Post-occupancy evaluation of residential buildings in Luxembourg with centralized and decentralized ventilation systems, focusing onindoor air quality (IAQ). Assessment by questionnaires and physical measurements.

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ContentslistsavailableatScienceDirect

Energy

and

Buildings

jo u r n al h om ep a g e :w w w . e l s e v i e r . c o m / l o c a t e / e n b u i l d

Post-occupancy

evaluation

of

residential

buildings

in

Luxembourg

with

centralized

and

decentralized

ventilation

systems,

focusing

on

indoor

air

quality

(IAQ).

Assessment

by

questionnaires

and

physical

measurements

Marielle

Ferreira

Silva

a,∗

_,

_Stefan

_Maas

b

_,

_Henor

_Artur

_de

_Souza

a

_,

_Adriano

_Pinto

_Gomes

c

a_Civil_Engineering_{Post-Graduate}_Program,_Federal_University_of_Ouro_Preto,_Mining_School,_Morro_do_Cruzeiro_Campus,_35400-000_Ouro_Preto,_MG,_Brazil b_University_of_Luxembourg,₆_Rue_{Coudenhove-Kalergi,}_L-1359_Luxembourg,_Luxembourg

c_Design_and_Project_Departament,_Federal_Institute_of_Minas_Gerais_at_Ouro_Preto,_Rua_Pandiá_Calógeras,_898,_Bauxita,_35400-000_Ouro_Preto,_MG,_Brazil

a

r

t

i

c

l

e

i

n

f

o

Articlehistory: Received17August2016

Receivedinrevisedform14February2017 Accepted18April2017

Availableonline27April2017 Keywords:

Indoorairquality Post-occupancyevaluation Residentialbuildings

Centralizedanddecentralizedmechanical ventilation

Heatrecovery

a

b

s

t

r

a

c

t

Completeknowledgeabouthabitsoftheoccupants,includingtheiropinionsregardingventilation sys-temsisanimportantconditionforreducingtheconsumptionofnaturalresourcesandimprovingindoor comfort.Inaddition,uncomfortedoccupantstendtotakemeasurestoimprovetheirsituation,which mayincreaseenergyconsumption.Advancedthermalmodelsforbuildingscanperhapspredict interac-tionsbetweentheIAQdeterminants,e.g.energyconsumption,ventilationandcomfort,butdonottake intoaccountthebehaviorofresidents.Byquestionnairesandphysicalmeasurementsthisstudy evalu-ateddwellingsequippedpartlywithcentralizedandpartlywithdecentralizedventilationsystemswith heatrecovery.Thisﬁeldstudyinvolvedtwopost-occupiedresidentialbuildingssituatedinthecityof Esch-sur-Alzette,Luxembourg,duringspringseason2015.Thus,boththephysicalmeasurementsand questionnaireswereconsidered.Theresultsobtaineddemonstratedthatmorethan80%oftheresidents weresatisﬁedandtheperceivedIAQwasjudged“normal”,“good”oreven“verygood”.Furthermore, themeasurementsperformeddetectedinsomecasesmalfunctionofventilationdevices,whereforethe occupantswereunable.

1. Introduction

Recentenergyraisingdemandandincreasingbuilding

construc-tionrates,aswellasenvironmental,epidemiologicalandeconomic

reasonshavepushedforwardthepressuretodesign,constructand

maintainuser-friendlyresidentialbuildingswithhighenergy

efﬁ-ciency,goodindoorthermalcomfortandnobleindoorairquality

(IAQ)[1–3].Comfortisastateofwell-beingandstability andit

ismeasuredbytherateofdissatisﬁedoccupants.Iftheirportion

islow,thecomfortisjudgedasacceptable.However,itshouldbe

notedthataverystablecomfortcanalsobeboringandvariations

aresometimeswelcome[4].

Poorhousingenvironmentscannegatively affecta resident’s

overalllifestyleandalsoaffectthehealth,productivityandcomfort

ofoccupants.Theymayalsocausephysical,psychologicalandsocial

∗ Correspondingauthor.

