Tag: circadian clock


Why you need A ZERO – CARBON home ?


Hidden in the middle of California is a house that is designed to revolutionise the homes we live in by making our buildings produce more energy than they use.

The project’s leader Michael Koenig told Factor that the project will help to create a zero-carbon lifestyle, but it has to give people financial reasons to want the technologies inside.

He said: “There should be some financial incentive, it should save them money on their utility bills or it should allow them to participate in an electrical market where they can buy and sell energy and create some financial value for themselves so that they are intrinsically motivated to have these types of homes and devices.”

The house hasn’t just been built for consumers though, or even for Honda to profit from the technologies further down the line, as Koenig explained: “One of the purposes of this project is to try to create a direct value to society and so one of things that we are trying to do is to advance the state of the art for green buildings, sustainability, and energy efficiency.”


To help achieve the goal of a zero-carbon house, Honda’s Home Energy Management System (HEMS) is included.

It is a joint hardware and software system that controls and optimises electrical generation and consumption through the house’s micro gird.

The system stores solar energy that been generated during the day so it can be used it night when more energy is needed by those in the house. It is heated using only 20 percent of the energy a typical home uses.


Smart adaptive lighting is also used, which adapts to the body’s natural clock: blue-ish tones are projected during the day and amber tones are projected at night.

Koenig explained that the home aims to improve the occupant’s quality of life by adapting to their needs.

He said: “Once we keep having these types of smart homes and connected appliances and connected systems you can start having some very nice improvements like different light scenes at different types of day for example.


“It seems pretty trivial but it is actually really nice to be able to come home and have different lights on compared to when you get up at 10pm for a glass of wine.”



Apple may have just announced its smart home kit for developers and customers to help make their homes interactive, but Honda are one step ahead of them. The company has built a smart home that has connected objects and also is capable of producing more energy than it uses. Not only is the house of the most sophisticated houses in the world it is also incredibly aesthetically pleasing. Here our some of our favourite features of the house:


Passive design: The home is designed to be incredibly energy efficient by accounting for local weather conditions including the sun’s direction. Sustainable materials: Across the house the designers, and engineers, tried to use as many sustainable materials as possible as the house seeks a number of green certifications from agencies in the US. Waste management: To further reduce the house’s impact on the environment 96% of the construction waste from the project, including brick, plastics and lumber, were recycled. Heating and cooling: In the ground beneath the Honda smart home’s garden are eight 20 foot bore holes that allow a geothermal heat pump to harness the ground’s relatively stable thermal sink to heat and cool the home’s floors and ceiling. Windows: The home’s south-facing windows are optimised for heating and cooling, while those facing the north are positioned to maximise natural light and ventilation to keep the conditions in the home comfortable whatever time of year it is.


Smart energy: The house has Honda’s home energy management system, which monitors and controls electrical generation and consumption through the microgrid. Data: There are more than 270 data streams recording information inside the house and feeding it back to the University of California, which has partnered with Honda for the project. Smart lighting: Occupants will be able to select lighting scenes that complement their daily rhythms and routines.


The Role of Light In Design

The daily cycles of day and night influence the experience in a number of ways. The main visual information is, beside the amount of light, the quality of the light. There are very different temperatures from morning to midday to evening. 

Generally from the light quality the time of day can be guessed quite accurately. These shades are of course heavily influenced by weather and time of year. This can lead to a confusion with heavy dark clouds pulling up in the afternoon and it can give a sense that time has jumped and it might at two o’clock like it is half five. On the other hand if spent a few hours indoors, in a dark corner of your house, and as you step out into the sunlight the quality of light can be confusing in terms of time of day. 

split time cafésplit time café
Image taken from philipperahm.com / A rendering of the interior, above the night zone in blue and below the day zone in yellow.

The light is identified by scientists as an important factor to set the body clock or circadian rhythm. This has been tested in experiments where participants spent weeks in caves with no daylight. The human body is able to maintain the cycles without the daylight reference for a long period. It does not depend on it as essential, but it provides a guidance to keep on track. 

With this background, the architect Philippe Rahm has proposed a café that mimics the light quality of different times of the day. In essence Split Times Cafe proposes a 24 hour coffee place where you can have day or night at any time of day. The different areas recreate daytime light and night time light quality. 

split time café
Image taken from philipperahm.com / A rendering showing the cafe in context.

It is possible to dring the morning coffee in the night light condition area and have a beer in the bright daylight zone. The day light zone is showing the characteristic yellow light indicating bright sunshine. The night zone on the other hand is fulled with blue tone light referencing the blue dark moon light. The cafe also offers a third place that is proposed in clear glass and therefore being filled with the actual quality of the light at that very moment. 

