In the world of lighting, there are a lot of terms and they can get confusing if you aren't familiar with them. If you have heard the term "light reflectance values" before, you may have some questions. Let's take a closer look at what this really means and why it matters.
What are light reflectance values (LRV)?
The term refers to the scale used to determine the quantity of visible, usable illumination reflected by any and all directions and wavelengths when a surface is illuminated. Basically, light reflectance values are how much light a color on a surface reflects or absorbs said light. The scale runs from 0% meaning it reflects no visible light at all to 100% meaning it reflects all the light on the surface. To put this in perspective, black surfaces have a light reflectance value of around 5% and white surfaces have an average of about 85% light reflectance but can reach 100% in certain white shades.
Why does LRV matter?
LRV is a scale used on paint rather than light fixtures, but it is still important to keep in mind. Even with the right light fixtures in place for a home or business, painting the walls a color incapable of reflecting high LRV will make the space seem dull and dim. It can also impact color temperature when choosing the light fixture. If you choose a fixture with high lumen output and the space still seems dim, it may very well be the LRV of the walls making the space seem dimmer than it really is because less light is being reflected off the walls. On the flip side, a surface with a higher light reflectance value can work to your advantage in terms of light fixtures. For example, if the walls are painted a color that reflects light at a high percentage, you may be able to get by without as many fixtures installed or even lower lumen outputs because so much light is being reflected off the surface to create a brighter space.
LRV also matters for the following reasons:
- Helps cut down on energy costs. If the surrounding walls are capable of reflecting light at a higher percentage, it can save your location money in terms of fixtures installed, but also in overall energy costs. If you have fewer fixtures, you have lower utility bills. It can also help with cooling in the summer since lighter colored walls absorb less heat than darker colored walls which in turn means lowered cooling costs to keep the space at the right temperature.
- Impacts visually impaired community. LRV is also important for those with visual impairments. In fact, the Americans with Disability Act Accessibility Guidelines (ADAAG) suggest a 70% light reflectance value or higher for individuals with impaired or low vision. While this is up to debate by some, this can be crucial in certain types of businesses and residences of such individuals to help with visibility.
- Changes color temperature of lamps suggested. The LRV also impacts the right color temperature for the room. If the space has a low LRV and you want to brighten it up, you would opt for a whiter color temperature on the lamps to brighten it up whereas a warmer color temperature would be ideal for making a high LRV a bit cozier or less harsh. It also impacts the color rendering index as well. If the surfaces have a low light reflectance value, you will want a higher color rendering index to counteract that for better visibility of different colors in the space.
What if I am unable to change the surfaces to impact the LRV?
If you are choosing to paint a space, you should absolutely consider the listed light reflectance value when choosing the color and paint type. In an ideal world, you would have total control over the light reflectance value of any paint or any surface in a location to help you choose the right lighting solutions in accordance. This isn't always the case for many people. If you are renter, unable to paint the walls, or simply stuck with the chosen paint color of the walls in a location for whatever reason, there are ways to work around the light reflectance value to get the desired outcome.
- If the LRV is too low, choose cooler (whiter) color temperature bulbs, a higher color rendering index, add more sources of light, and/or increase the lumens if possible. This will make the space seem brighter in spite of the low LRV.
- If the LRV is too high, choose warmer (yellow) color temperature bulbs, remove/turn off a few fixtures, decrease the lumens in the space if possible, and/or add diffusers to the fixtures. This will create a less harsh, warmer space in spite of the high LRV.