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Transcript of ASHRAE Distinguished Lecturer Talk · ASHRAE Distinguished Lecturer Talk ASHRAE India Chapter, ......
2/17/2013
Prof Chandra Sekhar, National University of Singapore, ASHRAE DL Event, Delhi, 21 Feb 2013 1
ASHRAE Distinguished Lecturer Talk
ASHRAE India Chapter, New DelhiASHRAE India Chapter, New DelhiEDUSAT HALL, EDUSAT HALL, G.B.PantG.B.Pant PolytechnicPolytechnic
February 21, 2013February 21, 2013
Chandra SekharPhD, Fellow ASHRAE, Fellow ISIAQ
Department of Building, School of Design and EnvironmentDepartment of Building, School of Design and Environment
1.Describe an integrated IAQ-Energy audit
Learning Objectives
methodology2. Interpret the IAQ and Energy audit data from
case studies in a hot and humid climate3.Describe two Decoupled Ventilation systems -
Single Coil Twin Fan & Personalised Ventilation4 Quantify the enhanced IAQ and Energy4.Quantify the enhanced IAQ and Energy
performance of these two decoupled ventilation systems
2/17/2013
Prof Chandra Sekhar, National University of Singapore, ASHRAE DL Event, Delhi, 21 Feb 2013 2
Integrated IAQ-Energy Audit Methodology
OBJECTIVES OF AUDITOBJECTIVES OF AUDIT
• Establish status of Indoor Air• Establish status of Indoor Air Quality (IAQ)
• Identify strategies for improving IAQ
• Basis for developing an IAQ audit p g Qand management program
2/17/2013
Prof Chandra Sekhar, National University of Singapore, ASHRAE DL Event, Delhi, 21 Feb 2013 3
Figure 11 : A comparison of MALE and FEMALE Building Related Symptoms (Mean of all five buildings) - Here and Now (% )
35
40
45
nts
m
s
Total Female MaleStu
dy
0
5
10
15
20
25
30
35
Per
cen
tag
e o
f o
ccu
pan
exp
erie
nci
ng
sym
pto
m
Dryeye Blocknose Drythroat Dryskin Headache Lethargy Wateryeye Runnose Chesttight Flusymp Rash Otherion
nai
re
Sekhar SC, KW Tham and KWD Cheong, Indoor Air Quality And Energy Performance of Air-conditioned Office Buildings In Singapore, Indoor Air – International Journal of Indoor AirQuality and Climate, 2003, Volume 13, Issue 4, pp. 315-331.
Building Related Symptoms
Total 30 26 29 30 17 27 7 13 10 15 10 3
Female 40 32 35 42 21 33 7 16 12 19 13 5
Male 14 19 14 10 10 18 6 11 8 8 4 0
Qu
esti
Acceptability of Indoor Air Quality (% Dissatisfied) Acceptability of Indoor Air Quality (% Dissatisfied) -- A Comparison of Singapore and EU studiesA Comparison of Singapore and EU studies
35.0%
40.0%
45.0%
10.0%
15.0%
20.0%
25.0%
30.0%
% D
iss
ati
sfi
es
0.0%
5.0%
Germ
any
Singap
ore
Switzer
land
Finlan
d
Franc
e
United
King
dom
The N
ethe
rland
s
Greec
e
Denm
ark
Norway
Countries
2/17/2013
Prof Chandra Sekhar, National University of Singapore, ASHRAE DL Event, Delhi, 21 Feb 2013 4
DIMENSIONS OF INDOOR AIR QUALITY
rem
ents
et
ers
• Chemical• Biological• Physical
ve M
easu
Q p
aram
eO
bje
ctiv
–IA
Q
Continuous Monitoring
• Chemical Contaminant Profiles (5 - 7 days)
• Ventilation Characteristics (Air Exchange Rates) (1 evening)(1 evening)
• Particulate Profiles (2 days per location)
2/17/2013
