Going for the Max with DELTA UC Berkeley: Center for the Built Environment (CBE: EdwardArens, Hui Zhang) Electrical Engineering and Computer Science (EECS) W asatch Collaboratory (Jeff Muhs) WiTricity Corporation
Problems, opportunities, solutions Thermal comfort in office buildings: BAD Energy cost of narrow thermostat setpoints Baltimore example 68 to 78 F 30% savings in summer + 10% savings in winter 40% savings total 68 78 satisfied with thermal environment Hoyt, T., E. Arens, and H. Zhang. 2015. Extendingair temperature setpoints: Huizenga,C; Abbaszadeh,S.; Zagreus, L. and E. Arens (2006). Air quality and Simulated energy savings and design considerationsfor new and retrofit thermal comfort in office buildings: Results of a large indoor environmental buildings. Building and Environment 88, 89-96. quality survey. Proceedingof Healthy Buildings 2006 , 3, 393 - 397. Our solution is to increase the HVAC dead-band to reduce HVAC loads and increase the thermal comfort and productivity of workers.
Work performance vs. temperature changes 3-8 % productivity increase from Cooling Heating DEL TA DELTA temperature DEL TA corrections +6 +3 0 -3 -6 Personal Neutral Temperature Correction (deg. C) (Productivity curve adapted from Wargocki and Seppanen et al. 2006, “ Indoor climate and productivity in offices ” ,REHVA Guidebook Corrective arrows based on: Zhang, H., E. Arens, Y. Zhai 2015, A review of the corrective power of personal comfort systems in non-neutral ambient environments, Building and Environment Vol. 91, 15 - 41 http://www.sciencedirect.com/science/article/pii/S0360132315001225
Our suite of DELTA devices for offices Designed to be both efficient and effective: • desk fan • heated/cooled wrist pad • heated/cooled chair • heated insole Wirelessly powered for convenience IOT-connected, to individualize HVAC control
Prototypes • Very low power use • User controls for cooling and heating IOT- data connected: • occupancy , control settings, temperature, RH • Rechargeable battery • Wirelessly powered Heated Desktop H/C wristpad Heated/cooled chair insole fan
Warm/cool sensitivity maps of hands and feet Warm sensation Cold sensation FEMALE FEMALE Thermal sensation Thermal sensation FEMALE FEMALE
Mapping sensitivity to warmth and coolth Warm sensation Cool sensation FEMALE FEMALE ) ) . . .u u . ( S a a ( S T Thermal sensation T Thermal sensation inner outer outer inner
Tests of spot-heated insoles on foot sensation very hot hot warm sl. warm neutral sl. cool cool cold very cold
Acceptability of DELTA combinations when heating (at 64 F)
Field study, heated/cooled chair, Apr-Oct 2016 San Mateo County office building, CA chair • Chairs improves comfort satisfaction • 96% thermal acceptability • People use chairs frequently • on average 77% of the time used when seated • 40 government office workers • People really like the chairs • 99% satisfaction (21 females, 19 males) • Measurements • Chair occupancy • I love Chosen heating/cooling settings thank you for it! allowing me • Occupant surveys to use the chair • Indoor environmental conditions
Value to the U.S. of increased productivity • Approximate annual cost of employment for U.S. office employee: $83,761 (Bureau of Labor Statistics) • Number of office employees in U.S: 41.3 million (Bureau of Labor Statistics) • Productivity increase from thermal comfort provided by DELTA: 3-8% (Seppanen 2006); we will assume 3%. However, 100% productivity in the Seppanen curve is for the group neutral temperature, at which at least 20% of the population will be feeling too warm or too cold. Since DELTA corrects all occupants to their individual neutral temperatures, the total of individual productivity increases will be greater than the group increase, say 5% more. (5% + 3% = 8%) • Conservatively assuming DELTA only improves productivity 20% of the time for employees in a typical building, the annual productivity increase is $55.4B [($83,761 x 41.3 million x 8%) x 20%] • Assuming 25% market penetration for DELTA, the total value of increased productivity in the U.S. is $13.8B ($55.4B x 25%)
Simple payback at the occupant level • T otal system additional price: -$400 • Annual energy costs: -$4 • Annual maintenance costs: -$25 • Annual energy savings from deadband increase: +$75 • Annual increase in productivity: +$1341 ($55.4B/41.3M) • Simple payback = initial cost / annualized return • Simple payback: = $400/($1341 + $75 - $4 - $25) = 3.5 months
Summary Efficient devices have been developed and tested in lab and in field • Energy efficient • Effective at providing comfort • Increases productivity • Uses IOT to connect to HVAC control • Cost effective • Ready for commercialization 13
Next steps? Collaborate with companies interested in developing efficient DELTA • Efficient heat transfer surfaces---licensees for our IP • Chair and furniture manufacturers, desktop devices, shoe insoles • HVAC control sequences for DELTA-equipped buildings • Wireless power transfer; untethered devices Note: The project team is open to both licensing and start-up pathways to market. earens@berkeley .edu zhanghui@berkeley .edu jeff .muhs@wasatchcollaboratory .com 14
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