The subjects who received sufficient light – either daylight or artificial – to stimulate their body’s natural sleep-wake cycle, or circadian rhythm, were able to fall asleep more quickly at bedtime, and experienced better quality sleep.
Office workers who receive bright light in the morning have better sleep and lower levels of stress than those who receive low light levels, scientists have discovered.
The subjects who received sufficient light – either daylight or artificial – to stimulate their body’s natural sleep-wake cycle, or circadian rhythm, were able to fall asleep more quickly at bedtime, and experienced better quality sleep. They also reported lower levels of stress and depression.
The finding was consistent during both summer and winter. The scientists, working at the Lighting Research Center at Rensselaer Polytechnic Institute in New York state, recorded each subject’s daily circadian stimulus or CS, the calculated effectiveness of light’s impact on the circadian system. It ranges from 0.1, the threshold for circadian system activation, to 0.7, the response saturation.
The team, led by Dr. Mariana Figueiro, found that office workers receiving a morning CS of at least 0.3, regardless of source, had stronger circadian rhythms, than those receiving a morning CS of 0.15 or less.
At bedtime, participants receiving low CS lay in bed for approximately 45 minutes before they could actually fall asleep, which can lead to reduced sleep duration for those with a fixed wake time.
The study included 109 participants at five office buildings across America. Each study participant wore a Daysimeter, a research tool developed by the LRC in 2004, and used in frequent studies to measure the amount of CS a person actually receives, along with their activity patterns. Each participant was asked to wear the Daysimeter as a pendant for seven consecutive days during data collection periods in winter, between December and February, and again in summer, between late May and August. Data collection was conducted between 2014 and 2016.
‘Our study shows that exposure to high CS during the day, particularly in the morning, is associated with better overall sleep quality and mood scores than exposure to low CS,’ Figueiro told Lux. ‘The present results are a first step toward promoting the adoption of new, more meaningful metrics for field research, providing new ways to measure and quantify circadian-effective light.’
‘We are supporting this type of research so we can learn more about the connections between lighting and health,’ said Bryan Steverson with GSA. ‘The data from this research will help support our efforts in developing new lighting practices that can optimize health benefits for federal employees working in our federal buildings.’
The results will be seized on by proponents of so-called human-centric lighting, in which artificial lighting levels and colour are manipulated during the day to better harmonise with our natural circadian rhythms.
Critics of the lit environment in the nation’s commercial workplaces say the sector lacks creativity
A THIRD of Britain’s office workers hate their lighting, a study by the respected pollsters Ipsos has discovered.
Some 32 per cent of white-collar employees told the researchers that they were unhappy with the light intensity, with only a fifth were able to alter the light level.
The results are sure to bolster critics of the lit environment in the nation’s commercial workplaces, who have slammed the sector for a lack of creativity. Top lighting designer Paul Nulty, founder of Nulty+, tweeted: ‘Bad lighting effects workplace productivity. Who’d have thought!?’
UK offices still have a preponderance of so-called Category 2 lights – recessed, deeply-louvred fittings designed to minimise reflections on computer screens – which deliver a gloomy environment.
The study of over 12,000 workers across 17 countries showed that the UK workers are the least satisfied with their office ambience. The study appeared to add weight to the argument that local lighting control boosts employee engagement and satisfaction, as the biggest issue was a lack of control. Only 39 per cent of respondents say they can adjust the temperature, while a mere 21 per cent can alter the lighting.
The so-called Category 2 light fixture has long dominated the UK’s offices, but its deep louvres are no longer necessary to prevent reflections on computer screens. Picture: Andrew Malone
‘This could be seriously affecting the concentration, productivity and engagement levels of workers, with the study showing that a lack of flexibility and control over the physical work environment correlates with a lack of engagement’, the study said. In contrast, highly engaged employees are those that have the most flexibility over how and where they work.
The situation in the UK is likely to be influenced by the country’s dominance of open-plan design, with 49 per cent of workers based in this kind of space due to its cost-saving benefits. However, this can limit employees’ individual control over their environment.
Christine Congdon, director of Global Research Communication told Lux: ‘Our research has consistently shown that the most engaged workers are those who have autonomy over how and where they work, whether adjusting the temperature, lighting, or workspace to suit their needs. ‘When people feel like they have choice and control over various aspects of their physical work environment, it leads to greater satisfaction overall.
‘Everybody is different and personal preference will depend on an individual’s natural physiology, their mood on a particular day and the task they are working on. To cater to these constantly changing needs, employers should pay more attention to providing a range of working environments, including the ability to adjust workspace basics as required.’
The study was commissioned by office furniture manufacturer Steelcase.
