providing better indoor environmental quality brings economic
TRANSCRIPT
CLIMA 2007 ConferenceJune 2007
William Fisk Olli Seppanen
Providing Better Indoor Environmental Quality Brings Economic Benefits*
Lawrence Berkeley National Laboratory
Helsinki University of Technology
*with significant contributions from Pawel Wargocki and colleagues at the Danish Technical University
How Better IEQ Can Improve Health & Productivity
Superior Work Performance Economic
Benefits
Better Health Reduced Health Care Costs
Less Absence
•Thermal state• Hearing and concentration
•Vision• Mood
•Mental performance
Improved Indoor Environmental
Quality
Better design, construction,
commissioning & O&M
The Costs of People Overshadow Building Costs
050
100
Rel
ativ
e C
ost
Energy
Maintenance
Rent
Salaries &Benefits
Significance
Very small percentageimprovements in work performance will pay for large percentage increases in operation and maintenance costs.
Source : Woods (1989) Occupational Medicine 4: 753-770
Health Care Costs Are Substantial
0
500
1000
1500
2000
2500
3000
3500
4000
4500
$ B
illio
ns
EmployeeCompensation
Total HealthExpenditure
Private Sector HealthInsurance
Commercial BuildingEnergy
*U.S. Data from 1995 or 1996
How the Impact of IEQ on Health and Performance Has Been Studied
Experimental modifications of temperature, ventilation rates, pollutant sources, etc. in laboratory, office building, call center, or classroom
Speed, accuracy of simulated work or simulated school workSpeed of interaction with call center clients plus information processingChange in prevalence of a health outcome
Cross sectional surveys of large numbers of offices or classrooms with natural building-to building variability in ventilation rate, temperature, or another IEQ parameter
Surveys of health symptomsRecording of absence daysPerformance on academic achievement testsClinical documentation of cases of disease
Benefits of Better Control
of Indoor Temperature
% Change in performance per 1 oC increase in temperature: Results of 24 studies
-10
010
20
Del
ta P
%/C
15 20 25 30 35
Temperature (C)
rep orted in each study
composite weighted
90 % CI of composite weighted
sample size wei gh ted
un weighted
Unweighted
Sample-size weighted
Sample size & outcome weighted
% In
crea
se in
Per
form
ance
per
1 o C
Mostly > 0
Mostly < 0
Relative Work Performance vs. Temperature(maximum performance at at 21.8 oC, 72 oF )
.8.8
5.9
.95
1
Rel
ativ
e P
erfo
rman
ce
15 20 25 30 35
Temperature (°C)
Performance Reduction Is Statistically
Significant Where Shaded Green
Estimated Economic Value of Work Performance Changes from 1 oC (1.8 oF) Shift
in Temperature Toward Optimum
Temp. Change Increase in Performance
Annual Economic Benefit Per Worker*
19 to 20 oC66.2 to 68 oF
0.9%680 €
$90020 to 21 oC
68 to 69.8 oF0.4%
300 €$400
23 to 22 oC73.4 to 71.6 oF
0.3%230 € $300
24 to 23 oC75.2 to 73.4 oF
0.6%460 € $600
*Assuming 760000 € ($100K) cost per worker for salaries and benefits
Temperature and School Work
70
80
90
100
110
120
18 20 22 24 26Temperature
Nor
mal
ized
per
form
ance
(spe
ed)
oC
%
R2=0.46; P<0.001
School Work Speed is Affected by Temperature
Source: Wargocki and Wyon, ASHRAE Journal, October 2006
Temperature and School WorkSchool Work Accuracy is Not Significantly Affected by Temperature
70
80
90
100
110
120
18 20 22 24 26Temperature
Nor
mal
ized
per
form
ance
(err
ors)
oC
%
R2<0.01; P<0.99
Source: Wargocki and Wyon, ASHRAE Journal, October 2006
Avoiding High Temperatures can also reduce Sick Building Syndrome (SBS) Symptoms
Relative risk for SBS-symptoms per degree C increase in temperature
00.20.40.60.8
11.21.41.6
20 21 22 23 24 25
Average temperature oC
RR
for S
BS
per o C
No effect
20% increase in symptoms
Example Benefit-Cost Analyses of Cooling a Helsinki Office Building
Factor Base Case
Mechanical
Cooling
Increased Operation
Time (No Mech. Cooling)
Increased Outdoor Air
Flow (No Mech. Cooling)
Increased annual energy plus first cost per person, €
-- 54 6.3 95