E-mailaddresses:mariellearq@hotmail.com(M.F.Silva),stefan.maas@uni.lu (S.Maas),henorster@gmail.com(H.A.d.Souza),adriano.gomes@ifmg.edu.br (A.P.Gomes).

problems,deterioratingthequalityoflife.In thiswayagreater

effort is essential to improve indoor environments to provide

everyonewithhigherstandardsofliving,toimproveoverallwork

orlearningperformanceand/orreduceabsenteeism[5,6].

Unfor-tunatelysomebuildingsfailtomeettheserequirementsoccupants

sufferfromtheso-calledSickBuildingSyndrome(SBS),because

theyshowvarioussicknesssymptoms.TheSBSisthereactionof

occupantstotheirnon-perfectindoorenvironment;areactionthat

cannotbedirectlylinkedtospecialproblems,suchasexposureto

anexcessiveconcentrationofaknowncontaminant,oranevident

defectsintheventilationsystem.PeopledevelopingSBSusuallysee

theirsymptomsdisappear,whentheyleavethebuilding[4].

Advancedtheoreticalmodelsofthebuilding’sbehavior

includ-ingthetechnicalbuildingsystemsandthenumberofpeoplecan

predicttheindoorairquality,aswellascomfortparametersand

thus estimateheat consumption inthedesign stageand deﬁne

requirementsfortheheatingandventilationsystems[3,7].

How-ever,theyareusuallydeterministicanddonottakeintoaccount

thebehavioroftheresidentsandmanyotherparameters,likethe

numberofpersonsandtheirtimeofoccupation,theemissionsfrom

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bedrooms35l/s Hallways30l/sper 100m2₎

5achb ₁₀_l/s

EN15251 0.42l/sm2 _N/C ₇_l/s _1.0_l/s_m2 _Kitchen _Bathroom _>15–20% ₅₀₀_(above_the

outsideair) Living room: 25–40 Bedroom: 20–35 20–26 20l/s 15l/s NBR16401 N/C Summer 0.20–0.25 Winter 0.15–0.20 N/C N/C Summer (0.5clo) 35–65% Winter(0.9 clo) 30–60% <700(above theoutsideair: 400) N/C Summer (0.5clo) 22.5–26.0 Winter (0.9clo) 21.0–24.0 Notes:

a_N/C:_nothing_in,_or_not_found_in_standard_references_for_this_parameter.

b _ach:_air_change_per_hour_(airﬂow_in_volume_units_per_hour_divided_by_the_volume_of_the_space_on_which_the_air_change_rate_is_based_in_identical_units.

activitieslikesmoking,orcooking,andemissionsfromfurniture,

carpets,cleaningproducts,hobbiesetc.[3,6].Thus,thepredicted

comfortandenergyconsumptionarenotprecise,duetoan

incor-rectestimationoftheindoorairqualityandcomfort conditions

[3,8].The incorrectand unpredicted useof ventilation systems

causesunexpectedandrandomairﬂow[3].

Indoorenvironment quality hasmediating effects and helps

toincreaseenergy efﬁciencyand overallresidentialsatisfaction.

So,themoretheresidentsareawareoftheimportanceofenergy

savings and energy costs, the higher the indoor environment

satisfaction[5,9].Contrarilyuncomfortedoccupantsarelikelyto

takeactionstohelpthemselvescomfortableandhasoftennegative

energyimplications [3,6,10,11].The degreeof occupant control

overtheenvironmentdependsnotonlyonthecharacteristicsof

thebuildingandonitssystems(buildingcontextualfactors),but

alsoonoccupantawarenessofthesefeatures[12].Inspiteof‘good’

and‘verygood’gradesfortheairqualityandcomfortperception,

theresidents’behavior isclosely reﬂectedby behaviorcustoms

thatleadtowindowopeninganduncontrolledheatlosses.Thus,

windowventilationispermanentlyrelatedtohumanhabitswhich

havetobeaccepted[3,12].Mechanical ventilationis astrategy

withahighimpactonthequalityoftheindoorairofabuilding

andthecomfortofusers,sinceit isdifﬁcultorevenimpossible

fortheusertoprovideasufﬁcientamountoffreshairbynatural

ventilation[13,14].