The light quality is achieved through the use of coloured glass. Yellow glass for the day and blue glass for the night. To support the atmosphere the furniture is distinct in the are the architects make use of the furniture. The day zone is organised horizontally where as the night zone’s furniture is oriented vertically.

split time café
Image taken from philipperahm.com / The plan showing the three different zones.


Bio-Adaptive Lighting



Understanding of the impact of light on human behaviour has advanced rapidly at the same time as lighting technology has undergone a major evolution with the advent of solid state lighting. It is now possible to use the principles of bio-adaptive lighting easily and cost-effectively in the workplace, at home and especially in sensitive environments such as schools and healthcare.

Results from recent case studies and research are very impressive and point the way towards harnessing the beneficial effects of lighting in new ways into many aspects of our lives. It’s not just about feeling better either; the right type and level of lighting can dramatically improve our performance of tasks and increase productivity and the lighting technology that is now being seen in the marketplace provides the means for everyone to realise the benefits of bio-adaptive lighting.

Bio-adaptive Lighting

The principle of bio-adaptive lighting is to provide artificial light controlled in such a way as to match the needs of human biological cycles, or circadian rhythms, in the most effective and appropriate way. It provides for improved health and wellbeing and supports aspects of human behaviour that benefit from varied and changeable lighting.


We are all governed to some degree by the circadian cycle (which is a little over 24 hours long) and light information from the environment resets the circadian clock every day to keep us in step. Light is the most powerful synchronizer of the human circadian clock, and the timing of light exposure during the course of a day is responsible for how circadian rhythms are synchronized with the environment. For example: Late-evening light exposure delays circadian rhythms, resulting in later sleep and wake times, and early-morning light exposure advances these circadian rhythms, resulting in earlier sleep and wake times.

It’s not just about lighting cycles though, as colour plays an important part too. One study from the Light Research Program at Thomas Jefferson University in Philadelphia found that blue light strengthens and stimulates connections between areas of your brain that process emotion and language. This means that blue light may, in turn, help people to better handle emotional challenges and regulate mood over time1.

Blue light is prevalent in sunlight, so your body absorbs the most during the summer and much less in the winter. Because of this, the researchers suggested that adding blue light to indoor atmospheres, as opposed to the standard yellow lights typically used, may help boost mood and productivity year-round, and especially during the winter.

This doesn’t necessarily mean that we should all now have lots of different coloured lighting since blue is often in white light and having the ability to vary the colour of white light, or the colour temperature as it is known, is a critical factor in effective bio-adaptive lighting. Introducing colour changes and even tints at certain times of the day is a highly effective way to deliver good bio-adaptive lighting.

The physiological effects of using bio-adaptive lighting also stretch beyond managing our circadian rhythms more effectively when we spend so much time in artificial light. In 2010 studies also indicated positive effects of lighting of different colour temperatures on various physical, psychological and performance outcomes of children, such as dental health, physical growth and development, attendance, alertness and academic achievement.

Another less physiological benefit of bio-adaptive lighting is handing control over the lighting to the individual affected by it. It sounds simple but there are very few office or workplace lighting installations that allow the Bio-adaptive Lighting workers to change the lighting. A study by the University of Exeter found that welfare and productivity are most likely to be optimized by practices that empower the workforce and that their experiments showed that empowerment was the key differentiating factor in increasing productivity by up to 32%. Today the solutions now exist with the capability to provide this over the hugely important aspect of lighting.

The effect on humans

In the evolution of human beings we have been exposed to artificial light for an extremely short amount of time. However, many of us now spend most of our time under artificial light and until very recently this lighting experience has failed to reproduce the light experience for which we are “programmed”. “Studies have shown that light affects sleep habits, depression and mental functions,” says Terry McGowan, FIES, LC, director of engineering and technology for American Lighting Association “The term ‘healthy lighting’ has been used to indicate that light can act like a drug where the strength, timing and type of light can be used to alleviate problems and enhance well-being. The ‘prescription’ is simple: People need bright days and dark nights that match the natural day/night circadian cycle.”

In fact, the healthiest way to stimulate your circadian rhythms is by exposing yourself to bright daytime light, says Fred Oberkircher, FIESNA, Educational IALD, IDA, LC, and emeritus associate professor for Texas Christian University. “It needs to be bright enough that you get a significant amount of light into your eyes, which is good for your circadian rhythms,” Oberkircher adds. “At night, when you want to keep lighting to a minimum, it’s a good idea to use controls such as dimmers. In this way, you can customise the lighting to fit your natural circadian rhythm.”

