Commercial lighting is lighting used for commercial spaces such as offices, stores, institutions, hospitals and government buildings, essentially those spaces that are not residential, industrial or for manufacturing. Compared to other types of lighting, commercial lighting tends to have a higher initial cost, longer lifespan, better durability, higher maintenance and service costs and better energy saving options.
In commercial buildings, accomplishing a task or activity is generally the most important function. A lighting design company should create designs that reflect the type of activity performed in the building to ensure that people working in the space are comfortable and that the lux level requirements and energy efficiency standards are suitable.
When MEP (Mechanical, Electrical and Plumbing) engineering design teams work with lighting consultants to select designs for a commercial space, some of the aspects that must be considered include; the illuminance of the space, the application for which the space will be used, the type of light fixture appropriate for the space and application and the lux level requirements based on guidelines and codes.
Types of light fixtures for commercial lighting design
When selecting light fixtures in commercial lighting design, their characteristics, application and function must be considered. Commonly-used commercial lighting design fixtures include T5 and compact fluorescent lights, however, given the reduction in prices, LED light fixtures are starting to be preferred.
To understand the type of light fixture best suited for a commercial space, the following descriptions may be useful:
Tubular Fluorescent Light Fixtures
This type of light fixture, based on traditional fluorescent technology, is typically set into ceilings and covered with a frosted lens. Depending on the amount of lighting required in the commercial space, standard fluorescent lights usually have one to four bulbs. They are regarded as one of the longer-lasting and more energy-efficient options for commercial lighting design.
Compact Fluorescent Light Fixtures
As a replacement for incandescent bulbs, compact fluorescent lighting is also built from traditional fluorescent technology and has a compact internal ballast. While it is as energy efficient as tubular fluorescent lighting, the light emitted provides a better natural white colour perception. It is commonly used in lighting application for tasks and downlight lamps in commercial spaces.
T5 Fluorescent Light Fixtures
Suitable for troffer or high bay (high ceiling) applications, T5 fluorescent light fixtures are often considered the best option for commercial lighting designs because they have a long life and their maintenance requirements are minimal. While the T5 fluorescent fixtures were designed with fluorescent lamps sources, they are now more often designed to accommodate LED bulbs.
LED Flood Light Fixtures
In the recent years, LED light fixtures have been widely adopted because they consume less power and have a longer operational life. While the initial adoption of LED fittings was a challenge, the reduction in cost, almost as low as T5 and fluorescent light fixtures, has led to an increase in preference for LED lighting fixtures in commercial lighting design.
Lux level requirements
The main objective when using a commercial building is to accomplish a task or conduct an activity, which is why illuminance or the focus and amount of light is important. While under lighting impedes several types of activities, over lighting also poses a problem in accomplishing tasks. To understand lux or illumination level requirements for commercial spaces, it is important to understand the units of measurement of light and the efficacy of their relationship.
- Lux or illuminance – Illuminance or lux is the unit of measurement of the intensity of the level of light, measured in foot candles. Typically, a brightly lit office would require around 400 lux of illumination.
- Lumen or ’luminous flux’ – Lumen is the measurement of the total ‘amount’ of light. One lumen is the measurement of the output of light. Typically, a 100W incandescent bulb used for an office space with ceiling panels for lighting would produce an output of 1600 lumens.
- The relationship between lux and lumen – Lux measurement helps determine the lumen (output) required given the area that is illuminated. One lux is equal to one lumen spread across one square meter. To achieve higher lumen when lighting a large area based on the lux level requirements, the number of light fixtures is usually increased.
- Wattage or watts is the measurement of the power required to operate a light fixture (luminaire) or the energy efficiency of lighting. Luminous efficacy, defined as the rate at which a light fitting or light source can convert power (watts) to light (lumens), is measured in lumens per watt (LPW). Typically, a T8 fluorescent lamp or 32W T5 used for an office space with ceiling lights would produce 50 lumens/watt.
Calculation of the lux level is required to determine the number of lights needed in a commercial space according to its size, the type of activity and the energy efficiency required. Typically, software programs such as DIALux or AGi32 are used for lux level calculations.
MEP engineering design teams and lighting consultants must take into consideration the guidelines and codes which state the minimum lux level that needs to be maintained. Commercial spaces, in particular offices, are typically over-lit based on the lux level requirement of the client which is usually more than guidelines or lighting codes.
Some of the handbooks and guidelines provided by different professional bodies include the IESNA Lighting Handbook, published by the Illuminating Engineering Society of North America, a series of guides provided by the Chartered Institution of Building Services Engineers (CIBSE) in the UK and codes by the Lighting Council Australia.
Most of the green building codes stipulate the lighting watts/m2 for office spaces should be within the range of 10 to 15 watt/m2, compelling lighting manufacturers to create light fittings with higher energy efficiency. With the introduction of LED light fittings, the watts/m2 in many cases has fallen to 5-8 watts/m2 without compromising the minimum lux level requirement.
Lighting consultants must comply with strict guidelines on the number of light fittings allowed in a specified area while maintaining the minimum lux levels required to ensure green building designs have low energy consumption and high efficiency.
In addition to green building design codes, a lighting design company must consider some of the other trending concepts in the lighting industry to provide more control on energy usage, data, efficiency and comfort. Some of the lighting trends that could be considered include; connected lighting, interactive lighting, LED fixtures with advanced lighting controls, balancing daylight and LED and harvesting technologies, which would support the new concept of customer-centricity in commercial spaces.
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