (over 1000 lux) with glare protection and low optical flicker” (in [ S9, footnote 3] refers to [ S1], asserting that the product has been “ tested according to IEEE 1789 - 2015)”. Manufacturers of LED drivers [ S10a-f: Xicato, Helvar, EldoLED, Unios, Optoga, New Horizon] for use in public and industrial spaces worldwide have developed drivers that conform to IEEE 1789 [ S1] to avoid the temporal light artefacts that lead to poor photographic images and negative impacts on human health and productivity from ‘invisible flicker’.

Improving Public Health

IEEE 1789 recommended practices underpin public health guidelines; for example, the conclusions and recommendations of a policy report (CRCE-RDD 01-2016) published by Public Health England [ S11] - ‘ Human responses to lighting based on LED lighting solutions’, part of the series ‘Protecting and Improving the Nation’s Health’ – drew heavily upon IEEE 1789, citing [ S1 and R5] on p.42 references: “ *Following IEEE [ S1], this report highlights the need for a practical flicker metric*” (p. 13). The report concludes on p.41 that “ flicker may be a risk factor for some adverse health effects” and recommends limiting flicker to avoid such effects.

In the USA, IEEE 1789 has driven major programmes of retrofitting of LED lighting in public contexts such as education and health facilities, in recognition of the health and economic benefits of flicker-free lighting; by 2019 more than 230 school districts, and leading universities had been retrofitted ( S12a) and by 2020 more than 60 health facilities had been retrofitted [ S12b].