Intermsofenergyefﬁciency,thepurposeofmechanical

ven-tilationis tocontroltheamountof airnecessarytoensureIAQ

withlowpowerconsumption andmakeuseofheatrecoveryto

reduceventilationlosses[14].Resultsshowthatenergysavingsin

ventilationheatrecovery(VHR)canbeverysigniﬁcant,depending

onthetypeofventilationsystem,andthetightnessofthebuilding

[13].Inpractice,thedesignandproperinstallationarecriticalfor

exploitingthe potentialof thesystem [13]. Reported problems

withventilationand spaceheating suggest thatcomprehensive

post-occupancyevaluationisessentialforimprovingthequality

ofdevelopmentsandcorrectingerrorswhichoccurrepeatedlyin

housingprojects[11].

Consideringtheseaspects,thispaperdevelopsapost-occupancy

evaluationinresidentialbuildings,consideringmechanically

ven-tilatedroomswhilefocusingonmeasuredandperceivedIAQand

theefﬁciencyoftheventilationsystems.

1.1. TheparametersforIAQevaluation

Inordertohaveaguidelineforevaluatingthephysical

measure-ments,fourstandardswereanalyzed.Table1isasummaryofthe

ASHRAE62.1[15]and62.2[16],EN15251[6]andNBR16401[17]

standardswiththemainparametersrecommendedforIAQ

evalu-ation.ItshouldbenotedthattheEuropeanstandardEN15251[6]

containsthelargestnumberofparametersrelatedtothe

evalua-tionofIAQ.Therefore,inthisstudyitwasusedasreferenceandis

relatedtothestandardEN15251[6]withanacceptable

satisfac-tionlevel.Thisstandardalsoconsidersthatthehumidiﬁcationof

indoorairisusuallynotnecessary,whileASHRAE62.1[15]suggests

amaximumlimitof65%forrelativehumidity,whichwasusedas

uppercomfortlimit.

2. Materialsandmethods

Thepaperpresentstheresultsofexperimentalinvestigations

conductedin16apartmentsoflowpowerconsumptionequipped

withfourdifferentmechanicalventilationsystemswithheat

recov-ery,distributedintworesidentialbuildingslocatedatthePierre

KrierSquareinthecityofEsch-sur-Alzette,Luxembourg(Fig.1).

TheIAQoftheresidentialbuildingsisexaminedfromthe

perspec-tiveoftheoccupants’acceptanceintwoaspects:indoorairquality

andventilation.

Originally built in 1957, the buildings were renovated in

theyears 2012–2014and equippedwithmechanicalventilation

systems.Threedecentralizedandonecentralizedmechanical

ven-tilationsystemwithheatrecoveryweremeasuredinmulti-family

homes.Forcentralizedventilationunits(namedsystemA)a

duct-workisusedtotransportthesupplyandextractair,whilethree

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Fig.1.Photosofthefrontfacades.

Fig.2.Typesofventilationunitsforresidentialbuildings. Source:[13].

Table2

Mechanicalventilationsystemsstudied. Namedsystems Typesof

ventilationunits

Characteristics

A Centralized Thesystemconsistsofacentralizeddeviceforventilationofallroomswithheatrecovery.Theairﬂowpassesfreely frombedroomsandlivingroomstoexhaustroomssuchasbathrooms,kitchensandlaundries.

B Singleroomunit Thesystemisadecentralizedsingleroomventilationunitwithrecuperativeheatrecovery.

C Pair-wiseunits Theventilationsystemusedhaspair-wiseunitsthatalwaysoperatetogetherwithfansandinternalmassstoragefor heatrecovery.

