Effects of acoustic environment on work in private office rooms and open-plan offices - longitudinal study during relocation

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  • Effects of acoustic environment on work in private office rooms and open-plan offices longitudinalstudy during relocation

    A. Kaarlela-Tuomaalaa, R. Heleniusa, E. Keskinenb and V. Hongistoa*

    aFinnish Institute of Occupational Health, Indoor Environment Laboratory, Lemminkaisenkatu 1418 B, FIN-20520, Turku,Finland; bDepartment of Psychology, University of Turku, FIN-20014, Turku, Finland

    The aim was to determine how the perceived work environment, especially acoustic environment, and its effectsdiffered in private office rooms and in open-plan offices. The subjects consisted of 31 workers who moved fromprivate office rooms to open-plan offices and who answered the questionnaire before and after the relocation. Privateoffice rooms were occupied only by one person while open-plan offices were occupied by more than 20 persons.Room acoustical descriptors showed a significant reduction in speech privacy after relocation. The noise levelaveraged over the whole work day did not change but the variability of noise level reduced significantly. Negativeeffects of acoustic environment increased significantly, including increased distraction, reduced privacy, increasedconcentration difficulties and increased use of coping strategies. Self-rated loss of work performance because of noisedoubled. Cognitively demanding work and phone conversations were most distracted by noise. The benefits that areoften associated with open-plan offices did not appear: cooperation became less pleasant and direct and informationflow did not change. Nowadays, most office workers, independent of job type, are located in open-plan officeswithout the individual needs of privacy, concentration and interaction being analysed. This intervention studyconsisted of professional workers. Their work tasks mainly required individual efforts, and interaction between otherworkers was not of primary concern, although necessary. The results suggest that the open-plan office is notrecommended for professional workers. Similar intervention studies should also be made for other job types.

    Keywords: open-plan offices; landscaped offices; private office rooms; work performance; indoor environment;productivity; speech; office noise; acoustics; office satisfaction; speech intelligibility; irrelevant speech effect

    1. Introduction

    There is a strong and increasing worldwide trend tobuild open-plan offices instead of small office rooms.Small office rooms can be occupied by a single personor can be shared by a couple of persons. In this study, aprivate office room is defined as a small office room,occupied only by one worker. Open-plan offices arefavoured because of, e.g. lower building expenses due tothe smaller number of partitions, lower rent costs dueto higher worker density, better adjustability and betteraccess of daylight especially in deep-framed buildings.Many architects prefer open-plan offices because of lessenclosure and spaciousness. Proponents of open-planoffices believe that they promote cooperation, socialrelations, communication, feedback, solidarity andknowledge-sharing between workers, as well as com-mitment to company values. However, there is norobust scientific evidence to support these beliefsespecially when different job types are considered.

    From the building owners point of view, an open-plan office is easier to rent than a private office because

    of its apparent flexibility regarding the degree ofenclosure and occupancy of space. Such premises leadto higher occupation and higher profit per investedcapital. It is common that a substantial proportion ofworkers resists open-plan offices. The lack of acousticand visual privacy, increased distraction by noise,reduced workstation size, uncontrollable socialcontacts and interruptions are the most feared featuresof open-plan offices. However, these facts do not playan important role when contacts are made becausethey are difficult to express using simple economicalmeasures, such as square metres per worker.

    This study concentrates on the comparison ofprivate office rooms and open-plan offices, applying alongitudinal survey method during the office relocationof a company. The study utilises moremultidisciplinary research methods than any previousstudies in the area. Measurements of building acousticsand subjective responses were included before andafter the relocation. Before presenting the researchquestions, a relevant literature review is presented.

    *Corresponding author. Email: valtteri.hongisto@ttl.fi

    Ergonomics

    Vol. 52, No. 11, November 2009, 14231444

    ISSN 0014-0139 print/ISSN 1366-5847 online

    2009 Taylor & FrancisDOI: 10.1080/00140130903154579

    http://www.informaworld.com

  • 2. Literature review

    There are five essentially different methodologicalapproaches to investigate the perception of workenvironments: cross-sectional survey; longitudinal sur-vey during relocation; retrospective survey; longitudi-nal field experiment; case study. The review focuses onthe first two methods because they give the mostreliable insight into the perceived differences betweenopen-plan offices and private office rooms.

