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Holistic Daylight Integrated Office Lighting Space for the Tropics

It’s absurd that we can conveniently resort to solar panels before we even talk about free renewable energy, daylight. Again, it’s something I won’t be blaming on any stakeholder because integrated daylight planning is subjected to a lot of interference throughout the design process. It could be due to cherry picking higher and easier points for green building assessments, lack of technical know-how, minimalist facade aesthetic, or simply not coming across that idea before and rushing through the drawings with the mind of commercial floor efficiency! However, if one is sincere to benchmark a true, green building that grants energy efficiency; ensuring optimum indoor environmental comfort, and combating nature deficiency order in office spaces, daylight fits perfectly well into the agenda of passive design.

But why are many just not getting daylight design right?

To start off, one needs to personally experience the dynamics of a naturally daylit office building. My first encounter with office lighting was four years ago which led me to study my master thesis on integrating task light with daylight. The art of daylighting office space could be easily misunderstood by many and its design and implementation process can easily deviate. It could be cost engineering, design aesthetics,  team synergy in delivering a unified work, or most of the time, the challenging one, and least mentioned, is anything within the internal office space and user behaviour. This, I can testify upon auditing multiple office buildings in Malaysia which I will share here.

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This is the current state of office building facade design. Fully glazed, quickly assembled, couple up a high-performance shading coefficient double glazing unit with a roller blind and voila! You have a very well facade heat gain performance and this glass box design turns up to be the design typology for green buildings in this very tropical climate. The current state of green building assessment systems (GBI, Green Mark) somewhat emphasises on energy efficiency more than occupants well-being regarding points weightage. Besides, the conversation of well-being is currently an intangible one where developers often selectively chase high energy efficiency points, and they are not the end users to appreciate the well being of the space eventually. This was what I addressed as the 3rd myth of green building HERE.

Of course, I am not against on the idea of having the provision of larger view to external space In fact, this is more than a marketing factor but a well-being for occupants to have direct contact with the surroundings too. This is well concluded via academic journals that the sight of surrounding is often cited as one reason why they prefer daylight. Interestingly, I once read a media coverage on Green Buildings stated:

“The bigger area of the window will ensure plentiful of daylight coming in throughout the day and occupants will not rely on electrical lighting”.

This is far from the truth in many buildings, even green buildings today. End users are inevitable to resort with roller blinds to deal with both direct sun and indirect bright sky glare. As observed from many offices with no external shading, roller blinds were drawn down permanently. Even so, Woh Hup new HQ pride with having a Green Mark Platinum certified office with 55% of the building claimed to be daylit but users are seen to have file folders sticking against the window to shield against from direct sun. In fact, the artificial lights were all on when I was there for the site visit and there was no roller blinds at all!

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Several examples of the significance of blinds but also defeats the purpose of daylight. Mostly shielding against direct morning sun but eventually not adjusted throughout the day with full reliance on electrical lighting.

Daylight will ensure nett Building Energy Reduction if Designed Correctly

Yes, only if it is designed correctly for. Unfortunately, many have seen either shrink or taken off sunshades entirely in a bid of cost cutting measurements. Hence, exposing facade to direct sunlight with immense glare and radiation heat into the AC space. Solar heat gain contributes around a quarter of the cooling load which is translated to 10% of the total building energy consumption. But, in the context of tropical climate, what we need is diffuse daylight only. Two reasons to this. Firstly, it has a better lumen efficacy. This means that given the same heat gain in comparison to direct the sunshine or even LED, diffuse daylight gives the best amount of ‘brightness’ with more than 130lumens/watt. Secondly, diffuse daylight illuminance level does not fluctuate as much as direct sunlight because of our cloudy sky. For an office space with the task, you would want a constant range of illuminance level (200-500lux). Unlike shopping mall atriums, fluctuating brightness due to direct sun and then sudden dim due to cloud cover is somewhat tolerable or even pleasant (300-2000lux).

Lighting Efficacy Comparison

Again, the nett reduction of heat gain, which translates into nett building energy consumption reduction, only means if the diffuse daylight has effectively reduced the need for electrical lighting. This sounds easy, but in reality, having a designated daylighting feature is far from over in making sure an office space has interaction with daylight. One can easily simulate the daylight feature and claim daylight factor coverage points. But, if it is not designed to consider occupants user behaviour and calibrated with sensors and lighting circuit, then you will have a nett increased of heat load instead of a reduction one instead.

