Keeping the human body in a thermal comfort state inside a room has become a challenge in recent years. While the most common strategy is to heat buildings, it requires a lot of energy. Reducing this energy consumption will have positive impacts, both economically and environmentally. We propose here to act directly on the personal thermal heating of the human body, by modulating the absorption and transmission properties of a synthetic polymer membrane in the mid-infrared (MIR). We show numerically that 5% SiO2 submicron particles inserted in polyethylene (PE) and nanoporous polyethylene (nanoPE) membranes increase the radiative heating of the membrane, reducing the required ambient temperature of a room by more than 1.1 °C. The proposed membrane can be flexible enough to be easily integrated into conventional textiles.

We study numerically the absorption and scattering properties of a polymer photonic membrane to thermoregulate the human body microclimate which corresponds to the area between the skin and a textile. We first show that the structuration of the absorbing photonic membrane with air holes leads to a modulation of the optical spectrum in the Mid-infrared range. indeed, we show that the membrane is able to modulate the transmission amplitude by 28% in benefit or deficit of both the absorption and reflection. We then studied the thermal balance between the human body and the surrounding environment through the photonic membrane. We found that, compared to a regular membrane, the photonic crystal structure behaves as a heating component that offers the possibility to reduce the temperature of the room up to +1 °C. The membrane is flexible, low cost, 3D-printable, free of metallic particles, and can easily be added to usual textiles.

Keeping the human body in a thermal comfort is a necessity for our own biological balance. Actually, to create a suitable thermal envelop in indoor areas, there are two strategies: using air conditioning systems (HVAC) to cool or warm the indoor space and/or clothing to adjust the temperature around the human body. The first strategy is showing his limitation due to the considerable energy consumption. In European Union, the building sector uses more than 40% of total energy consumption. [1] More than 50% of this energy is dedicated only for space heating. [2] This huge energy consumption is a worrying contribution to global warming. [3] In that assessment, clothes play a key role in our life to satisfy the human body thermal comfort by providing cooling in hot environment or heating in cold one. However, traditional clothes have a very limited thermal insulation performance. Indeed, a sudden variation of the ambient temperature can impact subsequently the thermal comfort of the body. The development of new textiles able to manage the temperature of the human body over a wide range of indoor temperatures, without providing additional external energy, appears to be an urgent necessity.Recently, personal thermal management has been demonstrated to be an efficient solution to replace the traditional ways of heating or cooling. [4,5] At normal skin temperature of 34 °C, the human skin emits thermal infrared (IR) radiations with a maximum peak around the wavelength 9.6 µm. In sedentary state, the infrared radiation accounts more than 50% of the total body heat losses. [6] By controlling the emissivity, transmissivity, and reflectivity of human body IR radiation through textiles, the temperature in the space between the skin and the textile (microclimate) can be controlled.Although many efforts have been made in the scientific community to develop radiative thermal management textiles, it remains, to this day, a major challenge. Tong et al. proposed an infrared-transparent visible-opaque fabric (ITVOF) which ensures the dissipation of thermal radiation emitted by the human body directly to the environment. [7] Hsu et al. have experimentally demonstrated that a nanoporous polyethylene (nanoPE) film presents both high infrared transparency and visible opacity. [8] The nanoPE film is opaque to human eyes Improving radiative heating performance of textiles is becoming one of the most current research topics to reduce the energy consumption used to control the indoor areas temperature. In this work, the properties of a textile-based asymmetric design for radiative heating are studied both theoretically and experimentally, and its remarkable efficiency over a wide range of temperature is demonstrated. By sandwiching a thin metallic layer characterized by a high reflectivity in the mid-infrared (MIR) between two polyethylene (PE) membranes of same thickness, it is proposed to control the MIR emissivity of the structure by the introduction of SiO 2 nanoparticles (NPs) in one of the two PE membranes. By reversing the fabric sid...