Prof Chandra Sekhar, National University of Singapore, ASHRAE DL Event, Delhi, 21 Feb 2013 5
Spot Measurements• Total Bacteria,
Yeasts & MoldsTemperature• Temperature, Relative Humidity, Air Movement
• PM10 Particulate levelsTotal time taken 30• Total time taken :30 minutes per location
VENTILATION STUDIES IN VENTILATION STUDIES IN NINE AIRNINE AIR--CONDITIONEDCONDITIONEDre
men
ts
amet
ers
NINE AIRNINE AIR CONDITIONED CONDITIONED OFFICE BUILDINGS IN OFFICE BUILDINGS IN
SINGAPORESINGAPORE
ve M
easu
atio
n p
ara
Period of Study : 1993 Period of Study : 1993 -- 19971997
Ob
ject
iv–
Ven
tila
A/P Chandra Sekhar, National University of A/P Chandra Sekhar, National University of SingaporeSingapore
2/17/2013
Prof Chandra Sekhar, National University of Singapore, ASHRAE DL Event, Delhi, 21 Feb 2013 6
Factors affecting ventilation performance
- space layout- fresh air quantityfresh air quantity- supply diffusers and return grilles Indoor air flow pattern- Short circuiting- Piston flow
Perfect mixing- Perfect mixing Flow pattern affects Indoor Air Quality (IAQ) Building energy consumption
A/P Chandra Sekhar, National University of A/P Chandra Sekhar, National University of SingaporeSingapore
THE VENTILATION MODELA f i
VENTILATION CHARACTERISTICSVENTILATION CHARACTERISTICS
Age-of-airaverage amount of time elapsed since
molecules in a sample entered the building
measured by tracer gas techniques
"youngest" air found where the outdooryoungest air found where the outdoor air comes into the room –
"oldest" air found at any other point in the room
A/P Chandra Sekhar, National University of A/P Chandra Sekhar, National University of SingaporeSingapore
2/17/2013
Prof Chandra Sekhar, National University of Singapore, ASHRAE DL Event, Delhi, 21 Feb 2013 7
TRACER GAS MEASUREMENTSTRACER GAS MEASUREMENTS
AGE OF AIR VALUESAGE OF AIR VALUES
LOCAL MEAN AGE OF AIRLOCAL MEAN AGE OF AIR
ROOM AVERAGE AGE OF AIRROOM AVERAGE AGE OF AIR
AIR CHANGE RATEAIR CHANGE RATE
Air Exchange Effectiveness (also known as Air Exchange Effectiveness (also known as Ventilation Effectiveness)Ventilation Effectiveness)Ventilation Effectiveness)Ventilation Effectiveness)
type of tracers used usually colourless,
odourless, inert gases (e.g. SF6)
Important aspect of TG measurements
- can be made in occupied buildings
slope of the tracer gas concentration decay curve
Air Change per Hour (ACH)
Li Pl t S i L Pl t
Concentration-decay method
Gas
(p
pm
)
Linear Plot
ACH = ln(C ln(C )Gas
(p
pm
)
Semi Log Plot
C0, t0)
Time
Trac
er ACH = ln(C0 – ln(C1)
t
Time
Trac
er G
C1, t1)
A/P Chandra Sekhar, National University of A/P Chandra Sekhar, National University of SingaporeSingapore
2/17/2013
Prof Chandra Sekhar, National University of Singapore, ASHRAE DL Event, Delhi, 21 Feb 2013 8
Perfectly mixed air - datum for all three AEE parametersAEE = 1
Air Exchange Effectiveness
AEEG = 2.0 "perfect" displacement flow
AEEG < 1.0 shortcircuitingAEEG > 1.0 displacement flowG p
the greater the deviations from unity,
more pronounced are the two flow patternsA/P Chandra Sekhar, National University of A/P Chandra Sekhar, National University of
