daylightfactor

Task Lighting & Daylighting – Efficient & Effective Workplace Lighting Solution

In 1897,Thomas Edison invented the first ever light bulb, that successfully glows for over 1500 hours after trying with thousands of different filaments.Then the lighting technology has made its great leap forward, from the incandescent light bulb, fluorescent Lamps, CFLs, and subsequently LED today, generally. All in the race to produce better performance lighting and thus saving energy.

Typical Office Design with Low Depth to Ceiling Ratio that requires Artificial Lighting.

Aesthetics? Power? Watts? 

But based on my observation in Malaysia, most lighting experts pay more attention to the aesthetics of lighting than how it actually affects the users. Most of them will study the lighting color temperature, most of the end users question the common note,  “Is it bright enough?” but rather seeking what is the appropriate brightness.

Many of us seek for the information of power or Watts to justify the electricity consumption of the light bulb but rather knowing much on the amount of brightness, LUX it produces. Typically there is a misconception that more Watts will produce more Brightness and thus means better.

Brighter Days Brighter Mood?

Not exactly, In contrast to the assumption made, it is known that brighter lighting, is in fact NOT desired by most workers. Providing too much light can lead to the wastage of electricity/energy, and also ultimately affects occupants emotional and physical discomfort, due to improper illumination of the workstation, or perhaps cases of glare.

A typical Philips CFL

Flux, Illuminance, and Luminance

To justify this scenario at a quantified manner, total flux, in lumens, is the parameter of the bulb manufacturers uses when describing the total amount of light given off by a bulb in all directions. However, that does not tell us how much light will be received where it is needed. Illuminance, on the other hand, tells us how much light will reach a given surface. Illuminance is generally measured in lux, which is a short form of lumens per square meter of surface area, the metric equivalent of footcandles. There are 10.00lux in one footcandle typically.

The total flux doesn’t specify how much illuminance will be provided when it is needed, this can be due to the design of the reflectors, lenses and other optical media that could affect the flow of the light from the source to the work surface. The example on the Left shows a CFL bulb producing 55lm per watt, with the total power of 11W, thus producing 610lumen. But that does not reflect on how much illuminance it provides.

The table below shows the recommended LUX Level for various workspace activities.

Typical Ceiling Lights defeat the purpose of healthy illumination as more often the ambient office lighting can go up to 500 when only 100 is needed, far more light than is necessary for getting around the office. A personal experience of mine tells me that having worked in an office space which uses ceiling lights all day could really deteriorate your health, having a constant illuminance of 500 during the day time and having even a greater contrast when the skyline turns dark will make you feel lethargic easily.

Monitor Glare

Having ambient lighting level as high as 500 lux to read printed documents is fine, but not when it is additional to the illuminance gave out from the monitors. The suitable lighting intensity for proper monitor viewing is 50-100 lux. Anything beyond it will lead to glare on the surface of the monitor, substantial energy waste and a variety of worker productivity issues. The only solution is to lower the overall ambient lighting levels and provide individuals with positionable task lights.

TASK LIGHTING- The Ergonomic and Economic Winner

It is irrefutably true to say that combined ambient task lighting is the most effective solution in any environment in which workers are doing both paperwork and computer work. Research shows that this concept is supported by human factors and also driven by demand for energy savings. The main key to lighting office space to accommodate individual preference is to take off conventional grid ceiling lighting, but rather design zones that incorporate sensors, either wise, PSALI aka Permanent Supplementary Artificial Lighting Interiors is another concept to suggest with. But the focus here is about task lighting with the assumption of sufficient surrounding ambient lighting 100-200lux.

Task Lighting Saves Eyes

Ergonomics is defined as a scientific discipline concerned with the understanding of interactions among humans and other elements of a system, in short, the science of making things comfortable or productive. Positionable Task lighting is extremely flexible and considerably more effective means of lighting a working station than typical overhead fixtures, which can be costly and inefficient.

“The most common design error, clearly, is the mismatch between where light is being delivered and where people are utilizing that light” Alan Hedge.

They can be directed to light documents or moved to avoid screen glare, and everything is within the convenience and comfort of the occupant rather than a fixed, helpless ceiling down light. Eyestrain is the major issue for most typical office open layout with massive ceiling down lights, and that can affect the performance of work, it’s a work hazard, that bad.

