Review of Numerical Modelling of Outdoor Thermal Comfort

The 2005 World Sustainable Building Conference, 06-026 Tokyo, 27-29 September 2005 (SB05Tokyo) REVIEW OF NUMERICAL MODELLING OF OUTDOOR THERMAL COMFORT

Leonardo Marques MONTEIRO1

1 Department of Technology, Faculty of Architecture and Urbanism of University of Sao Paulo, Sao Paulo, Brazil, [email protected]

Keywords: thermal comfort, thermal stress, outdoors, numerical modelling, comfort indexes

Summary Although most thermal comfort studies consider only the indoor conditions, there are significant researches concerning outdoors. Evaluating open areas requires the comprehension of additional factors, which are not taken into account in a typical indoor situation, bringing more complexity to the thermal analysis. This paper reviews the researches in outdoor thermal comfort, specifically the numerical models proposed by several authors through thermal balance methodology and empirical researches. The first experiences made are illustrated by the empirical work of Houghten (1923), Vernon & Warner (1932), McAriel (1947) and Missenard (1948), originally published as nomograms. The equations and parameters of the former following empirical works are presented: Siple & Passel (1945), Belding & Hatch (1955), Yaglou & Minard (1957), Webb (1960) and Masterton & Richardson (1979). The following researches based on thermal physiological model are considered: Gagge (1967), Givoni (1969), Jendrizky (1979), Domínguez (1992), Brown & Gillespie (1995), Blazejczyk (1996), Höppe (1999), Pickup & Dear (1999) and Jendritzky (2003). The adaptative model of Aroztegui (1995) is presented and also two new empirical works: Givoni & Noguchi (2000) and Bluestein & Osczevski (2002). Last, the developing works of the Commission 6 of ISB (2004) are presented, which aim a universal thermal climate index. The contribution of this paper is a summarized historical review and current state-of-the-art in outdoor thermal comfort researches, presenting the equations and parameters proposed and a brief discussion of its limitations and possible new approaches.

1. Introduction Hipocrates (400bC) has already qualitatively described the main parameters that influence the thermal comfort: temperature, humidity, winds and radiation. The first registered temperatures measures were taken in Florence and Beijing, in the XVII century. During the XVIII century, thermal sensation opinions were collected, but they were always supposed to be evasive (Watson, 1979; apud Araujo, 1996). At the begging of the XIX century, in Europe, the first thermal stress studies were made, motivated by miners and textile workers health problems. Although some standardization has been already made, methods to measure variables and correlated them to thermal comfort were developed only in the begging of the XX century, motivated in part by the artificial air conditioning systems (Banham, 1975; apud Araujo, 1996). So, most researches focused just the relevant variables to typical indoor environment. Some of these studies were adapted to outdoors and others were specifically developed to it. This paper will present a review of the researches concerning outdoor thermal comfort, focusing the numerical modelling of their indexes.

2. First Indexes Houghten et al. (1923), of ASHVE laboratories, propose the Effective Temperature (ET), determined by dry and wet bulb temperature and wind speed. Researchs of Glickman, 1950; Smith, 1958 and Givoni, 1963 (apud Givoni, 1969) show that ET super estimate humidity. Vernon & Warner (1932) propose the New Effective Temperature (ET*) substituting dry bulb temperature by globe temperature. This index was adopted by ASHRAE, in 1967. McAriel et al. (1947) develop the Predictable Four Hour Sweat Rate - P4SR, based in physiological responses of four hour exposure to certain climate conditions. This index considers globe and wet bulb temperatures, wind speed, metabolism and two clothing ensembles. Missenard (1948), doing similar experiments to the Houghten, but with longer exposures, proposes the Resultante Temperature (RT). According to Givoni (1963, apud Givoni, 1969), this index presents better results than ET does. These four indexes were originally presented as nomogram charts and their equations were not originally published.