Scottish start-up creates first ever Li-fi office in Paris. PLUS The German rail network installs one million luminaires to cut energy use by 25 percent. AND The American Medical Association warns that outdoor LEDs may damage health. Lux Today 28 June 2016.
The Time Square office building in Bracknell is home to Bracknell Forest Council. The building is typical of many UK office blocks and required a complete refurbishment, including a lighting upgrade.
The old lighting comprised 1x58W switchstart luminaires with cat 2 louvres arranged in rows within a metal plank ceiling across the office space. The luminaire design combined with old technology meant the ceiling and walls appeared very dark, creating a gloomy effect below the optimum lighting specification for offices.
Two schemes were put forward for consideration: 1x55W TC-L with high frequency dimmable
control gear and 1x42W LED with dimmable gear. The latter scheme was chosen with the contemporary recessed Quattro LED luminaire because it offered maximum energy savings. In comparison to the existing 1x58W switchstart luminaire, Quattro LED offered a 37% energy saving on connected load. Significantly, over a 12-year period, Quattro LED also offered an energy and maintenance saving of £45,543 compared to the fluorescent alternative.
Lighting controls further increase energy savings
Part of the upgrade also included the installation of daylight and presence lighting controls using Sensa Link to ensure the lighting uses the minimum amount of energy required to meet the new design specification. The new lighting levels have been designed to achieve 450 lux on the working plane with sensors programmed to dim the lights in groups according to daylight and occupancy. With the inclusion of lighting controls, lighting is only used when required, increasing the energy savings over and above the 37% achieved by upgrading to LED.
Comfortable lighting fit for the environment
The office lighting has been brought up to the latest lighting standards to support the wide variety of
office-based tasks. With excellent colour rendition and superb light quality, the Quattro LED luminaires have transformed the working environment into a bright, vibrant space. The office is now a comfortable place to work, facilitating everyday tasks such as reading, writing and working with a computer screen, as well as clear communication between people As well as the lighting technology upgrade, the office has also been redecorated. This has increased the reflected light within the space and in turn creates further energy savings.
As part of the refurbishment, the emergency lighting has also been upgraded to LED using the Thorn Voyager LED series range. The addition of Explorer emergency lighting controls give a central emergency testing facility across the building.
Controls used
Sensa Link controls
Explorer emergency controls
Key Facts
Energy consumption reduced by 37%
450 lux
Colour rendition: Ra80
The humble Cat 5 cable – now capable of carrying power to your lights as well as data
Lux reports: LED lighting is helping buildings around the world slash their electricity bills because the amount of energy needed to run LEDs is so much lower than that consumed by traditional forms of lighting.
But lower energy consumption isn’t just about saving money and being kind to the environment. It’s starting to demonstrate other benefits too.
The electrical load of LED sources is now so low that you don’t even need mains cables to power them – you can use standard network cables, so it’s easier and cheaper to connect and control your lights.
This technology is called ‘power over Ethernet’ (PoE) and, as the name suggests, it’s a way of providing power for electrical equipment through Ethernet cables – the same ones that already form the backbone of the IT network in your office.
Ethernet uses ‘cat 5’ (or more recently cat 5e or cat6) cables – the kind you plug into your router, with the plastic clip on the end that clicks into place.
Cat 5 cables are really designed to carry data, not power. But as long as the load is below a certain wattage (up to about 60W at the moment) they can power and communicate with devices at the same time. Which turns out to be really useful.
So what are the advantages for lighting? Well, everyone knows that wiring up a new lighting system can be an expensive headache, and to install a control system, you’ll need yet another network of wires up in the ceiling, along with the power cables.
If you want control but can’t face all that wiring, you’ve got three options: send the data wirelessly (using specially equipped drivers), send the data over your power cables (using power-line communication, offered by the likes of Lumenpulse and Echelon), or send the power over your data cables – in other words, PoE.
The great thing about using cat 5 cables for this kind of thing is that they’re cheap to buy and even cheaper to install – no need for an electrician, just click the cables into place and you’re away. Philips, one of the suppliers of power over Ethernet systems for lighting, reckons installation is up to 25 per cent cheaper than conventional wiring.
But that’s just the beginning – the real savings are in the longer term.
The next big advantage is the level of intelligence that an Ethernet-based control system can bring. Every light becomes a point on a network, with its own IP address. That makes it easy to control and monitor them (including remotely over the web), and if your light fittings incorporate presence sensors, temperature sensors, light sensors and so on, you can track that data too.
PoE brings lighting into the ‘internet of things’, allowing you to connect your lighting to other devices and systems in the building, such as heating, ventilation, IT services and security. The facilities manager has a single system that shows exactly how the building is being used.