Task Lighting Saves Energy

The whole concept of task lighting is again, that you only need to light up where you need it to be. A task light using a 26-watt compact fluorescent lamp will consume far less energy as illustrated in the table below. Furthermore, by having lower energy consumption operating the lamp, you could save air conditioning energy as you have reduced the overall heat gain much more effectively too.

“Comparative analyses indicate significant energy and cost savings through separation of ambient and task lighting system, as high as 60 percent for energy and almost 50 percent for life cycle cost” Ernest Orlando Lawrence Berkeley National Laboratory 2003 Study 

To sum it all up, the following is a video documented by IEN consultant on an energy efficient task lighting. Well, it’s a rather cute LED Tasklight available from IKEA! Hope the illustration helps.

 

It is said that the rule of thumb of recommended illuminance around the monitor display should be at least one-third of the monitor brightness.

This is my office desk with approximately around 150 lux. Good enough for a laptop work, but if I would need extra light to assist me in some paper reading, then I could just adjust the blinds beside me to let daylight fill in which could increase the lux to 220. We should always consider available daylight source before thinking of using artificial lighting.  In which, more about it will be described here.

 

Harvesting the free and healthy light – DAYLIGHTING

We see that the task lighting strategy can be applied to almost any workplace in the world, but Malaysia, as a tropical country, certainly we have much more to offer when we have so much free daylight all year round. It was mentioned just now on the ambient surrounding lighting created by the artificial ceiling lights, but in here we want to push the limits to use daylight to light up as many floor space as possible. It is common sense and practical strategy to harvest daylight and rainwater in any tropical climate country.

There were a daylight survey results carried out among 569 office building occupants in Manila, Philippines. Seems that most of them prefer the equal distribution of daylight and electrical light, but the second percentile states clearly that there’s an interest on daylight itself.

Understanding Spectrums

While it was discussed just now that too much lighting or glare could affect one’s performance in work, here we talk about how much a daylight could help you. Daylight is ultimately essential for any human beings or living things, and artificial lighting should not be taken as a substitute for it.

This issue is wide concern for certain groups such as Navy or Astronauts on Spacecraft that are commonly away from the daylight/sunlight for few days, and the type of unnatural lighting has an influence on the depressive behavior such as lack of energy, increased appetite, irritability, also known as SAD Seasonal Affective Disorder.

The whole reason behind this is that artificial lighting does not resemble the full spectrum of day lighting.  Light is invisible, that’s why we take it for granted, but when you look behind the curtain of white light and see all the colors of the spectrum, you suddenly realize: white is not = white.” Margit Brusda, Co-Founder VivaLite

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Other Benefits

Daylight does not flicker; fluorescent lights can have a noticeable flicker. People blame this for a multitude of
problems like a headache, eye strain, and attention deficit problems. Fluorescent lights than run on electronic
ballasts have considerably reduced flicker problems, but only daylight guarantees a total absence of flicker.

The inherent variability of daylight as clouds move through the sky, successively obscuring and revealing the
sun. Some studies have shown that this variability of daylight has relaxing effect on the eyes (Sze-Hui Au,
Leony (1999)

On the other hand, luminous efficacy is a measure of how well a light source produces visible light in comparison with its electricity demand. Daylight is known to be cool, desirable and green of course, in tropical climate, note that we refer to daylight rather than harvesting direct sunshine, which is a disturbing glare to many,

A Simple yet Precise Design

Designing a building or facade to capture daylighting can be quite easy but to really know if it is performing relatively suitable for the occupant or environment, quantitative studies or simulations have to be done to prove it right. Generally, daylighting design strategies in the tropics covers 4 rules:

Control Solar Heat Gain – Capturing Daylight means having Openings at your facade, but having too many openings, that will increase your Window to Wall Ratio, thus increasing possible heat gains too, causing more heat entering through the fenestration that heats up the building, increase electricity cost to cool down the building, generally.

Control Glare from Clear Sky and Direct Sun – Daylighting means absorbing diffused light from the North and South Facade in general, not the direct sunshine that glares through the West and East facades. However, having a good facade shading strategy will help.

