The current state of the economy has companies more concerned with maximizing budgets, while global warming and concern for the environment has put anything viewed as “green” or “sustainable” in high demand. With those factors in mind, more and more organizations are looking to implement tactics — such as recycling programs, transportation initiatives and building upgrades — that will allow them to save money and show a commitment to the environment.

Daylighting is one environmentally friendly option catching corporate interest. Many companies, however, only have limited knowledge as to its advantages and how to best implement a comprehensive program. This article will explain what daylighting is and how it can be implemented, while discussing specific advantages and benefits for facility managers, employees and key decision makers concerned with the bottom line. 

Daylighting Overview

What is daylighting?

Daylighting is the practice of using natural light to illuminate interior building spaces. Instead of relying solely on electric lighting during the day, this method brings indirect natural light into a building. Daylighting reduces the need for electric lighting and is meant to create a more calm and productive environment, connecting people to the outdoors.

While most individuals realize daylighting involves natural light, few understand that a well thought-out daylighting plan requires more than just the simple integration of windows and skylights within a building. However, with a properly planned daylighting system comes the need for specific controls. To harness and direct natural light, passive controls are necessary. Whereas in order to provide artificial light, when natural light is not available, active electronic controls are needed.

Passive Controls

While windows and skylights are the most traditional passive controls for allowing natural light into a building’s space, there are many ways to implement daylighting into almost any design. For example, architects and designers use passive control devices such as light shelves, light reflectors, sunshades and sunscreens to direct, reflect and control daylight into a building. 

Light shelves are white or reflective horizontal elements, typically installed on the inside of a window in order to bounce direct sunlight deeper into the space. Light reflectors share a similar purpose.  However, they are placed on the exterior of a building to direct and reflect the sun’s rays to a more useful orientation.  The use of sunscreens and sunshades on horizontal and overhead glazing allows for maximum daylight while controlling heat and glare.

Active Electronic Controls

Aside from devices for directing and reflecting daylight, a building needs active electronic control systems designed to manage and direct the level and timing of artificial light. These systems, using sensors and actuators, are directly linked to artificial lighting systems to detect the amount of daylight currently available. Then, the systems adjust the amount of artificial light provided based upon the current amount of natural light available from the sun and passive controls. 

The specific types of lighting controls best suited for a building depends on lighting usage patterns as well as the type of space and a building’s layout. The use of dimmers and time scheduling are both popular options for daylit offices as some workers prefer lower levels of light. Time scheduling, often used in larger open office areas, allows lighting to be controlled through automatic switching at fixed hours of the day. 

Daylighting Benefits

With a decreased use of artificial lighting and the use of controls and elements of design to maximize the energy provided by the sun, it’s easy to realize the basic energy-saving and economical benefits of daylighting.

The overall objective of daylighting is to minimize the amount of artificial light and reduce electricity costs, but it can also lower HVAC (heating, ventilation and air-conditioning) costs as well. Electrical lighting in modern buildings produces a lot of heat; whereas if properly directed, natural lighting generates hardly any heat at all. This approach takes into account the effects of lighting on heating and cooling. In addition, the budgeted amount for electrical lighting, as well as heating or cooling loads and the amount of cooling required keeping a building at a specified temperature,  can be redirected toward lighting systems and HVAC equipment.

A high-performance daylighting system may initially require a significant investment. However, if the project team uses an integrated, strategic design approach, a company’s overall long-term savings often make up for any initial dollars spent on daylighting.

For most buildings incorporating daylighting, the overall energy savings typically range from 15 to 40 percent. Although energy savings and sustainability may be the reasons companies initially opt for daylighting, it can have a significant, measurable impact on the productivity and satisfaction of employees, students and even clients and retail customers.

Overcoming Daylighting Challenges

Although daylighting provides numerous positive results in regards to worker performance, if a daylighting program has not been executed properly, it can produce many negative results. Below are a few strategies to help architects, designers and facility planners overcome the challenges of daylighting.

Glare Control – Avoiding Direct Sunlight on Worksurfaces

Direct sunlight penetration in classrooms and office spaces often produces an unpleasant glare on worksurfaces, making it difficult to work or view a computer screen.

The proper orientation of windows and skylights can admit sunlight and diffused daylight, producing the best combination of light for a building while also reducing glare. The selection and orientation of windows and skylights should determined by the amount of energy needed and based upon climate and the building’s design.  

Light Shelves extend the penetration of sunlight in to a building.  Usually located above the occupied zone, these elements function to increase the effective area as well as diffuse incoming light.  These horizontal planes bounce light upwards to illuminate the ceiling of a space.  Light bouncing from the ceiling not only lights the work surface, but a lit ceiling also makes a space appear brighter overall.  An amplification of the longstanding practice of white ceiling surfaces, the daylighting provided by light shelves enhances the quality of light in a space.  Light shelves can be incorporated in to a window framing system or decorative elements supported by the building structure.

Light reflectors are more often used to aim sunlight in the proper direction.  These can be as simple as reflective glazing on a nearby wall, or as complex as motorized sun tracking arrays.  Often, the best application of this approach is where site or building constraints do not allow glazing to face the optimal solar orientation.  Sun tracking arrays are now commercially available in a complete skylight assembly.  These have proven useful in warehouse and industrial buildings where high single story spaces allow diffusion of daylight through distance.  A more traditional application of a sunlight reflector are pools of water on the equator side of a building façade.  Reflectors are most effective when used in conjunction with techniques for diffusing direct sunlight.

Light Without Heat – Increasing Daylight, but Not Cooling Loads

Since the sun is such a powerful source to light buildings, it can also produce tremendous amounts of heat. If not planned properly, using natural lighting can result in undesirable heat gains.

Therefore, it seems almost impossible to increase the amount of light without extra heat. However, the use of window treatments, window films and glazing can properly shade a window or diffuse direct sunlight, in result minimizing heat exerted from the sun. This can reduce overall cooling loads, eliminating the need for a larger cooling system, resulting in additional overall savings.

Daylight Obstruction –Maximizing Wall Openings Efficiency

Too much heat or light are not the only challenges associated with daylighting. Some architectural features, such as a building’s roof, atrium shapes or a building’s angles can obstruct daylight from illuminating a space. To prevent daylight obstruction, architects can place wall openings in strategic places within the space to utilize their efficiency.

For example, if elements that can block daylight are located high up in the space they should be as far from wall openings as possible. In a plan that features both open and enclosed spaces, open space areas should be close to the wall openings. This maximizes the illumination of daylight, reflecting light deeper into the space.

The Best Implementation of Daylighting within Design

So, what is the ultimate solution for daylighting needs? There isn’t just one answer. Each situation, depending on overall goals, budget and building design, requires a unique plan and set of options.

Regardless of the solution that will work best for a certain building, successful daylighting will depend greatly on planning and foresight. Therefore, choosing the right project team, architect, designer and construction manager is the most important step in implementing an effective daylighting plan.