Thermal and Air Quality Effects on Performance in the Workplace

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SATISFACTION AND SELF-ESTIMATED PERFORMANCE IN RELATION TO INDOOR ENVIRONMENTAL PARAMETERS AND BUILDING FEATURES
Pawel Wargocki1, Monika Frontczak1,2, Stefano Schiavon2, John Goins2, Ed Arens2 and Hui Zhang2
1International Centre for Indoor Environment and Energy, DTU Civil Engineering, Technical University of Denmark
2Center for Built Environment, University of California, Berkeley, USA
Presentation given at the Workplace Trends 2012 Conference: Wellbeing and Performance, Thursday 25 October 2012, One Bishop's Square, London, E1 6AD.

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Thermal and Air Quality Effects on Performance in the Workplace

  1. 1. SATISFACTION AND SELF-ESTIMATEDPERFORMANCE IN RELATION TO INDOORENVIRONMENTAL PARAMETERS ANDBUILDING FEATURESPawel Wargocki1 (Monika Frontczak1,2, Stefano Schiavon2,John Goins2, Ed Arens2 and Hui Zhang2)1InternationalCentre for Indoor Environment and Energy, DTU CivilEngineering, Technical University of Denmark2Center for Built Environment, University of California, Berkeley, USA
  2. 2. Research regarding thermal and air qualityeffects on performance 24-10-2012
  3. 3. Ventilation and performance of office work(in relation to 6.5 L/s per person) 1.05 1.04 Performance 1.03 1.02 1.01 1.00 0 10 20 30 40 50 60 Outdoor air supply rate (L/s per person) 24-10-2012 Source: Wargocki and Seppanen (2006)
  4. 4. Temperature and performance of officework 1.00 0.95Performance 0.90 0.85 0.80 0.75 15 20 25 30 35 Temperature (°C) 24-10-2012 Source: Seppanen et al. (2005)
  5. 5. BACKGROUND Occupants of buildings are exposed to all indoor environmental parameters simultaneously It is likely that comfort is a result of a combined effect of different IEQ parameters It is also likely the quality of building including furniture, colors and other building amenities contribute to satisfaction with indoor environment Standards for IEQ provide requirements for single parameters not their combination Very few studies on the combined effects of IEQ parameters and building features on human comfort and satisfaction Some studies have shown that satisfaction with IEQ is related with the self-estimated job performance 24-10-2012
  6. 6. HANEDA ET AL. 2008 24-10-2012
  7. 7. OBJECTIVES To investigate which subjectively evaluated indoor environmental quality parameters and building features mostly affect satisfaction and self-estimated job performance in office buildings To examine the link between occupants’ satisfaction with their personal workspace and self-estimated job performance To quantify the size of the effects 24-10-2012
  8. 8. DATA Data collected by the survey conducted by Center for the Built Environment (CBE) Data collected over a 10-year period in 600 buildings (offices, hospitals, schools,…) Present study: 52,980 responses from occupants in 351 office buildings, mainly located in the U.S. (397 surveys) Background questions (gender, age, type of work performed, office type, distance from a window) Questions re. perceived satisfaction and self-estimated performance Building information form filled out by building facility manager providing information about the building and its systems: building’s age, location and size, number of floors, number of occupants, type of HVAC system, solar shading and controls, buildings’ LEED rating, energy use and cost of building 24-10-2012 construction, etc.
  9. 9. PERCEIVED SATISFACTION  Amount of space  Air quality  Visual privacy  Amount of light  Ease of interaction  Visual comfort  Furniture comfort  Noise level  Furniture adjustability  Sound privacy  Color & texture of surroundings  Building cleanliness  Temperature  Workspace cleanliness  Building maintenance 24-10-2012
  10. 10. OBSERVED SATISFACTION LEVELS 24-10-2012
  11. 11. SELF-ESTIMATED JOB PERFORMANCE ……………………………  Air quality  Office layout  Thermal comfort  Office furnishings  Lighting quality  Acoustic quality  Cleanliness and maintenance of the building 24-10-2012
  12. 12. OBSERVED SELF-ESTIMATED JOB PERFORMANCE 24-10-2012
  13. 13. IMPACT OF INDOOR ENVIRONMENTAL QUALITY AND BUILDINGFEATURES ON SELF-ESTIMATED JOB PERFORMANCE  24%: no effect  33%: job performance decreased by environmental conditions by at least 5% 24-10-2012
  14. 14. STATISTICAL ANALYSIS Workspace satisfaction = f(satisfaction with environmental and building parameters) using proportional odds logistic regression (odds ratios: the strength of association between variables) Self-estimated job performance = f(satisfaction with personal workspace) using simple linear regression (regression coefficient: percentage change of self-estimated job performance caused by a unit change of a predictor variable) Self-estimated job performance = f(satisfaction with environmental and building parameters) using multivariate linear regression (regression coefficient: percentage change of self-estimated job performance caused by a unit change of a predictor variable) 24-10-2012
