Many manufacturing facilities have hot processes located indoors. Many other types of facilities have high-heat loads located indoors; a data center is a prime example. Hot process equipment includes such things as extruders, metal melting pots (e.g., aluminum pots), reaction vessels, and finishing ovens.
In most cases, it would be financially insane to try to isolate these hot processes and high-heat loads from everything else by putting them in their own buildings. Consequently, they share walls (and roof and floor) with air-conditioned spaces.
Sometimes, these spaces are separated by barriers as flimsy as plastic strip curtains because of the need for constant traffic flow between areas. Better “easy traffic” barriers do exist, though selecting one isn’t an electrical problem. Those better barriers, however, typically rely on sensors and motors and thus do get electrical people involved. Barriers are often added as an afterthought using retrofits that are selected more for expediency (do something now) rather than thoughtful design (do something, but do something right). Even barriers that were put into an original design might be subpar.
The maintenance department, especially the electrical element of it, can take ownership of this problem. We’ll discuss how, momentarily. But first, it’s important to note that this co-location results in another problem.
The original calculations for cooling (taking into account geometric issues, airflow, cooling unit capacity, etc.) may not have correctly accounted for the amount of heat thrown off by hot processes or high-heat loads. Or if they did, maybe the loads have changed (in a data center, for example, density may have increased as more server racks were added in the same building space). Or maybe something else has changed; for example, ventilation increased, but the additional heat from more outside air is too much.
Solutions for this second problem typically include controls on the exhaust fans to reduce “wasted ventilation” and thus less ingress of outside air into the air-conditioned space. Adding hoods to the exhaust fan intakes also reduces entraining cool air so that you are exhausting more of the hot air.
A solution often called for is to just replace an existing air conditioning unit with a bigger one. But that can result in less cooling due to roof curbing mismatches, ductwork mismatches, flow problems, and coil freezing.
So how can electrical people take ownership of these problems? Advancing on the theory that it is better to work from the data than to make guesses, you can provide the data and explain what they mean.
How do you get the data? Through instrumentation. Here are some examples:
- Use thermography. This tool is often thought of as a means for identifying “screws that need to be tightened” (actually, you do not tighten them if they are loose, you replace them because their clamping power is a function of the elasticity of the metal, which degrades with each use). But in the hands of a trained thermographer, it is a very accurate way of seeing what is going on with anything that involves heat. Even an untrained thermographer can use a good camera to pinpoint most of the issues we’re discussing.
- Install temperature monitors. Although thermography can give you an in-context view of everything in a facility, it’s literally taking a snapshot in time. You can supplement this powerful tool by installing temperature monitors at strategic locations (e.g., exhaust intakes, make-up air intakes, key work stations) and trending the temperatures over time.
- Install counters. There’s only so much money to go around. You’ve got a hot process area adjacent to an air-conditioned space. There are six doors between the two spaces. If you had to seal three of these doors and automate the other three with sensors and motors, which doors would you pick? What’s most sensible is to match the door selection with the existing traffic patterns. Put counters at each door to know which doors have the most traffic.
Many of the issues that need to be solved will require the expertise of some other trade or profession — maybe architectural or mechanical, for example. But to avoid having the wrong resources working on the wrong solution, the electrical element of the maintenance department can provide the temperature and other data upon which to make informed decisions. You’ll not only save energy, you’ll help assure the resources for doing so are correctly allocated.