3. Wind Chill Temperature (WCT) Siple & Passel (1945; apud Williamson, 2003) developed the Wind Chill Temprature from the data obtained with experiences in Antarctica. The equipment were two plastics cylinders, filled with water, exposed to different temperatures (-9ºC~56ºC) and wind speeds (0m/s~12m/s). The water freezing time was observed. The experimental data was treated, generating a regression line. The equation proposed is:

WCT = (12.15 + 11.6 • v10/2 - v10) • (33 - ta) (1)

where: ta = air temperature, in ºC; v10 = air speed at 10m high, in m/s; -9ºC ≤ ta ≤ 10ºC; v10 ≤ 22.3m/s

- 2252 - The 2005 World Sustainable Building Conference, Tokyo, 27-29 September 2005 (SB05Tokyo)

4. Heat Stress Index (HSI) Belding & Hatch (1955, apud Givoni, 1969) propose the Heat Stress Index. Considering the thermal balance model, they make four physiological suppositions: (1) the heat load in the body is equal to required evaporative sweat: Ersw = M + R + C; (2) the physiological strain is determined by the relation Ersw / Emax; (3) the skin temperature is constant during the thermal stress: tsk = 35°C; (4) the maximum sweat rate during an eight hour period is 1L/h, that is equivalent to 2400 Btu/h or 390 W/m2 for a male, 75 kg, 1.70m. The authors propose the following equations for estimating the heat storage:

0.5 Ersw = M + 22 · (trm - tsk) + 2 · v · (ta - tsk) (2) 0.4 Emax = 10 · v · (psk - pa) (3) where: [22 · (trm - tsk)] = radiation loads, in Btu/h; trm = mean radiant temperature, in ºF; tsk = superficial skin 0 5 temperature, in ºF; [2 · v , · (ta - tsk)] = convection loads, in Btu/h; ta = air temperature, in ºF; v = air speed, in ft/min; Ersw = required evaporative sweat, in Btu/h; Emax = maximum evaporative capacity, in Btu/h; psk = skin vapor pressure, in mmHg; pa = air vapor pressure, in mmHg

Table 1 brings the index. It is determined, considering Ersw and Emax in W, by the greatest value between:

HSI = (Ersw/Emax) ·100 & HSI = (Ersw/632.27) ·100 (4)

This index is valid when: ta: 21-49 ºC; pa: 3-42 mmHg (22.5-315.0 kPa); v: 0.25-10.0 m/s and M: 86-430 W.

Table 1: Heat Stress Index (HSI), Belding & Hatch (1955; apud Givoni, 1969 and Parsons, 1993) HSI Interpretation 0 - 10 no thermal stress (thermal comfort) 10 - 30 light response, intellectual work decrease as well as heavy mechanical work efficiency 40 - 60 several response, danger to non acclimatized people, mechanical work efficiency decrease 70 - 90 very several response, just little percentage of people support to work under such conditions 90 - 100 maximum response tolerated daily by acclimatized and adapted young man 100 - 200 heat storage (thermal stress)

5. Wet Bulb Globe Temperature (WBGT) Yaglou & Minard (1957) proposes the wet bulb globe temperature. Without direct solar radiation, the index is given by equation 5. With direct solar radiation, the index is given by equation 6 (ISO 7243, 1989).

WBGT = 0.7 · tnwb + 0.3 · tg (5)

WBGT = 0.7 · tnwb + 0.2 · tg + 0.1 ta (6) where: tg = globe temperature, in ºC; tnwb = natural wet bulb temperature, in ºC, ta = air temperature, in ºC

6. Equatorial Comfort Index (EC) Webb (1960, apud Santamouris & Asimakopoulos, 1996) developes the Equatorial Comfort Index, based on reseaches in Cingapure. The air temperature, pressure and speed data are correlated to the still and saturated air which would give the same thermal sensation. The experimental equation given is:

0,5 EC = 0.574 · ta + 0.2033 · pv - 1.8 · v + 42 (to twb > 25ºC and ta = trm) (7) where: ta = air temperature, in ºC; pa = vapor pressure, in mmHg; v = air speed, in m/s

