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Adaptive temperature limits: A new guideline in The Netherlands A new approach for the assessment of building performance with respect to thermal indoor climate

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  Adaptive temperature limits: A new guideline in The NetherlandsA new approach for the assessment of building performancewith respect to thermal indoor climate § A.C. van der Linden a, *, A.C. Boerstra b , A.K. Raue c , S.R. Kurvers a,d , R.J. de Dear e a Faculty of Architecture, Department of Building Technology, Technical University Delft, The Netherlands b  BBA Indoor Environmental Consultancy, Rotterdam, The Netherlands c  Raue IEQ, Rotterdam, The Netherlands d  Apogeum, Gouda, The Netherlands e  Division of Environmental and Life Sciences, Macquarie University, Sydney, Australia Received 2 December 2004; received in revised form 11 January 2005; accepted 23 February 2005 Abstract The first guidelines for thermal comfort in buildings in The Netherlands were developed in the late 70s and in the 80s. They were based onthe PMV-PPD relationship. In this article new guidelines are presented, based on the international research on adaptive thermal comfort. Twobuilding/climate types are introduced: ‘‘Alpha’’ and ‘‘Beta’’, analogous to the categories in the field studies on adaptive thermal comfort. Foreach building/climate type operativeindoor temperature limits are given as a function of the running mean outdoor temperature and classifiedaccording to NPR-CR 1752. Finally some initial temperature simulations are shown, the results of which are plotted in the new comfort zone. # 2005 Elsevier B.V. All rights reserved. Keywords:  Thermal comfort; Adaptive model; Guidelines; Temperature simulations 1. Introduction Whether or not users are satisfied with a building islargely determined by the quality of the thermal indoorclimate.Thisimpliesthatdesignersshouldhavedirectionsattheir disposal that give them an insight into people’sexpectations of the indoor climate. These directions shoulduse a performance indicator that is not only valid andtestable, but is also easy to use in the dialogue with buildingend-users and clients [1].In The Netherlands, there have been guidelines for thethermal indoor climate of buildings since the end of the 70s.See the survey that was published in this journal in 2002 [2].However,Fanger’sthermalcomfortmodel[3],whichwas the basis for these directives, was developed based onexperiments with individuals in a climate chamber situation,where the climate was held constant just like in fully closedbuildings with air conditioning. Originally, the model hadbeen meant for the predictions of users’ evaluations of theindoor climate in that type of buildings, where one indoorclimate has to satisfy many individuals at the same time.Extensivefield research,forwhich the dataweregatheredby de Dear et al. [4], shows that people evaluate the climate differently in buildings where they can open windows andinfluence the thermal indoor climate. Especially in periodswith higher outdoor temperatures, higher indoor tempera-tures in such buildings are more acceptable than Fanger’smodel predicts. Various adaptation mechanisms play a partin this phenomenon, but the most important one is probablypeople’s expectation of the building’s climate, based on the www.elsevier.com/locate/enbuildEnergy and Buildings 38 (2006) 8–17 §  Notes : (1) This article is a continuation of an earlier publication in Energy and Buildings . Therefore, some aspects will be discussed here onlybriefly, with reference to [2]. (2) The adaptive temperature limits (ATG)discussed in this paper apply to office spaces or office buildings andcomparable spaces and buildings. (3) This guideline refers exclusively togeneral thermal comfort, but local thermal comfort, as well as indoor airquality issues are equally important when designing, operating and eval-uating buildings and other occupied spaces.* Corresponding author. Tel.: +31 6 22 419 606; fax: +31 30 699 43 84. E-mail address:  a.c.vanderlinden@bk.tudelft.nl (A.C. van der Linden).0378-7788/$ – see front matter # 2005 Elsevier B.V. All rights reserved.doi:10.1016/j.enbuild.2005.02.008  outdoor temperature of that particular day and of thepreceding days. This thermal adaptability enables the designof buildings with less stringent temperature ranges, andtherefore, reduced dependence on mechanical cooling,provided that occupants have windows that can be opened.On the basis of extensive literature search, new indoorthermal climate directives have been formulated for TheNetherlands, taking effects of adaptation into account. Theresult of this research was published in [5]. In this article we briefly discuss the backgrounds and the basis of the newdirectives and indicate how they can be applied in practice.The new Dutch guidelines also gives a good connectionto the new ASHRAE standard 55-2004 [6] in whichacceptable operative temperatures are given for naturallyconditioned spaces, based on the same research of de Dearand Brager. 2. Adaptive thermal comfort Thermal comfort models that take into account humanadaptability have been developed over the years [3,6]. Theconcept of adaptive thermal comfort can be described as [7]:‘ When a change occurs causing thermal discomfort, peoplereact in such a way that their thermal comfort is re-established  .’ This description refers to behavioral adaptationthat can be discerned in personal, technical, environmental,cultural and organizational adaptation. Physiological adap-tation or acclimatization does not seem to affect peoples’neutralities, but there is some evidence that the acceptabilityis altered [8]. Psychological adaptation implies a changedperception of, or response to, sensory information. Thermalsensations are influenced by an individual’s experiences andexpectations in a direct manner.When applying models of adaptive thermal comfort, oneshould distinguish between different types of buildings,usage and climatic circumstances. An important criterionhere is the possibility of individual control. Occupants of naturally ventilated buildings have possibilities for increas-ing the air velocity in the room by operating windows. Bydoing so, they can still create a comfortable environment inhigher indoor temperatures. Additionally, it turns out thatpsychological adaptation plays an important part especiallyin this type of buildings: because of the more direct contacttotheweatheroutside,highertemperaturesarealsoexpectedfor the indoor climate.Fanger’s PMV-model can only take the effects of behavioural adaptation into account: the adjustment of clothing and the level of activity, and the increase of the airvelocity. The model therefore is only truly appropriate forsealed air-conditioned buildings. In comparing results of field research in air-conditioned buildings with predictionsmade by the PMV-model, a strong correlation has beenfound [3]. Thegeneralization of the PMV-model for non-air-conditioned rooms might be considered as inappropriate,although this has frequently been done [8,11]. 