D Pair-wiseunits Theventilationdeviceisdecentralizedpair-wiseunitswithheatrecovery,butdifferentsupplierasC.

directlyinthefacadeofthebuilding,Fig.2.Theircharacteristics

areshowninTable2.Alltheroomsofeachapartmentare

venti-latedwiththesamemechanicalsystem,exceptbathroomswhere

theairisalwaysexhausted.Thecentralized(systemA)andthe

sin-gleroomunits(systemB)userecuperativeheatexchangerswhere

theincomingandoutgoingairisseparated,whilethepair-wise

units(systemC andD)heatupaceramicor aluminumstorage

masswiththeexhaustairfortypically1min.Thentheﬂow

direc-tionisreversedandthestoragemassiscooledbytheincomingair

for1min,i.e.thereisalwaysapairofdeviceswithoppositeﬂow

direction.

Eachbuildinghasﬁveﬂoors:thebasement,streetlevel,1stFloor

and2ndand3rdFloorswithcompoundduplexapartments.The

twobuildingshavethesameexternalandinternalwall

mount-ing.Theexternalswallsarebuiltofbrickswiththicknessof49cm

andthermalisolationof30cm.Theinternalwallsarealsobricks

of24cmthickness.Eachﬂoorisdividedintofourapartmentswith

totalﬂoorareaof57m2 _up_to₁₃₁_m2_._Table₃_shows_the_type_of

mechanicalventilationsystemforeachapartment(systemname

andtheapartmentno.)forbuildingsIandII.

Theinvestigationwasdoneintwostages.Intheﬁrststage,

ques-tionnairesaboutthequalityofairandventilationweresuppliedto

theresidentsoftheapartments.Inthesecondphase,experimental

measurementswereconductedinthesamedwellings.

ThequestionnairewasbasedonmodelsbySilva[18]andRoulet

[4] andconsisted of21 questions includingaspectsof personal

information, suchassex and age,periodof permanency in the

residence,andnumberofpeoplelivingineachapartment(ref.to

appendices).Thefocusofthequestionsisrelatedtotheefﬁciencyof

ventilationsystemsinrelationtoindoorairqualityincluding

envi-ronmentalthermalsensation(temperatureandrelativehumidity),

CO2 concentration(bytheodor),noise,anddatarelated tosick

buildingsyndrome(SBS).ThequestionnairesforbuildingsIandII

wasdistributedon9and10March2015between9amand3pm.

Firstthequestionnairewaspresentedandthepurposeofthis

ques-tionnairewasdiscussed.Afterexplanationanyuserhadaperiod

of1hforanswering,withoutinterferenceoftheinterviewer,who

waspresent.Weobtainedatotalof16adultresponders,onefor

eachapartment.Thisnumberofrespondentscorrespondsto67%

of24apartments,dividedinto12womenandfourmen,withage

between26and71years.Ofthetotalnumberofapartments,16%

werevacatedand17%ofresidentswerenotinthedwellingatthe

timeoftheinterview.Accordingtotheresponsesoftheoccupants,

theapartmentswererentedforoversixmonthsafterrenovation

ofthebuildings.

Formeasurementsinsitu,weusedtheWöhler[19]andDIFF

Airﬂow[19,20]equipment.The“WöhlerCDL210CO2-Datalogger”

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(A) (A) (A) (A) roomunit (B)

Units(D) units(D) units(C)

1 2 3 4 13 14 15 16

Fig.3.Thenotesofresidentsin%relatedtotheindoorenvironment.

airtemperatureandrelativehumidity.Thedatafromthisdevice

wereusedfordeterminingtheIAQ.TheCO2 levelwasobtained

byinfrared measurement. The automatic DIFF airﬂow is a

sin-glemeasureairﬂowdevice,whichisbasedonthezero-pressure

method.Thepressuregeneratedbyaninternalresistance

measure-mentdeviceis automaticallycompensatedbythezero-pressure

methodwithrespecttoatmosphericpressureoutsidethedevice.