7. New Standard Effective Temperature (SET*) Gagge (1967) presents the New Standard Effective Temperature (SET*), defining it as the air temperature in which, in a given reference environment, the person have the same skin temperature (tsk) and wettedness (w) that in the real environment. So, the reference and the real environments are equivalent in physiological strain and thermal comfort. The reference environment is defined as: mean radiant temperature (trm) = air temperature (ta); air speed (va) = 0.15 m/s; relative humidity (ur) = 50%; metabolism (M) = 1.2 met; clothes resistance (Iclo) = 0.9 clo. The SET* is determined by a two-node-model of human body thermal regulation, as proposed by Gagge et al. (1986), following the steps: (1) determination of tsk and w for a given environment; (2) input of tsk and w found, solving the equations to found a new air temperature (ta), considering trm=ta; v=0.15 m/s; ur=0.5; M=1.2 met; Iclo = 0.6 clo; (3) the ta found is the SET*.

8. The Index of Thermal Stress (ITS) Givoni (1969) proposes the Index of Thermal Stress, which considers the heat exchanges, metabolism and clothes. Originally, it did not consider the radiation exchanges. In order to consider them, the author suggests to use the globe temperature, instead of air temperature. Afterwards, solar radiation started to be The 2005 World Sustainable Building Conference, Tokyo, 27-29 September 2005 (SB05Tokyo) considered in the model. So, taking into account these adaptations and summarizing all the equations presented by the author in a unique equation, the index can be presented as:

0,3 0,2 ITS = {0.8 M + 20 + α · v · (tg - 35) + In · Kpe · Kcl · [1 - a · (v - 0.88)]} · (8) 0,3 0,3 · exp [ 0,6 · (0.8 M + 20 + α · v · (tg - 35) / p · v ·(42 - pv) - 0.12 )] where: M = metabolism, in kcal/h; α = clothing convective coefficient, dimensionless; v = air speed, in m/s; tg = globe temperature, in ºC; In = normal solar radiation, in kcal/h; Kpe = ground and posture coefficient, dimensionless; Kcl = clothing coefficient, dimensionless; a = clothing short wave radiation coefficient, dimensionless; p = clothing evaporative coefficient, dimensionless; pv = vapor pressure, in mmHg. According to the author (p. 91-92), α, Kcl, a, p are 15.8; 1.0; 0.35; 31.6 to bathing suit and hat and 13.0; 0.5; 0.52; 20.5 to lighting summer clothing. Kpe is, sitting with back to sun, 0.386 (desert) or 0.379 (forest) and, standing with back to sun, 0.306 (desert) e 0.266 (forest).

9. Humidex Masterton & Richardson (1979) propose the Humidex, an equivalent temperature to air temperature and humidity. It is used by the Environment Canada Meteorological Service (2000) to alert people of the heat stress danger. Considering a generical formulation to estimate the vapor pressure, the Humidex is given by:

7.5 · tar / (237.7+ tar) HU = ta + (5/9) · [(6,112 · 10 · ur/100) - 10] (9) where: ta = air temperature, in ºC; ur =relative humidity

Table 2: Humidex, Environment Canada (2000). Humidex (HU) Interpretation ≤ 30 no discomfort 30 - 40 some discomfort 40 - 45 much discomfort, avoid physical strain ≥ 45 danger situation ≥ 54 thermal stroke

10. Klima Michel Model (KMM) Jendrizky et al. (1979; apud Jendritzky & Nuble, 1981) developed the Klima Michel Model. It is an adaptation of Fanger (1970), with a short wave radiation model, computed in the mean radiant temperature. This radiation model is considered through the FM 12 synoptic data of World Meteorological Organization (WMO). Concerning the individual parameters, it was done standardization, from where derives the name of the model. Michel is a typical German name, alluding what Jendritzky calls a reference German: male, 35 years, 1,75m, 75 kg, walking at 4 km/h (2.3 met). Concerning clothing, it is selectively chosen between 0.5 and 1.75 clo (summer and winter German clothing ensembles respectively). Considering these, PMV is determined according to Fanger equations. Due to model limitations, specifically because of the determination of skin temperature and sweat rate, the values found are not coherent to subjective answers commonly found.

