Cultural heritage institutions play a crucial role in preserving and displaying precious artifacts for future generations. The appropriate use of lighting is essential in these spaces, not only for optimal display but also for the preservation of sensitive materials. In recent years, LED lighting for museums has emerged as a highly effective solution to meet these requirements.
Perhaps you are re-evaluating your exhibition lighting. Or you are preparing for a new exhibition and need to choose specific lights for it. In 2023, chances are you already have LED lights or know that you’re supposed to get LED lighting, but do you know exactly why or which ones?
Did you know that, according to the Canadian Conservation Institute, “the majority of LED lamps on the market in 2018 did not meet the criteria for good or excellent lighting”? This would mean that if you have LEDs that were installed in 2018 or earlier, they are probably not as harmless as you would hope.
In this post, we will explore six key characteristics of good LED lighting that you must be sure to understand before you start replacing any lamps.
Reduced heat emissions
One of the primary benefits of LED lighting for museums is their low heat emission, which helps maintain a stable environment for sensitive artifacts and reduces the amount of energy the lit object receives. Higher heat levels can accelerate the deterioration of organic materials, change colors, and cause cracks on sensitive materials (wood panels, paint layers, plastics). LED lights emit minimal heat, providing a safer environment for preservation.
“There is no infrared radiation from LED lamps, so the light beam is completely “cold.” In general, if LED lighting is used only to attain museum-level intensities, and this is done without heavy filtering of an overly powerful lamp, then LED lamps can even be used inside cases without causing a temperature rise of more than a degree or two. And given the extremely long life of LED lamps, the risk to objects due to such infrequent lamp changes may be acceptable. Mabuchi et al. (2015) measured the temperature rise in very large wall cases lit to 100 lux by four rows of small LEDs at the top and one row at the bottom. The middle of the case rose by only 1°C and the top, by 2°C. Due to case buffering, RH dropped only 2%.”
-Canadian Conservation Institute’s Technical Bulletin 36, Heat from LED lamps.
Improved energy savings
LED lights consume less energy than traditional lighting sources such as incandescent or halogen bulbs, making them a more sustainable option. For the United States and Canada, the Energy Star energy efficiency labeling program provides information on how efficient or “green” a lamp may be. Improved efficiency not only lowers energy costs for cultural institutions but also reduces their carbon footprint, contributing to a more sustainable future for heritage preservation.
Keep in mind, however, that energy efficacy (how well a lamp turns electricity into light without losing energy through heat) will not be your only concern when choosing a new lamp, as color rendering is also extremely important. While most LED lamps sold for general use in Canada and the US will meet the Energy Star specifications, they may still not be appropriate for museum use, so make sure you check before purchasing or trialing.
Enhanced color rendering
Accurate color representation is crucial for displaying artifacts in museums, but also in galleries, libraries, and archives. LED lighting for lights in these institutions offers superior color rendering capabilities, ensuring that the true colors of objects are faithfully reproduced.
We can’t talk about color rendering for LEDs without mentioning The International Commission on Illumination (CIE) and their Color Rendering Index (CRI) measurements. The method uses 14 different color samples, 8 of which are pastels. The average color rendering (Ra) of all 14 cards gives us the CRI. Aside from that general CRI number, the CIE’s measure for color rendering calculations most relevant to museum use, as used by the Canadian Conservation Institute, is the R9.
The R stands for Rendering and the 9 is the designated number for a saturated red color. Red is the most difficult color for LED lamps to render well and is an essential color for seeing items with a reddish tinge, such as earth tones, skin tones, woods and any other material with red in it.
It is recommended to find LED lamps of CRI 90 or above and R9 of at least 50 (good) or above 90 (excellent), especially if there is a lot of color red in your exhibits. You should note that while CRI can be easily found for lamps, R9 information will not be as easily available, so you will have to go to the manufacturer’s catalogs. It will also be easier to find high R9 LED lamps with cooler temperatures (below 4000K).
Dimmability and flexibility
The ability to control light levels is essential for protecting sensitive materials from excessive light exposure. LED lights can be highly dimmable and can be easily adjusted to provide the ideal illumination for a specific artifact or exhibit. In addition, LED lighting systems can be programmed for specific time periods, allowing institutions to regulate light exposure and minimize potential damage to their collections. The flexibility of LED lighting can make it a versatile option for diverse cultural heritage settings.
This said, be aware that most LED lamps will require special dimmers and dimming capabilities might cause certain flickering. This flickering, called “invisible flicker” because it may not necessarily be perceived by a visitor or even the museum staff, will still be enough to cause headaches, malaise and distraction depending on the person (Canadian Conservation Institute’s Technical Bulletin 36). See “museum fatigue” for more information on this topic.
UV and IR radiation protection
Ultraviolet (UV) and infrared (IR) radiation can cause irreversible damage to cultural heritage objects, particularly those made from organic materials. LED lighting for lights emits little to no UV and IR radiation, significantly reducing the risk of damage to sensitive artifacts through direct exposure to LED systems. However, we must not forget that light damage remains the result of exposure time and light intensity (lux) so that LEDs will not be any different in this respect than regular lamps with a UV filter on them.
Longer lifespan and reduced maintenance
LED lights have a considerably longer lifespan than traditional lighting sources, lasting up to 50,000 hours or more, which is about 8 years if they are lit for 12 hours every day. This extended lifespan translates to lower maintenance costs over time and reduced frequency of bulb replacements, minimizing disruptions to cultural heritage spaces. Keep in mind that fewer lamp replacements also means a reduced need to move collections out of the way during lighting system maintenance efforts and, by extension, limit the potential for accidental damage to collections.
Conclusion
Whether you are itching to replace your old halogens or tungstens for LEDs or have just realized that your pre-2018 LEDs may not have been as good as you thought, make sure you look at all the necessary specifications before making any purchases with your hard-earned budget.
Regardless of whether you decide to install a new LED lighting system or stick with what you’ve got now, make sure you still measure your lux and UV periodically to keep track of what your lamps are doing and how they change over time. That way, if they ever become “not good enough”, you will be ready to replace them with an improved solution.
If you have any questions about environmental monitoring, integrated pest management, or just want to talk about preventative conservation, please reach out to us! Don’t forget to check out our blog or join our community of collections care professionals where you can discuss hot topics, connect with other conservators or even take a course to get familiar with the Conserv platform.