SingaporeSingapore
Figure 1 : Summary of Air Change per Hour (ACH) values
A
D
CC
Bu
ildin
g
0 1 2 3 4
ACH
2/17/2013
Prof Chandra Sekhar, National University of Singapore, ASHRAE DL Event, Delhi, 21 Feb 2013 9
Figure 5 : Comparison of Localised Air Exchange Effectiveness (AEEL) Values
C C
E E
A
C
E
C C
Bu
ildin
g
0 0 . 5 1 1 . 5 2
A
AEEL
A/P Chandra Sekhar, National University of A/P Chandra Sekhar, National University of SingaporeSingapore
8
6
Nordic Climate
Continental Europe
Mediterranean Europe
h-1
)
Zuraimi MS, Roulet C-A, Tham KW, Sekhar SC, David Cheong KW, Wong NH & Lee HK, 2004. “A comparative study of VOCs in Singapore and European Office Buildings”, Building and Environment, Volume 41, Issue 3, March 2006, Pages 316-329
6
4
2
Tro
pic
al
Clim
ate
Oce
anic
E
uro
pe
r ch
ang
e ra
tes
(h
SPO
RE
GR
EEC
E
UK
SW
ISS
GER
MAN
FR
AN
CE
FIN
LAN
D
NO
RW
AY
DEN
MAR
K
0
Ai
Air change rates (ACH) measured in the European and Singapore buildings studied
2/17/2013
Prof Chandra Sekhar, National University of Singapore, ASHRAE DL Event, Delhi, 21 Feb 2013 10
Energy Measurements
A/P Chandra Sekhar, National University of A/P Chandra Sekhar, National University of SingaporeSingapore
Summary of measured and computed parametersThermal Comfort, IAQ, Ventilation and Energy
2/17/2013
Prof Chandra Sekhar, National University of Singapore, ASHRAE DL Event, Delhi, 21 Feb 2013 11
Causes Pollutants Recommendations
Occupant Density Total BacteriaTotal Y&M
Occupant Density
AHU-installed Bacteria Killers
Fresh air filter into AHU
Particulate Better filtration
Replace carpets
Renovation - Close libraryPurging
Filtration(F/A Intake; AHU)
Downwash zone + Door mats at entrance
Replace carpetsTVOCs/
Formaldehyde
Fresh Air Provision
Renovation Purging
Filtration(F/A Intake; AHU)
Fresh Air Provision
Equipment(Photocopiers;
Computer Clusters)
Carpets
Demand Control VentilationDemand Control Ventilation
Photocopiers (separate exhaust)Computer clusters
Equipment(Photocopiers;
Computer Clusters)
Carpets
Carbon Dioxide
Energy Efficient Healthy BuildingsEnergy Efficient Healthy Buildings
• Single Coil Twin Fan System
• Personalised Ventilation System
2/17/2013
Prof Chandra Sekhar, National University of Singapore, ASHRAE DL Event, Delhi, 21 Feb 2013 12
Single Coil Twin Fan
2000 – To date
Single Coil Twin Fan(SCTF) Air-conditioning &Air distribution system
Sekhar, S.C., Uma Maheswaran, C.R., Tham, K.W, and Cheong K.W, 2004. Development of energy efficient single coil twin fan air-conditioning system with zonal ventilation control, ASHRAE Transactions, 2004, Vol. 110, Pt 2, pp 204-217 (Paper presented in Nashville, June 2004).
Cheyyar, R U M, S C Sekhar, K W Tham and K W Cheong, "Single coil twin fan air-conditioning and air distribution system -Towards the development of a mathematical model of the compartmented coil". HVAC&R RESEARCH - International Journal of Heating, Ventilating, Air-conditioning and Refrigerating Research, 12, no. 3c, pp 825-842 (Special Issue) (October 2006).