Something else to keep in mind: As people age, it becomes harder for them to adapt to changes in the amount of light to which they’re exposed. “Older people’s sleep and wake cycles are harder to maintain if they are not exposed to daylight early in the day and sleep in a dark room at night,” McGowan says. “Even the colour of the light is important.

The human circadian system is more sensitive to the blue portion of the spectrum than other colours, so it may be beneficial to limit the blue content of lights used for illumination during the evening.” The bluer the light, the greater the stimulation to our circadian rhythms, Oberkircher says. “Your circadian system is quite biased to blue light – so exposing yourself to blue light at night will delay your sleep,” he adds. “The blue light will suppress melatonin in your system and make you more alert. So it’s best to limit your evening lighting to warmer-coloured light.”

The wavelength of visible light determines its colour and recent research has identified the impact from certain wavelengths. For example a study by the School of Psychology in Adelaide showed that the shorter wavelengths of 470, 497, and 525 nm showed the greatest melatonin suppression from 65% to 81%. It is important to manage certain wavelengths of the visible light spectrum at the right times in order to deliver effective bio-adaptive lighting.

The role of the colour of light is key to effective bio-adaptive lighting. In a study into lighting and clinical depression, people who were exposed to bright blue light for an hour each morning for just three weeks experienced more improvements in their depressive symptoms than the control group, which was exposed to red light. They also had increased levels of melatonin in the evening, which helps with sleep and regulating the internal body clock, and lower levels of the stress hormone cortisol. Further, the improvements felt by the light-therapy group were comparable to those experienced by using antidepressant drugs4.

In another study exposure to blue LED was shown to affect sleep quality and median body temperature peak in Alzheimer’s disease patients. Median body temperature peak was delayed by approximately two hours after exposure to blue LEDs compared with exposure to red LEDs and sleep quality was improved. This pilot study demonstrated that light, especially LED lights can be an important contribution to helping such patients regulate their circadian functions5.

A study in the Netherlands found that increasing illuminance levels in schools at certain times and changing the colour temperature of the lights indicated a positive influence pupils’ concentration6. The Philips Schoolvision case study in Hamburg showed remarkable results from applying controllable adaptive lighting in a school environment and empowering the teachers with the ability to affect the lighting conditions. Reading speed increased by almost 35%, concentration improved dramatically and the frequency of errors dropped by almost 45%. Hyperactivity and aggression were also examined. Although the perceived reduction in aggression was not found to be significant, video evidence showed a distinct change in levels of hyperactivity. Observed hyperactivity was reduced by up to 76% when pupils were given a mathematical problem to solve under the Calm lighting scene, a figure that the baseline measurement and control group did not even come close to.

One of the more high profile examples is from NASA who is spending £7m to replace fluorescent lighting in the International Space Station with LEDs so that the colour, intensity and timing of lighting can be controlled to help astronauts sleep better and awake refreshed.

The Visible Light Spectrum Over the past decade, neuro-scientific research has uncovered the existence of a previously unknown non-visual optic pathway modulated by the substance melanopsin (which has a unique sensitivity to distinct parts of the visible light spectrum). Unlike other projections of the visual system, these pathways seem to play a minimal role in perception and processing of vision and image-formation; instead they have been found to be fundamentally responsible for entrainment and maintenance of circadian rhythms and other physiological functions. They also had increased levels of melatonin in the evening, which helps with sleep and regulating the internal body clock, and lower levels of the stress hormone cortisol. Further, the improvements felt by the light-therapy group were comparable to those experienced by using antidepressant drugs4.

In another study exposure to blue LED was shown to affect sleep quality and median body temperature peak in Alzheimer’s disease patients. Median body temperature peak was delayed by approximately two hours after exposure to blue LEDs compared with exposure to red LEDs and sleep quality was improved. This pilot study demonstrated that light, especially LED lights can be an important contribution to helping such patients regulate their circadian functions5.

Bio-adaptive lighting in context

At work Perhaps the most important consideration for lighting in the workplace is the use of natural daylight, however many work environments rely on artificial light either wholly or partially. Here, the lighting should ideally be capable of delivering varying levels of illuminance and also colour, especially ranges of cool to warm whites and be subject to control systems capable of delivering bio-adaptive effects. In particular workers should be empowered with control over their own individual lighting as far as possible and where practical. The good news is that lights are becoming available for these purposes in standard office configurations and control systems such as amBX are capable of delivering bio-adaptive lighting effects as well as multi-faceted controls.

Lighting can energise working environments through increased illuminance and changes in colour temperature and when delivered at the right time of day can have a powerful impact on worker wellbeing and productivity.