The Challenge of Light Shelf Design

There are dozens of ways to design for daylighting.  You can refer to a full compilation by IEA SHC Task 21 Project HERE. However as mentioned, we would only want diffuse daylight in the tropical context, for both of the interest of energy efficiency and visual comfort. The conventional daylighting feature for Tropics is the light shelf. It is useful as it does not only reflect diffuse light deeper into the office space but providing sun shade to the facade too. Again, such light shelf needs to use low specularity material to scatter light across instead of reflecting direct sun like a mirror. Otherwise, any form of shading against direct sunshine when the facade is oriented to North-South is best practice. I wrote an extended piece of benefits of light shelf HERE.

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The range of factors in play with facade design, often more than just the interest of daylighting.

However, the light shelf is a hard feature to go about. Three big reasons why design team including the client discounts light shelf are maintenance, cost and aesthetic. To many, facade represents corporate branding and impression which often matters more than indoor environmental quality like daylighting. Furthermore, buildings can be compliance with pre-requisites to facade heat load performance with the usage of high-performance glazing. These glazing will typically need to have Shading Coefficient value of 0.20-0.30 to achieve ETTV/OTTV compliance. The downside? They will probably have a Visible Light Transmittance of 30-50%. Which, significantly jeopardise daylighting effort, especially when coupled with low VLT roller blind. Nevertheless, it is possible to balance all of these, and I will share some examples later of this post. But first, let us revisit some fundamentals.

What makes a Successful Daylight Office Space?

Earlier on we have defined that a successful daylighting strategy is one that is proven to have lower nett building energy heat gain due to the reduction in electrical light gains while ensuring visual comfort. I have also pointed out that it’s entirely possible that buildings score for daylighting credits merely by simulation results but in reality, roller blinds are used, and there is no proof of savings in electrical lighting usage. In short, based on my experience in walking through daylight office spaces with my illuminance meter in hand, the art of daylighting is more than the facade. The typical daylighting for building manuals such as IEA Task 21 will focus on daylighting feature itself. From the site context to the sun path, to the facade design, and to the depth of office space. But here’s how I attempt to summarise into a flow chart:

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It is relatively easy to simulate, design and preach through a daylighting feature to the design team when compared to understanding social behaviour of end users. Along the way to tenancy, there will be hurdles in making sure contractors furnished the right details such as circuiting of electrical lighting, the width of the light shelf, position and angle of the photosensor, just to name a few. But eventually, it’s important to understand previous tenants’ office experience with lighting level as a totality because it is very easy for them to move in and feel visually discomfort and override everything. One has to understand different space has a different task which requires different luminous environment (e.g., precision engineering or transition space).

1. IEN Consultant Office @ Bangunan Syed Kechik – User Behaviour and Adaptation

The first experience of an office space with daylight design is my first office. Bangunan Syed Kechik is a >40 years old building on the peak of Bangsar, Kuala Lumpur. Back to the good days of holistic design with available technology and without any green building assessment methods, it’s probably the only building with perimeter planter box. Daylighting here is done very simply with shallow office depth, clear glazing and horizontal louvre. With the ceiling panels removed, it’s visually more pleasing and theoretically this allows daylight to bounce in further. The electrical lights are only switched on during overcast sky close to rain.

Regarding illuminance level, the perimeter space (3 meters from the edge) achieves 150-300 lux level while anything deeper goes all the way down to 50 lux. Is it really dark that hinders work performance? Not really according to a survey because the majority of work are done with the laptop which is self-illuminated. If not, task lights are available to assist paperwork. The task lights used are IKEA’s TERTIAL with 5W CFL Bulb, which is in the market for more than a decade now thanks to its flexible arm and glare free hood. Another lesson is that sometimes, evening direct sun can be pleasant for a break space like the pantry, transition space or atrium. This goes well with the theme of biophilic of interaction with outdoor weather conditions. I wrote another piece on the office itself which was also submitted to TheStar.