F/A VAV Fan
F.A Filter
F/A CompCoil
SCTF Air-conditioning and Air Distribution System(US and PCO Patents)
2000 - 2003
F/A VAV Box
R/A VAV Box
MixingBox
To other VAV Boxes In Other Zones
P
P
R/A
F/A
R/A Filter
R/A Comp Coil
R/A VAV R/A VAV Box
CO2 TR/A
S/A
Typical Zone VAV Box
CHWS
CHWR
Modulating Valve
By-pass Damper
VAV Fan
2/17/2013
Prof Chandra Sekhar, National University of Singapore, ASHRAE DL Event, Delhi, 21 Feb 2013 13
Comparison of Energy Consumption
14
W)
SCTF Prototype Findings
0
24
68
1012
14
Co
olin
g C
apac
ity
(kW
0
Conventional SCTF
Type of System
C
Outside AirO/A : ON CoilVAV System 1 : Coil Condition Curve O/A : OFF Coil
Space Condition
Return AirR/A : ON CoilVAV System 2 : Coil Condition CurveR/A : OFF Coil
Space Condition
10-15% energy savings
SCTF system for independent conditioning of fresh air and return air streams –A Psychrometric Performance
2/17/2013
Prof Chandra Sekhar, National University of Singapore, ASHRAE DL Event, Delhi, 21 Feb 2013 14
Field Trial –A Test-Bedding Project
The Enterprise Challenge(TEC) Grant2004 - 2007
Bldg TOP = June 2005SCTF Installed = June 2005
Air-conditioned = 2,750m2
Floor Area for SCTF system
DESIGN DATAF/A = 5,400 cmhR/A = 60,000 cmhCoil Cap = 86 kW (F/A)
233 kW (R/A)
Field Trial – A Test-Bedding Project
Conference Room
Meeting Room
SCTF AHU
Core
Return-duct mountedT & CO sensors
OpenPlan Space
F/A 12
3
4
Conference Room
Meeting Room
SCTF AHU
Core
Return-duct mountedT & CO sensors
OpenPlan Space
F/A 12
3
4
T & CO2 sensors
Staircase
Individual Offices
F/A
R/A12
5
T & CO2 sensors
Staircase
Individual Offices
F/A
R/A12
5
The Enterprise Challenge (TEC) Grant
2/17/2013
Prof Chandra Sekhar, National University of Singapore, ASHRAE DL Event, Delhi, 21 Feb 2013 15
roje
ctF
ield
Tri
al –
Test
-Bed
din
g P
r
9 ppm
A T
2/17/2013
Prof Chandra Sekhar, National University of Singapore, ASHRAE DL Event, Delhi, 21 Feb 2013 16
Temperature (Level 3)
182022242628
06
06
06
06
06
06
06
06
-1
-2
-2
T(C)
point 1
point 2
point 3
point 4
point 5
– Pro
ject
r te
mp
erat
ure
:
21.8
-23
.8
Cg
e =
23 C
06/2
6/0
06/2
6/0
06/2
7/0
06/2
8/0
06/2
8/0
06/2
9/0
06/3
0/0
06/3
0/0
2006
-7-
2006
-7-
2006
-7-
Time
Relative Humidity (Level 3)
606570
%)
point 1
point 2
Fie
ld T
rial
–A
Tes
t-B
edd
ing
P
Ind
oo
rra
ng
e A
vera
g
mid
ity
H
40455055
06/2
6/0
6
06/2
6/0
6
06/2
7/0
6
06/2
7/0
6
06/2
8/0
6
06/2
8/0
6
06/2
9/0
6
06/3
0/0
6
06/3
0/0
6
2006
-7-
1
2006
-7-
1
2006
-7-
2Time
RH(
%
point 3
point 4
point 5
A
Ind
oo
r re
lati
ve h
um
ran
ge
: 47
-54
%R
HA
vera
ge
= 5
0 %
RH
Energy consumption (W/m2)
40
50
60
70
80
mp
tio
n(W
/m2
)
Energy consumption (w/m2)
0
10
20
30
50:
00 A
M
50:
00
AM
50:
00
AM
50:
00
AM
50:
00
AM
50:
00 A
M
50:
00 P
M
50:
00 P
M
50:
00 P
M
50:
00 P
M
50:
00 P
M
50:
00 P
M
50:
00 A
M
50:
00
AM
50:
00
AM
50:
00
AM
50:
00
AM
50:
00 A
M
50:
00 P
M
50:
00 P
M
50:
00 P
M
50:
00 P
M
50:
00 P
M
50:
00 P
M
50:
00 A
M
50:
00
AM
50:
00
AM
50:
00
AM
50:
00
AM
50:
00 A
M
50:
00 P
M
50:
00 P
M
50:
00 P
M
50:
00 P
M
50:
00 P
M
50:
00 P
M
50:
00 A
M
En
erg
y c
on
su
m
3/22
/200
7 1
0:5
3/2
2/2
007
8:5
3/2
2/2
007
6:5
