Measures to Save Electricity with Outdoor Units of Air Conditioners: Greta Coat and Energy-saving Cover

GS Construction Limited Partnership

Publication date	February 9, 2021 (Posted on May 19, 2022)
Sector	Industrial and economic activities, Human Health, Life of Citizenry and Urban Life

Company Overview

Climate Change Impacts

The number of excessively hot days is increasing due to the rising temperatures caused by heat island phenomenon and global warming. As the outdoor temperature and radiant heat increases, the indoor temperature rises and leads to the risk of heat stroke.

The increase in outdoor temperature and radiant heat also affects equipment. The temperature inside the outdoor units of the air conditioners/electric power facilities/ communication facilities/vending machines, will rise, consume extra power, and even lead to malfunctioning due to the heavy load on the internal device.

There has also been significant impacts on animals. For example, the roof surface temperature of cattle sheds, pigpens, chicken coops, and stables sometimes exceed 70° C during the summer. Since a high level of infrared rays are radiated inside, it has become a major cause of heat stress.

Adaptation Initiatives

The ambient temperature of the air conditioner outdoor unit (hereinafter referred to as “outdoor unit”) may rise to approximately 70°C during the summer. In winter, frost may adhere to the outdoor unit and freeze. In such installation environment of the outdoor unit, the air conditioner consumes a large amount of power so it is necessary to introduce the following power saving measures:

• Summer: measures to prevent high temperatures around the outdoor unit (more energy is required to cool the heated outdoor unit)
• Winter: measures to prevent low temperature around the outdoor unit (more energy is required to warm the cold outdoor unit).

The following are physical measures for the above. However, there are also some challenges when such measures are taken:

• Spraying water on outdoor units during the summer time to reduce the rise in ambient temperature. → Silica and other substances can adhere to the heat exchanger of the outdoor unit, causing it to malfunction.
• Covering the outdoor units with screens or nets to create shade. → The nets could get blown away by strong winds.

So as an alternative measure, we developed a highly functional water-based thermal insulation coating, Greta Coat. This coating can reduce the temperature around the outdoor unit, from approximately 70°C to about 40°C during summer (Fig.1, 2).

Also, by applying this coating to the outdoor unit and its surrounding area, and installing a further cover (energy-saving cover) on the heat exchanger (external insulation), direct and radiant heat can be blocked and the surrounding temperature can be lowered in summer. In winter, the heating efficiency can be increased by reducing the frost adhesion and cold air (Fig. 3).

These measures are expected to reduce power consumption by an average of 10% to 20% per year (depending on the installation environment of the outdoor unit).

Effects / Expected Benefits

The application of high-performance water-based thermal barrier and thermal insulating paint "Greta Coat" is expected to save energy. When the same amount of energy is used in the summer, the air conditioner with the coated outdoor unit can make the room temperature lower compared with the unit with no coating. Therefore, it could be expected that Greta Coat will reduce the risk of heat stroke.