Scientists at Stanford University have developed a new type of super insulating fabric made through an immersion in a solution of silver nanowires, which allows the user to stay warm despite being exposed to low temperatures. An advance that could help greatly reduce the need for heating in homes.
The researchers report that currently 47% of global energy is spent on indoor heating, and, from this, 42% in residential heating. This highly insulated clothing could be a big reduction in costs.
‘Most strategies to reduce indoor heating focus on improving the insulation of the buildings, such as by using high R-value insulation and low-emissivity windows. However, a large portion of the energy is still wasted on heating empty space and inanimate objects’, said Dr. Yi Cui, responsible for research.
In order to be more efficient, researchers decided to put into practice a new strategy called ‘private thermal management‘, which is centered on people and how to heat them properly, showing that the black clothes in a solution of metal nanowires (AgNW) achieve insulation.
The main advantage of the clothing is coated with reflecting AgNW 90 percent more heat emanating from the body of the individual, ie, radiation, infrared. This reflection is much greater than the ‘work’ that makes even the warmest wool sweater that barely reflects 20% of body heat.
This increase in reflectance is due to differences in the emissivity of materials. Those ones with a low emissivity, such as silver, emit less radiation and thus provide better insulation than materials with a high emissivity as common textiles. But wearing clothes made of silver would be in contradiction to the idea of reducing costs, it would not be very comfortable and the skin would be unable to breathe.
However, the AgNW garments solve this last problem due to the porous structure of the nanowires that are separate 300 nanometers one from another, which offers enough space to allow the water vapor molecules transit but is also too small to allow body heat to pass through, since the human body radiation has a wavelength of approximately 9 micrometres thus this radiation will reflect when interacting with the nanowires.