3/2
2/2
007
4:5
3/2
2/2
007
2:5
3/22
/200
7 1
2:5
3/21
/200
7 1
0:5
3/21
/20
07 8
:5
3/21
/20
07 6
:5
3/21
/20
07 4
:5
3/21
/20
07 2
:5
3/21
/200
7 1
2:5
3/21
/200
7 1
0:5
3/2
1/2
007
8:5
3/2
1/2
007
6:5
3/2
1/2
007
4:5
3/2
1/2
007
2:5
3/21
/200
7 1
2:5
3/20
/200
7 1
0:5
3/20
/20
07 8
:5
3/20
/20
07 6
:5
3/20
/20
07 4
:5
3/20
/20
07 2
:5
3/20
/200
7 1
2:5
3/20
/200
7 1
0:5
3/2
0/2
007
8:5
3/2
0/2
007
6:5
3/2
0/2
007
4:5
3/2
0/2
007
2:5
3/20
/200
7 1
2:5
3/19
/200
7 1
0:5
3/19
/20
07 8
:5
3/19
/20
07 6
:5
3/19
/20
07 4
:5
3/19
/20
07 2
:5
3/19
/200
7 1
2:5
3/19
/200
7 1
0:5
Time
Normalised Energy Consumption in terms of coil capacity (W/m2)– Compartmented Cooling Coil SCTF system (Level 3)
2/17/2013
Prof Chandra Sekhar, National University of Singapore, ASHRAE DL Event, Delhi, 21 Feb 2013 17
Zero Energy Building @ BCA Academy
2008 - 2011
F/A
F/A Filter
F/A CompCoil
F/A Fan speed
SCTF Compartmented Coil FCU
CO2
R/A
R/A Filter
R/A Comp Coil
R/A Fan speed
To S/A Diffusers
T
Tmix1+2
TRA
CO2RA
TZ1 - Zone Set-point Temperature(TRA, which will track TZ1 is used to control the speed of the R/A fan)
CHWS
CHWR
Modulating Valve
Zero Energy Building Project : FCU 1‐3 & 1‐4
CO2Z1 - Zone Set-point CO2 level(CO2RA which will track CO2Z1 is used to control the speed of the F/A fan)
2/17/2013
Prof Chandra Sekhar, National University of Singapore, ASHRAE DL Event, Delhi, 21 Feb 2013 18
SCTF vs Conventional VAV System
AHU 2‐1 AHU 3‐1 AHU 3‐2 AHU 3‐3
Design Recirculated Airflow [m3/h] 11484 4248 3600 5580Design Recirculated Airflow [m /h] 11484 4248 3600 5580
Design Fresh Airflow (F/A) [m3/h] 2268 396 900 720
SCTF System F/A(Ventilation Efficiency=1)
[m3/h] 2268 396 900 720
Conv VAV System F/A 3/Conv VAV System F/A(Ventilation Efficiency=0.8)
[m3/h] 2835 495 1125 900
SCTF System ‐ % F/A [%] 16.5 8.5 20 11.4
Conv VAV System ‐ % F/A [%] 20.6 10.7 25 14.3
AHU 2-1 AHU 3-1 AHU 3-2 AHU 3-3
IMPROVED FRESH AIR CONTROL = LESS ENERGY !!!
AHU 2 1 AHU 3 1 AHU 3 2 AHU 3 3
Baseline
cooling[kW] 14300 7930 5600 4530
Actual
cooling[kW] 12400 7530 3950 3890
g
Percent
difference *[%] 13.28 5.05 29.46 14.13
* SAVINGS FOR APRIL 2010.
2/17/2013
Prof Chandra Sekhar, National University of Singapore, ASHRAE DL Event, Delhi, 21 Feb 2013 19
2002 – To Date
Personalised Ventilation (PV) system
Personalised Ventilation(PV) System
Deliver fresh air directly to theOccupant breathing zone
Potential to enhance• Acceptability of ventilation• Acceptability of ventilation• Indoor Air Quality• Thermal comfort
2/17/2013
Prof Chandra Sekhar, National University of Singapore, ASHRAE DL Event, Delhi, 21 Feb 2013 20
Desk-mounted PV System i t t d ith
2002 - 2004
integrated with Ceiling Supply MV System
Sekhar S C N Gong K W Tham K W Cheong A K Melikov D P Wyon and P O Fanger "Findings of personalised
Gong, N, K W Tham, AK Melikov, DP Wyon, S C Sekhar and K W Cheong, "The acceptable air velocity range for local air movement in the Tropics". HVAC&R Research, International Journal of Heating, Ventilating and Air-Conditioning Engineers (ASHRAE), Vol 12, No. 4, pp 1065-1076, (October 2006). (United States).