At home

In addition to simple settings for comfort, reading etc. lighting can be used in many ways to deliver the benefits of bio-adaptive lighting in the home. With appropriate lighting fixtures and controls lighting that supports circadian rhythms can be used widely and products such as Philips Hue & RGB+W Led strip lights are good examples of controllable colour-changing lighting that is available today.


Applying the principles of bio-adaptive lighting to the retail environment can bring a number of benefits for staff and shoppers alike. Lighting can be adapted to the time of day, season of the year and even the ambient daylight conditions without detraction from retail display. With LED lighting and new standards of control available today retailers can add the ability to change, adapt and improve their environments at the same time as they look to take advantage of the energy and running cost benefits of LED lighting.


Venues and hospitality facilities have much to gain from adopting bio-adaptive lighting. Apart from the ability to create the perfect ambience and have flexibility in the lighting system, consideration now has to be given to the power of lighting to influence emotion and visitors response to events.

8 Northumberland in London already promotes its ability to energise conference audiences and add impact to presentations with dynamic lighting effects. They even offer daylight underground as a way of keeping participants engaged throughout the day where there is no real daylight. The colours and movement of daylight are reproduced within the space in subtle ways which go unnoticed but support circadian rhythms.

Lighting is also used for combatting the effects of jetlag with introduction into hotels and even early attempts at managing the lighting in flight. The Hotel Rafayel in London offers jetlag recovery lighting in a number of rooms and 8 Northumberland have jetlag lighting scenes in their function rooms for use by delegates. The management of environments for maximum comfort and effect will include these aspects of lighting control in the hospitality sector as awareness increases and the cost and simplicity of implementation reduces.


The benefits of bio-adaptive lighting are becoming well defined and clearer and are applicable in many fields of lighting. Importantly, the advent of digital lighting and its inherent ability to deliver far greater levels of fine-grained control renders this capability at affordable and economic cost levels into many lighting installations today and we can expect this to extend to mass market and commodity-type lighting in the not too distant future.

Sources & References:

1&4. Dr Mercola – Light Therapy Promising for Treating Major Depression, January 26, 2011 , Physorg January 7, 2011, Archives of General Psychiatry January 2011

2. Hathaway WE. A study into the effects of types of light on children -a case of daylight robbery. Retrieved 1 December 2010, from http://www.nrc-cnrc.gc.ca/obj/irc/doc/pubs/ir/ir659/ hathaway.pdf.

Rautkylä E, Puolakka M, Tetri E, Halonen L. Effects of correlated colour temperature and timing of light exposure on daytime alertnessin lecture environments. Journal of Light and Visual Environment 2010; 34: 59-68.

3. The Relative Merits of Lean, Enriched, and Empowered Offices: An Experimental Examination of the Impact of Workspace Management Strategies on Well-Being and Productivity. Craig Knight and S. Alexander Haslam, University of Exeter

5. Spectral Sensitivity of the Circadian System. Mariana G Figuerio, John D Bullough & Mark S Rea, Lighting Research Center, Rensslaer Institute Troy NY.

6. The Impact of Light on Outcomes in Healthcare Settings Anjali Joseph, Ph.D., Director of Research, The Center for Health Design

7. Lighting affects students’ concentration positively: Findings from three Dutch studies. P Sleegers, N Moolenaar Department of Organization and Management. University of Twente, M Galetzkab, Department of Consumer Psychology, University of Twente and B van der Zandenc, c Philips Lighting, Eindhoven, The Netherlands


Adaptive Circadian Lighting

Adaptive Circadian Lighting — Honda Smart Home US

CLTC and UC Davis have partnered with affiliate American Honda Motor Co., Inc. on the Honda Smart Home US project. Groundbreaking took place April 23, 2013 at UC Davis West Village. Project leaders from UC Davis and Honda celebrated the project’s completion at an open house event on March 25, 2014. The zero net energy (ZNE) home is a model of residential sustainability, demonstrating best-practice solutions for lighting in new construction projects.

CLTC collaborated on the design of a circadian-friendly, energy-efficient LED lighting system for the Honda Smart Home US as part of the lighting solutions it is contributing to the project. The lighting is designed to minimize circadian disruption, benefiting occupants by supporting cognitive function during the day and enhancing safety and sleep quality at night.

LED light sources also minimize the home’s energy load, helping the Honda Smart Home US consume no more than it generates through its photovoltaic (PV) system. Lighting controls that adapt light levels based on occupancy and scheduling further eliminate energy waste during periods of vacancy or low activity.

Other systems demonstrated as part of the project include the Honda Energy Management System (HEMS), water conservation measures, and advanced HVAC solutions developed through UC Davis’s Western Cooling Efficiency Center.

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