Crystal Bridges is open Wed. through Mon. with free, timed tickets required.

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Crystal Bridges is open Wed. through Mon. with free, timed tickets required.

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February 18, 2014
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Keeping the Art Comfortable: Climate Control at Crystal Bridges

As winter storm Nika made her way across 32 of the 50 United States, most people were wondering how to best keep warm–bumping up their thermostats, pulling out their chili pots, and settling in for a long winter’s nap. But what do you do if you’re a conservator or collections manager at a museum?


Nothing, that’s why you have all those fancy thermostats and temperature monitoring gadgets, right? Well, yes and no. Having worked in the frozen tundra known as Ohio, I can say from experience:  conservators and collections management staff still get worried when the neighborhood weatherman predicts a 25-degree drop in only a few hours’ time.

Condensation forming on the inside doors in Great Hall Corridor, due to the dropping external temperatures (thanks Nika!). Photo taken 2/5/14

Condensation forming on the inside doors in Great Hall Corridor, due to the dropping external temperatures (thanks Nika!). Photo taken 2/5/14

Think of it this way: the night before a major temperature dip you take optimum precautions to make sure you aren’t frozen solid come morning. You turn up the thermostat, put on the flannel pajamas, and find the heaviest quilt in the house. Yet somehow, despite all that preparedness, there is still that slight winter chill when you wake up in the morning that sends you racing for the coffee.

Well, it’s sort of the same process for works displayed in museums. Beginning in the fall, many museums in cold weather climates begin rotations of fragile works away from windows, doors, and other entry/exit points that would be susceptible to temperature fluctuations. Outdoor sculpture that could sustain damage in inclement weather might be de-installed. Paintings, such as old master works on wood panel, may be brought off view or are hung from special hardware to allow them to expand/contract, without causing harm to the surface of the painting. Once these and any other initial precautions are taken, museums rely on HVAC systems and data loggers (a warm cup of coffee so to speak) to keep our collections at a comfortable resting rate of 70 degrees +/-3, and 50% relative humidity (RH) +/-5.

So what is an HVAC system? HVAC stands for heating, ventilation, and air-conditioning systems. This system is responsible for creating the optimal temperature and relative humidity in museums (you can thank the HVAC for December temperatures in July). The HVAC is monitored constantly to make sure that any dip outside of the accepted range (70-degrees +/-3, and 50% RH +/-5) is reported to collections management and corrected.

The "brains" of Crystal Bridges' HVAC system.

The “brains” of Crystal Bridges’ HVAC system.

This is the brains of the HVAC system. All of the data that is collected by sensors is sent here, compiled by a processor within the unit, and is then relayed to the computer. And it all happens in real-time, 24 hours a day, 7 days a week, Christmas and New Year’s too.

Schematic of one of the Museum's galleries, showing real-time temperature and humidity readings.

Schematic of one of the Museum’s galleries, showing real-time temperature and humidity readings.

Here you can see an individual gallery recording data in real-time. If any sensor ever goes out of acceptable range, a text message is immediately sent to the HVAC supervisor to alert them to the problem. How do you determine an acceptable range? Well that question is a little long and complicated, but the short of it is museum professionals noticed early on that extreme temperature fluctuations (like that 25-degree drop mentioned earlier) caused damage to collection items. The best way to help prevent or lessen these fluctuations is by maintaining a stable temperature and relative humidity inside the museum.

data loggers

This is a PEM2 data logger. They are located throughout the galleries, and are constantly recording the environmental readings in the galleries. The information from the data logger is downloaded, and the uploaded to an online server, which stores all our readings, and compiles the facilities report seen on my computer screen. The graph on the right shows our temperature range, and the left one shows RH.

Data log

Data log. The graph on the right shows our temperature range, and the left one shows RH.

The facilities report is kind of like our report card. It allows other museums to view our temperature recordings to see how our galleries manage temperature fluctuations in July versus in December. This aspect of the facilities report is key as it tells potential lenders and collaborators that we can provide the optimum care for their collection items, despite that crazy winter storm Nika raging outside.

So what happens to art when climate is not monitored or controlled? Well it can be a pretty ugly picture, depending on the severity. For very minor fluctuations +/-10-15, works will experience minor to no damage based on media. More severe cases, such as works left exposed to unregulated climate control and the elements can result in art that is seriously damaged. The most famous example of a work left open to the elements in an uncontrolled environment for a prolonged period of time is Leonard da Vinci’s The Last Supper. The fresco is in the refectory of the Convent of Santa Maria delle Grazie in Milan, Italy, and was left exposed to the unregulated climate for decades. The combination of unregulated climate control and experimental techniques by Leonardo resulted in a work that was almost completely lost if not for a massive restoration and conservation effort. Luckily, this beautiful piece of work found a happy ending, however many works that are not properly cared for are permanently destroyed.

So the next time you visit a museum and wonder why it feels like the arctic tundra inside, or wonder why conservators are so persnickety about temperature, or see collections management staff with concerned faces because the doors are icing from the inside, remember it’s not because we’re a bunch of curmudgeons who don’t enjoy those 60-degree days in February. We just want to make sure the art also enjoys those days…as well as many more to come.

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