Lighting Considerations for Optimum Productivity in Commercial Buildings
What makes commercial buildings productive? Well, in essence, they should have an environment, system or workflow that encourages inhabitants to perform their tasks to the best of their ability. Commercial buildings may consist of offices, retail establishments, institutions, hospitals, etc. Pleasant working conditions can be created in such buildings through a number of ways, with effective lighting being a significant contributor. The right lighting can lead to optimum functioning, satisfaction and a ‘task-centric’ atmosphere. Commercial lighting may be expensive initially, but it is designed to be longer lasting, more durable and have better energy saving options than lighting for other settings. It is important that M&E design consultants, or MEP engineers, collaborate with lighting experts to determine the right combination of lighting for commercial spaces.
Essentially, lighting designs should cater to the type of indoor activity in the commercial building such that the lux levels and energy sufficiency standards are duly maintained. Lighting designs should review the illuminance of the internal spaces, the function to be performed at those spaces and appropriate light fixtures for the spaces.
Humans are attracted to light, and thus, light has a considerable influence on both our bodies and minds. The right quantities of daylight and artificial light can positively affect our health. Sufficient daylight and artificial light in an office space can improve satisfaction and efficiency, through a creative, dynamic and motivating environment. It has been proven over the years that light can inspire, improve communication, set a mood and influence emotions. Spaces can be made desirable, resulting in a general sense of well-being.
Over-lighting can be just as detrimental as under-lighting in commercial spaces. People should have enough light to perform and complete their tasks but not so much that it becomes blinding. Tasks that require a high degree of detailing, such as drafting, requires more light than one that involves walking. The IESNA Lighting Handbook, published by the Illuminating Engineering Society, is a popular reference source for lighting design.
Before referring to this handbook, design consultants must understand illuminance, or the amount of light that hits a surface. For example, in an office, it is relevant to know the illuminance on a desk. The unit of measuring illuminance is a foot candle (FC) or lux, and 1 FC is the amount of light on 1 square foot of any surface using 1 lumen of light from 1 foot away from the surface – 1 lumen per square foot. Similarly, 1 lux is the amount of light on 1 square metre of any surface using 1 lumen of light from 1 metre away from the surface – 1 lumen per square metre. Also, 10 lux is approximately 1 FC. An illuminance of 400 lux would be sufficient for a well-lit office.
Another factor to consider is lighting power density, or LPD, which is the amount of power used by lighting per unit of building area. For instance, in the United States, LPD is measured in watts per square foot, whereas this may differ from country to country and is dependent on local and international codes. The watt measurement includes power used by lighting fixtures, ballasts, controls, transformers or any other device or component involved in lighting. Calculations for LPD may be performed using the Building Area Method or the Space-by-Space method, which has been shown to be more accurate and enable a lower LPD estimate.
The IESNA Lighting Handbook recommends light levels for most conceivable spaces. A few of them that are relevant to commercial buildings can be found below:
|Light Level (FC)
|Light Level (Lux)
|IECC 2015 LPD (Watts Per Sf)
Types of Light Fixtures
Generally, T5, compact fluorescent lights and LED light fixtures are used in commercial buildings.
- Tubular fluorescent lights – usually set into ceilings, frosted lens covering, 1-4 bulbs, long lasting and energy efficient
- Compact fluorescent lights – compact internal ballast, energy efficient, natural white colour perception, used for downlight lamps
- T5 fluorescent lights – suitable for troffer or high bay use, long lasting, minimal maintenance
- LED lights – uses less power, long lasting, economic
Requirements of Lux Levels
In large areas, to achieve a higher lumen, the number of light fixtures is increased accordingly. The lux level required is calculated based on the size of the space, the activity that takes place there and the required energy efficiency. Software tools, such as DIALux or AGi32, are employed for lux level calculations.
Guidelines and local codes determine the minimum lux levels required in different environments. Lighting consultants and M&E design consultants must be careful not to completely give in to certain clients who ask for lux levels higher than those designated in guidelines and lighting codes in offices and other commercial spaces.
Consultants should ideally employ new concepts in the lighting industry to help contain energy usage, efficiency and comfort, such as connected lighting, LED fixtures with advanced controls and interactive lighting. Daylight, LED light and harvesting technologies must be balanced.
Lighting in offices, besides being at optimum levels to help perform and complete tasks, must also meet the biological lighting needs of office personnel in the future. Here’s how it could be possible to help employees stay healthy and alert:
- Creation of an ambience to develop creativity – A combination of direct, indirect and vertically lit surfaces have been found to be pleasing for most employees. When the desk light can be individually controlled, greater motivation and accuracy in tasks has been noticed. Designers should try to avoid designing lighting that only has downward-directed illumination.
- Need light for both people and tasks – Light intake influences good sleep and a feeling of wellness, resulting in higher productivity. Natural light helps people tell the time of day. When there is a lack of natural light, the body’s circadian rhythm loses its pace, and as a result, people become tired and listless. A mix of different lighting options can reduce this effect.
- How daylight influences emotions – Spaces can feel smaller due to insufficient light. A person’s work area should ideally enjoy a minimum of 3 percent of daylight. This ensures that people are emotionally upbeat, and an outside view is an added bonus.
- Preventing SAD (seasonal affective disorder) – During a season that causes people to experience less light intake, a type of depression linked to lack of light (SAD) can result. Moodiness and listlessness are symptoms. Sufficient amounts of bright light can help treat and prevent this disorder. An illumination level of 2000 lux at work in the morning and afternoon reduces physical reactions to stress and energises the body.
- Changing light to suit the time of day – When people need to work throughout the night or a good part of the night, light intensities should be increased and so should the quantity of bluish white light in the room. When tasks are almost complete and people are winding down for the day, the light setting should be warm and of low intensity to encourage a calming effect.
- Installation of applications to negate the blue light effect – Sometimes, there is difficulty in falling asleep after a long day in front of the screen. This is because of the high blue light content of backlit screens, which at night upsets the circadian rhythm and can affect one’s health. Applications, such as F.lux. or Twilight, can reduce the blue light on Android phones. Other applications can relate a screen’s colour and brightness to that location’s daylight. Therefore, it can be beneficial to have warm light sources combining with indirect and general light with varying colour temperatures near the working space.
So, with so much at stake in lighting design, it may be necessary to employ lighting consultants that have an in-depth understanding of the effects, both drawbacks and advantages, of lighting options that would optimise productivity in commercial buildings. Along with precise electrical design services and experience in building services coordination, service providers must be able to deliver BIM services which can incorporate the detailed considerations of modern-day lighting options for commercial buildings.