11. Expo’92: criteria for outdoor sweat rates The outdoor climate conditioning of Sevilla Expo, in 1992, was part of the developing program of the Governmental Society for Expo’92, created in 1987. The aim was to found technically and economically viable solutions to improve outdoor thermal comfort. The research results of the Termotecnia Group of Sevilla University were published by Dominguez et al. (1992). The authors assumed that all sweat is evaporated to keep thermal comfort, and they argue that, although it is desirable no sweat at all, it was accepted low sweat rates according to the conditioning required. In walking zones, where there is a mid level conditioning, the sweat rate was fixed under 90 g/h. In staying zones, where there is a high level conditioning, the sweat rate was fixed under 60 g/h.

12. Comfort Formula (COMFA) Brown & Gillespie (1995) propose an outdoor Comfort Formula based on thermal budget with some particularities in its terms. The general equation is:

B = M’ + Rabs - Remit - C - Esk (10) where: B = thermal budget; M’ = metabolism minus respiration losses; Rabs = absorbed radiation; Remit = 2 emitted radiation; C = convective excahnge; Esk = skin latent heat loss; all of them in W/m . The sensible and latent respiration losses are empirical considered in the metabolism, as following:

M’ = (0.85 - 0.0173 · pv,ta - 0.0014 · ta) · M (11) where: M = metabolism, in W/m2; pv,ta = vapor saturated pressure at ta, in kPa; ta = air temperature, in ºC The 2005 World Sustainable Building Conference, Tokyo, 27-29 September 2005 (SB05Tokyo)

The formulas above are the commonly found in literature, but presented in a different way. The emitted radiation equations can be found in Brown & Gillespie (1995, p. 172). To the absorbed radiation, the authors give three possibilities (pp. 175-84): (a) in loco measures, (b) estimation by meteorological data, (c) estimation by numerical equation. They also present convective and evaporative exchanges (pp. 171-2) and a model to estimate air speed from meteorological data (pp. 185-6). All these equations are also commonly found in technical literature. The table 3 shows the interpretation of the index COMFA.

Table 3: COMFA Index, Brown & Gillespie (1995, p. 173). Budget W/m2 Interpretation B < -150 would prefer to be much warmer -150 < B < -50 would prefer to be warmer - 50 < B < 50 would prefer no change 50 < B < 150 would prefer to be cooler 150 < B would prefer to be much cooler

13. Outdoor Neutral Temperature (Tne) Aroztegui (1995) proposes the Outdoor Neutral Temperature, based on Humphreys (1975). This author has proposed the Neutral Temperature (Tn), defined as the average thermal neutrality temperature to given population. The Tn is linearly related to mean month temperature (tmm), as shown in equation 12. It is valid indoors with low air speeds and mean radiant temperature close to air temperature (18,5ºC~28,5 ºC). Aroztegui, also based on Givoni (1969), took into account the solar radiation and air speed. Considering sedentary activity, clothing resistance of 0,8 clo and relative humidity between 35% and 65%, he established the Tne, which is presented in equation 13.

Tn = 17.6 + 0.31 · tmm (12) 0,2 0,3 Tne = 3.6 + 0.31 tmm + {100 + 0,1 Rdn [1 - 0,52 (v - 0,88)]} / 11,6 v (13)

2 where: tmm = mean month temperature, in ºC; Rdn = normal direct solar radiation, W/m ; v = air speed, in m/s.

