how poor indoor environmental quality affects performance in...
TRANSCRIPT
How Poor Indoor Environmental Quality Affects
Performance in Work Environments and
Educational Buildings
Pawel Wargocki
International Centre for Indoor Environment and EnergyDepartment of Civil EngineeringTechnical University of Denmark
THE CONTEXT
A framework for organisations is:
to measure how their building impacts on their most valuable asset, their employees
Source: World Green Building Council (2014)
TYPICAL BUSINESS OPERATING COSTS
Source: World Green Building Council (2014)
Based on a typical split of business operating costs:
modest gains in staff health and wellbeing can deliver significant financial savings
ENERGY &NON-ENERGY BENEFITS
ARE LOW HANGING FRUITS…
Source: curtbeavers.com
Source: ASHRAE Journal. 2013;55(3):46-52.
Building design and operation
Benefits Value of the benefit
Indoor Climate (IEQ)
Human responses
IEQ & HUMAN PERFORMANCE ABILITY TO PERFORM WORK
Source: Seppanen et al. (2005)
POTENTIAL MECHANISMS
IEQ
MOTIVATION
AROUSAL
SLEEP QUALITY
DISTRACTION & ATTENTION
NEUROBEHAVIORAL SYMPTOMS
ACUTE HEALTH SYMPTOMS
COGNITIVE PERFORMANCE
ABSENTEEISM
Source: Wargocki and Wyon (2017)
YERKES-DODSON LAW
Source: Yerkes and Dodson (1908)
ACUTE HEALTH SYMPTOMS AND PERFORMANCE
0.0023
0.0024
0.0025
0.0026
0.0027
0.0028
Office employees
Res
po
nse
tim
e-1
(1/
ms)
Continuous performance task
7.2% lower workrate (P<0.001)
Any SBS symptoms No SBS symptoms
0
0.3
0.6
0.9
1.2
1.5
1.8
Office employees
Err
or
rate
(%
)
Symbol-digit substitution task
30% higher error rate (P=0.07)
Any SBS symptoms No SBS symptoms
Source: Nunes et al. (1993)
SATISFACTION w/IEQ IMPORTANT FOR self-estimated PERFORMANCE
◼ Satisfaction with temperature, noise level and air quality = satisfaction with IEQ
◼ For example, ~15% increase in satisfaction with temperature would increase self-estimated job performance by ~1%
Importance for self-estimated performance
(regression coefficient)
Satisfaction with…
Source: Wargocki et al. (2012)
BUILDING FEATURES ARE IMPORTANT FOR SATISFACTION
◼ All important (p<0.05)
◼ The most important is 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
◼ Other important parameters include satisfaction with, noise level, visual privacy, colors and textures, etc.
◼ IEQ is not the most important
Importance for satisfaction/comfort
(odds ratio) Source: Frontczak et al. (2011)
EVIDENCE: OFFICE WORK
Elevated temperatures and poor air quality can affect performance of office work by 5% (laboratory) to 10%
(field)
Outdoor air supply rate (L/s per person)
Perf
orm
ance
0 10 20 30 40 50 60
1.01
1.00
1.02
1.03
1.04
1.05
VENTILATION AND PERFORMANCE OF OFFICE WORK
Source: Wargocki and Seppanen (2006)
Reduction in p
erf
orm
ance
Thermal sensation vote
Source: Lan et al. (2011)
THERMAL DISCOMFORT AND PERFORMANCE OF OFFICE WORK
EVIDENCE: SCHOOLWORK
Elevated temperatures and poor air quality can affect performance of schoolwork by children by over 15-20%
(field)
VENTILATION AND PERFORMANCE OF SCHOOLWORK
Source: Wargocki et al. (in the Press)
VENTILATION AND PERFORMANCE OF SCHOOLWORK
Source: Wargocki et al. (in the Press)
TEMPERATURE AND PERFORMANCE OF SCHOOLWORK
Source: Wargocki et al. (2019)
EVIDENCE: ABSENCE RATES
Poor IEQ increases the short term sick-leave by few
days, usually by 1-2 days
(SOME) UNSOLVED MATTERS AND CHALLENGES◼ Which pollutants can be associated with the
effects on performance?
◼ Are there any risks for performance associated with the use of adaptive thermal comfort model?
◼ Do green buildings promote performance?
◼ How can performance be reliably measured?
◼ Can the evidence on the effects of IEQ on performance be used in economic calculations?
◼ What is the combined effect of several IEQ parameters on performance?
◼ To which extent is performance affected by sleep quality that is affected by IEQ?