    A cross-sectional survey is the simplest method togather comparative information from different envir-onments. It consists of parallel and identical measure-ments in many office buildings. The measurement ismade only once and no experimental change in theworkplace is included. Therefore, the method cannotbe used to prove causal relationships. A summary ofspecial cross-sectional surveys, which have comparedopen-plan offices and private office rooms, is presentedin Table 1. It indicates that human-borne noise,especially co-workers speech, and lack of privacy arethe strongest environmental factors producing dissa-tisfaction in open-plan offices. The studies agree thatprivacy, self-rated performance and ability to concen-trate are lower and distractions stronger in an open-plan office. There is some disagreement about whetheropen-plan offices support communication. Unfortu-nately, there are a number of frequently cited cross-sectional surveys that could not be included in Table 1because the office type is not reported (Klitzman andStellman, 1989, Zweers et al. 1992), the samplecontains only buildings with indoor air problems(Lahtinen et al. 2004) or the study is restricted to acertain office type (Veitch et al. 2007).

    A longitudinal study during relocation aims toshow the perceptions of the same occupants in twodifferent offices. These studies contain obvious experi-mental features and causality effects can be proved to alimited extent. The present study belongs to thiscategory, focusing on the comparison of the mostextreme office types, private office rooms and open-plan offices. Although there is permanent debate aboutthe benefits of both office types, there were only twoprevious papers where these two office types are ofprimary interest, keeping in mind that private officeroom is defined as a room for only one worker (Table2). Perception of noise was investigated in both studiesbut the results were not clearly reported. Sundstromet al. (1982) compared four office types. Unfortunately,noise ratings were reported only for the whole work-place but not for the special group experiencing therelocation from private rooms to open-plan offices.Acoustic conditions have been considered very little byZalesny and Farace (1987). It can be concluded thatthe experience of noise has been studied very little even

    in these two relocation studies, which have a similarexperimental set-up as the present study.

    Table 3 consists of miscellaneous longitudinalsurveys during relocations where private rooms andopen-plan offices have been compared. The workershave had private rooms, shared rooms and open-planoffices both before and after relocation. The relativeshare of the open-plan office has becomemore prevalentafter relocation. These do not present a scientificallyvalid analysis between private rooms and open-planoffices because of the small amount of occupantsexperiencing the relocation from private rooms to open-plan office. Three frequently cited relocation studies,Boyce (1974), Sundstrom et al. (1994) and Brill et al.(1984), have reported only the average result of alloccupants in both open-plan offices and small officerooms. Therefore, they were omitted from Table 3.

    In a retrospective relocation survey, subjectsanswered the questionnaire only once (Table 4). Thesubjects were asked to remember the workingconditions before the relocation and compare that tothe present conditions in the new premises. Thereliability of retrospective surveys is questionablebecause the evaluation of prior working conditions isdifficult especially when the questionnaire is performed2 years after the relocation. The studies are inagreement that noise and lack of privacy became aproblem after relocation. Performance changes arecontradictory as is the quality of communication.Retrospective surveys of Boje (1971) and Oldham(1988) were not included in Table 4 because they lack acomparison of private rooms and open-plan offices.

    Self-rated performance has been investigated inmany studies shown in Tables 14. However, it was notpossible to distinguish the role of noise in performancedecrements. In this study, the effect of noise onperformance in different office environments is ofprimary concern.

    Nowadays, more and more work is informationand knowledge intensive. The performance of complexwork tasks often requires not only a successfulperformance of the individual task but also socialnetworking and teamwork. These set differentrequirements for the work environment and for thecognitive processes. Work tasks are often complex andthe analysis of required skills and process types isdifficult in field conditions. In psychological laboratorystudies, tasks are typically divided into verbal,mathematical, visual and motor tasks. Generalcognitive activities that are needed in human actionare, for example, perception, attention, memoryfunctions and decision making. These activities maysuffer differently from various environmental,situational and individual disturbances. Very fewprevious field studies have considered these questions

    1424 A. Kaarlela-Tuomaala et al.

  • Table

    1.

    Listofcross-sectionalsurveys*

    includingprivate

    office

    rooms(PRO)andopen-planoffices(O

    PO).

    Source

    Noise,

    office

    satisfaction

    Concentrationandwork

    perform

    ance

    Privacy,communication,functional

    efficiency,personalrelations

    Becker

    etal.(1983)

    Noisedisturbance

    inOPO

    reducedthe

    abilityto

    dowork

    requiringhighlevel

    ofconcentration.Office

    satisfaction

    notstudied.

    Noisein

    OPO

    increasedthelength

    of

    timespentin

    theoffice,length

    oftime

    tocomplete

    atask,anddecreasedthe

    amountofwork

    accomplished.

    Distractionsin

    OPO

    reducedthe

    abilityto

    conduct

    meetingswith

    students

    onsensitiveissues.