14. Man-Environment Heat Exchange Model (MENEX) Blazejczyk (1996; apud Blazejczyk, 2002) proposes the Man-Environment Heat Exchange model, based on thermal balance. Its specificities are: evaporative loss pondered by sex (1.0 for men; 0.8 for women), radiation exchanges pondered by nebulosity, solar radiation possibly considered by three different models: (1) SolDir, that considers direct, diffuse and reflect solar radiation; (2) SolGlob, that considers global solar radiation; (3) SolAlt, that can be used when there is no solar radiation data. These models consider clothing thermal resistance and pondered albedo of skin and clothes, presenting different equations according to solar elevation and nebulosity. The twelve equations of these models can be found in Blazejczyk (2000, pp. 138-40). The author proposes three criteria, which are supposed to be considered as a whole: Heat Load (HL), Intensity of Radiation Stimuli (R’) and Physiological Strain (PhS). He also proposes the Subjective Temperature Index (STI) and the Sensible Perspiration Index (SP).

14.1. Heat Load (HL), Intensity of Radiation Stimuli (R’) and Physiological Strain (PhS) The equations for determining the Heat Load are:

[ 2 - 1/(1+Rc)] 2 2 HL = [(S + 360) / 360] if S ≤ 0 W/m and Esk ≥ -50 W/m (14) [ 2 + 1/(1+Rc)] 2 2 HL = [(S + 360) / 360] if S > 0 W/m and Esk ≥ -50 W/m (15) [ 2 +1/(1+Rc)] 2 2 HL = (E/-50) · [(S + 360) / 360] if S > 0 W/m and Esk < -50 W/m (16) [ 2 - 1/(1+Rc)] 2 2 HL = (E/-50) · [(S + 360) / 360] if S ≤ 0 W/m and Esk < -50 W/m (17) 2 where: S = heat storage; RC = short wave radiation; Esk = evaporative skin losses; all in W/m The Intensity of Radiation Stimuli is calculated considering the solar radiation absorbed by the nude body. So, it must not consider the clothing factor (fcl) and its transmissibility (τcl). The equation is:

R’ = αsk · Isol (18) 2 where: αsk = short wave absorption of skin, dimensionless; Isol = total incident solar radiation, in W/m The Physiological Strain is defined by the two principal heat exchanges. In cold strain, it is the convective heat loss (C); and in hot strain the evaporative heat loss (Esk). So, the given equation is:

PhS=C/Esk (19) The 2005 World Sustainable Building Conference, Tokyo, 27-29 September 2005 (SB05Tokyo)

Table 6: Heat Load (HL), Intensity of radiation stimuli (R’), Physiological Strain (PhS), Blazejczyk (2001). HL Interpretation R’ Stimuli PhS Interpretation ≤ 0.810 great hot stress < 60 weak < 0.25 extreme hot strain 0.811 - 0.930 moderate hot stress 60 - 120 moderate 0.25 - 0.49 great hot strain 0.931 - 1.185 thermal neutrality > 120 strong 0.50 - 0.99 slight hot strain 1.186 - 1.600 moderate cold stress 1.00 - 1.99 slight cold strain ≥1.600 great cold stress 2.00 - 4.00 great cold strain >4.00 extreme cold strain

14.2. Subjective Temperature Index (STI) and Sensible Perspiration (SP) The equations for determining the Subjective Temperature Index are:

0.75 -8 4 0.25 2 STI= trm - [ ISl / (5.39 · 10 ) + 273 ] -273 if S < 0 W/m (20) 0.75 -8 4 0.25 2 STI= trm + [ ISl / (5.39 · 10 ) + 273 ] -273 if S ≥ 0 W/m (21) 2 where: trm = mean radiant temperature, in °C; S = heat storage, in W/m The Sensible Perspiration gives a subjective evaluation of secreted sweat that is not effective evaporated. The equation of its index is:

SP= -0.3 · 5 · (Ersw/Emax) (22) 2 2 where: Ersw = required evaporative sweat, in W/m ; Emax = maximum evaporative capacity, in W/m

Table 7: Subjective Temperature Index (STI) and Sensible Perspiration (SP), Blazejczyk (2002). STI Interpretation SP Interpretation ≤ 38.0 very cold 0 Dry forehead and body -38.0 a -0.5 cold 1 Wet skin without visible humidity - 0.4 a 22.5 cool 2 Visible humidity 22.6 a 31.9 comfortable 3 Wet forehead and body 32.0 a 45.9 warm 4 Partially wet clothing 46.0 a 54.9 hot 5 Almost completely wet clothing ≥ 55.0 very hot 6 Completely wet clothing

