Fisk William, Seppänen Olli. Providing Better Indoor Environmental

Providing Better Indoor Environmental
Quality Brings Economic Benefits*
CLIMA 2007 Conference
June 2007
William Fisk
Lawrence Berkeley
National Laboratory
Olli Seppanen
Helsinki University of
Technology
*with significant contributions from Pawel Wargocki and colleagues at
the Danish Technical University
How Better IEQ Can Improve Health &
Productivity
•Thermal state
• Hearing and concentration
•Vision
• Mood
•Mental performance
Better design,
construction,
commissioning &
O&M
Improved Indoor
Environmental
Quality
Better Health
Superior Work
Performance
Less
Absence
Reduced Health
Care Costs
Economic
Benefits
0
R e la tiv e C o s t
50
Very small
percentage
improvements in
work
performance will
pay for large
percentage
increases in
operation and
maintenance
costs.
100
The Costs of People Overshadow
Building Costs
Significance
Source : Woods (1989) Occupational Medicine 4: 753-770
Energy
Maintenance
Rent
Salaries &
Benefits
Health Care Costs Are
Substantial
4500
$ Billions
4000
3500
3000
2500
2000
1500
Employee
Compensation
Total Health
Expenditure
Private Sector Health
Insurance
Commercial Building
Energy
1000
500
0
*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 work
Speed of interaction with call
center clients plus information
processing
Change in prevalence of a
health outcome
Surveys of health symptoms
Cross sectional surveys of
large numbers of offices or
classrooms with natural
building-to building variability
in ventilation rate, temperature,
or another IEQ parameter
Recording of absence days
Performance on academic
achievement tests
Clinical documentation of
cases of disease
Benefits of
Better Control
of Indoor
Temperature
20
Unweighted
rep orted in each study
compos ite weighted
Sample-size weighted
90 % CI of c ompos ite weighted
sample
siz e w
ei gh &
ted outcome
Sample
size
un weighted
weighted
0
10
Mostly > 0
Mostly < 0
-10
% Increase inDelta
Performance
P%/C per 1 oC
% Change in performance per 1 oC increase
in temperature: Results of 24 studies
15
20
25
Tempe rature (C)
30
35
Relative Work Performance vs. oTemperature
o
.95
.9
.85
Performance
Reduction Is
Statistically
Significant Where
Shaded Green
.8
Relative Performance
1
(maximum performance at at 21.8 C, 72 F )
15
20
25
Temperature (°C)
30
35
Estimated Economic Value of Work
Performance Changes from 1 oC (1.8 oF) Shift
in Temperature Toward Optimum
Temp. Change
19 to 20 oC
oF
66.2 to 68
20 to 21 oC
oF
68 to 69.8
23 to 22 oC
oF
73.4 to 71.6
24 to 23 oC
75.2 to 73.4
oF
Increase in
Performance
0.9%
0.4%
0.3%
0.6%
Annual Economic
Benefit Per Worker*
680 €
$900
300 €
$400
230 €
$300
460 €
$600
*Assuming 760000 € ($100K) cost per worker for salaries and benefits
Temperature and School Work
School Work Speed is Affected by Temperature
Normalized performance
(speed)
%
120
R2=0.46; P<0.001
110
100
90
80
70
18
20
22
24
26
o
C
Temperature
Source: Wargocki and Wyon, ASHRAE Journal, October 2006
Temperature and School Work
School Work Accuracy is Not Significantly Affected by Temperature
Normalized performance
(errors)
%
120
110
100
90
R2<0.01; P<0.99
80
70
18
20
22
24
26
o
C
Temperature
Source: Wargocki and Wyon, ASHRAE Journal, October 2006
Avoiding High Temperatures can also reduce Sick
Building Syndrome (SBS) Symptoms
RR for SBS per oC
Relative risk for SBS-symptoms per degree C
increase in temperature
1.6
1.4
1.2
1
0.8
0.6
0.4
0.2
0
20% increase in symptoms
No effect
20
21
22
23
Average temperature oC
24
25
Example Benefit-Cost Analyses of
Cooling a Helsinki Office Building
Factor
Increased annual energy
plus first cost per
person, €
Effective lost work
hours per person-year, h
Value of lost work
hours per person-year, €
Value of improved
work, €
Total annual savings
per person, €
Increased
Increased
Mechan Operation Outdoor Air
Base
Flow
Time
ical
Case
Cooling (No Mech. (No Mech.
Cooling)
Cooling)
--
54
6.3
95
21.2
15.5
12.6
6.5
686
501
408
211
--
184
278
475
--
131
272
380
Source: Wargocki et. al (2006) REHVA Guidebook 6 [65000 € per employee-year]
Importance of
Building
Ventilation*
*outdoor air supply
Unweighted
reported in each study
6
composite weighted
Sample-size weighted
95% CI of composite weighted
4
90% CI of composite weighted
Sample
size & outcome
sample size weighted
weighted
-2
0
2
unweighted
90% CI
95% CI
-4
Delta P%/(10 Change
L/s-person) (%)
Performance
% Increase in work performance per 10 L/sperson increase in ventilation rate
0
10
20
30
40
Ventilation Rate
Ventilation
Rate(L/s-person)
L/s-person
1 L/s = 2 cfm
50
Performance relative to performance with
6.5 L/s-person (13 cfm/person)
Result of Analyses of 8 Studies with 24 Total Data Points
Relative Work
Performance
1.05
Current code min.
for most U.S.
schools
1.04
1.03
RP = (5.56 x 10-8) V.3
–(1.48 x 10-5) V 2 +
(1.49 x 10-3) T + 0.983
1.02
Current code min.
for most U.S.