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2. Office Interior – Menara Binjai Kuala Lumpur – Platinum but Glare

As a pilot platinum certified interior space project, this office is a typical scenario of top-down management driven aspiration to go sustainable but have not considered indoor environmental comfort to its staffs. The lighting audit was excellent; they manage to score almost half of the office space to be fully daylit, and my data log showed an estimated lighting energy savings of 65%. But! A post-occupancy survey has revealed more than 20% of the occupants have to deal with glare. Indeed, this is a typical clean facade office building with no daylight feature. Though the clean interior design with no partitions is commendable and crucial to daylighting, there is no glare prevention at certain spaces. The provision of the roller blind is inevitable because glare is not necessarily caused by direct sunlight but anything with contrast such as bright skylight. In fact, some office desks are arranged to have their laptop screen against the facade which is an obvious hindrance to visual performance.

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3. Green Energy Office – Best Daylighting Example of Daylighting Low Rise Office

It was radically engineered to achieve zero energy office at first. Nevertheless, with Building Energy Intensity of 35kwh/m2/year,  it’s one of the best examples of passive design where the facade is self-shading, and there is a dedicated light shelf level glazing. Furthermore, taking advantage of a low-rise office where M&E space will not fully occupy rooftop space, the skylight is extensively used here. Note that these are not direct openings but rather a “dog house’ shape so to only harvest diffuse overhead sunlight, scattered across the office space by a diffuser.  The measured lighting consumption (6 months data) during office hours was only 0.56 W/m2!

A prime example to optimise light shelf is to design two levels of glazing with two different glazing properties. The high-performance vision window shall be assumed to have roller blinds let down due to bright sky glare unless it is facing a building or hill that will not pose any significant contrast in the lumen. However, the glazing level that is contributing to the entrance of redirected light from light shelf shall be as clear as possible to capture more daylight into the office space. Then there shall be a shading device above the light shelf glazing level to prevent direct afternoon sun and improve the overall facade thermal performance. For the case of GEO building, self-shading layout design has delivered the similar intent.

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4. Menara Mustapha Kamal Block D – Best Daylighting Example for High Rise Window Wall System

This is probably one of the most extensive daylight audits I have done. What’s more impressive is the dedication of the design team (principally Architect A61 and IEN Consultants) in delivering this through by challenging the conventional ceiling space design. The idea is to have a daylight trough throughout the ceiling space instead of the conventional light shelf design. This is significantly different and better because diffuse daylight is coming directly from overhead instead of sideways where shadows may cast. The daylight performance for this system is incredible, with both simulated and site measured data agreed on sufficient daylight performance as deep as 7 meters.

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There are much more details on ROI and maintenance which I have written in a separate post HERE. Also, an open access academic paper is available HERE. The audit also has assumed that occupants will draw down roller blinds, but it is never an issue as natural daylight is from overhead. In this design, we emphasised on having a 300mm shading on top of the daylight trough glazing entrance. This is crucial as you want to maintain and minimise the fluctuation of illuminance throughout the day by avoiding direct sunlight. Similarly to what was mentioned previously. However, I will keep my excitement as I am more interested in the final results of tenancy when fit out is done by the end users. It’s one thing to harvest diffuse daylight into the office space, but it’s yet another thing to ensure the interior design is optimised to distribute daylight further in. This can be learnt by the next example.

5. Energy Commission Building Putrajaya – Extensive Daylight Feature but Disturbing Interior Fit Out

Built even before Green Building Index was launched, Energy Commission Building, or better known as “ST Diamond” gets a double platinum GBI and Green Mark certification. It’s self-shading tilted facade, and daylighting design has contributed largely to the nett reduction of building cooling load. The internal light shelf and responsive atrium allow extensive daylight to be available throughout the day. However, if given the option for an improvement, I would not have designed a tilt surface, and I would remove the internal louvres which was meant to prevent any bright sky glare upon looking up the light shelf glazing from inside out. The tilted facade may have helped in reducing solar heat gain, but it has also effectively reduced the total external daylight components as the ‘view out’ from the window has reduced. The internal louvres are theoretically important for glare prevention but given the neighbouring buildings which are blocking direct sky view, the louvres are only reducing the efficiency of lights bouncing off from the light shelf.