15. Munich Energy-Balance Model for Individuals (MEMI) Höppe (1999) proposes the Munich Energy-Balance Model for Individuals, based in some parameters of Gagge (1967) two node model. The MEMI differs from Gagge model in the way it calculates the regulatory sweat and heat fluxes, considering separately the temperature of clothed parts of the body and unclothed ones. The equations 14-16 show respectively: the thermal balance, the heat flux from the core of the body to skin surface; the heat flux from skin surface to external cloth surface. Solving this three equation system, it can be found the temperatures of the external cloth surface (tcl), the skin (tsk) and the core of the body (tc).

M - W + R + C + Qres - Edif - Ersw = 0 (23)

Fc-sk = vb · ρb · cb · (tc - tsk) (24)

Fsk-cl = (tsk - tcl) / Icl (25) where: vb = blood flux from core to skin, em l/s·m2; ρb = blood density, in kg/l; cb = blood specific heat, in 2 W·s/K·kg; all heat fluxes in W/m . 15.1. Physiological Equivalent Temperature (PET) Höppe (1999) defines the Physiological Equivalent Temperature of a given environment as the equivalent temperature to air temperature in which, in a reference environment, the thermal balance and the skin and core temperatures are the same of that found in the given environment. The reference environment is defined as: mean radiant temperature (trm) = air temperature (ta); air speed (va) = 0.1 m/s; vapor pressure (pv) = 12 hPa (relative humidity (ur) = 50% at ta=20 °C); metabolism (M) = 114W; clothes resistance (Iclo) = 0.9 clo. The PET is found as following: (1) determination of tsk e tc for a given environment, using MEMI; (2) input of tsk and tc found, solving the equations to found a new air temperature (ta), considering trm=ta; v=0.1 m/s; pv=12 hPa; M=114W; Iclo = 0.9 clo; (3) the new ta found is the PET.

16. Outdoor Standard Effective Temperature (OUT-SET*) Pickup & Dear (1999) propose the Outdoor Standard Effective Temperature based on an adaptation of the New Standard Effective Temperature (SET*) of Gagge (1967), considering detailed radiative exchanges through an specific model (OUT-MRT), that gives an equivalent mean radiant temperature to be used in The 2005 World Sustainable Building Conference, Tokyo, 27-29 September 2005 (SB05Tokyo)

Gagge two node model. Potter & Dear (1999) present the field study to calibrate the index. The OUT-MRT equations, and a positive comparative study between the results of this model and of Blazejczky (1996), can be found in Pickup & Dear (1999). Possible applications of OUT-SET* are in Dear & Pickup (1999).

17. Thermal Sensation Index (TS) Givoni & Noguchi (2000) describe experimental research of outdoor thermal comfort, sponsored by Fujita Corporation. Thermal sensation and global comfort sensation were studied in a park in Yokohama, Japan. The aim was to quantify the effect of the architectural project in solar radiation and wind incidence. The field research was done in some days during the four seasons of the year, considering the commonly used clothes in the different seasons. A questionnaire was applied to three couples (a man and a woman in each couple), which one of them in a different environment conditions: shade, sun exposed, sun exposed but protect from wind. The three areas were near each other, and the couples changed places after 20 minutes, answering the questionnaire in 5 minutes, while environment conditions were measured: air temperature, humidity and speed, and superficial temperatures. Thermal sensation were scaled from 1 (very cold) to 7 (very hot), as well as comfort sensation (very uncomfortable/very comfortable). The value 4 represents the neutrality in both cases. Considering the experimental data, the following equation is proposed:

TS = 1.7 + 0.118 ta+ 0.0019 IH - 0.322 v - 0.0073 ur + 0.0054 ts,ent (26) 2 where: ta = air temperature, in ºC; IH = incident solar radiation, in W/m ; v = air speed, in m/s; ur = umidade relative, in %; ts,ent = mean superficial air temperature of the surroundings, in ºC.

