Indoor Thermal Environmental Control and Satisfaction: Advanced HVAC systems and occupant satisfaction and comfort

Transcription

1 Indoor Thermal Environmental Control and Satisfaction: Advanced HVAC systems and occupant satisfaction and comfort Fred Bauman Project Scientist Center for the Built Environment University of California Berkeley, CA USA CENTER UNIVERSITÀ FOR THE IUAV BUILT DI ENVIRONMENT VENEZIA 3 July JULY

2 Presentation overview 1. CBE organization and research areas 2. Brief history of early pre-cbe comfort research at UC Berkeley 3. Task-ambient conditioning and UFAD systems 4. Personal comfort systems 5. Radiant systems

3 CBE organization Building science laboratory founded at UC Berkeley in 1980 CBE established in 1997 with support and oversight from the U.S. National Science Foundation Industry Advisory Board sponsors and guides the research agenda Semi-annual conferences in April and October emphasize collaboration, shared goals, and problem solving

4 Making a difference: Industry/University Collaboration Center for the Built Environment (CBE) Originally established in 1997 as an NSF Industry / University Collaborative Research Center (I/UCRC) Mission: To improve the design, operation, and environmental quality of buildings by providing timely, unbiased information on building technologies, evaluation tools, and design techniques Architects Engineering Contractors Manufacturers Utilities Government agencies Building owners

5 CBE Industry Advisory Board (38 members) Architects EHDD Architecture Perkins+Will Yost Grube Hall Architecture WRNS Studio ZGF Architects Architects/Engineers DIALOG HGA Architects and Engineers HOK LPA Inc. RTKL Associates SOM Contractors DPR Construction Swinerton Builders Webcor Builders Engineers Affiliated Engineers, Inc. Arup Atelier Ten Buro Happold Charles M. Salter Assoc. CPP Integral Group P2S Engineering Southland Industries Syska Hennessy Group Taylor Engineering WSP Government Agencies California Energy Commission U.S. Department of Defense U.S. General Services Admin. Manufacturers Armstrong World Industries BASF Corporation Big Ass Fans Google, Inc. Price Industries REHAU Utilities Pacific Gas & Electric San Diego Gas & Electric Southern California Edison

6 CBE research team Faculty Prof. Edward Arens, PhD Prof. Gail Brager, PhD Prof. Stefano Schiavon, PhD Project Scientists, Research Specialists, Professional Researchers Fred Bauman, PE Darryl Dickerhoff Tyler Hoyt Paul Raftery, PhD Tom Webster, PE Yongchao Zhai, PhD Hui Zhang, PhD Students/Visitors ~ Graduate Student Researchers ~ 5-10 Visiting Scholars Partner Relations/Communications David Lehrer Program Administrator Jessica Uhl UC Berkeley Collaboration Faculty and student researchers from architecture, engineering, business, computer science.

7 CBE visiting scholars program CBE accepts visiting scholars at any level University faculty Building industry professionals Submit application, including CV and description of research topic you would like to study while at CBE. Proposed topic must be related to ongoing research at CBE Priority given to scholars who can stay for at least 12 months CBE does not provide major financial support for visitors For additional details, please see:

8 CBE research areas 1. Advanced Integrated Systems Underfloor Air Distribution (UFAD) Radiant Systems Displacement Ventilation Personal Comfort Systems Natural Ventilation / Mixed-Mode Energy Simulation Tool Development 2. Envelope Systems Operable Windows and Thermal Comfort Mixed-Mode Buildings High-Performance Facade Case Studies Measuring Facade and Perimeter Zone Performance

9 CBE research areas, continued 3. Indoor Environmental Quality (IEQ) Occupant IEQ Survey Research Advanced Thermal Comfort Model Acoustical Performance 4. Controls and Information Technology Wireless Lighting Controls Demand Response (DR) Enabling Technologies Building Energy Visualization 5. Standards and Guidelines Adaptive Comfort Model Air Movement Standards Performance Measurement (PMP) ASHRAE UFAD Design Guide

10 Comfort: part of Indoor Environmental Quality (IEQ) Thermal comfort Lighting / visual comfort Indoor air quality Acoustics

11 Why is IEQ important? (Hint: follow the $$) 30-year costs of a commercial building Personnel 92% 2% 6% Capital costs Operations & Maintenance

12 Why is IEQ important? (Hint: follow the $$) Typical office building costs in $/sf per year Annually, people costs are 2 orders of magnitude more than energy costs

13 ASHRAE Standard 55 comfort zones Comfort zone represents acceptable conditions for 80% of the people Based on laboratory studies -size- Energy intensive: broad application of narrow setpoints In practice (summer) Narrow zone: ~ F ASHRAE = American Society of Heating, Refrigerating and Air-Conditioning Engineers

14 ASHRAE Research Project RP-462 In , UC Berkeley (pre-cbe) conducted a field study of 10 office buildings in the San Francisco Bay Area. We took detailed physical measurements at each workstation that we visited (2,342) using a portable thermal environment measurement system. During the same visit, we surveyed the occupant to obtain their subjective responses using a portable laptop computer (pre-internet). We analyzed the data to determine if current comfort standards (ASHRAE Std. 55, ISO Std. 7730) were being met.