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A detailed account on the key sustainable feature is available in my article HERE. Nevertheless, the highlight here is that the effectiveness of daylight stops just right at the first row of the perimeter cubicles. There’s a clear effort in innovative daylight design, but the poorly coordinated interior design has obstructed daylight from reaching further in. The cubicle partition (35% VLT) and clutteredness of office documents only mean daylight is limited to the perimeter of the office space. Interestingly, despite audit values around showing very low illuminance value (50-150lux), occupants are not complaining about it. Some have said that they are adapted to the low light level while working on self-illuminating laptop work. If not, task light is always available.

6. Best Daylighting Example for High Rise Curtain Wall System

If one wants to maintain the status quo of minimalist glass box facade design, then this is probably the easier approach. One of the latest green building tower in Malaysia, KKR2 under the public works department shows blinds and interior space arrangement are all it needs to get nearly half of the space to be fully daylit. Instead of using conventional roller blinds, the perforated horizontal louvres is adjusted to allow daylight to be bounced in despite occupant may close it against any glare. More importantly, the interior design is arranged in such that office cubicles at parameters do not have partitions higher than a document size. This is followed by individual cubicle partitions which use clear glass instead of frosted glass. The corridor is also purposely placed in the middle of the office space as it requires lower lighting level which is within reach of daylight.

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However, a key contribution of this example is also the relatively larger window to the floor area. Given the horseshoe shape layout, this allows more daylight availability for the same area of a typical square office layout. This, I am uncertain if there is a higher solar heat gain per m2. Interestingly, the comparison of DF, lighting energy savings and visual comfort of the two mentioned buildings (Energy Commission and KKR2) is my latest working paper. As shown, it is clear that KKR2 has a higher % of space that complies with daylight factor. However, both have an equal percentage of lighting energy savings (based on representative floor survey), and there is no significant difference in visual comfort (based on survey results from 180 samples and 70 samples from KKR2 and ST building respectively). This shows an interesting observation that performance of daylight does not necessarily correlate with lighting energy savings and visual comfort.

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Controllability Matters in Totality – Task Light

I believe personal controllability is one of the key design to achieve zero energy building. Another familiar theme to green building is smart building, which taps the potential of the algorithm in understanding individual’s usage pattern and preference for their indoor environmental quality. This means that we can supply just the right amount of lighting and cooling to each. Though still at the infant stage, I am still advocative of the back to the good old basics, task lights. It’s strange that everyone is pushing for energy efficient LED lighting but yet we should be able to channel brightness to where it is needed and not the entire office space. I wrote an extended piece HERE on the potential of daylight and task light.

The Future Lighting Scene of Office

Eventually, the equation to an energy efficient lighting design for office space that is also visually comforting for end users lies in flexibility and personal controllability. This is because everyone’s preference is different, be it indoor environmental parameters such as lighting, acoustics or thermal, or as well as other factors such as organisational or personal motivation. Again, often there is an interesting observation on social behaviour overriding IAQ priorities such as user compromising glare to sit a distance away from management. Hot Desking in an open plan office, with the options of glass cubes for private conversation, is the office of the future. I have also pointed out that present green building assessment system, unlike impressive ones like Living Building Challenge, is heavily skewed to Energy Efficiency and not holistic enough.

It is only hopeful that more professionals in the consultancy line will recognise effective lighting design for the office space in pursuit of sustainability that includes biophilic design as well. Yes, I am biased for a daylight office space but pragmatic in its approach. Yes, there are LED technologies today that are capable of mimicking the spectrum of daylight (17000K), but they are not able to replicate the dynamic luminous environment of daylight due to the changing in sun path over the seasons. But ultimately, we are all outdoor beings who yearn for connection to nature, and it’s pitiful on the current state of building design that confines us in artificial cubes. In fact, it’s against the building regulation if you don’t provide sufficient daylighting (>2% Daylight Factor) for office spaces in Denmark.  There’s more that can be done than just another array of light fittings in a place where people spend more than half of their day. What makes a green building outstanding? Yes, you can have a highly efficient chiller plant, but eventually, public in general or potential clients buy into the idea of a physically seen green building feature like daylighting that’s pleasing to visual comfort.