Hi there, welcome in!

      We are PerCOMFORT.

      Here is the website page of our project!


Since the industrial revolution began, more energy-related technologies emerged as key methods to speed up the world’s economic growth and improve capabilities of human that can replace human power. However, our use of energy has created unacceptable climate-change risks. A lot of important but challenging research to explore potential approaches for solving the climate issue are conducted in different fields, which leads to another industrial revolution with affordable, accessible, and sustainable sources of energy [1].

Despite the significant growth in the use of nuclear and renewable energy, petroleum, natural gas, and coal still dominate in the United States energy consumption by fuel in 2020. In this case, how efficiently and effectively we use existing energy sources is very essential to this industrial revolution. Especially for the aspect of thermal management like space heating and cooling, which counts as the majority in total United States energy consumption by end-use sectors in 2019 [2], is not negligible if our community intends to save more energy.

Problem Statement

Instead of heating or cooling the entire building, it is more convenient and energy-saving to regulate the surrounding space of human body. Meanwhile, the temperature preference of individuals even differs when they are in the same building. In different seasons, the perfect temperature range for individuals differs as well so that the setting of Heat, Air Ventilation, and Cooling (HAVC) system will be changed frequently. The initial point where the name of our team PerCOMFORT came up is that we prefer personalized comforts.  

Here, we demonstrate an electronics system equipped with electrochemically tunable materials that can automatically adjust the potential of power supply, and then control the emissivity of materials once it monitors the temperature difference between human body and ambience. Different emissivity means that the materials can either absorb, reflect, or transmit the radiation heat from human body with materials attached to achieve personal thermal management.



Inspiration and Goals

Here, we are going to introduce the inspiration part of PerCOMFORT project.

Beside adjusting the HAVC system temperature frequently, there is another method enabling us to live more comfortably and save more energy conveniently: personalized comfort (PerCOMFORT). It focuses on heating/cooling the local environment only around the human body. Unlike traditional air-conditioner providing temperature adjusting to the whole room space, PerCOMFORT can significantly reduce the energy consumption. In addition to the energy saving, PerCOMFORT can provide a higher level of thermal comfort via its individual temperature adjusting function; instead of making all people in the sample space experiencing the same temperature, PerCOMFORT can customize different heating or cooling depending on users’ preference.

Regards the implementation of PerCOMFORT, heat transfer, materials selection, and circuit designing are going to become the core of our PerCOMFORT project.

Mainly, heat transferring through bodies in three ways: convection, evaporation, and radiation. Radiation has been often overlooked in traditional personal thermal management, but it is an important factor of heat dissipation for human body. Up to 40% of heat loss comes from radiations at normal room temperature; the heat is given off in the form of infrared rays, a type of electromagnetic wave [4]. Therefore, by enhancing or suppressing the thermal radiation can help to adjust the body temperature.

Figure 5: heat loss of human body

When light or radiation hits an object, it is transmitted, absorbed, and/or reflected. Transmission means light passes through a substance; absorption means light energy hitting the surface converted to heat energy; reflection means light bounces off a surface. In thermodynamic equilibrium, the percent of emitted light is equal to the absorbed light.

If we apply these basic optics fundamentals to PerCOMFORT, our main strategy is reflecting solar light and transmitting body radiation for cooling and absorbing solar light and blocking body radiation for heating.

Figure 6: Radiation equations

Based on this main strategy, there are many new advanced materials and fabrication methods have emerged in this personal thermal management area. Here, because different materials have different emissivity, we can choose or even design the material with desired emissivity to fit the heating or cooling requirement. But if we think about a type of materials with tunable emissivity, isn’t it more convenient? After carefully consideration and chemical synthesis, a material with tunable emissivity and easy accessibility called polyaniline. It has three states. The three states correspond to different emissivity.

When we change the potentials that we apply to this material gradually, the emissivity will be changed gradually as well. The emissivity contrast could be up to 48.6%. This contrast means the temperature variation could be at least 10°C.

Our goal is to design a small and portable device. When it detects the difference of human body temperature and ambient temperature. it will evaluate the value of emissivity immediately and then apply the appropriate potential to the materials. During the evaluation process, we also need to consider the influence of humidity. For example, when human stays in a hot and wet room, lower temperature and colling are required to maintain comfort.

  • Wearable
  • Portable
  • Monitor Temperature and Humidity 
  • Change Temperature around an individual

System Decomposition

The whole system can be divided into three sub-systems: Electronics, Simulation & Modelling, and Hardware. The Electronics module contains five sub-modules: Power Supply, Sensor, Micro-controller, Operational Amplifier Module, and Materials. Esp32 is used as the micro-controller of the entire circuit. LM324N and 4558D constitute an operational amplifier module. ELEGO and Battery pack are served as the power supply module. DHT11 and thermistor work as temperature and humidity sensors.

Because our materials need to be provided  with  a voltage range of -0.5V to 0.5V, we designed the entire circuit system to realize a monitoring function; the sensor detects ambient temperature and humidity, then transmits the electrical signal to a Micro-controller through a specially designed amplifier module. The function of the Microcontroller is to output the corresponding voltage which is required by the material.


Future Work

  • Short Term:

       As for the short-term plan, an enclosure can be built in order to place the system and make sure it is portable.

  • Long Term:

        As for the long-term plan, here are two goals that can be achieved.

  1. Add two more sensors (one for temperature and one for humidity) into the system to collect the temperature and humidity difference. So that the equation as well as the code can be operated without problem.
  2. The system can be more functional by adding Blood Pressure, Heart Rate, Oxygen Saturation  sensors on it.


[1] Chu, S., & Majumdar, A. (2012). Opportunities and challenges for a sustainable energy future. nature488(7411), 294-303.

[2] Source: U.S. Energy Information Administration, Monthly Energy Review, Tablle 2.1, April 2020, preliminary data

[3] Li, X., Xie, W., Sui, C., & Hsu, P. C. (2020). Multispectral thermal management designs for net-zero energy buildings. ACS Materials Letters2(12), 1624-1643.

[4] Cengel, Y. A., & Ghajar, A. J. (2007). Heat and mass transfer. A practical approach.

[5] Handbook, A. F. (2017). American society of heating, refrigerating and air-conditioning engineers. Inc.: Atlanta, GA, USA59.

[6] Gh.R. Roshan, M. Farrokhzad, S. Attia (2017), Defining thermal comfort boundaries for heating and cooling demand estimation in Iran’s urban settlements,Building and Environment,Volume 121.

[7] Kaynakli, O., & Kilic, M. (2005). Investigation of indoor thermal comfort under transient conditions. Building and Environment40(2), 165-174. 

[8] Borgnakke, C., & Sonntag, R. E. (2017). Fundamentals of thermodynamics. John Wiley & Sons.