Two design hiccups. Two varying applications.

One highly effective solution for each—indirect lighting.

The owners of a new tea shop in Boston wanted to try something new for their yet-to-open brasserie—linear lighting. They wanted the look of a classic café fare application with a contemporary, but inviting atmosphere served one cup at a time.

But challenges loomed. The Shinmio Tea House was just 450 square feet, and the owners had a limited budget. Also, the lighting needed to complement the brand, which used cool color temperatures.

Across town, building owners at the 33-story high-rise office in Beantown’s financial district had lofty expectations for its lowest-level office space: They wanted it to feel like a lounge—fresh, vibrant, with splashes of natural light all around.

One catch: The space was under underground. No windows, no sunlight.

What to do?

The solution to both problems, designers later learned, was applying best practices for indirect lighting, which is when light is directed onto a surface—commonly the ceiling or wall—and illumination reflects off it.

Wall washing, for instance, is a form of indirect lighting. So is the moon. The illumination you see atop the nighttime sky is indirect light from the sun.

Here are five frequent questions you may have about indirect lighting for your next big architectural design—and their answers.

What Are the Design Benefits of Indirect Lighting?

Indirect lighting is an ancient but ageless tool for designers, emitting dazzling shadows and a soft, pleasant glow to any architectural space, increasing the environment’s perceived spaciousness. Each was a must-needed benefit for the small-sized tea shop example above, boosting the retailer’s perceived luxury and spaciousness.

And because indirect lighting is a proven method for providing the soothing illusion of natural light, it’s also a go-to method for design applications where sunlight is severely lacking or nonexistent. For example, designers used indirect light to accentuate the architectural waffle-slab ceiling in the basement-level office application detailed above. With the room underground sans natural light, the indirect light created a warm and inviting entertainment space for meetings and presentations—just as the clients wanted.

Likewise, indirect light improves comfort and alertness—a combo that frequently makes indirect lighting the most comfortable illumination to work underneath. Similarly, the method is a valuable design tool for wayfinding in retail that highlights merchandise and for creating desired atmospheres in hospitality applications that studies show millennials will pay more to experience.

What Types of Indirect Lighting Are There?

To underscore the architectural superiority of your design, two major categories of indirect lighting spring to mind. Each has its pluses and negatives, packaged with its distinctive aesthetic personality.

The first category—indirect lighting fixtures—is the most common type of indirect lighting. Consider a lamp, any lamp—table, floor, desk, wall, overhead. With each lamp, there are two pieces you almost always see: the light, of course, and the lampshade, a semitransparent encasing that morphs direct lighting into indirect light.

The shade provides two benefits: It tunes down the light’s harshness and softly expands the lighting to give a space a much-needed increase in brightness.

The second category is reflective lighting. It’s not as commercially popular as the above subcategory, but it’s a designer’s favorite.

Reflective lighting is a method where uses a structured surface as a diffuser. There is no lampshade, no shining light directly onto an enclosure attached to the fixture. Instead, you shine light onto—and off—a wall, floor or ceiling.

It’s a gorgeous, discreet illumination method for making your architectural masterpiece the focal point of attention. Standard fixtures used to emit this light include indirect or direct/indirect pendants and linear systems, track heads, wall mounts, downlights and track systems.

Which Applications Use Indirect Lighting Most?

Architects and designers have countless design options at their disposal. However, the solution they pick—direct or indirect illumination—typically comes down to aesthetics and application.

Alternatively, indirect lighting is preferred in applications where relaxation and leisure are desired, like retail, business and hospitality environments such as hotels and restaurants.

The opposite of indirect light—direct lighting—is ideal for task-oriented environments where focus and attentiveness are essential. Think classrooms, distribution centers, manufacturing facilities and health care patient and lab rooms.

Are There Downsides to Using Indirect Lighting?

For all its glory, indirect lighting does come with a few red flags. Because it creates more of an ambient luminescence, you can lose control of the room.

It’s also essential that with indirect lighting, you include enough direct light for specific tasks, including reading—even if it’s not ideal for reading. Older and younger workers, as well as customers, require different lighting needs. This broad divide is one of many examples of why it’s best to pair indirect lighting with task lighting imperative, with the former serving as general lighting.

Is There a Fixture-To-Ceiling Distance Ratio for Indirect Lighting?

Experts have stressed that a bare minimum of 12 to 18 inches away from the ceiling is a legitimate mark to start

But others offer other not-so-scary lighting math tips to guide your design. For ceilings, the average luminance should not exceed 500 candelas per square meter (cd/m²), and within limited areas of the ceiling, no more than 1500 cd/m2 is wise. If you’re utilizing indirect lighting for wall applications, be sure to limit your luminance to 1000 cd/m2

Other formulas can also apply. The ratio between the ceiling and your working area, for instance,, should be 1:1 or 1:2. Nevertheless, studies show that a lighting distribution of 50-50—half indirect light, half direct light—is oftentimes preferred.

With so much arithmetic–however simple–involved, how do you know which formula to apply? The answer, experts advise, depends on the application.

What will those in the space be doing following the completion of your design? Reading, walking, working—and if working, what kind of work?

And equally important, where? Certain parts of the space will be utilized for activities that others are not.

Look at two Boston examples, the tea shop and the underground conference space. Each headline-making project was designed with various purposes in mind, in different pockets of the application.

Regardless, the winning light strategy each time was undisputed—indirect.

Want to Learn More?

To learn more about the architectural and behavioral benefits of stellar indirect LED lighting, read: “Top Linear Lighting: A Checklist for Architects.”