Wax tiles Markedly Cut Energy use for Heating and Cooling

By employing a temperature-sensitive “wax motor,” scientists have developed a dynamic roofing tile system that maintains a comfortable room temperature of 18 °C (65 °F). This innovative system achieves a remarkable 3.1X decrease in cooling energy usage and a 2.6X reduction in heating energy consumption.

The concept is a collaboration among mechanical engineering professors at UC Santa Barbara, and its functionality is straightforward. Essentially, it consists of louvers positioned on a roof. When these louvers are shut, they expose a flat surface made of black chrome-coated aluminum, which efficiently absorbs heat and minimizes the emission of infrared radiation, contributing to the warming of the area below.

Louver Opening Unveils Secondary Layer with White Barium Sulfate Coating for Effective Radiative Cooling

Upon opening the louvers, a secondary layer is exposed, now coated with a white barium sulfate material renowned for its infrared-emissive characteristics and exceptional radiative cooling abilities. This assists in extracting heat from the space and dissipating it.

However, the ingenious aspect lies in the wax motor responsible for the louvers’ movement.

In fact, the selected wax has a melting point of 18.2 °C (64.8 °F), and the system is engineered to leverage the substantial expansion of the wax upon melting. This expansion drives pistons that open the louvers as the wax melts and closes them as it solidifies. The wax motors, situated beneath the roof, respond to the room’s temperature.

And that summarizes the system. The scientists note that the louvers have a complete range of opening and closing within a margin of less than 3 °C (5.4 °F). However, this means they respond promptly to fluctuations in the day’s temperature, consistently working to approach the 18 °C melting point, adjusting as the temperature deviates in either direction.

Efficient Temperature Regulation

And that summarizes the system. The scientists note that the louvers have a complete range of opening and closing within a margin of less than 3 °C (5.4 °F). This means they respond promptly to fluctuations in the day’s temperature, consistently working to approach the 18 °C melting point, adjusting as the temperature deviates in either direction.

However, the researchers conducted tests on the adaptive tiles, comparing them to two static controls—one featuring the black chrome-coated aluminum surface and the other using white barium sulfate paint. The results showed that during nighttime, the adaptive tiles reduced heat loss by a factor of 2.6 compared to the white tile, and during the heat of the day, they decreased heat input by a factor of “at least 3.1” compared to the static black tile. These measurements were based on the energy required to be added or removed to maintain an 18.2 °C temperature.

Innovative Application of Wax Motors

While wax motors are not a novel technology, commonly found in household appliances like dishwashers and washing machines, as well as in aerospace applications, their use in driving a temperature control system like this is innovative. However, this approach holds significant potential for passive heating and cooling in buildings. The wax selection can be tailored to specific objectives, and the system’s relevance may be enhanced by employing different thermal coatings based on manufacturing and usage locations.

Mechanical Engineering Professor Elliot Hawkes mentioned, “While the device remains a proof-of-concept, our aspiration is that it paves the way for future technologies capable of positively influencing energy efficiency in buildings.”

Read the original article on: New Atlas

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