offices
1.01
1
0
10
20
30
40
50
Ventilation Rate (L/s per person)
Source: Seppanen, Fisk, Lei-Gomez (Indoor Air Journal 2005)
Ventilation Rates and Performance in Schools
Results of a Danish Study* - Work Speed
School Work Speed Increases with Ventilation Rate
Normalized performance
(speed)
%
120
110
100
90
2
R =0.43; P<0.001
80
70
0
2
4
6
8
10 L/s/person
Outdoor air supply rate
*Wargocki and Wyon, ASHRAE Journal, October 2006
Ventilation Rates and Performance in Schools
Results of a Danish Study* - Work Errors
School Work Errors Not Significantly Affected by Ventilation Rate
Normalized performance
(errors)
%
120
110
100
90
2
R =0.02; P<0.30
80
70
0
2
4
6
8
10 L/s/person
Outdoor air supply rate
*Wargocki and Wyon, ASHRAE Journal, October 2006
Decrease in Respiratory Illness or Absence
With Increased Ventilation Rates
70
% Decrease
60
50
All reductions
statistically
significant
Respiratory Illness
Absence
40
30
20
10
0
1
Higher
Vent.
Rate
in
Barracks
1000 ppm
less CO2
in
Classrooms
Higher
Vent. Rate
More space
in Nursing
Home
Higher
Vent.
Rate
in
Jail
Source: Fisk Annual Rev. E&E 2000
Higher
Vent.
Rate in
Offices
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
2.00 %
2.0
1.5 days
per year
1.5
40 buildings
in study
1.45 %
1.0
0.5
0.0
12 L/s
24 cfm
24 L/s per person
48 cfm per person
460 € ($600) per
worker per year
with annual cost of
76000 € ($100000)
Sick Building Syndrome (SBS) Symptoms
Increase With Decreased Ventilation rate
† With lower ventilation
rate:
†
†
20 of 27 studies found
statistically significant
increase in symptoms
9 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
Workday avg. ∆CO2
∆CO2 Reference
Results of a
Critical Review
100%
increase in
symptoms
Odds Ratio
Source: Seppanen et al. Indoor Air 1999
Estimated Average Value of 5 L/s-person
(10 cfm/person) Increase in Minimum
Ventilation Rate
†Better Work Performance
†
0.42% performance increase
†
+ 320 € ($420) per worker per
year*
†Reduced Absence
†
0.7 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 Background
Purpose
Method
† Use outdoor air for cooling
when less expensive than
mechanical cooling
Usage
† Common in large HVAC
† Considered too expensive
for small HVAC
% Outdoor Air
† Reduce HVAC energy
† Maintain minimum vent.
rate
100%
Code Minimum
No economizer
Outdoor Temp.
25 oC
Estimated Annual Benefits of Economizer in a
Washington D.C. Office Building
Increase in annual average vent. rate
Normally considered benefit
Annual Energy cost savings
Normally neglected benefits
Annual value of reduced absence*
Annual value of productivity increase
Total
10 L/s-person
23 € ($30) per person
320 € ($420) per person
760 € ($1000) per person
1080 € ($1420) per person
Estimated savings from increased work performance and
reduced illness-related
absence is 50 times the energy cost savings,
*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
Performance (%)
100
P<0.0001
Source was sample of carpet from a
complaint building
98
96
94
92
90 source source
source source
present absent present absent
3
10
30
L/s per person
Source: Pawel Wargocki, Danish Technical University
0.0E+00
Mobidity
Upper Bound
4.0E+08
Lower Bound
8.0E+08
Upper Bound
1.2E+09
Bronchitis &
Pneumonia
Asthma
Lower Bound
1.6E+09
(€)
† Based on
estimated
numbers and
unit costs for
health effects
† Potential
savings are
higher in much
of Europe
because of
higher smoking
rates
Annual Cost per 106 Population
Possible Health-Related Economic
Benefits of Eliminating Indoor Tobacco
Smoking in the U.S.
Premature
Death
Cost of Damp and Moldy Homes
Statistical Analyses of 33 Studies
Increase Risks in Damp or
Moldy Homes
Cough
50%
Wheeze
44%
Asthma Development 30%
Current Asthma
50%
Average of 6 Studies
Percentage of US Homes with
Dampness or Mold
Asthma Attributable to
Home Dampness or Mold
4.6 million cases in U.S.
21%
47%
Update of Two Prior Analyses
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.
Workplace Dampness or Mold Also
Increases Risks of Health Effects
Few studies, but nearly all find increased health effects
† Examples
†
†
†
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 work
Working in moldy buildings in Finland Æ 54% more adults
developed asthma
In 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
Summary
† Better temperature control Æ Large potential
financial benefits from improved work
performance
† Increased ventilation rates up to ~ 20 L/s per
person Æ Large potential financial benefits from
improved work performance and health
† Reducing indoor pollutant sourcesÆ Substantial
potential economic benefits from improved work
performance and health
†
†
Without the energy needed for increased ventilation
Indoor 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 10
Per employee savings up to 500 € per year
Limitations
† Uncertainty in magnitude of work performance and
health improvements remains large
†
†
Improvements will vary among buildings and with type of
work and with outdoor air quality
Benefits 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 making
† Cost 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 Do
Current Practice
Aims for:
Adequate IEQ
Future Practice
Aims for:
Future Practice
IEQ that
Aims for Large
Maximizes
Energy Savings
Health &
Performance
‰ Make greater effort to
design buildings that
improve IEQ while saving
energy
‰ Implement periodic or
continuous commissioning
to maintain building and
HVAC performance
‰ Educate building
professionals
‰ Develop incentives for
better IEQ
‰ Develop better methods to
integrate energy
conservation and IEQ
improvement