15 Environmental measurements: Air temperature, radiant temperature, humidity, air movement, light levels 1 st of it s kind! (1985) New & improved (1990) UFAD Commissioning (2006) Wireless with real-time monitoring (2012)

16 Results from RP-462 (McIntyre vote) Despite being largely maintained within ASHRAE Standard 55 thermal comfort zone, 60% of occupants wanted no change, while 20% wanted warmer and 20% wanted cooler conditions.

17 Thermal comfort Traditional approach Satisfy up to 80% of building occupants by maintaining thermal environment within comfort zone (based on laboratory studies) Personal control approach Allow personal control of the local thermal environment satisfy up to 100% of occupants reduce occupant complaints Existing fan-driven supply outlets provide sizable range of temperature control: desktop ~ 13 F (7 C) 17

18 Personal Environmental Module (PEM) Around 1990, Johnson Controls developed the PEM to control (1) airflow (volume and temperature), (2) radiant heater, (3) sound masking, (4) task lighting, and (5) operation with occupancy sensor. UC Berkeley conducted field study ( ) that showed 100% satisfaction with thermal comfort when occupant used PEM.

19 Research begins on underfloor air distribution (UFAD) Task-ambient conditioning (TAC) systems, such as the PEM, showed promise in the lab and field, but adoption by the building industry was very limited. The TAC devices were considered to be too expensive and too complicated for widespread use. UC Berkeley was looking for a technology that was more practical (less expensive and less complicated) that could provide improved comfort (with personal control), improved energy performance, and other advantages. We began a long and large research effort to help develop

20 Basics: Overhead (OH) vs. UFAD C (55-57 F) supply temp C (60-65 F) supply temp.

21 Potential UFAD benefits Improved occupant comfort, productivity and health Improved ventilation efficiency and indoor air quality Reduced energy use Reduced life-cycle building costs Improved flexibility for building services Reduced floor-to-floor height in new construction 21

22 Underfloor air distribution (UFAD) Multi-year, multi-faceted project began in early 1990s, as UFAD systems were being adopted CBE became UFAD research leader, through simulations, lab, and field research Developed advanced understanding of benefits and limitations (and dispelled myths) Created numerous resources for designers, manufacturers, owners and operators Room Height [ft] η=0 η=0.38 η=0.65 η= Temperature [ F]

23 Design practice Lack of familiarity previous experience Design tools and guidelines No standardized design guidelines No UFAD design tools, only conventional tools Research Gaps in fundamental research o Room air stratification o Underfloor plenum performance o Whole-building energy simulations

24 UFAD deliverables UFAD Technology Website (2000) ASHRAE Design Guide (2003) EnergyPlus simulation capability, Cooling Load Design Tool (2010) Extensive technology transfer through workshops, journal papers, and articles Commissioning tools and guidelines ASHRAE UFAD Guide (2013)

25 Transition to research on other advanced technologies By 2012, UFAD was routinely considered as a design option with nearly 10% of all new U.S. office buildings using UFAD. Energy savings compared to conventional VAV overhead systems was good (10-15%), but less than hoped for. Comfort with adjustable floor diffusers was also better, but there was still room for further improvement. A review of existing buildings revealed that significant comfort and energy performance enhancements were still needed and possible. Climate change and state/federal legislation was focusing increased attention on the need for dramatic reductions in building energy use (all new commercial buildings in California must be zero-net-energy (ZNE) by 2030).

26 Energy vs. comfort in buildings We are overcooling buildings in summer, wasting energy and making people uncomfortable. Mean SBS

27 Thermal sensations in air-conditioned buildings (Summer, indoor temperatures 70-75ºF, 21 24ºC) 71ºF 75ºF 21ºC (70ºF) 22ºC (71.6ºF) 23ºC 23ºC (73.4ºF) 24ºC (75ºF) 7-point Thermal Sensation (TS) scale: Cool (-3 < TS <-0.5) Neutral (0.5 < TS < 0.5) Warm (0.5 > TS > 3) Relatively fewer people are too warm in summer we are over-cooling buildings Data from 160 buildings worldwide, ASHRAE 884-RP database

28 Naturally ventilated buildings (summer) People are comfortable over a wide range of conditions Acceptability above 85% 80-85% 70-80% below 70% n=26, /F CENTER FOR THE BUILT ENVIRONMENT 100 JULY 2014