Sekhar, S C, N Gong, K W Tham, K W Cheong, A.K. Melikov, D.P. Wyon and P.O. Fanger, Findings of personalisedventilation studies in a hot and humid climate". International Journal of Heating, Ventilating, Air-conditioning and Refrigerating Research (HVAC&R Research), Vol 11, no. 4
Experimental Protocol
• Ambient and PV air temperatures
• Thermal comfort parameters within the occupied zone
• Breathing temperature in the occupant breathing zone
• Concentration levels of various indoor pollutants
• SF6 tracer gas measurements - ventilation effectiveness
• Questionnaire responses
52
2/17/2013
Prof Chandra Sekhar, National University of Singapore, ASHRAE DL Event, Delhi, 21 Feb 2013 21
1 21.41.61.8
2io
n
ness
PV
WithoutPV
00.20.40.60.8
11.2
Ven
tila
tE
ffectiven
262
262
262
262
260
• Higher the Better• Saves ENERGY 6-23-15
6-26-15
6-20-7
6-23-7
6-0-15
Experimental conditions
Saves ENERGY
1.00
fort
y
With PV W/O PVVery Acceptable
-0.50
0.00
0.50
1 2 3 4 5 6 7 8 9 10 11
The
rmal
com
fac
cept
abili
ty
-1.00
Subjects
Mean responses of Thermal Comfort acceptability
Very Unacceptable
2/17/2013
Prof Chandra Sekhar, National University of Singapore, ASHRAE DL Event, Delhi, 21 Feb 2013 22
0 400.600.801.00
ab
ilit
y
with PV without PV
Very Acceptable
-0 80-0.60-0.40-0.200.000.200.40
1 2 3 4 5 6 7 8 9 10 11
IAQ
ac
ce
pta
-1.000.80
Subjects
Mean responses of IAQ acceptability
Very Unacceptable
PV system
C i d f h l f & IAQ iConsistent trends of thermal comfort & IAQ ratings
Observed – INCREASE with INCREASING PV flow rate
And DECREASING with INCREASING PV temps at
Ambient temp of 26 C
59
2/17/2013
Prof Chandra Sekhar, National University of Singapore, ASHRAE DL Event, Delhi, 21 Feb 2013 23
• A warmer space temperature, such as 26 C, accompanied by a
Energy savings occur due to
p p p y
PV air temperature of 23 C, implies that the space cooling load
is reduced in comparison with a conventional air-conditioning
system in which the space is typically maintained at 23 C.
• An absolute reduction in the total fresh air quantity provided
is possible as it is now directly supplied as inhaled air to theis possible, as it is now directly supplied as inhaled air to the
occupant breathing zone.
Practical Applications
Personalised Ventilation Systems
Practical Applications –
Challenges
Aesthetics
Possibilities
2/17/2013
Prof Chandra Sekhar, National University of Singapore, ASHRAE DL Event, Delhi, 21 Feb 2013 24
C ili M t d PV S t
2007 - 2009
Ceiling-Mounted PV System integrated with
Ceiling Supply MV System
Ceiling mounted PV System integrated with ambient MV system
YANG, B, Arsen Melikov and S C Sekhar, "Performance evaluation of ceiling mounted personalized ventilation system". ASHRAE Transactions 2009, Vol. 115, Part 2, pp 395-406. (United States).
Yang, B, S.C.Sekhar and Arsen Melikov, “Ceiling mounted personalized ventilation system integrated with a secondary air distribution system – A human response study in hot and humid climate” Indoor Air –
Yang, B and S C Sekhar, "Three dimensional numerical simulations of a hybrid fresh air and recirculated air diffuser for decoupled ventilation strategy". Building and Environment, (2007), Vol.42, Issue 5, pp 1975-1982. (United Kingdom).
secondary air distribution system A human response study in hot and humid climate . Indoor Air International Journal of Indoor Environment and Health (2010). Volume 20, no. 4 (2010): 309-319. (Denmark).
YANG, B, S C Sekhar and Melikov Arsen, "Ceiling mounted personalized ventilation system in hot and humid climate–An energy analysis". Energy and Buildings, (2010). (Switzerland).