Thepressurecompensationisproducedbyabuilt-infan,whichis

controlledbyadifferentialpressuresensor.Thismeasuringdevice

canbeusedfordeterminationofthesupplyorexhaustairﬂowat

in-andoutlets.

3. Resultsanddiscussion

3.1. Questionnaire

Fig.3showstheresultsin%fromtheanswersoftheresidents

withrespecttotheairqualityandcomfortperceptionrelatedto

theindoorenvironment,focusedontheindoorairtemperature,

relativehumidityofindoorair,noise,odorelimination,overall

per-ceivedIAQandtheventilationsystem.

Itshouldbenotedthat69%ofresidentsclassiﬁedtheindoorair

temperatureas“neutral”and56%consideredthehumidity

“nor-mal”.Atotalof69%thinkthatthenoiseproducedbytheventilation

systemsis“verylow”upto“normal”.Regardingtheefﬁciencyofthe

ventilationsystemstoeliminateodors,57%ofthepeopleanswered

“normal”to“verysufﬁcient”and43%ofthemanswered

“insufﬁ-cient”to“veryinsufﬁcient”.ForoverallperceivedIAQ,88%ofthe

residentsclassiﬁeditas“normal”to“verygood”,whilethe

venti-lationsystemswithheatrecoverywereclassiﬁedas“normal”to

“verygood”in82%ofresponses.

Statisticallythewomenhadadifferentperceptionofthe

ther-malenvironmentthanman,sotherearemoresensitivetothelow

temperaturesthanmanincoolconditions,withapreferencefora

warmerenvironment[21–23].As75%ofrespondentsinthisstudy

werewomen,thisstudyshouldbeexpandedtoachieveasimilar

percentageofmenandwomenformoreaccurateresults.

Residents were requested to answer whetherthey had any

symptoms(Fig.4a)relatedtotheSickBuildingSyndrome(SBS),and

whetherthesesymptomsdisappearedwhentheyleftthe

apart-ment.Allsymptomsputinthequestionnairewerementioned,and

runny nosewasthemostfrequent (23%). For64% ofoccupants

thesesymptomsdisappeared,oncetheywereoutsidethebuilding

(Fig.4).Howevertoknowtheexactcausesofthisphenomenon,

newstudiesandmeasurementsintheapartmentsneedtobe

per-formed.

Residentswerealsoasked,iftheyopenedthewindowsandat

whattime.88%ofthemanswered“yes”aftercooking,and38%also

answered“yes”whensleeping.

During explanation of the questionnaires and studying the

responses,itwasobservedthatresidentshaddifﬁcultiesin

under-standingthefunctioningofventilationdevicesandtheirinteraction

withopenwindows.Onlyperceivedinformationcanbeusedand

inthissensethesystemsaswellastheinformationpolicyneeds

improvement.

3.2. Insitumeasurements

AtﬁrsttheapartmentswereequippedwithWöhlersensors[19]

tomeasuretherelativehumidity,temperatureandCO2

concen-trationoftheindoorair.Intotal,17measuringpointsregistered

every15minmeasureddataforonemonthintotalduringspring

2015.ThesecondevaluationusedDIFFAirﬂowequipment[19]to

measurethevolumeairﬂow.

Thedatafromtheexternaltemperatureandexternalrelative

humidityofEsch-sur-AlzettecityintheperiodofMarch9,2015to

April14,2015areshowninFig.5.Thesewereobtainedfromthe

dailyweatherserviceprovidedbythewebsiteFREEMETEO[24].It

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Fig.4.PercentageofSBSsymptomspointedoutbyresidents.

Fig.5.EvolutionofexternaltemperatureandrelativehumidityforthemeasuringperiodfromMarch9,2015toApril14,2015inEsch-sur-Alzettecity(L). Source:[13].

Fig.6. ConcentrationofCO2aboveorbelowathresholdvaluein%ofmeasurementtime.

and20◦C.Inadditiontheoutdoorrelativehumiditywasbetween

65%and100%.