Effective lost work hours per person-year, h 21.2 15.5 12.6 6.5
Value of lost work hours per person-year, € 686 501 408 211
Value of improved work, € -- 184 278 475
Total annual savings per person, €
-- 131 272 380
Source: Wargocki et. al (2006) REHVA Guidebook 6 [65000 € per employee-year]
Importance of Building
Ventilation*
*outdoor air supply
% Increase in work performance per 10 L/s-person increase in ventilation rate
-4-2
02
46
Del
ta P
%/(1
0 L/
s-pe
rson
)
0 10 20 30 40 50
Ventilation Rate (L/s-person)
reported in each studycomposite weighted
95% CI of composite weighted
90% CI of composite weighted
sample size weighted
unweighted
Unweighted
Sample-size weighted
Sample size & outcome weighted
Perf
orm
ance
Cha
nge
( %)
Ventilation Rate L/s-person
90% CI
95% CI
1 L/s = 2 cfm
Performance relative to performance with 6.5 L/s-person (13 cfm/person)
1
1.01
1.02
1.03
1.04
1.05
0 10 20 30 40 50
Ventilation Rate (L/s per person)
Rel
ativ
e W
ork
Perf
orm
ance
Current code min. for most U.S. offices
Current code min. for most U.S. schools
Result of Analyses of 8 Studies with 24 Total Data Points
RP = (5.56 x 10-8) V.3–(1.48 x 10-5) V 2 + (1.49 x 10-3) T + 0.983
Source: Seppanen, Fisk, Lei-Gomez (Indoor Air Journal 2005)
Ventilation Rates and Performance in SchoolsResults of a Danish Study* - Work Speed
*Wargocki and Wyon, ASHRAE Journal, October 2006
School Work Speed Increases with Ventilation Rate
70
80
90
100
110
120
0 2 4 6 8 10
Outdoor air supply rate
Nor
mal
ized
per
form
ance
(spe
ed)
L/s/person
%
R2=0.43; P<0.001
Ventilation Rates and Performance in SchoolsResults of a Danish Study* - Work Errors
*Wargocki and Wyon, ASHRAE Journal, October 2006
School Work Errors Not Significantly Affected by Ventilation Rate
70
80
90
100
110
120
0 2 4 6 8 10
Outdoor air supply rate
Nor
mal
ized
per
form
ance
(erro
rs)
L/s/person
%
R2=0.02; P<0.30
Decrease in Respiratory Illness or Absence With Increased Ventilation Rates
Source: Fisk Annual Rev. E&E 2000
0
10
20
30
40
50
60
70
1
% D
ecre
ase
HigherVent. Rate
inBarracks
1000 ppmless CO2
inClassrooms
HigherVent. Rate
More spacein Nursing
Home
Higher Vent. Rate
in Jail
Higher Vent.
Rate inOffices
Respiratory Illness
AbsenceAll reductions statistically significant
An example of data on ventilation and short term sick leave of office workers
Milton et al. (2000) Indoor Air Journal
Short term sick leave
0.0
0.5
1.0
1.5
2.0
12 L/s 24 L/s per person
1.45 %
2.00 %
1.5 daysper year
460 € ($600) per worker per year
with annual cost of 76000 € ($100000)40 buildings
in study
24 cfm 48 cfm per person
Sick Building Syndrome (SBS) Symptoms Increase With Decreased Ventilation rate
With lower ventilation rate:
20 of 27 studies found statistically significant increase in symptoms9 studies found >80% increase in prevalence of at least one symptom
Suggestion of benefits of increasing ventilation rate up to about 20 L/s-person
Source: Seppanen et al. Indoor Air 1999
Wor
kday
avg
. ∆C
O2
Odds Ratio
∆CO2 Reference100% increase in symptomsResults of a
Critical Review
Estimated Average Value of 5 L/s-person (10 cfm/person) Increase in Minimum
Ventilation RateBetter Work Performance
0.42% performance increase+ 320 € ($420) per worker per year*
Reduced Absence0.7 days per year +190 € ($250) per worker per year
*at 76000 € ($100K) annual salary plus benefits
Analyses of Energy and Non-Energy Benefits of Economizer Systems
Economizer BackgroundPurpose
Reduce HVAC energyMaintain minimum vent. rate
MethodUse outdoor air for cooling when less expensive than mechanical cooling
UsageCommon in large HVACConsidered too expensive for small HVAC
Outdoor Temp. 25 oC
100% Code Minimum
% O
utdo
or A
ir
No economizer
Estimated Annual Benefits of Economizer in a Washington D.C. Office Building
Estimated savings from increased work performance and reduced illness-related
absence is 50 times the energy cost savings,
Increase in annual average vent. rate 10 L/s-person Normally considered benefit Annual Energy cost savings
23 € ($30) per person