    Dissatisfactionwithprivacy

    wasvery

    highin

    OPO.Open

    layoutim

    paired

    facultystudentinteraction,in

    many

    waysreducingthequality

    offeedback.

    100subjects{

    threebuildings

    threeoffice

    layouts

    compared

    onemeasurement

    USA,university

    faculties

    Danielsson(2005)

    Noiseandlack

    ofprivacy

    werestrongest

    office

    dissatisfiers.Workersin

    PRO

    weremost

    andworkersin

    OPO

    least

    satisfied.Office

    environment

    satisfactionwashighestin

    PRO.

    Notstudied.

    Communicationreinforced

    most

    inflex

    office

    andleast

    insharedroomsfor

    twoto

    threepersons.

    469subjects

    26buildings

    seven

    office

    layouts

    compared

    onemeasurement

    Sweden,alltypes

    ofcompanies

    Jensenet

    al.(2005)

    Satisfactionwithnoiselevel

    waslowest

    inOPO.Acousticswasthestrongest

    predictorofoffice

    building

    satisfaction.

    Acoustic

    quality

    ofoffice

    interfered

    with

    perform

    ance

    most

    inlow-partition

    OPO

    andleast

    inPRO.

    Satisfactionwithprivacy

    waslowestin

    OPO.

    23,450subjects

    142buildings

    fiveoffice

    layouts

    compared

    onemeasurement

    USA,alltypes

    ofcompanies

    Pejtersen

    etal.(2006)

    Adverse

    noiseperceptionswere10-fold

    inlargeOPO

    comparedto

    PRO.

    Concentrationdiffi

    cultieseight-fold

    inlargeOPO

    comparedto

    PRO.

    Notstudied.

    2301subjects

    22buildings

    fiveoffice

    layouts

    compared

    onemeasurement

    Denmark,alltypes

    ofcompanies

    Haapakangaset

    al.(2008)

    Noisewasstrongestindoorenvironment

    problem

    inOPO.Satisfactionwith

    work

    environmentasawhole

    was

    betterin

    PRO.

    Concentrationdiffi

    cultiesweremore

    frequentin

    OPO

    thanPRO.Selfrated

    perform

    ance

    loss

    dueto

    noisewas

    two-fold

    inOPO

    comparedwithPRO.

    Acoustic

    privacy

    andcomfort

    lower

    inOPO.Teamwork

    andcommunication

    equalin

    OPO

    andPRO.

    689subjects

    11buildings

    tw

    ooffice

    layouts

    compared

    onemeasurement

    Finland,alltypes

    ofcompanies

    *In

    thesestudies,thequestionnairewasperform

    edonce.

    { Studentsresponses(n

    356)wereignoredin

    thisreview.

    Ergonomics 1425

  • although it is of primary interest for space andworkstation design in workplaces.

    Workers may try to compensate for the disruptionand distraction created by different factors. When oneis highly motivated one may be more alert and makean even greater effort. Such an individual state cantherefore have an impact on work performance.Moreover, individual traits such as noise sensitivity(Weinstein 1974), extroversion (Eysenck and Eysenck1972), trait anxiety (Spielberger et al. 1970) and locusof control (Rotter 1966) have been associated withnoise effects on annoyance and performance indifferent laboratory studies. However, very few studieshave been conducted on the effect of individual factorson the perception of noise in offices.

    Workers may not only change their strategy ofdoing a task but also behave differently at theworkplace to compensate for the environmentalfactors that decrease their ability to perform. Suchcoping methods are, for example, interruptingworking or taking work home. At work, one may alsotry to affect the factors that are detrimental by, forexample, making a proposal for an improvement tothe management. None of the previous studies hasproperly investigated the ways of coping in differentoffice environments although coping is expected tohave a strong connection with work performance.

    Although many of the studies of Tables 14concentrated on noise effects, few of them haveincluded acoustical measurements along withquestionnaires (e.g. Nemecek and Grandjean 1973,Boyce 1974, Sundstrom et al. 1982, Veitch et al. 2007).In addition, most of the above-mentioned studies lacka description of the open-plan office although it playsa fundamental role in the perception of the acousticenvironment and privacy. According to Virjonen et al.(2009), acoustic privacy can vary significantly betweendifferent open-plan offices. Privacy in open-plan officeswith very low screens (bullpen) is significantly lowerthan in open-plan offices where workstations areenclosed by high screens (cubicles). Sound absorbersalso become more efficient in the latter type of spaces.Good speech privacy is easier to achieve in large andhigh open-plan offices than in small ones because oflower intensity of room reflections. In this study, thesefactors have been considered with sufficient accuracyso that the effect of the physical environment can bediscussed along with questionnaire data. This isimportant...

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