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CONFORTUL TERMICSR ISO 7730

1. INDICII PMV I PPD -

2. CRITERII DE CONFORT TERMIC LOCAL

1. INDICII PMV I PPD -

PMV - predicted mean vote (votul mediu previzibil)-reprezint opinia medie a unui grup important de persoane care i exprim votul privind senzaia termic n raportcu mediul termic nconjurtor, pe o scar cu 7 niveluri:

Nivel Senzaie resimit

+3 foarte cald

+2 cald

+1 cldu

0 neutru

-1 rcoros

-2 rece

-3 foarte rece

- predicts the mean value of the votes of a large group of persons on the thermal sensation scale.+3 hot

+2 warm

+1 slightly warm

0 neutral

-1 slightly cool

-2 cool-3 cold

Echilibrul termic se obtine cand energia produsa de corp este egala cu pierderea de caldura spre mediul ambiant.

The thermal balance is obtained when the internal production in the body is equal to the loss of heat to the

environment.

Indicele PMV se calculeaz cu relatia:PMV=(0,3038*exp(-0,036*M)+0,028)*((M-W)-3,05*10^(-3)*(5733-6,99*(M-W)-pa)-

0,42*((M-W)-58,15)-1,7*10^(-5)*M*(5867-pa)-0,0014*M*(34-ta)-3,96*10^(-8)*fcl*((tcl1+273)^4-(tr+273)^4)-

fcl*hc*(tcl1-ta))

tcl=35,7-0,028*(M-W)-Icl*(3,96*10^(-8)*fcl*((tcl+273)^4-(tr+273)^4)+fcl*hc*(tcl-ta))

tcl - the the clothing surface temperature, in degrees Celsius}

hc=2,38*(tcl-ta)^0,25 {for 2,38*(tcl-ta)^0,25>12,1*SQRT(var)}

hc=12,1*SQRT(var) {for 2,38*(tcl-ta)^0,25

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PPD - predicted percentage dissatisfied

- reprezint procentul de persoane susceptibile de a avea senzaia de prea rece sau prea cald n raport cu mediulambiant i furnizeaz informaii privind disconfortul termic.

- establishes a quantitative prediction of the percentage of thermally dissatisfied people who feel too cool or too

warm

PPD=100-95*exp(-0,03353*PMV^4-0,2179*PMV^2)

-2 -1,5 -1 -0,5 0 0,5 1 1,5 20

10

20

30

40

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80

PMV

PPD

Se poate considera ca acceptabil pentru confortul uman o ambian caracterizat de un indice PPD mai mic de 10%,ceea ce corespunde unui indice PMV cuprins n domeniul:

- 0,5 PMV+ 0,5

2. CRITERII DE CONFORT TERMIC LOCAL

LOCAL THERMAL DISCOMFORT (disconfort termic local)

a). DRdraught(disconfort creat de curenti de aer) - is expressed as the percentage of people predicted to bebothered by draught

DR=(34-tal)*(val-0,05)^0,62*(0,37*val*Tu+3,14)

tal=22 {the local air temperature, in degrees Celsius}

val=0,10 {the local mean air velocity, in m/s}

Tu=40 {the local turbulence intensity, in percent}

b). Diferente de temperatura pe verticala

Vertical air temperature difference

O diferenta de temperatura mare intre glezne si cap creaza o stare de disconfort termic

A high vertical temperature difference between head and ankles can cause discomfort

Procentul persoanelor care au senzatia de disconfort termic in functie de diferenta de temperatura pe verticala,(delta_tav)

Percentage dissatisfied (PD_draught) as a function of the vertical temperature difference between head and ankles

(delta_tav)

delta_tavdiferena de temperatur ntre cap i glezne

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PD_draught=100/(1+exp(5,76-0,856*delta_tav))

1 2 3 4 5 6 7 80,1

1

10

100

tav

PDdraught

Warm and cool floors(pardoseli calde i reci)Procentul persoanelor care au senzatia de disconfort in functie de tempeartura pardoselii.

Percentage dissatisfied (PD_floors) as a function of the floor temperature

PD_floor=100-94*exp(-1,387+0,118*tf-0,0025*tf^2)

5 10 15 20 25 30 35 401

10

100

tf

PDfloor

Radiant temperature asymmetry (asimetria temperaturii radiante)- persoanele sunt sensibile la asimetria temperaturii radiante cauzate de tavane calde sau pereti reci.

- people are sensitive to radiant asymmetry caused by warm ceilings or cool walls (windows)

Procentul persoanelor care au senzatia de disconfort in funcie de asimetria temperaturii radiante Percentage dissatisfied (PD) as a function of the radiant temperature asymmetry

Tavan cald:

PD_warm_ceiling=100/(1+exp(2,84-0,174*delta_tpr_warm_ceiling))

0 4 8 12 16 200

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tpr;warm;ceiling

PDwarm;ceiling

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Pereti reci:

PD_cool_wall=100/(1+exp(6,61-0,345*delta_tpr_cool_wall))

0 4 8 12 16 200

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tpr;cool;wall

PDcool;wall

Tavan rece:

PD_cool_ceiling=100/(1+exp(9,93-0,50*delta_tpr_cool_ceiling))

0 4 8 12 16 200

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tpr;cool;ceiling

P

Dcool;ceiling

Perete cald:

PD_warm_wall=100/(1+exp(3,72-0,052*delta_tpr_warm_wall))