Heating, ventilation and air conditioning (HVAC) accounts for almost half of the energy used in a typical U.S. home and about 13 percent of all energy consumed in the nation. Implications of this energy consumption include negative effects on the environment and climate, wasted money from inefficient heating and cooling of buildings as well as lower productivity of office workers because they are too hot or too cold.
What if each of us had our own heating and cooling system that could regulate our individual thermal comfort? What impact could that have on reducing overall energy consumption? The U.S. Department of Energy’s Advanced Research Projects Agency-Energy (ARPA-E) Delivering Efficient Local Thermal Amenities (DELTA) program is exploring the possibilities of such innovative “localized” thermal management systems. ARPA-E has estimated that such an approach, if widely implemented, could save two percent of energy consumed in the U.S. Additionally, these systems would allow every person in a building to be comfortable regardless of their metabolism or clothing choices.
Funded by ARPA-E through the DELTA program, SRI is leading a multidisciplinary team that includes University of California, Los Angeles and Stanford University. We are combining novel technologies for a highly efficient, wearable system that works synergistically with the human body to manage a person’s heating and cooling individually.
Our Approach: It’s Personal
SRI’s research team is leveraging the human body’s thermal regulatory system by transferring heat through glabrous (non-hairy) skin—that’s mainly the palms of the hands, soles of the feet and the upper facial area. These areas have very dense networks of blood vessels that act as heat exchangers for the body, which is similar to a car radiator. A person may have cold hands and feet not because they have poor blood flow but because when they are cold the body restricts blood flow to those areas.
The personal thermal regulation system we are developing is enabled by “active textile” technology, comprised of low-cost electroactive polymer materials and structures that efficiently manage active heat transfer and boost passive cooling while being quiet and comfortable. The system is versatile and can be incorporated into various clothing accessories, such as armwear similar to many existing braces or gel-filled comfort wraps used by office workers, insoles or socks that are compatible with shoes and other amenities such as scarves and eyewear. This technology would allow a person to continue to wear their existing clothing. Additionally, the system could be integrated with smart watches, fitness bands and other wearable technology for data logging and communications with other systems.
Through communication with a building’s HVAC system via a smart watch, the personal thermal regulation system can help optimize the use of a building’s HVAC system by not overheating or overcooling areas within the building where the occupants do not reside, all while enhancing personal comfort for the occupant.
In addition to the potential energy savings realized from using personal thermal regulation systems, we are also looking at other applications where the system would bring heating and cooling benefits to the user, such as physical activities in extreme environmental conditions. For example, humanitarian aid workers in countries where there is a need to wear extensive personal protection equipment—including face shields or goggles, medical masks, gloves, gowns, aprons and waterproof boots. These environments are very hot and humid, resulting in limited time that the workers can be in their equipment. A personal thermal regulation system can be worn with the equipment and increase the workers’ comfort while potentially extending the amount of time they can wear their protective equipment. Personal thermal regulation systems can also make recreational or fitness activities more enjoyable and productive.
By incorporating the means for heating and cooling into thin, light and flexible active textiles, we’re creating a versatile technology platform that can be used in many applications. Because the system can be worn with existing clothing, we believe the features will allow for products that augment wearable technologies and thus achieve the widespread adoption needed to save energy while providing comfort on a large scale.
Acknowledgment: The information, data, or work presented herein was funded in part by the Advanced Research Projects Agency-Energy (ARPA-E), U.S. Department of Energy, under Award Number DE-AR0000532.
Disclaimer: The information, data, or work presented herein was funded in part by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof.