Hui Zhang

Closed (1) Heated and cooled chairs for comfort and energy efficiency on campus

Applications for fall 2021 are now closed for this project.

Brief history: Personal comfort systems (PCS) offer individualized comfort, and energy savings from relaxed thermostat setpoints. HVAC energy decreases 10% per °C as thermostats are relaxed in either direction. PCS provide over 3⁰C relaxation, enabling a 30% energy saving in both heating and cooling. (PCS itself uses very little energy: 100 times less, per occupant, than the building’s HVAC system). At the same time PCS allows all individuals in a given space to be comfortable, including both the warm- and cold-sensitive ones.

My team at CBE has designed and built several types of PCS, including heated and cooled chairs. These are extremely efficient, requiring maximum only 3W for cooling and 14W for heating; able to run for multiple days on a rechargeable laptop battery. In a six-month field study of 40 occupants in a major county office building, the chair delivered 97% thermal satisfaction, much higher than in conventional buildings. In a different field study where we could relax thermostat settings, 40-50% HVAC savings were achieved. We have published such findings in the main building science journals.

Benefits to students: Students often study in evenings in libraries where they report cold discomfort. Also, some common rooms in the UCB dorms do not have air-conditioning systems. The H/C chairs can provide students with cooling in spaces with inherently efficient natural ventilation.

Project goals: Demonstrate the comfort effects of heated/cooled chairs for UCB students, and also their energy benefit, in a total of three campus buildings. The goal is to encourage campus-wide adoption of PCS. The approach is: 1) design and fabricate 10 battery-powered heating/cooling cassettes that attach to chairs on UCB’s purchase list; 2) demonstrate comfort effects for students in a library and a common room in a dorm; 3) quantify the HVAC energy savings potential in one open-plan office space.


Working with a team, the students will 1) joining the design and fabricate of the heated and cooled chair control boards, one with IOT function and one without. 2) joining the fabrication of 10 battery-powered heating/cooling cassettes.

Day-to-day supervisor for this project: Hui Zhang, Staff Researcher

Qualifications: (some or any of the following): knowledge of basic electronics and telecommunications theory, skills/work experience with design of printed circuit boards (e.g. KiCad), good skills in microcontrollers (e.g. ATmega, stm32) programming (e.g. C++), experience in design of power efficient systems using batteries; preferred but not required: work experience in IoT (wireless sensor networks); love to design and build prototypes. An EECS department student is preferred.

Weekly Hours: 3-5 hrs

Related website: https://cbe.berkeley.edu/research-category/indoor-environmental-quality/personal-comfort-systems/
Related website: https://cbe.berkeley.edu/

Closed (2) Sensing/activating/tracking desk fan base

Applications for fall 2021 are now closed for this project.

Climate change and the increasing frequency of extreme temperatures require more efficient approaches to cooling buildings. Room fans offer the single greatest opportunity for increasing the efficiency and resilience of space cooling. The energy consumed by a modern five-foot ceiling fan (~10W) is less than a LED bulb, and buildings equipped with them require 30% less air-conditioning energy (saving 800-1000W/occupant) in Bay Area climates, with no loss in occupant comfort. The savings come from elevating the thermostat cooling setpoint; a 1 ⁰C increase typically causes 10% reduction in total HVAC energy. In addition, as climate changes, there will be tendency to convert traditional naturally ventilated (NV) buildings into air-conditioned building, which greatly increases their energy consumption.

This project will design and build a desk fan base that a USB desk fan can be put on top and connected with the base. The fan-base will install infrared sensors which will sense whether cooling is needed for a person; then the base will turn the fan on if cooling is needed. The base will also track the occupant if the person moves. , Staff Researcher

Qualifications: Advanced skills in CAD and product design, basic knowledge of electronics theory, experience in electrical systems using batteries. Love to design and build prototypes in multidisciplinary teams. A ME department student is preferred who has experience and interesting in building devices.

Weekly Hours: 3-5 hrs

Related website: https://cbe.berkeley.edu/research-category/indoor-environmental-quality/fans/
Related website: https://cbe.berkeley.edu/