how poor indoor environmental quality affects performance in...

How Poor Indoor Environmental Quality Affects

Performance in Work Environments and

Educational Buildings

Pawel Wargocki

paw@byg.dtu.dk

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)

QUESTIONS……

(paw@byg.dtu.dk)

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)