Up and running
Philips already has a PoE lighting control system up and running at a new Amsterdam office building occupied by accountancy firm Deloitte.
UK-company Prolojik also has a power over Ethernet system, Light Matrix, that it sells with luminaire makers Future Designs and Phi Lighting. The system is installed in a meeting room at the offices of PricewaterhouseCoopers in central London, to power and control 20 direct/indirect luminaires.
Other companies working on PoE for lighting include Iowa-based Innovative Lighting and California’s Nuleds.
To use Prolojik’s power over Ethernet system, you need a black box called an Ethernet switch, which converts AC mains power to the DC that goes through the cat 5 cables (achieving 10 per cent efficiency savings over a standard setup where mains power goes all the way to the driver, Prolojik says). Once the switch is installed, the electrician’s work is done. It can power up to 3kW of lighting: it has ports for 48 cables, each of which can be used to power and control 60W of lighting – enough for maybe one or two luminaires each. Any luminaires rated up to 60W can be used with the system, although it does require Prolojik’s Dali drivers.
Mark Vincent, commercial director of Prolojik, says the ease of installation is a big draw for clients. ‘When we’ve been presenting this, I’ve been apologising to electricians and contractors, because we’re taking their business away,’ he says. But the real benefits are in fully addressable control of lights, and the long-term energy-efficiency benefits.
As with Prolojik’s system, the Philips system works with third-party luminaires, and talks to any existing control systems that may already be installed in a building. Philips’ PoE system is based on a network of small Ethernet switches, so it can be scaled from powering a handful of luminaires to 1,000 of them.
Jeff Cassis, senior VP of global lighting solutions at Philips Lighting, says: ‘You can extract whatever data you want, whenever you want. Not only can you monitor energy consumption per light source, you have this really granular ability to look at what’s happening on my floor or building, aggregate that and understand how people are using the spaces. If you have multiple sites or buildings, you can look at how different buildings are managed. You could see how to use certain areas better, cool areas down that aren’t being used and make extra savings due to occupancy.’
Modern offices are increasingly dominated by display screen technology. Whilst appreciable quantities of paper documents are still in use they are normally in association with computers, and this balance is gradually moving toward increasing display screen use and decreasing quantities of written or printed text. A side-effect of this is the reduction in the amount of filing requirements as documents are stored on a computer disk.
This has resulted in a change in office furnishings with fewer storage cabinets and an increase in technology, and also in a fundamental shift in task position, from predominantly horizontal documents to predominantly vertical display screens.
Additionally in many offices collaborative working is encouraged where formal or informal face-to-face discussions occur to consider short-term issues or long-term plans.
Building design has also developed as energy costs and sustainability issues gain importance, resulting in a high proportion of modern office space receiving significant levels of daylight.
Best practice
These changes impact all aspects of the design of modern office building services including artificial lighting. Lighting must be designed to prevent disturbing reflections on display screens, requiring a high level of optical control and technical competence in luminaire design. Lighting must also provide adequate illuminance to occupant’s faces, modelling features sympathetically and therefore allowing good visual as well as aural communication. This interplay of display screen versus human requirements needs careful planning of a lighting installation to produce a fulfilling space suitable for the task. Recommendations for lighting for DSE and also for modelling of faces and vertical surfaces are provided in the European Standard EN 12464-1:2011 Light and lighting – Lighting of work places Part 1: Indoor work places.
EN12464-1 provides recommended illuminance levels for a variety of office tasks. These illuminance values are task related and best practice is to layer the lighting levels, balancing the level on the task, the level on the surrounding area and the level on the background. It has been shown that the perception of how light or gloomy a space appears is based upon a 40° band in front of the viewer. This is generally the room walls and a portion of the ceiling. It is therefore important that room surfaces are lit to prevent a gloomy, oppressive ambience and EN 12464-1:2011 recommends an average illuminance of 75lx on the walls and 50lx on the ceiling.
Taking control
Supplying comfortable and effective light is not the same as supplying controlled and energy-efficient light. A lighting system should interact with the space, dimming in response to increasing levels of daylight, turning on or off in response to occupancy within the space, and with increasing use of technology, especially within meetings, allow lighting scenes to be set to provide the optimal conditions for the task at hand. Lighting should be an integral part of the office ambience, giving a calm or lively atmosphere dependant upon the needs of the task and space, providing a fulfilling workplace for people to enjoy and be stimulated in, benefiting both the individual and the business.
Call us today to discuss your office lighting needs, tel: 0208-540-8287, or email: sales@novelenergylighting.com. We supply a full range of LED panels, tubes, and downlights suited to office requirements. Visit us at www.novelenergylighting.com to explore our range of Thorn LED products.
Comfortable lighting fit for the environment