18. New Wind Chill Temperature (NWCT) The New Wind Chill Temperature was determined considering the works of Bluestein & Zecher (1999) and Osczevski (2000a, 2000b). Bluestein & Zecher (1999) develope a new index based on Siple & Passel (1945) original index, which gives unreal high values, specially on low air temperatures and high wind speeds. Bluestein & Zecher verify that Siple & Passel did not took into account the physic model resistance in their experiments, overestimating heat transfer. The new index is based on a numerical model of the heat exchanges between the human head and the environment. Osczevski (2000a, 2000b) presents two indexes: one combining air temperature and speed considering a correction factor to solar radiation and other to determine the risk of frostbite. The author developed a computer controlled thermal head mannequin and also made experiments with volunteers in acclimatized chambers. Bluestein & Osczevski (2002) propose the NWCT. They describe the physical modelling of a face exposed to wind: front half of a vertical thermal cylinder of 180mm external diameter, with 25 concentric layers, simulating heat exchanges. Individual speed was set to 4,8 km/h, obtained from researches with pedestrians in crossing corns, to which the wind speed is added. To radiation exchanges, it assumes to be a clear sky night. So, the NWCT is calculated to a relative air movement of 4,8 km/h, representing a situation in which the heat loss and skin temperature are equivalent to the real one. The equations of NWCT and Frostbite time (Ft) are:

0.16 0.16 NWCT = 13.12 + 0.6215 · ta - 11.37 · v10 + 0.3965 · ta · v10 (27) -1.668 Ft = {{-24.5 · [(0.667 x v10) + 4.8]} + 2111} x (-4.8 - ta) (28) where: v10 = air speed at 10m high, in km/h; Ft = Frostbite time, in min; ta ≤10 ºC and v10 ≥ 4,8 km/h

19. New Perceived Temperature (PT*) Jendritzky (2003) proposes the New Perceived Temperature. Due to limitations of KMM, it would be adapted many times. Firstly, in 1995, the model started using the Perceived Temperature (PT) of Staiger et al. (1998), instead of the PMV index of Fanger (1970). In 1998, KMM radiation model was revised considering the VDI 3789 Part 2 (VDI, 1994), developing the RayMan model, by Matzarakis et al. (2000). Finally, in 2000, considering Gagge et al. (1986) proposition of PMV*, the PT* was established. The KMM now comprehends: (1) the RayMan model; (2) the mean radiant temperature (trm) of Fanger; (3) the thermal balance; (4) the PT* calculation. The reference environment for its calculation is: trm=ta; relative humidity (ur) = 50%; relative air velocity (vr) = 4 km/h; metabolism (M) = 172.5 W; clothing resistance (Icl) between 0.5 and 1.75 clo, selectively chosen according to climatic conditions.

