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


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


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


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


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


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


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


2/17/2013


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)


2/17/2013


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


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


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


Energy Measurements


Summary of measured and computed parametersThermal Comfort, IAQ, Ventilation and Energy

2/17/2013


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


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


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


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


roje

ctF

ield

Tri

al –

Test

-Bed

din

g P

r

9 ppm

A T

2/17/2013


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:

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50:

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50:

00 P

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50:

00 P

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50:

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50:

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50:

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50:

00

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50:

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00

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50:

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00

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50:

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50:

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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


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


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


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


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


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


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


• 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


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


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


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

2/17/2013


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

2/17/2013


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)

2/17/2013


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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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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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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