Natural and Artificial Lighting in Commercial Buildings
Most owners would insist on the inclusion of natural lighting in residential project designs that brings a certain cheer or charm to a room or space, but is it really necessary with commercial buildings? Reports do prove that natural lighting contribute to the increase of occupant productivity and comfort. A carefully laid out lighting design not only gives you the indoor quality of a commercial building project but most importantly, harvested freely available sunlight to illuminate at least 30% of the floor areas can already reduce monthly energy consumption quite significantly. However, incorporating natural lighting into the building design does not rule out the need for any artificial lighting to illuminate areas which may become dingy or dark due to weather changes or time of day. Solving for natural and artificial lighting in commercial buildings design predicaments can just be a matter of finding the right balance between freely available natural and electrically powered artificial lighting with an understanding of designobjectives.
Looking at Lighting in Commercial Buildings
Architects and their professional teams consider certain factors to successfully combine natural and artificial lighting in reaching maximum benefits for building occupants and owner operations.
1. Distinguish Illumination from Lighting
Light and illumination are technically not the same thing, therefore should be approached differently when it comes to specifications. Light is measured in terms of lumens while illumination, in lux. Lumens refers to the amount of light coming from a source while lux measures the intensity of that light.
Lux is equal to an illumination level of one lumen per square meter. When designing lighting, it is important to carefully differentiate these two instead of taking them on as a combined factor. Each space reacts differently to varying lumens and lux requirements. Using the same specification for all spaces could waste of unnecessary energy, time and most of all, the project’s long-term operation and management costs.
To demonstrate, general lighting such that of offices, retail stores, supermarkets, counters, meeting rooms, and similar active spaces, may ideally need at least a minimum of 500 lux. Car parks and roadways need only 20-30 lux while washrooms, foyers, dining rooms need around 200 lux.
Define and compute for the lighting capacity strategically so you can better explore ambiance effects without sacrificing a lot of aesthetic intentions and still meet the energy saving objectives.
2. Consider Daylight Factor
It is commonly known that poorly planned utility systems bring huge cost setbacks for commercial building owners. The right amount of daylighting entering the building can then greatly reduce some of the financial problems. That is why daylight factor is commonly used to determine the ratio of internal to external light levels.
Architects and designers can use this formula to compute for natural lighting:
DF = (Ei / Eo) x 100%
Ei = illuminance due to daylight at a point on the indoors working plane
Eo = simultaneous outdoor illuminance on a horizontal plane from an unobstructed hemisphere of overcast sky.
However, do remember that there is more to the formula than simply computing for the daylight factor. At times these factors can still be quite subjective or confusing which need expert consultancy to balance every design considerations.
Benchmark daylighting first before determining the type of artificial lighting a building needs specially for a tropical environment where often times the available sunlight can be quite overwhelming and thermally discomforting when not managed correctly. While natural light can be overly generalized as an economical and ecological quick fix to energy savings, by not tackling the entire lighting as a system in itself, the outcome may actually work against making buildings sustainable.
3. Orient Building Fenestration
Sunlight, sun path orientation, position of windows and any other building openings make way for determining the kind and amount of artificial lighting that could be allowed into the building. In the Philippines, the rising sun from the East side and the prevailing winds from the Northeast Monsoon suggests that most windows or openings could be positioned to take advantage of that direction. However, capturing daylighting does not stop in only finding the right positions for windows or openings. To take full advantage of natural lighting, other factors such as glare, ceiling slopes, latitudes are also taken into design considerations.
Careful planning can bring further occupant health and disposition benefits from the natural light that comes in a given space, thus validating the recommended amount of artificial lighting integrated into a building can be a valuable asset to any commercial projects.
4. In Terms Of Lumens Than Watt
After all natural lighting specifications are built into the design, we now look into the role of artificial lighting. There are notable advances in the technology development nowadays of electrical light sources in terms of efficiency. Incandescent light bulbs were first introduced using electrically heated filaments to create artificial light. We also learned that incandescent light bulbs emit a lot of wasteful excess energy which then quickly paved the way for Fluorescent lamps in the market. Fluorescent lamps harness the chemical reaction of mercury and neon gas to produce light that lasts longer than incandescent bulbs and give off lesser heat. But that kind of technology was a bit more complex to set up and limited in terms of decorative potential so CFL or compact fluorescent lamps took over as the next alternative. Still the most alarming disadvantage of CFL specially to environmentally educated users would be the presence of mercury in the use of the product. Nowadays, the popular lighting choice is light emitting diode technology or better known as LED lighting. LED light technology relies on semiconductors which consumes so little energy for the amount of brightness they provide when charged.
Prior to LED lighting technology, the brilliance of a light fixture is dependent on the amount of power it consumes. Hence, watt is the unit used to measure the electrical power a lighting device consumes as a connotation to the amount of light it delivers. But since the advent of LED technology, the use of power was made less significant compared to the output of illuminance. Therefore in choosing lighting systems today, it is best to think in terms of lumens rather than in terms of watts when you consider lighting strategies.
5. Identify Artificial Lighting Intentions
To determine the lighting direction of a commercial space, it would be best to simplify the intentions into three major categories: task lighting, ambiance lighting, and accent lighting. Task lighting refers to general lighting for work concentration or functional activities that normally make use of wide spread white light such as in office or preparatory kitchens. Ambiance lighting plays more with moods and may have a softer glow to a place for lounging or relaxation and would typically take advantage of indirect warm whites or yellow lights. Accent lights bring interest to a certain architectural or interior feature by casting light and shadow drama using focused light as a means to highlight artistic expressions such as on paintings or sculptural pieces.
Organizing your lighting intentions into these three major categories, whether with natural light or artificial light, can already help one visualize fixture placements, interior layout, and make better decisions on lighting locations.
The Best of the Tropical Countries
In a tropical country such as the Philippines, it can be a fun challenge to get into building sustainability projects with great considerations for natural light. The weather in the Philippines are so unpredictable that the ranges in sudden heavy torrential rains to extreme midday solar radiation can either become a constraint or as an advantage where there are plenty of opportunities to design adaptations to those elements and create something iconic and sustainable.
With proper perspective, keen eye for details, and foresight, taking time to design proper natural and artificial lighting in commercial buildings can minimize pitfalls and concerns which may affect the project’s sustainability development and overall maintenance and operational costs. When done right, incorporating natural lighting design with artificial lighting can be more than just illuminating a space. With proper technical considerations, planning, and spatial experience, buildings can become a site-specific work of architectural art.
What’s your best building lighting project? Hook us with your comments. We’d love to hear from you.