MEASURING FRAMEWORK FOR PERFORMANCE
◼ Physical: temperature, light level, CO2, noise, view
◼ Perceptual: physical comfort, job satisfaction (e.g., organizational commitment, engagement, corporate image)
◼ Financial: absenteeism, staff retention, revenue, medical symptoms and costs, complaints to building manager
Source: World Green Building Council (2014)
SLEEP AND HEALTHY LIVING
◼ People sleep over 20 years during their life time
◼ High quality sleep is vital for humans◼ Sleep improves cognitive performance
(memory and learning, and creativity), reduce health risks (dementia, Alzheimer’s disease), regulates hunger and fullness (obesity), reduce risks for car accidents, improves concentration and next-day performance
◼ People are getting more and more deprived of sleep, length (<7,5 hrs) and quality
◼ Is IEQ important?
Source: Walker (2017)
ECONOMIC BENEFITS
ESTIMATED BENEFITS OF IMPROVING IAQ IN U.S. BUILDINGS
◼ Total benefits - $62.7 billion/year
◼ Productivity gains = $54.7 billion
◼ Health-related savings = $8 billion: acute respiratory diseases = $1.2 billion; building-related illness (e.g. humidifier fever) = 0.8$ billion; IAQ illnesses including SBS = $6 billion)
◼ Total costs - $87.9 billion (initial)(in 40% of US buildings regarded unhealthy)+ 4.8 billion/year (maintenance)
RELIABLE IAQ METRIC IS A MUST
Source: Steinemann et al. (2016)
◼ Lack of IAQ metric or disagreement what should constitute IAQ metric is a significant barrier holding back innovation of IAQ conducive technologies, emergence of undocumented methods of measurements of IAQ claiming their high efficiency and authenticity, this all resulting in undervaluing the importance of IAQ in different credit schemes and compliance metrics related to built environment
OVERVIEW OF THE MOST OFTEN USED IAQ INDICES
◼ “Ventilation rate”
◼Carbon dioxide (CO2) [CO2 => Ventilation rate]
◼Acceptability of (or the percentage of dissatisfied with) indoor air quality
◼Total concentration of volatile organic compounds (TVOCs)
WHAT IS IEQ?
13 Green Building Certifications
European standard EN16798
7 European projects
14 Research articles
➢ Level(s)➢ OsmoZ➢ HQE➢ BREEAM➢ KLIMA➢ DGNB➢ ITACA➢ LiderA➢ BES
➢ CASBEE➢ LEED➢ WELL➢ NABERS
IEQ
Thermal environment
Indoor air quality
Acousticenvironment
Visual environment
19 indicators
39 indicators
20 indicators
12 indicators
Source: Wei et al. (in the press)HB2019 Asia, session 20
TAIL INDEX AS A METHODOF CLASSIFYING IEQ
Four components:◼ Thermal environment◼ Acoustic environment◼ Indoor air quality◼ Light – Luminous (visual)
environment
Overall IEQ:◼ I II III IV
Source: Wargocki et al., ASHRAE Journal December 2019
CONCLUSIONS AND “TAKE AWAYS”
◼ It is well documented that both thermal conditions and indoor air quality do affect the performance of office work and schoolwork.
◼ The mechanisms that mediate the effects of thermal conditions and indoor air quality on performance are surprisingly similar.
◼ Thermal conditions and indoor air quality tend to affect performance “across the board”, suggesting that it is the ability to concentrate and to think clearly that is affected, as this is common to all aspects of mental performance.
◼ It is not proven that subjective acceptance of indoor environmental conditions leads to optimal performance.
◼ Self-estimated performance is not an indicator of objectively measured performance.
◼ Motivation to perform well may itself be influenced by the indoor environment.
◼ Performance tests, however environmentally sensitive, may not in fact predict the performance of real work.
◼ The results obtained in laboratory experiments using paid subjects, simulated work and limited exposure times must be validated in field intervention experiments in which the performance of real work is monitored over time in normally functioning offices and schools.
Source: Wargocki and Wyon (2017)
DOES CO2 AFFECT (DECISION-MAKING) PERFORMANCE?
Source: Satish et al. (2012)
Source: Lan et al. (2013)
DOES ADAPTIVE THERMAL COMFORT CREATE RISK?
◼ Negative effects on performance will increase progressively with increasing temperature even if some subjective habituation takes place
◼ Acceptance (psychological) of undesirably warm thermal conditions should not be equated with achieving thermal comfort
◼ Physiological and mental changes occur in response to warmth: headache, fatigue, difficulty in thinking clearly, dry eyes, reduced oxygen saturation and increased CO2 levels in blood, and decreased tear film quality (all affecting performance)
◼ Objective adaptation due to behavioral changes may not always occur: inconveniently high velocities, dress code, etc.
