Preventive Conservation: What Is Active Environmental Monitoring?

by | Feb 14, 2024 | Blog, Preventive Conservation

Environmental monitoring is a key aspect of preventive conservation for heritage collections. It involves measuring and recording environmental parameters, such as temperature, relative humidity, light, and pollutants, that can affect the longevity of cultural objects. By monitoring the environment, heritage professionals can identify potential risks and take appropriate actions to prevent or mitigate damage.

However, in current practices, there are two main types of monitoring: active and passive. In this article, we will seek to explain the difference between them and the reasons why passive monitoring is less likely to help you achieve your preventive conservation goals. Before we go straight into this question, let’s start with some preparatory background information.

Why is environmental monitoring important for heritage collections?

For a collections professional, this question should have a pretty straightforward answer. We know material objects are affected by their surrounding environment, and we try to keep environmental conditions in areas where we store or display heritage as controlled as reasonably (sometimes not that reasonably) possible.

The types of damage we are seeking to avoid include, but are not limited to, mold growth, cracking, corrosion, swelling, shrinking, brittleness, fading, staining, discoloration, and even absolute destruction due to pest damage.

What are the stages of control in preventive conservation?

The four stages of control as defined by the Canadian Conservation Institute (CCI) Framework for Preserving Heritage Collections are Avoid, Block, Detect and Respond. They are referring directly to the ten agents of deterioration (physical forces, fire, pests, light UV and infrared, incorrect relative humidity, incorrect temperature, thieves and vandals, water, pollutants, and dissociation).

  1. Avoiding is the best way. If you can avoid the agent completely, it will be much better than having to fix things after objects and infrastructure have already been damaged. If you can’t avoid the agent because of your particular situation, then you need to move to the next option.
  2. Blocking is what you need to do when an agent cannot be avoided, so you need to make sure it does not directly affect your collections. Many of the agents can be blocked by good enclosures (think of the building envelope).
  3. Detecting becomes absolutely key when an agent cannot be blocked. Think about security cameras to minimize the risk of theft or vandalism and real-time leak or fire detectors to catch flooding and fires early.
  4. Responding is the absolute last in this list because it is what you have to do when the agent has already been detected and is potentially causing active damage. Hypothetically speaking, you never want to have to get to this point. Realistically, it is a common occurrence. At this point, time is of the essence, and you need to block the agent as soon as possible. If you are dealing with something dire like a fire or a theft, you must be able to respond within seconds or minutes. If you are being affected by water, you may have some hours or days. Pests and light may give you a little bit longer.

How is environmental monitoring conducted in heritage institutions?

“To ensure that agents of deterioration are detected early enough to prevent extensive damage, regular inspection is necessary.”

~CCI Framework for Preserving Heritage Collections

This really depends on the institution. Size, budget, and type (museum, archive, gallery, historic property, etc.) will determine the workflows of the staff – or just volunteers in some cases. So, let’s draw our distinction between active and passive environmental monitoring here.

Passive environmental monitoring

For small institutions that do not have a lot of staff or budget, this is considered better than nothing. Even large institutions with a lot of staff will do it if they feel their staff time is available. It entails the use of USB or Bluetooth data loggers without gateways. These types of devices require manual download by a human in order to get the environmental data in them. Some typical characteristics of passive monitoring are:

  • Very small staff or volunteer-only organization. This is potentially a small site under a larger umbrella institution.
  • Very limited budgets.
  • No staff with in-depth preventive conservation training.
  • Facilities staff may be available for the larger overhead institution, but staff in the smaller subsection may not have access to them or their systems.
  • Environmental data gets downloaded, looked at briefly and archived – normally by a single person who is in charge of it. Monitoring stops completely if this person is unavailable.
  • Data can be used to show baseline conditions of spaces and potentially leveraged for upgrades.
  • Leaks, floods, sudden temperature or relative humidity spikes will not be noticed until the data is downloaded, sometimes many weeks after the event.
  • “Human sensors” can be more effective at detecting unusual environmental conditions. For example, someone walking into a room and noticing a temperature change or a mildew smell.
  • There are potentially long periods of time where no one has the opportunity to download the data, so that the information is not reviewed regularly.
  • Loaning institutions are less likely to be comfortable to send objects into an environment that is being monitored in this way.
  • There may be potentially long periods of time where there is no monitoring being done at all because the device has malfunctioned or run out of battery without anyone noticing.
  • In terms of the four stages of control presented above, avoidance and blocking are challenging, detecting is slow, and response is reactive in nature – although historical data may be used for some proactive measures.