Normally neglected benefits Annual value of reduced absence* Annual value of productivity increase Total
320 € ($420) per person 760 € ($1000) per person 1080 € ($1420) per person
*estimated with disease transmission model calibrated with empirical data; 76000 € ($100K) annual compensation
Benefits of Indoor Pollutant Source Control
In Some Cases Removal of Pollutant Sources* has Increased Work Performance
*Unlike increased ventilation, pollutant source control usually consumes no energy
90
92
94
96
98
100 P<0.0001
sourcepresent
sourceabsent
sourceabsent
sourcepresent
3 10 30
Per
form
ance
(%)
L/s per person
Source was sample of carpet from a complaint building
Source: Pawel Wargocki, Danish Technical University
Possible Health-Related Economic Benefits of Eliminating Indoor Tobacco
Smoking in the U.S.
0.0E+00
4.0E+08
8.0E+08
1.2E+09
1.6E+09
Ann
ual C
ost p
er 1
06 Pop
ulat
ion
(€)
Mobidity Premature Death
Low
er B
ound
Low
er B
ound
Upp
er B
ound
Upp
er B
ound
Asthma
Bronchitis & PneumoniaBased on
estimated numbers and unit costs for health effectsPotential savings are higher in much of Europe because of higher smoking rates
Cost of Damp and Moldy Homes
Increase Risks in Damp or Moldy Homes
Cough 50%Wheeze 44%Asthma Development 30%Current Asthma 50%
Percentage of US Homes with Dampness or Mold
47%
Asthma Attributable to Home Dampness or Mold
4.6 million cases in U.S.
21%
Annual Health Cost of Asthma in U.S.
$16.8 Billion
Cost of Asthma Attributable to Home Dampness and Mold
21%
$3.5 Billion/ year in U.S.
Statistical Analyses of 33 Studies
Average of 6 Studies
Update of Two Prior Analyses
Workplace Dampness or Mold Also Increases Risks of Health Effects
Few studies, but nearly all find increased health effectsExamples
US office building with history of dampness: Current asthma was 120% > normal; adult onset of asthma was 230% > normal; 12% of sick leave attributable to respiratory symptoms at workWorking in moldy buildings in Finland 54% more adults developed asthmaIn 80 complaint US office buildings where drainage of cooling coil drain pan was poor, number of occupants with multiple asthma symptoms was increased by 260%*
*Note: Findings not replicated in analyses of data from 100 non-complaint office buildings
SummaryBetter temperature control Large potential financial benefits from improved work performance Increased ventilation rates up to ~ 20 L/s per person Large potential financial benefits from improved work performance and healthReducing indoor pollutant sources Substantial potential economic benefits from improved work performance and health
Without the energy needed for increased ventilationIndoor tobacco smoking and dampness deserve special attention
Potential economic benefits are large relative to costs of improved building design or operation
Benefit cost ratios can exceed 10Per employee savings up to 500 € per year
LimitationsUncertainty in magnitude of work performance and health improvements remains large
Improvements will vary among buildings and with type of work and with outdoor air qualityBenefits may be distributed among employer, building owner, employee
Research to date has not evaluated how IEQ affects high level cognitive performance such as critical decision makingCost benefit analyses have not accounted for true long term cost of energy use and climate change
Strongly encourage use of energy efficient technologies and practices to improve IEQ
We don’t yet understand why or how IEQ affects work performance
Motivation? Metabolic rate? Fatigue? Mental processing?
What You Can DoMake greater effort to design buildings that improve IEQ while saving energyImplement periodic or continuous commissioning to maintain building and HVAC performanceEducate building professionalsDevelop incentives for better IEQDevelop better methods to integrate energy conservation and IEQ improvement
Current PracticeAims for:
Adequate IEQ
Future PracticeAims for:IEQ that
MaximizesHealth &
Performance
Future PracticeAims for Large Energy Savings