BeforetheinstallationoftheWöhlermeasuringdeviceanyuser

wasaskedtoidentifywhethertheliving roomorthebedroom

wasmostsuitedandhenceselectionforinstallationofthesensor.

Finally15ofthe24apartmentsweresuccessfullyanalyzed.

Fig. 6 shows the CO2 concentration divided by the limit of

1500ppmintotwointervals.

Onlytheapartments15,22and24,i.e.20%oftheapartmentshad

CO2 concentrationsabove1500ppmin20–30%ofthemeasured

time,i.e.badair.

Fig.7 showstheindoorair temperaturevaluesgroupedin3

intervalsin%ofmeasuredtime.

Fromtheresults,wecannoticethattheindoorairtemperature

wasbelow20◦Cformorethan20%ofthemeasuredtimeinseven

apartments,whichis46%oftheapartmentsanalyzed.Therefore,it

canbeconcludedthattheairtemperaturewasquitelowthere.

Fig.8showsthevaluesresultingfromtherelativehumidityof

indoorairinpercentageofthemeasuredtime.

Itcanbeobservedthatonlyoneapartment’srelativehumidity

exceededthe65%limitby76%ofthemeasuredtime,andthiswas

apartment24.

Inordertounderstandtheuser’ssensation, wecancompare

themeasurements ofindoor airtemperature, relative humidity

andCO2concentrationtotheresponsesfromthequestionnaire,

knowingthatconcentrationofCO2isoftenusedaspollution

indi-cator.Itwasobservedthatinapartmentswithhighconcentrations

of CO2 (nos.15, 22 and 24,Fig. 6)theoccupants classiﬁedthe

IAQdifferently. The ventilationsystemwasjudges“Very good”

inapartment15,eventhoughtheCO2 concentrationwasabove

1500ppmformorethan20%ofthemeasuredtime,while

apart-ment 22 wasclassiﬁed “Bad”and apartment 24 as “Very bad”

(Table4).

Comparingthemeasuredtemperaturewiththeanswersofthe

question6(Howdoyoufeeltheambienttemperatureinyour

apart-ment?), itwasobservedthat manypeopleclassiﬁedtheindoor

environmentas“slightlycool”and“cold”(Table4),which

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Fig.7.Indoorairtemperaturegroupedin3intervalsin%ofmeasuredtime.

Fig.8.Relativehumidityaboveorbelowathresholdvaluein%ofmeasuredtime.

Table4

Theresponsesofoccupants(sittingorrestingactivity).

No.ofApt Gender Ageoftheperson Questionsrelatedto

Temperature Humidity CO2

Question6 Question7 Question17 Question18

3 Woman 40 Neutral Normal Normal Normal

5 Man 30 Neutral Low Good Normal

7 Woman 28 Neutral Normal Normal Normal

9 Woman 36 Neutral High Normal Normal

11 Man 44 Neutral Normal Normal Normal

12 Woman 36 Neutral Normal Normal Good

13 Woman 71 Neutral Normal Good Good

15 Woman 38 Slightlycool Low Verygood Verygood

16 Woman 49 Slightlycool Low Normal Verygood

17 Woman 30 Neutral Normal Verygood Verygood

18 Woman 49 Neutral Normal Good Bad

19 Woman 26 Slightlycool Normal Good Good

20 Man 65 Neutral High Normal Normal

22 Woman 46 Cold Veryhigh Verybad Verybad

23 Man 43 Neutral Normal Good Verygood

24 Woman 37 Cold Veryhigh Bad Bad

morethan20%ofmeasuredtime(Fig.7).Apartment15was

classi-ﬁedas“Slightlycool”andapartments22and24as“cold”.Hereit

wasobservedthattheindoorairtemperaturesinFig.7werebelow

20◦Cformorethan30%ofthemeasuredtime.

Asnotedpreviously,onlyapartment24hadarelativehumidity

abovethelimitfor 76%ofthemeasuredtime(Fig.8),in

agree-mentwiththeresponsesoftheoccupants,whoalsoclassiﬁedthe

humidityas“veryhigh”(Table4).

