Cooling clothing, especially cooling vests have gained popularity in recent years. Next to the comfortability effect in warm environments, cooling vests are in the focus especially for professionals who work under stressful circumstances and sweat a lot. Due to increasing awareness on heat related health dangers like lower concentration, tiredness and illnesses like overheating or heat stroke, different types of cooling vests have been developed. As time progressed, more sophisticated types of vests have been emerging all over the market.

What is a cooling vest?

As the name suggests, it’s a vest that is made to keep the body temperature at an acceptable level and to prevent overheating by cooling the skin. Reasons for the up-warming of the body can be high physical stress, working in protective clothing with low breathability, hindered evaporation of sweat under warm circumstances or similar. The vests are particularly worn by professionals in various field of work, such as: First responders (firefighters, medical workers, police officers etc.) or outside workers such as construction workers who need to wear protective clothing (PPE) that does not allow the needed evaporation of sweat and hinder the natural body cooling mechanism. Athletes tend to use body cooling to reduce the core body temperature and ensure longer lasting performance by this.

Evaporative cooling vests

The first type of cooling vest is an evaporative cooling vest, which is typically worn close to the body but over other clothing items such as T-shirts. It is one of the most common and inexpensive options on the market. Like it is done for centuries with wet towels and other fabrics, the principle works with water evaporation. The clothing needs to be submerged into water for short period of time (e.g. 3-5 minutes), once submerged the special fabric material (sometimes filled with crystals) starts absorbing a high amount of the water and can expand up to one hundred times their weight. When worn, the water starts evaporating by removing heat from the body, cooling the body in the process. The main advantage of the evaporation vest is that the principle is simple, it can be recharged relatively quickly and often. However, due to the high amount of absorbed water, the vests get heavy and sometimes do feel moist. Even though the modern fabrics take up more water than a standard cotton towel, the vests do not last very long and recharging with a bucket of water is not always possible or desired. That is the case when the vest is especially worn under other protective clothing. To keep the vest functioning properly, it needs change a of cloth and a free space for evaporation under the protective clothing is not always possible. Evaporative vests are often used during leisure times, sports or in private environments.

Ice-pack cooling vest

The second type of cooling vest is the ice chilled vest. It’s a vest that makes use of special ice packs. The vests have special compartments on the inside of the garment that hold ice packs. These ice packs are frozen overnight and are pliable even when frozen. This distinctive design allows the ice packs to be lightweight and easy to wear during any activity. Since these vests can get very cold, they’re typically worn over other clothing items for safety purposes, mainly to avoid frostbites. Ice pack cooling vests are versatile in their design in order to easily swap ice packs out when the original ones have melted. The advantage of an ice-pack cooling vest is, that they immediately cool down the skin, this effect is independent from the outside conditions. It also works when breathability of the clothing and water evaporation are not possible. On the other hand ice-pack cooling vests are relatively heavy in order to have a longer time effect. It is worth noting that, the cooling time is relatively short due to the limited cooling power that can be stored in the ice. Preparation of cool-packs requires time and a fridge or a cooling unit. For replacement packages, cooling boxes need to be carried. In addition, the very cold ice can effect in a shrinkage of the upper skin which results in a closure of the perspiratory glands. This hinders the natural body cooling by sweat transport and can have a negative effect on the body cooling and regulation of the core body temperature. Ice cooling is often used by athletes to cool down the body, either before a competition or in-between competitions in order to cool down and increase endurance.

Phase change materials (PCM) cooling vest

The next type of cooling vest is the PCM cooling vest. In order to overcome the disadvantage of ice, which solidifies/melts at 0°C and is therefore very cold when worn around the body, Phase Change Materials (PCM) (mostly made from miscellaneous oils and fats), solidify/melt at temperatures designed by the producer. Like the ice pack cooling vest mentioned above, PCM cooling vests are standard clothing items that features special compartments for PCM filled cool-packs. What makes these cooling packs unique, is that they solidify/melt at higher temperatures (e.g. 15°C or 20°C) and therefore quicker than ice and take a longer time to melt when compared to ice. Their advantage is that they release the stored cooling energy more slowly and the do not overcool the skin as much as ice. Nevertheless, the total cooling energy that can be stored is relatively low, this is due to the fact that if more cooling power is stored, the vest gets heavier. Therefore, PCM based cooling vests do not last very long. The preparation of the cool-packs requires time and a cool place. PCM vests cool from the start of usage and cannot be regulated, which can be sometimes not desirable, because heating of the body only takes place after a while. Depending on the solidify/melt temperature, a fridge may not be needed but will speed up the recharging process. Phase change material cooling vests are due to it adjustable temperature range and free garment design, mostly used in both private and professional applications.