3. Temperature limits depending on outdoortemperature In a number of studies it is demonstrated that the comforttemperatures and clothing insulation are more stronglycorrelated to the ‘running mean outdoor temperature’(RMOT) than to the actual or mean outdoor temperatureduring the day [14].Thisimpliesthatbesidestoday’sweatheralsotheweatherofthepastfewdays’hasinfluenceontheclothingvaluesandthe perception of comfort temperature. The RMOT is anexponentially weighted, mean outdoor temperature and ismore appropriate as an input variable than, for example, themean monthly temperature [14]. 4. New performance indicator: adaptive temperaturelimits (ATG) In ASHRAEStandard 55-2004 [6]an optional method fordetermining acceptable thermal conditions in naturallyconditioned spaces is given. This method may be appliedwhen certain requirements are met. The most important arethat thermal conditions are primarily regulated by theoccupants through opening and closing ofwindows that opento the outdoors. Mechanical cooling is not allowed in thesespaces,butmechanicalventilationwithunconditionedairmaybeutilized.Occupantsareengagedinnearsedentaryactivitiesandaresupposedtofeelfreetoadapttheirclothingtothermal(indoor/outdoor)conditions. For all otherspaces the standardis based on the PMV. An alternative for the adaptive comfortlimits is given [12] by an extension of the PMV model. An‘‘expectancy’’ factor isaddedtothePMVindex,basedon thehypothesis that this factor is influenced by the presence of airconditioned buildings in the near surroundings. This inter-esting assumption needs to be addressed further before anypractical implications can be concluded.Brager and de Dear define air conditioned buildings as‘‘sealed centrally air-conditioned buildings with open planfloor layouts that provide minimal adaptive opportunity andthe occupants are presumed to have no option to open/closewindows’’. Naturally ventilated buildings are defined as‘‘buildings with operable windows and ceiling fans withinsmallsingle ordual occupantofficesthat affordhighdegreesof adaptive opportunity’’. In The Netherlands and incomparable climate zones in Europe and elsewhere thisdistinction seems impractical due to the fact that mostbuildings are somewhere on a continuum between these‘‘extreme’’ building types. No doubt there are buildingswere the above mentioned building types can be applied to,but a substantial part of the office buildings have operablewindows and a variety of room or group sizes, from singlecellular offices to large open plan landscaped offices.Furthermore those buildings combine operable windowswith many different types of HVAC systems, from varioustypes of all air systems to passive facade ventilation systems  A.C. van der Linden et al./Energy and Buildings 38 (2006) 8–17   9  and from induction units to simple mechanical ventilationwithout cooling or systems with cooled ceilings.To move away from these confusing terms two buildingor climate types are introduced: ‘‘Alpha’’ and ‘‘Beta’’. To beabletoapplytheappropriatecomfortlimitsandperformanceindicator to the different buildings/climates a flow chart(Fig. 1) has been developed, based on the interrelatedaspects ‘‘experience and expectancy’’, ‘‘air-conditioned andfree-running’’ and ‘‘adaptive opportunities’’. This is by nomeans a definitive method. Further study will be performedto test and improve this method.In Figs. 2 and 3, limits are specified for 90, 80 and 65% acceptance of the thermal indoor climate. These limits werederived from de Dear and Brager’s [14] research. The 65%acceptance line was calculated specifically for this Dutchguideline in addition to the research reported in [4] and [14]. In de Dear and Brager’s diagrams the ‘effective temp-erature’ is used on the horizontal axis. The graphs have beenconverted to the outdoor air temperature, taking into accountaverage Dutch climatological norms for relative humidity.The upper limit for 90% acceptability is similar to thePMV limit +0.5. According to Fanger this limit correspondsto a predicted percentage of dissatisfied (PPD) of 10%. TheTO and GTO-methods (see Appendix A) allow this limit tobe exceeded in 10% of the time of use at most, so that theresult was: at least 90% satisfied users during at least 90% of the time [15].For the new directive we require that a ‘good’ indoorclimate is characterized by 80% acceptance. Therefore, thelimit values for 80% acceptance as calculated by de Dearand Brager can simply be used as the central criterion for abuilding’s indoor thermal climate performance. Since thenew limit values ‘slide along’ with the outdoor temperature,there is no need (or much less need) to allow the limit valuesto be exceeded. Therefore, in order to meet the functionalrequirement of a ‘good’ indoor climate, it is required that thebuilding’s performance never exceeds the limit values for80% acceptance at a specified outdoor climate. Around thiscentral requirement various indoor climate categories can bedefined.Explanatory remarks on the diagrams:- The lines for the maximum allowable indoor temperatureindicate the operative temperature, here assumed as thearithmetic mean of the air temperature and the radiationtemperature.  A.C. van der Linden et al./Energy and Buildings 38 (2006) 8–17  10Fig. 1. Diagram for determining type of building/climate Alpha or Beta.   A.C. van der Linden et al./Energy and Buildings 38 (2006) 8–17   11Fig. 2. Building/climate typeAlpha.Maximallyallowedoperativeindoor temperature fora specifiedacceptancelevel, as a function ofthe outdoor temperature T  e,ref  .Fig. 3. Building/climate type Beta. Maximally allowed operative indoor temperature for a specified acceptance level, as a function of the outdoor temperature T  e,ref  .

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Jul 23, 2017
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