◼ People can often avoid discomfort by working less => one of the most reported behavioral adjustments is to ’take a break’ or to slow down work speed that definitely leads to decreased performance at high temperatures
CONSEQUENCES OF ELEVATED TEMPERATURES
Source: Lan et al. (2011); Krogstadt et al. (1991)
GREEN BUILDINGS AND PERFORMANCE
◼ Review of 37 peer-reviewed papers and 12 white papers or reports
◼ Self-estimated productivity generally improved in green buildings (n=14); in n=3 studies reversed effect was seen.Size of the effect 2-16%.
◼ Sick-leave reduced at the level 5-39% but no information whther the effects remain at the same level after years of working or are temporary.
Source: da Silva (2015)
DISBELIEF ON BENEFITS FOR PRODUCTIVITY IN GB
◼ It was examined how building stakeholders (n=112, sample of convenience) incl. owners, tennats, operators, designers, understand impacts of IAQ and associated energy costs
◼ Benefits and costs of ventilation and filter upgrade (9.5 to 19 L/sp and MERV 6 to 11 (G3=>F6))
◼ Minorities of respondents indicated benefits for productivity (45%), absenteeism (23%) or health (39%)
◼ Estimates for energy costs were 2-4 times higher than the estimates obtained through modelling
◼ Respondents holding green building credentials were not more likely to affirm IAQ benefits and less willing to pay for it
◼ Majority doubted or were uncertain of benefits and oversetimate the costs so IAQ community must reconsider existing education and outreach strategies to bridge the gap of understanding about the real benefits and costs of IAQ
Source: Hamilton et al. (2015)
NO AGREED & VALIDATED METHOD FOR VERIFICATION◼ Absence from work or workstation, unavailability on the telephone.
◼ Health costs, including sick leave (absenteeism), accidents and injuries.
◼ Interruptions to work, observed downtime.
◼ Controlled independent judgments of work quality and mood.
◼ Self-assessments of productivity.
◼ Component skills, task measures, speed and accuracy of work, for instance using simulated office work comprising arithmetical calculations, proof-reading and creative thinking, as well as tasks embedded in normal office work or schoolwork.
◼ Output from pre-existing work groups and existing company measures such as talk-time in call centers or claim handling time in insurance companies.
◼ Cost for the product of service.
◼ Exchanging output in response to graded reward.
◼ Voluntary overtime or extra time.
◼ Staff turnover.
◼ Cycle time from initiation to completion of process;.
◼ Multiple measures at all organizational levels.
◼ Individual measures of performance, health and well-being at work.
◼ Development of measures and patterns of change over time.
◼ Diagnostic psychological tests of short duration examining specific skills such as psychomotor performance, memory, verbal ability, mood, perceptual ability, etc., used normally to study the effects of drugs, sleep deprivation and relatively strong stressors;
◼ Physiological measures such as cerebral blood flow, measures of voice quality and breathing patterns.
MEASUREMENTS OF SELF-ESTIMATED PERFORMANCE
On the following 5 scales, please rate how you have been working this past week:
◼ The work seemed:Very Easy --------- Very Hard
◼ My level of effort was: Low ---------------- High
◼ The time pressure was:Low --------------- High
◼ I worked at: 0 -- 100% of my full capacity
◼ My performance was:Poor -------------- Excellent
SELF-ESTIMATED PERFORMANCE
IS NOT EQUAL TOPERFORMANCE MEASURED OBJECTIVELY
Source: Clausen and Wyon (2008)
REAL WORK DATA ARE NECESSARY
Source: Wargocki and Wyon (in the Press)
(SOME) UNSOLVED MATTERS AND CHALLENGES◼ Which pollutants can be associated with the
effects on performance?
◼ Are there any risks for performance associated with the use of adaptive thermal comfort model?
◼ Do green buildings promote performance?
◼ How can performance be reliably measured?
◼ Can the evidence on the effects of IEQ on performance be used in economic calculations?
◼ What is the combined effect of several IEQ parameters on performance?
◼ To which extent is performance affected by sleep quality that is affected by IEQ?