  15. 15. WORKSPACE SATISFACTION AS A FUNCTION OF INDOORENVIRONMENTAL PARAMETERS AND BUILDING FEATURES  All parameters statistically significant (p<0.05)  The most important parameters: satisfaction with amount of space, noise level and visual privacy  Satisfaction with amount of space the most important regardless occupants’ gender and age, type of office (single office, shared office, cubicles) and distance from a window 24-10-2012
  16. 16. AMOUNT OF SPACE VS. AREA PER PERSON  Satisfaction with amount of space almost independent of area per person  Spearman rank correlation ρ=0.03, p<0.001  Limitations  A rough estimation of real area per person  No data on amount of storage space in a vertical direction 24-10-2012
  17. 17. SATISFACTION VS. OFFICE TYPE  Occupants in private offices more satisfied with workspace than those in shared offices or cubicles (p<0.001) 24-10-2012
  18. 18. SATISFACTION VS. WINDOW DISTANCE  Occupants close to a window more satisfied with workspace than those further from a window (p<0.001) 24-10-2012
  19. 19. SELF-ESTIMATED JOB PERFORMANCE AS A FUNCTION OFSATISFACTION WITH INDOOR ENVIRONMENTAL PARAMETERS ANDBUILDING FEATURES  The most important parameters: satisfaction with temperature, noise level and air quality  One-unit (~15%) increase in satisfaction with temperature would increase self-estimated job performance by about 1% 24-10-2012
  20. 20. SELF-ESTIMATED JOB PERFORMANCE AS AFUNCTION OF SATISFACTION WITH WORKSPACE Workspace satisfaction affects self-estimated job performance  Statistically significant (p<0.001)  Regression coefficient with 95% CI: 3.72 (3.67- 3.78)  One-unit (~15%) increase in satisfaction with workspace would increase self-estimated job performance by about 3.72% 24-10-2012
  21. 21. % 100 Simulated office work (lab) 98Performance 96 94 (R2=0.784; P=0.008) 92 110 90 Office work (call centre) Performance 0 10 20 30 40 50 60 70 % 105 Dissatisfied with air quality 100 95 90 0 10 20 30 Outdoor air supply rate (L/s per person) Elevated temperatures and poor air quality can affect performance of adults by 5% (laboratory) to 10% (field), and schoolwork of children by over 20% (field) 24-10-2012 Source: Wargocki et al. (1998; 2004)
  22. 22. CONCLUSIONS Lowest satisfaction levels observed for sound privacy and temperature Building occupants generally satisfied with their personal workspace In order to increase overall satisfaction with personal workspace, increase firstly satisfaction with amount of space, noise level and visual privacy Self-estimated job performance affected by workspace satisfaction The biggest increase in self-estimated job performance achieved by increasing satisfaction with temperature, noise level and air quality 24-10-2012
  23. 23. DISCUSSION OF DISCREPANCY BETWEEN RANKING OFPARAMETERS RE. THEIR IMPORTANCE FOR SATISFACTIONAND PERFORMANCE No clear explanation Amount of space is likely related to the status and position at work, the higher status the higher satisfaction Status may not be related to performance Changes to indoor environmental parameters easier “correlated” (memorized) by individuals with work performance than building features 24-10-2012
  24. 24. IMPLICATIONS Present results can guide building users, operators and employers in making decisions on how working indoor environment can be improved most effectively by selecting these parameters which promote comfort and working morale at the most 24-10-2012
  25. 25. Productivity gain of just 10% would offset the full running and installation costs Although there is some level of uncertainty to which extent IEQ affects productivity even improvements <1% are COST-EFFECTIVETHE EFFECTS ARE SUFFICIENTLY HIGH TO PROMOTEINVESTMENTS IN HIGH INDOOR ENVIRONMENTAL QUALITY Source: Wargocki and Seppänen (2006); Building Value, Energy Design Guidelines 24-10-2012 for State BuildingsOffice of the State Architect, California (1976
  26. 26. The primary purpose ofoffice building is to provide an optimalconditions for work and not to conserve energy 24-10-2012
  27. 27. BUILDING CERTIFICATION SCHEMES, LEED Provide a framework to design and build green buildings as well as to assess sustainable building performance. Is voluntary, though considered prestigious. Have been on the construction market for the last 15 years and are not anymore a niche segment. LEED Section Possible Points Sustainable sites 26 Points Water efficiency 10 Points Energy and atmosphere 35 Points Materials and resources 14 Points Indoor environmental Quality 15 Points Total 100 Points Innovation in Design 6 Points Regional priority 4 Points 24-10-2012
  28. 28. BUILDING CERTIFICATION SCHEMES, BREEAMBREEAM adopts a ‘balanced score-card’ approach to the assessment and rating of buildingperformance; to achieve a particular level of performance the majority of BREEAM credits can betraded.BREEAM sets minimum standards of performance in key areas like energy, water, waste etc. 24-10-2012
  29. 29. THANK YOU, QUESTIONS? 24-10-2012
  30. 30. Thank youpaw@byg.dtu.dk 24-10-2012

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