29 Personal comfort systems (PCS) Person-based instead of space-based conditioning Objective Explore the ability of PCS to: Save energy and keep people comfortable over a wider range of room temperatures Enhance comfort and productivity Key findings PCS provide acceptable comfort under temperatures from 64 F to 84 F Traditional mixing overhead system Desktop fan Foot warmer Heated and cooled chair

30 1 st generation PCS units Fan unit 4W air temperature and occupancy sensors 4W User controls Field studies Control and monitoring of: air temperature speed and warmth choices occupancy USB to workstation computer Footwarmer unit average 30W average 30W occupancy sensing pressure plate

31 Project overview Objective Demonstrate that using a PCS can reduce HVAC energy consumption while providing individual occupant thermal comfort Method Installed 17 PCS units in an office building at UC Berkeley Monitored plug loads at each workstation Monitored HVAC energy use using smap software Gradually changed the heating set point from 70 to 66 F (21 to 19 C) Collect data from September 2012 through April 2013

32 Workstations tested in the office Office building, UC Berkeley

33 Interior views of the field demonstration office Office building, UC Berkeley

34 Project timeline and set point adjustment 21 C 19 C

35 Right now, how acceptable is the thermal environment at your workspace? (Thermal Acceptability) Right now, you feel: (Thermal Sensation) Right now, your feet feel: (Thermal Sensation)

36 Preliminary results (footwarmer): Thermal acceptability Acceptability remained high as indoor heating setpoint in offices dropped from 70 to 66 F (21 to 19 C) Right now, how acceptable is the thermal environment at your workspace?

37 Preliminary results (footwarmer): energy savings Significant energy savings (~50%) as indoor heating setpoints dropped from 70 to 66 F (21 to 19 C) Minimal energy usage from footwarmer Power [w] Average Footwarmer and HVAC Power for each setpoint temperature Colder outside No PCS Setpoint Temperature o F Outside Temperature Footwarmer HVAC Outside Temperature Footwarmer HVAC Colder outside Cool outside lower heating setpoint

38 2 nd generation: low-energy heated / cooled chair Patent pending, company selected to manufacture commercially Lab studies: 90% acceptability (chair + desk fan) over a range of F (18-29 C) ambient temperature Field studies: 75 chairs constructed and being tested in UC campus buildings

39 Energy savings from PCS Energy savings come from expanding the range of ambient air temperature setpoints (7-15% per C) Secondary effects of our PCS Makes less-controlled or slowly-responding systems more feasible, e.g., naturally ventilated buildings or radiantly cooled buildings Provides more & better sensor data for central HVAC control Expanded comfort with PCS Hoyt, T., H.L. Kwang, H. Zhang, E. Arens, T. Webster, 2009, Energy savings from extended air temperature setpoints and reductions in room air mixing. International Conference on Environmental Ergonomics PCS Temperature ( F)

40 Chair features Highly directed heating and cooling of the body Energy efficient enclosure and power management

41 Human subject laboratory test Approach Subjects: 12 females and 11 males Subjects free to control their chair Chair tested with and without cover fabric Two cool conditions: 61 F (16 C) and 64 F (18 C) 61 F clothing: T-shirt + long-sleeve shirt + long pants 61 F extra clothing session: Same as above + light jacket 64 F clothing: T-shirt + long-sleeve shirt + long pants Warm conditions: 84 F (29 C) T-shirt and long-pants Extra session with 1.2 watt USB fan

42 Human subject test Objective Quantify the comfortable ambient air temperatures with the chairs Approach Human subject test Development of IT components

43 Results: Comfort at 61 F Very Comfortable Whole body thermal comfort (16 C) (61 F) Comfortable Just Comfortable Just Uncomfortable Uncomfortable Very Uncomfortable cover no cover extra clo reference % voting comfortable:

44 Results: Comfort at 64 F Very Comfortable Whole body thermal comfort (18 C) (64 F) Comfortable Just Comfortable Just Uncomfortable Uncomfortable Very Uncomfortable cover no cover reference % voting comfortable:

45 Results: Comfort at 84 F Very Comfortable Whole body thermal comfort (29 C) (84 F) Comfortable Just Comfortable Just Uncomfortable Uncomfortable Very Uncomfortable cover no cover chair+fan reference % voting comfortable:

46 Cesar Chavez Student Union (summer and winter) Objective Evaluate thermal comfort provided by PCS in a building without mechanical cooling Approach Distributed 14 PCS chairs and 4 footwarmers Installed wireless temperature sensors in each of 18 workstations Surveyed - survey (Sept Feb. 2014), 1300 responses received Funding CEC/PIER, by CIEE (SPEED program)