Inorder toverifythereasonsfor thehighconcentrations of

CO2 inapartments15,22and24andthehighrelativehumidity

inapartment24,newmeasurementsweretakenwiththeDIFF

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Table5

Valuesformeasuredairﬂowtobedroom2inapartment15,–pair-wiseunits(D). Date Function Airﬂow(m3_/h) _Indoor_air_temperature₍◦_C) 26/May/2015 Supply 10.2 20.4

2/June/2015 Supply 19.6 21.8 2/June/2015 Supply 0.9 22.5

Table6

Valuesformeasuredairﬂowtobedroom3inapartment24,–pair-wiseunits(C). Date Function Airﬂow(m3_/h) _Indoor_air_temperature₍◦_C) 17/June//2015 Exhaust 2 24.8

24/June/2015 Supply 4.8 23.5 25/June/2015 Exhaust 0.8 24

ittopreviousresults. Tables5and 6presenttheairﬂowvalues

measuredinbedroom2ofapartment15andinbedroom3of

apart-ment24.Unfortunatelyitwasnotpossibletotakemeasurements

inapartment22,becausethetenantdidnotlikeit.

AccordingtoASHRAE62.1andEN15251theseapartmentsneed

minimum airﬂow ratesof 12 and 14m3_/h _{respectively,} _which

isbyfarmorethanthemeasuredvaluesinaverage.Inaddition,

thevalues oftheairﬂowmeasurementsvariedconsiderably,for

instanceinapartment15between0.9and19.6m3_/h₍_Table₅_),_and

from0.8to4.8m3_/h_for_apartment₂₄₍_Table₆_)._Hence_the

ven-tilationdevicesdidnotworkproperlyandapparentlythesystem

hadproblems,whichwerelateranalyzedandsolvedbyspecialized

technicians.

4. Conclusions

Thepost-occupancyevaluationintwonewlyrenovated

apart-mentbuildingsinLuxembourgfocusedonIAQandtheeffectiveness

ofventilationsystems.Theanalysiswasdoneusingquestionnaires

togetherwiththephysicalmeasurementsoftheCO2,temperature

andrelativehumidity.

Itwasdetectedthatin3apartments(15,22and24)the

mechan-icalventilationwasnotworkingproperly:thetemperaturewastoo

low;andtheCO2oftenexceededthecriticalthreshold.Sometimes,

butnotalways,theoccupantsfeltthemalfunctioning,butdidnot

notifythelessor.Itwasobservedthatwhentherearetwoormore

parametersabovethecomfortrange,peopleseemtodetectmore

easilyproblemsofthetechnicalsystem.

Thestudypresentsofcourselimitations:thereare75%women

andhenceonly25%men,whoﬁlledoutthequestionnaires,though

itisknownthatbothgenderanswerdifferently.Furthermore,the

evaluationandmeasurementperiodswerequiteshortandnotall

knowncomfortparametersweremeasured,ase.g.theradiant

tem-perature,theairdraft,temperatureasymmetry.

Inadditionitisknownthatmultipleothersubstancesinsmall

concentrationsarepresentinsidethebuildingsandareinﬂuencing

thewell-being,e.g.manychemical,physicalandbiological

pollu-tants.Thelackofquantitativedataisanobstacleandshouldtackled

byresearchers.

However,itcanbeexpectedthatinsitustudiesaboutoccupant’s

acceptanceanduseofenergyefﬁcientventilationsolutionshelpto

minimizeorcorrectproblems.Theyarenecessaryfordetectionof

malfunction,andforoptimizationoffutureprojects.

Acknowledgments

The authors gratefully acknowledge the University and the

“SociétéNationaledesHabitationsàBonMarché(SNHBM)”of

Lux-embourg,theUFOP,theFAPEMIGandtheCAPES,Brazilfortheir

valuablesupport.

AppendiceQuestionnaireaboutindoorairqualityand mechanicalventilation

Questionnairemechanicalventilation(TheUniversityof

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