Water flow cooling vest

This type of cooling vest features water filled pipes/tubes that are incorporated into the vest. Cold water is pumped with the support of an electrical pump through these pipes, which cools down the body. Some of these vests have a water reservoir which is cooled down by an ice block in the beginning. Once the ice is molten, body heat warms up the water, needing to refilled with fresh ice. In order to overcome the disadvantage of the above mentioned vests in terms of durability of the cooling, some water flow vests feature a compressor that constantly cools down the water. Others need an external cooling circuit where the vest is connected with it. The advantage of those vests, is that once they are connected to a cooling unit, they deliver a constant cooling power. On the other hand, they are relatively heavy due to the water circulating and inflexible due to the compressor and storage tank, which needs a high electrical power if a compressor is used. Water flow cooling vests are often used with professionals who do not move a lot and therefore are able to have a compressor with a water reservoir close by. They are for example, also offered in combination with demining suits.

Air blowing vest

Some years ago, a Japanese tools manufacturer, started to offer an air blowing vest mainly for outside workers. It led to be copied a lot by other east Asian companies, as the concept of the vest is relatively simple. A normal work jacket is equipped with two electrical powered fans that blow outside air into the jacket. An airflow is created, removing humid air and giving a blowing effect around the body. The main advantage of this vest is that it is lightweight, along with the blowing effect that lasts for a long time . Due to the vest being battery operated, they do not require any preparation time. The man disadvantage is that, the air blowing vest will blow up the jacket and they do not fully remove the sweat by guiding the air humid air out. A similar principle is also used by some suppliers of cooling vests as they connect their cooling vests with pressurized air to have a similar effect. Air blowing vests are often used as a reasonable priced equipment for construction workers in hot countries to have a constant blowing effect during work.

Active Air Cooling Vest

At last, there is the self-regulating Active Cooling Vest from Teijin Smart Safety. This vest uses and enhances the natural cooling mechanism of the human body, which is sweating. It works by effectively evaporating and removing the sweat from the body, the cooling effect will also function under closed protective garments, which are extensively used by firefighters, industry workers, medical personnel and others. In order to achieve this, the vest uses a guided airflow through a special 3-D-fabric. The airflow is powered by six electric driven fans and channeled in a specifically made 4-layered fabric. It shares the advantage of a long lasting effect, based on the current battery charge. In comparison with water flow and air blowing vests, the vest is lightweight since it does not carry any cooling material and does not need any preparation time. Due to the effective sweat removal, the protective clothing stays dry making it more pleasant to be used again after a break. The vest regulates itself in the sense that, it does not cool the body if the body is not sweating anymore, making overcooling not possible. A regulation by an on/off switch is build-in, since the vest is made from a special fabric, it cannot easily replace existing garments but can be worn in addition. Size and position of the fans might be conflicting with equipment depending on the job/users requirements, requiring to be first tested. The vest needs to be worn tight in order to take up the sweat, so using the right garment-size is important. Teijin offers its Active Cooling Vest especially for firefighters, industry and medical workers at workplaces where protective clothing limits the natural cooling of the body and heat related illnesses are known to be a problem.

Choosing the right type of cooling vest

It is very important to choose the right type of cooling vest, as the different vests have their own advantages and disadvantages. A vest that it is tailored to your needs, can make a difference in not only work-performance but will also reduce the risk of heat related illnesses such as overheating. It is advised that before the acquisition of a product such as this, extensive research on product regulations and uses needs to be conducted in order to guarantee full personal and work-place safety.

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