Make a Daylight factor more uniform – Generally, it’s best to design space according to the availability of daylight that could hit a minimum 1% of daylight factor, uniformly distributed along the openings.

Increase Daylight factor deep in the building – This comes with the extra innovation on how to catch daylight even further into the building. Typical opening fenestration can deliver light into a depth of 5meters with 1% Daylight factor, but however, with the new channeling of the day lights, we can achieve as deep as 7 or 8meters! Illustration as shown:

However, the point is that we need not go into that technical or deep to study on how to deliver daylight into that deep yet, the facade itself has many strategies to play with to study on how to “bounce” the light rays into the deeper part of the room. Following is a study of the facade of ST Diamond Building, where light shelf and  window sill bounce the light further deeper into the room. This looks simple but studies need to be done for different buildings as it depends on your microclimate, ceiling height, etc.

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The building is 50% daylit. The façade daylighting system consists of a mirror light shelf and a white painted window sill. Both reflect daylight onto the white ceiling for improved daylight distribution until 5 meters from the façade + 2 additional meters of corridor space. Installed office lighting is 8.4 W/m2, but 1-year measurements show consumption of only 4 W/m2 showing 50% reliance on daylighting

The Ultimate Combination –  DAYLIGHT responsive lighting + TASK LIGHTING

With the mention of both lighting strategy, here comes to a conclusion on how both can be incorporated to an efficient and effective workplace lighting solution.

Case Study: Green Energy Office, Bangi

GEO Building is a research building and also a research project for Green Tech Malaysia. It was taken into use in November 2007 and at present, the Energy Index is 35kw/meter square year, or just 15% of the typical office building.

This is what it looks like without ANY lights on! IF you have mistaken the down ceiling light is on, that is actually the daylighting openings from the rooftop. Probably being the best example of daylight design, the building’s electric lighting only needs to be on 5% of the time of working hour. Following is a LUX/brightness study of the working space.

There is no artificial lighting require at all as you can see, however when it comes to an event of gloomy weather or insufficient daylight, the efficient mechanical lighting, T5 lighting kicks into supplying lighting. And all of these are regulated by sensors, and lighting zones are designed to as an even more sophisticated method to save electricity and controlling equality of brightness throughout the open space.

This is the light levels measured in GEO early this year. 

As it was seen, the staffs are absolutely all right with generally low ambient lighting level but by using the 6.2 watts LED task light which gives a suitable 700+ lux of brightness to read materials. I personally have been there too and just notice that some staffs really appreciate their LED task lights because it offers them flexibility and contrast in sight brightness from time to time, instead of a typical office design with constant 300-500 lux everywhere, and that’s not encouraging!

Conclusion

It is proven that Daylight helps much more compared to Artificial Lighting, as perhaps for some of us we tend to evaluate monetary more and saying that designing a building with daylighting is too expensive, why not just layout ceiling lights? That is obviously ethically wrong as you are not only wasting energy/electricity in the long term, but there is substantial money sacrificed from all the health problems too eventually.

Daylight helps a lot if glare and heat are controlled! Supplementary Lights and Daylight indeed is the most useful lighting combination for office spaces in the tropics.

Credits to IEN Consultants for Infographics and information, For more details of their projects, please visit them at HERE

Credits to publishing papers (Daylight vs Artificial Light by Kalle Hashmi, Swedish Energy Agency) and (Task Learning Solutions, by Karin Tetlow, Humanscale)

ADDITIONAL INFO

IEN is in planning a detailed daylight documentation of the GEO Building, Malaysia, for which we did the daylight design and which has been in operation since 2007. The documentation will consist of:

1) Data logging of daylight levels at 12 workspaces in the building
2) Data logging of energy consumption of general lighting + task lighting
3) Monitoring the user-pattern of task lights and general lighting
4) Occupant surveys with specific questions on how people like to work in a daylight working environment. Pros and cons.

The results of this study will be published in a scientific journal, as well as in more popularly ready magazines (for example in FuturArc Magazine).

To my knowledge, this is the first time that a detailed documentation study is done for a tropical office building that has been successfully designed for daylighting.

Kind regards,
Gregers Reimann, MD
IEN Consultants
http://www.ien.com.my