2/17/2013
Prof Chandra Sekhar, National University of Singapore, ASHRAE DL Event, Delhi, 21 Feb 2013 25
CFD simulation
more fresh air is supplied directly into the breathing zone without mixing with recirculated air and much better IAQ in the occupied zone can be realized.
D
Xnl
Xnl
Vo
city nl
Xnl
X, V
Cen
tre-
line
Vel
oc
Xnl : Neutral Level under various scenarios
No BlockageOr thermal plume
Blockage (unheated manikin)
Blockage & Thermal Plume(heated manikin)
2/17/2013
Prof Chandra Sekhar, National University of Singapore, ASHRAE DL Event, Delhi, 21 Feb 2013 26
912
nles
sel
-Xnl
/D16 L/s12 L/s8 L/s4 L/s
A B C D
036
0 4 8 12 16 20personalized airflow rate (L/s)
dim
ensi
onne
utra
l lev
e
Dimensionless neutral level as a function of
personalized airflow rates Heated Manikin
A B C D
◊ 23.5/21
□ 23.5/23.5
∆ 26/21
Ceiling-mounted PV system in conjunction with ceiling supply mixing ventilation system
Χ 26/23.5
﹡ 26/26
0.2
0.3
lity
ble
, b
le/a
ccep
tab
le,
e
0.0
0.1
0.1
0.2
0 4 8 12 16
PV airflow rate (L/s)
Inhal
ed
air
qual
Y-a
xis
-1=
very
un
acce
pta
b0
=ju
st u
nac
cep
tab
+1
=ve
ry a
ccep
tab
le
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Prof Chandra Sekhar, National University of Singapore, ASHRAE DL Event, Delhi, 21 Feb 2013 27
Desk-mounted PV SystemIntegrated with
2008 - 2010
Integrated withUFAD System
Li Ruixin, S.C.Sekhar and Arsen Melikov, “Thermal comfort and IAQ assessment of under-floor air distribution system integrated with personalized ventilation in hot and humid climate”. Building and Environment journal, Vol 45 (2010): 1906-1913. (United Kingdom).
Li, Ruixin, S.C.Sekhar and A.K.Melikov, 2011. Thermal Comfort and Indoor Air Quality in rooms with Integrated Personalized Ventilation and Under-Floor Air Distribution Systems. HVAC&R Research, Volume 17, Number 5, pp 829-846 ,ASHRAE .
Field Environmental Chamber (FEC) experimental setup- Desk mounted PV with UFAD system
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Prof Chandra Sekhar, National University of Singapore, ASHRAE DL Event, Delhi, 21 Feb 2013 28
Methods- Experimental ConditionsTable 1 Experimental Conditions
System Type Exp.
Condition(Session no )
Temperature (˚C)/ (˚F) PV flow rate(L/s)/(CFM)
Total volume ventilation
system (UFAD) flow
(Session no.)rate
(L/s)/(CFM)
Troom TUFAD supply TPV supply
UFAD+PV 22-26-5 26/78.8 22/71.6 26/78.8 5/10.6 480/1017
UFAD+PV 22-26-10 26/78.8 22/71.6 26/78.8 10/21.2 480/1017
UFAD+PV 22-22-5 26/78.8 22/71.6 22/71.6 5/10.6 480/1017
IAQ‘10 – November10-12, 2010
UFAD+PV 22-22-10 26/78.8 22/71.6 22/71.6 10/21.2 480/1017
UFAD+PV 18-26-5 26/78.8 18/64.4 26/78.8 5/10.6 360/763
UFAD+PV 18-26-10 26/78.8 18/64.4 26/78.8 10/21.2 360/763
UFAD+PV 18-26-5 26/78.8 18/64.4 22/71.6 5/10.6 360/763
UFAD+PV 18-22-10 26/78.8 18/64.4 22/71.6 10/21.2 360/763
Cold Feet
Thermal sensation at feet and acceptability of air movement at feet (Thermal sensation scale: =‐3 cold, =‐2 cool, =‐1 slightly cool, =0 neutral, =+1 slightly warm, =+2 warm, =+3 hot; Air movement acceptability: 0 ~50 = very unacceptable ~ just unacceptable,
50~100 = just acceptable ~ very acceptable)
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Prof Chandra Sekhar, National University of Singapore, ASHRAE DL Event, Delhi, 21 Feb 2013 29
Facial Thermal Sensation
Cooler (better) h l ithermal sensation
at face
Whole Body Thermal Sensation
Cooler (better) thermal sensation
– whole body
y = 1.4807x - 41.198R² = 0.8582
70
80
90
100
70
80
90
100
emp
erat
ure
fres
hn
ess
i h l d i f h
y = -0.6024x + 84.891R² 0 6871
20
30
40
50
60
20
30
40
50
60
erce
ived
in
hal
ed a
ir t
e
Per
ceiv
ed i
nh
aled
air
f inhaled air freshness
inhaled air temperature
R² = 0.6871
0
10
0
10
70 75 80 85 90
PeP
Acceptability of perceived air quality
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Human Response Studies Human Response Studies -- Key ObservationsKey Observations
• The use of PV-UFAD improved subjects’ thermal sensation in
comparison with UFAD alone or mixing ventilation. g
• The “cold feet” complaint decreased when the temperature of the
air supplied from the UFAD was increased.