47 2. Cesar Chavez Student Union : Summer and winter Building No mechanical cooling Objective Provide occupant thermal comfort Approach Installed wireless temperature sensors in each of 18 workstations Survey finished Without PCSs (Sept , base case) With PCSs (Oct Feb. 2014) About 1300 survey responses received Funding USB fan CIEE through SPEED program CBE chair PCS chair

48 Acceptability rates with and without PCS (summer) Indoor air temperature ( F) Without PCS, acceptability rate is about 50 75% With PCS, acceptability rate is about 75 90%

49 Comfort ranges with PCS (summer and winter) Acceptability rate Indoor air temperature (ºF) Indoor air temperatures (ºF) PCS keeps occupants in or near comfort over ambient air temperature 68 80ºF

50 Near ZNE buildings with radiant systems Objective Provide new and improved information, guidance, and tools for designing and operating near zero-net-energy (ZNE) buildings using radiant cooling and heating systems Approach Two case studies (in progress) EnergyPlus simulations (in progress) Developed online map of radiant systems as resource (complete) Laboratory testing of radiant cooling loads (complete and published) Funding and schedule California Energy Commission Public Interest Energy Research (CEC/PIER) October 2012 March 2015

51 Near ZNE case studies Sacramento Municipal Utility District (SMUD) East Campus Operations Center, Sacramento, CA 200,000 ft 2, LEED Platinum Radiant slab, ceiling fans Chilled beams Geothermal exchange, thermal energy storage PV panels Stantec See CBE Centerline, Winter 2014 David Brower Center, Berkeley, CA 45,000 ft 2, LEED Platinum Radiant slab ceiling with UFAD Advanced shading, operable windows PV panels Solomon E.T.C. WRT, Integral Group

52 Field study approach Occupant satisfaction survey Energy Star Site visit to install wireless measurement toolkit to collect more detailed performance data; supplemented with BMS trend data CBE survey results Energy use data Indoor climate monitor

53 Progress: SMUD East Campus Operations Center Installed 50 wireless sensors (CBE toolkit) on 2 nd level open plan office area in December 2013 Collecting live data from CBE toolkit and BMS to smap (simple measurement and actuation protocol) for analysis Working with SMUD building operators to review controls of radiant slab zones Several operational problems have been identified and corrective adjustments have been made

54 SMUD office building Ceiling fans for warm temperature conditions No compressor cooling from 2-8 pm Suspended sound-absorbing acoustical panels Advanced window blinds redirect solar radiation onto ceiling

55 Installation of wireless sensors Radiant ceiling slab surface temperature Indoor Climate Monitor: air & globe temperature, air velocity, humidity, light level, CO 2 Stratification pole

56 Sensors and radiant zones on 2 nd level, SMUD

57 Temperature ( F) Water valve position (%) Radiant slab system control in early December Radiant cooling valve turning on at 10 am 12 pm each day Zone air temp. Slab surface temp.

58 Temperature ( F) Water valve position (%) Heating performance in southeast zone Radiant heating valve turned on for most of weekend Slab surface temp. Zone air temp.

59 New setpoint control schedule, SMUD, 2 nd level Original New

60 Water valve position (%) Water control valves on 2 nd level, SMUD New setpoint schedule implemented on March 13 Valve operation stops on weekends Frequency and magnitude of valve operation reduces on weekdays wknd wknd wknd wknd wknd March 13

61 Next steps, SMUD field study Continue to monitor radiant slab control as warm weather arrives Investigate slab pre-cooling strategies based on next day temperature forecast Study impact of ceiling fan operation during warm afternoons Monitor building energy use and compute Energy Star rating Conduct CBE occupant satisfaction survey Future field studies planned to investigate impact of installing PCS chairs in SMUD building Provide heating during cool mornings Provide cooling during warm afternoons

62 Update of radiant webpages and technology transfer CBE website has been updated Research on radiant systems: Research on near ZNE buildings with radiant systems: Review of radiant cooling design methods Critical review of water based radiant cooling system design methods. Feng, J., F. Bauman, and S. Schiavon. Proceedings of Indoor Air 2014, Hong Kong, July Online map of radiant system buildings Online map of buildings using radiant technologies. Karmann C, Schiavon S, Bauman F. Proceedings of Indoor Air 2014, Hong Kong, July Radiant cooling loads Cooling load calculations for radiant systems: Are they the same as traditional methods? Bauman, F., J. Feng, and S. Schiavon ASHRAE Journal 55(12). Experimental comparison of zone cooling load between radiant and air systems. Feng, J., F Bauman and S. Schiavon Accepted in Energy and Buildings.

63 Questions? Fred Bauman CBE website Centerline Newsletter Online map of radiant systems