BEDROOM IEQ IN BUILDINGS TODAY
◼ Split AC in the Tropics reduce temperature and RH but reduce air quality due to need to conserve energy
◼ Housing insulation conserve energy but increase bedroom temperatures during summer
◼ CO2 levels in bedroom reach 5,000 ppm indicating very poor ventilation
Source: Bekö et al. (2010); Sekhar & Goh (2011)
TEMPERATURE AND SLEEP
◼ It is difficult to fall asleep and to stay asleep when the bedroom is too cold or too hot
◼ There is no single temperature that is ideal at all stages of the night
◼ Sleep quality seems to be enhanced when bedroom temperatures are warm when falling asleep and when waking but cool in between
Source: Pan et al. (2014); Lan et al. (2016)
IAQ AND SLEEP
Source: Zhou et al. (2014); Strøm-Tejsen et al. (2016)
Baseline(CO2 1620-3300 ppm)
Ge
ne
ral s
leep
qu
alit
y sc
ore
Improved vent.(CO2 795-935 ppm)
◼ Both sleep quality and next-day performance can be negatively affected when the outdoor air supply rate to the bedroom is reduced
◼ A small current of fresh air to the breathing zone seems to improve sleep quality
MEASUREMENTS OF PERFORMANCE
Laboratory
◼ Physiological indicators
◼ Psychological tests
◼ Component skills (text typing, arithemtical calculations, proof-reading, logical thinking)
◼ Self-estimated fatigue, neurobehavioral symptoms and performance
Field
◼ Existing measures (operator time in call centres, claim processing time)
◼ Self-estimated fatigue, neurobehavioural symptoms and performance
◼ Absence rates
TEMPERATURE AND PERFORMANCE OF OFFICE WORK
15 20 25 30 350.75
0.80
0.85
Temperature (°C)
0.90
0.95
1.00
Perf
orm
ance
Source: Seppanen et al. (2005)
Source: Hongisto et al. (2005)
NOISE AND PERFORMANCE OF OFFICE WORK
SPEECH TRANSMISSION INDEX
LO
SS
OF
PR
OD
UC
TIV
ITY
(%
)
MEASUREMENTS OF PERFORMANCE OF SCHOOLWORK
Laboratory
◼ N/A
Field
◼ Psychological tests
◼ Typical school tasks (math and language based)
◼ Standardized (national) tests
◼ Absence rates
70
80
90
100
110
120
18 20 22 24 26
Per
form
ance
Temperature
oC
%
8%
(2-4% per 1oC
Source: Wargocki and Wyon (2012)
TYPICAL SCHOOL TASKS CLASSROOM TEMPERATURE
85
90
95
100
105
110
0 2 4 6 8 10
Per
form
ance
(sp
eed)
Outdoor air supply rate
L/s/person
%
2x
8%
(14%)
Source: Wargocki and Wyon (2012)
TYPICAL SCHOOL TASKS CLASSROOM VENTILATION
40
50
60
70
80
90
0 2 4 6 8 10
% o
f st
ud
ents
wh
o p
asse
d t
he
test
Outdoor air supply rateL/s/person
%
Reading
Math
15%
(3% per 1 L/sp)
2x
Source: Haverinen-Shaughnessy et al. (2013)
STANDARDIZED TESTSCLASSROOM VENTILATION
Source: Haverinen-Shaughnessy and Shaughnessy (2015)
STANDARDIZED TESTSCLASSROOM TEMPERATURE
SCHOOLWORKNOISE AND DAYLIGHT
◼ Text comprehension and memory were negatively affected by increased noise from airplanes; the effect was linear
◼ There were no strong effects of traffic noise (cars) on the performance of schoolwork – cognitive tasks, only episodic memory was slightly affected
◼ School grades in elementary schools were improved by 21% for pupils in classes with much daylight compared with classes with least daylight
Source: Heschong (2002); Stansfeld et al. (2005)
Re
du
ctio
n in
sic
k-d
ays
Air change rate (1/h)
0 1 2 3 40
0.2
0.4
0.6
0.8
1.0
Source: Wargocki and Seppanen (2006)
SHORT-TERM SICK-LEAVE AND VENTILATION
**
Source: Mendell et al. (2013)
1-1.5% reduction in absence rate per 1 L/sp
ABSENCE RATESCLASSROOM VENTILATION
ARE THE EFFECTS CAUSED BY CO2, BIOEFFLUENTS, BOTH?
Source: Zhang et al. (2016)
0.94
0.96
0.98
1
1.02
1.04
1.06
1.08
1.1In
crea
se in
pro
du
ctiv
ity
Old building New buildingNew building
No individual control With individual control
INDIVIDUAL CONTROL IMPROVED CLAIM PROCESSING BUT NOT SELF-
ESTIMATED PERFORMANCE
Source: Kroner et al. (1992)