Controlling radiative heat flows in interior spaces to improve heating and cooling efficiency

Area of Science:

• Building science
• Materials science
• Energy efficiency

Background:

• Building heating and cooling systems consume approximately 20% of global energy.
• Current systems maintain occupant thermal comfort by regulating interior air temperature setpoints.
• Significant energy savings are achievable by decoupling thermal comfort from air temperature setpoints.

Purpose of the Study:

• To propose a novel mechanism for enhancing building energy efficiency.
• To demonstrate the potential for energy savings by dynamically tuning the thermal emissivity of interior surfaces.
• To decouple mean radiant temperature from actual surface temperatures.

Main Methods:

• Investigated the dynamic tuning of thermal emissivity for interior building surfaces.
• Analyzed the impact of low emissivity (0.1) and high emissivity (0.9) surfaces on thermal comfort setpoints.
• Simulated performance in both cold and warm weather conditions.

Main Results:

• In cold weather, a low emissivity of 0.1 reduced the heating setpoint by up to 6.5°C from a 23°C baseline.
• In warm weather, low-emissivity surfaces led to a 4.5°C decrease in the cooling setpoint compared to high-emissivity surfaces.
• Tunable emissivity is crucial for maximizing year-round energy efficiency.

Conclusions:

• Dynamically tunable surface emissivity offers a promising strategy for substantial building energy savings.
• This technology allows for maintaining thermal comfort across a wider range of temperature setpoints.
• Further development of tunable emissivity materials can revolutionize sustainable building design.