Beyond Evaporative: Why Phase Change Cooling is a Critical Part of the Heat Stress Global Toolkit

MikeF
May 15
3 min read

When it comes to combating heat stress in the workplace, there is no one-size-fits-all solution. While our ActiKewl® evaporative cooling technology is highly effective in many environments, there are specific conditions where its performance is limited. In areas of high humidity, low airflow, or enclosed protective gear, evaporative cooling simply cannot perform as intended.

A worker carrying out essential maintenance in a confined space

That’s where QOOLPAX®, our phase change cooling range of solutions comes in.

With both ActiKewl® (evaporative) and QOOLPAX® (phase change) technologies available, we are able to ensure our clients are equipped with the right personal cooling system for any working environment.

#1: What Is Phase Change Cooling (PCM) and How Does It Work?

In practical terms, a garment powered with PCM cooling technology absorbs excess body heat and stores it, helping workers remain cooler for longer periods during their working day without depending on air circulation or external conditions.

Imagine you’re working in a confined space and you put on a cooling vest filled with (PCM) packs. Here’s how it helps cool you down in 5 steps . . .

PCM Starts Cold
Before wearing, the PCM packs are placed in a freezer, icebox, or a cool environment for approximately 35 minutes to "activate" them. This means they absorb cold and store it, just like ice does.
Heat Absorption
Once the vest is on, your body naturally gives off heat. The PCM inside the vest absorbs this excess heat from your body.
Temperature Regulation
Unlike ice (which gets too cold and uncomfortable), PCM stays at a steady temperature (either 18°C or 28°C). This keeps you cool but not freezing, making it comfortable for 2 to 3 hours wear.
Slow, Long-Lasting Cooling
As you continue wearing the vest, the PCM slowly changes state from a solid to a liquid pulling heat away from your body. This process helps keep your body at a safe and comfortable temperature for a longer period.
Warming Up & Recharging
Once the PCM has fully liquified and absorbed enough heat, it stops cooling. At this point, you need to recharge it by putting it back into a cooling environment to reset and activate it for the next use.

#2: So When Is PCM the Right Choice?

There are specific conditions where PCM is the preferred solution over evaporative cooling, however the technology is particularly effective where tasks are required in:

High Humidity Environments: When relative humidity exceeds 80–85%, evaporative cooling loses efficiency. PCM works independently of humidity.
Enclosed or Confined Workspaces: PCM is ideal in spaces where air circulation is minimal or non-existent, such as aircraft bellies, maintenance tunnels, or the internal corridors of data centres, where ambient temperatures can regularly exceed 40°C due to heat generated by servers and electronics.
Heavy PPE or Hazmat Suits: In situations where airflow to the skin is obstructed by protective clothing, PCM continues to provide cooling relief.

In these scenarios, PCM becomes not just a better option—it becomes essential.

A maintenance team at work using a thermal imaging camera to measure cabinet heat levels in a data center environment

#3: How to Choose a PCM Solution

At Heat Stress Global, we tailor every PCM cooling solution to your specific operational needs. When selecting the right PCM vest or insert, we assess:

Duration - most PCM cooling inserts last 2–4 hours before needing a recharge (usually in under an hour). We help identify the minimum cooling duration required to deliver ROI in productivity and safety.

Budget - cost varies depending on the PCM material and design. We offer a range of organic PCM's as standard, striking an ideal balance between performance, cost-efficiency, and availability.

Weight - PCM vests tend to weigh 4–5 lbs, which can feel bulky at first. However, once on the shoulders that added weight is often a small price to pay for consistent cooling and improved performance in extreme conditions.

Modularity - from fire rated fabrics to the level of relative comfort required, we offer a wide range of shapes and configurations to suit diverse job functions and gear setups.

Durability - durability is non-negotiable in industrial environments. Our PCM inserts are sealed in high-quality encapsulation materials like TPU and nylon, ensuring leak-proof performance and long service life.

#4: A Range of PCM Options

Get the Right Cooling Solution for Every Environment

At Heat Stress Global, we know that effective heat stress management is about more than product; it’s about fit, training, integration, and ongoing support. That’s why our heat stress trials and pilot studies help our clients experience the difference firsthand.

If your workforce undertakes tasks in high humidity, enclosed spaces, or high-heat environments such as data centres, fuel terminals, hazmat operations, or heavy infrastructure zones, our Phase Change Cooling products may be the solution you’ve been missing.

Take a look at our best selling products . . .