Active environmental monitoring

Active environmental monitoring is more likely seen in medium and bigger institutions who have either seen the value of active monitoring after a harrowing personal experience which they do not care to repeat or who were initially less limited by budget to consider doing anything less. This kind of monitoring requires a real-time data logger device which is on a wireless network. Some typical characteristics of active monitoring (regardless of the brand used) are:

  • The institution can be any size, but medium or large are more likely. Staff can be either limited or very large.
  • Budgets can be either limited or relatively healthy.
  • There may be very experienced staff with in-depth preventive conservation knowledge or even researching staff on the topic.
  • Facilities staff may be available with in-depth working knowledge of monitoring equipment for HVAC systems.
  • If the institution is on the small or medium size, it is possible that they have had a negative past experience where a severe disaster was not detected in time and caused serious consequences for the collection and its patrons. This past experience was enough to push them into an active monitoring system in spite of perceived elevated financial costs to set up.
  • Environmental data is reviewed constantly in real-time, often by more than one person.
  • Equipment sends real-time alerts whenever something out of the ordinary happens.
  • Any gaps in data collection are easily seen.
  • Devices have alerts for low batteries.
  • Loaning institutions are comfortable with borrowers who can show active monitoring during a loan.
  • The software associated with the equipment is generally more advanced than with non-wireless loggers and can help make decisions related to exhibition times and storage conditions.
  • In terms of the four stages of control presented above, avoidance and blocking have probably been more developed, detecting is immediate or almost immediate, and response is more likely to be proactive.

How much does environmental monitoring cost?

This answer is not straightforward. It depends on the size of your institution, how many spaces need to be monitored, how much staff you have and how much they earn for their time, as well as what equipment you decide to buy.

The monitoring cost itself can be relatively low if you decide to use passive environmental monitoring with USB sensors and unpaid volunteers in only two spaces,

while it can be prohibitively high if you have 20 galleries and a senior staff preventive conservation researcher using high-end wireless devices.

Using ballpark numbers only, you can get a range anywhere from a thousand dollars (or less) to several hundred thousand dollars. For this reason, asking how much environmental monitoring costs may not be the best question to start with.

What are the potential consequences of not doing environmental monitoring?

The question you really need to ask yourself is not how much environmental monitoring costs but rather, how much a disaster would cost to fix if the monitoring currently in place is not a system that effectively detects the agents of deterioration in a timely manner. Are your collections secure if you rely on passive monitoring? Is your budget sturdy enough to take a severe hit if something goes awfully wrong? An important question to ask yourself in your particular situation is:

What is more expensive for us? The costs or the opportunity costs?

This question is more about your risk tolerance and the opportunity costs of not being active in your environmental monitoring rather than the strict operational costs of running a preventive conservation program. Remember that environmental monitoring is an aspect of preventive conservation, and the whole point of preventive conservation is to prevent damage.

Active environmental monitoring Passive environmental monitoring or no monitoring at all
Monitoring equipment – $$ to $$$$ Monitoring equipment – 0 to $
Staff time – $ Staff time – $$ to $$$
Potential monetary loss due to undetected agent – $$ to $$$ Potential monetary loss due to undetected agent – $$ to $$$$$$$$$
Approved for loans? – yes (as long as conditions are met) Approved for loans? – maybe or no
Detection stage – immediate or short delay Detection stage – likely delayed or extremely delayed
Response stage – immediate or short delay Response stage – likely extremely delayed
Effect on patrons – small or nonexistent Effect on patrons – small to extensive
Damage to collections – small or nonexistent Damage to collections – small to complete destruction
Likelihood of proactive decision making – medium to high Likelihood of proactive decision making – medium to nonexistent


If we take the discussion beyond just the monetary cost, what else can be affected? As a heritage institution with collections, then both your reputation and your mission will be affected.

We are very understanding in the heritage industry, and all know of at least one institution that had a major mold outbreak which caused a multi-million-dollar expense to fix. We won’t condemn you for having found yourself in that situation. But that may not be enough to make you feel any better about this “failure” – and the general public and the media may also be less understanding.

On top of that, issues such as severe mold outbreaks have direct effects on health and safety standards – which means you have to close for disinfection and remodeling, so your patrons will not have access to your collections anymore. As an institution whose mission it is to serve the public, this is a big deal.

What is active environmental monitoring?

While we have all been taught the importance of monitoring, passive environmental monitoring with outdated devices runs the risk of becoming just another checkbox. It is a task that you do because it’s in your job description, and the equipment that you have does not make it easy or pleasant. You are busy and have so many things to think about and do that it’s possible to lose sight of the purpose and goals of the monitoring.

Is it impossible to have a good monitoring system with after-the-fact data logging devices? Maybe not impossible, but only if you make sure that you run your download schedules with discipline, perhaps as often as once a week and that you make actionable recommendations based on your data so that you reduce the risk of having to react to a sudden emergency. You want to strengthen the avoid and block stages as much as possible because your detection and response stages are, by nature, delayed.

Suddenly, passive monitoring doesn’t sound as good as it used to. If you intend to do it properly, it means constant vigilance and downloading – which you likely do not have the time for. Whether you choose Conserv or another preservation partner, we invite you to reevaluate active environmental monitoring with a fresh set of eyes.

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 your peers or even take a course to get familiar with the Conserv platform.

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