• The use of the PV provided the subjects with the preferred slightly
cool thermal sensation at the head and face.
• Local cooling of the head and face could be achieved by
decrease of the temperature of the personalized air or increase
of its flow rate, i.e. increase of the air velocity at the head and
face region.
Tracer gas measurementsTracer gas measurements
Two indices, as defined below were calculated to evaluate the performance of the integrated PV and UFAD systems: personal exposure effectiveness (PEE) and Personal exposure index (PEI).and Personal exposure index (PEI).
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Prof Chandra Sekhar, National University of Singapore, ASHRAE DL Event, Delhi, 21 Feb 2013 31
Methods The PEE index expresses the percentage of personalized
air in inhaled air. It is derived from the following equation
PEE = (CR,SF6 – CI,SF6)/(CR,SF6 – CPV,SF6)
C-R, SF6 = SF-6 concentration of the tracer gas in the exhaust/return air (ppm),
CPV, SF6 = SF6 concentration of the tracer gas in personalized air (ppm),
CI, SF6 = SF6 concentration of the tracer gas in the inhaled air (ppm).
The local ventilation effectiveness for the removal of pollutants, εV, also called the PEI, is expressedp , V, , p
PEI = (CR – C∞)/(CI – C∞)
CR = contaminant concentration in the exhaust/return air (ppm),
CI = contaminant concentration in the inhaled air of a person (ppm)
C∞ = contaminant concentration in the outdoor supply air (ppm).
UFAD integrated with PV System
0.4
0.5
1.6
2.0
0.0
0.1
0.2
0.3
0.0
0.4
0.8
1.2
PE
E
PE
I
PEI
PEE
PV L/s
PV S/A
PEE and PEI valuesCermak, R., 2004, Design strategies for personalized ventilation. PhD Thesis (ISBN 87-7475-318-5), International Centre for Indoor Environment and Energy,Department of Energy Engineering, Technical University of Denmark. Chapter 5, 63-92.
Cermak, R., Melikov, A.K., Forejt, L. and Kovar, O., 2006, Performance of personalized ventilation in conjunction with mixing and displacement ventilation,International Journal of heating, Ventilation and Refrigeration Research. Vol.12, no.2, pp.295-311.
UFAD S/A
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Prof Chandra Sekhar, National University of Singapore, ASHRAE DL Event, Delhi, 21 Feb 2013 32
S/A temp of PV air has stronger effect on
Tracer Gas Studies Tracer Gas Studies -- Key ObservationsKey Observations
the PEE and PEI than PV air flow rate.
The cooler PV air results in higher PEE and PEI.
UFAD supply conditions have a marginal
ff t th PEE d PEI b t teffect on the PEE and PEI, but not
comparable to that of PV. The cooler UFAD
supply air temp tends to result in lower PEE and PEI.
Integrated IAQ – Energy Audit – IAQ parameters, Ventilation parameters, Human Response, Energy performance
Final Words
Case Studies
Energy Efficient Healthy Buildings – Single Coil Twin Fan Systemg y
Energy Efficient Healthy Buildings – Personalised Ventilation System
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