20. Universal Thermal Climate Index (UTCI) The Universal Thermal Climate Index is being developed by Comission 6 of International Society of Biometeorology (ISB, 2004). The commission, chaired by Jendritzky, was created in November 2000. The first meeting was in Friburg, in July 2001 and the second one in Genebre, in May 2003 (ISB Comission 6, 2001; 2003). It was already established that UTCI: (1) will be a temperature index equivalent to the air temperature of a reference environment that provides the same heat exchange conditions as the given environment; (2) should cover the whole continuum of thermoregulation, considering human adaptation (clothing) in order to keep comfort; (3) will deal with total body conditions as well as with bare skin problems to avoid frostbite risks, (4) will be based on the most advanced multi-node models of human thermoregulation. As criteria for input data, it was set: (1) general topography will be a flat landscape, with The 2005 World Sustainable Building Conference, Tokyo, 27-29 September 2005 (SB05Tokyo) two hemispheres; local topography can be considered for urban bioclimatic assessment; (2) short and longwave radiant fluxes considered by calculating mean radiant temperature (Trm); (3) wind reference height of 1.1 m (according to ISO 7726); considering 2/3 of observing station wind speed (usually measured at 10m) and assuming wind blows at 90 degrees of the walking subject (wind and walking speeds are vectorially added). The reference environment of the equivalent temperature is: (1) tmrt = ta; (2) relativy humidity (ur) = 50%; (3) still air with relative air velocity (vr) of 1.1 m/s; metabolism (M) = 135 W/m²; (2) clothing resistance Iclo = 0.5 ~ 2.0 clo. It is assumed that people adapt by clothing more or less reasonable to the thermal environment in a wide range of heat exchange conditions in order to achieve thermal comfort. Outside the theoretical comfort range the clothing value will be kept fix. This requires a model that distinguishes between bare skin and covered compartments. It seems reasonable to revert to an already published model. However, it is understood that everybody can use any model that fulfils demonstrably and sufficiently the model comparison. The next step of the Commission is exactly to compare the different models commonly used with the data provided by the simulations with multi-node models and to discuss how to assess the physiological data in terms of a single index. The final aim is to establish a universal temperature scale index that considers all thermal regulatory processes in a wide range of climatic situations. However, considering adaptation and acclimatization as important aspects for comfort and warning criteria, the output values of UTCI will also be classified in terms of comfort and danger scales to be applied regionally.

21. Final Considerations This paper presented over twenty models and indexes for outdoor thermal comfort assessment. Historically, the first goal was to determine an empirical index universally valid. However, the researches showed that empirical models present significant responses only to the specific situation they were established, or to similar situations. Trying to get universal validity, thermal balance models were developed, bringing the advantage of an analytical evaluation of the different thermal exchanges. Considering the current state-of-art researches, on one hand we have the empirical researches of Givoni & Noguchi (2000), whose Thermal Sensation Index was generated by field studies obtaining responses to the specific given situation, and of Bluestein & Osczevski (2002), whose New Wind Chill Temperature take into account just two variables (air speed and temperature) aiming a particular usage. On the other hand, there are the analytical model researches trying to coming to a universal validity. Blazejczyk (1996) proposed the MENEX, a one-node model which gives several scale indexes (HL, R’, PhS, STI, SP) which, in a whole, evaluate the thermo physiological processes. Höppe (1999) proposed the MEMI, a two-node model, aiming a more detailed thermal-regulatory description. This author also proposed the PET, a temperature index, instead of a predefined scale one. Temperature indexes were used in the first developed empirical models of the last century, aiming to give an easy and comprehensible interpretation of thermal comfort. The Gagge (1967) two-node model, was already used with a temperature index: SET*. It was based on Gagge works that Pickup & Dear (1999) proposed the OUT-SET*, considering radiation by the OUT-MRT model. Jendritzky (2003) reviewed the KMM model, also considering a specific radiation model (Rayman, developed by Matzarakis, 2000) and, leaving the PMV index of Fanger (1970), proposed the PT*, based on Staiger et al. (1998) and also Gagge et al. (1986). Although Gagge (1967) has proposed a two-node model with a temperature index, in Gagge et al. (1986) the model is adapted with PMV* due to the great acceptance of PMV for indoor thermal assessment. Curiously, for outdoors, there is a tendency to adopt not predefined scales, but index temperatures, as can be seen in Höppe (1999), Pickup & Dear (1999) and Jendritzky (2003), all of them somehow based in the former researches of Gagge. The usage tendency of a temperature index is confirmed by the developing works of ISB Comission 6 (2004). However, comfort and danger scales will be applied regionally, as it is recognized that adaptation and acclimatization play important rule in comfort interpretation and warning criteria. Maybe this indicates the future researches: on one hand, developing universal analytic models representing thermal regulatory processes and, on the other hand, specific calibrations considering adaptation and acclimatization. Maybe, also, it is already possible to glimpse the development of transient analytical models that consider the thermal and physiological processes, including acclimatization, leaving to calibration the work of correlating the model with the behavior adaptation and the thermal sensation preferences.

Acknowledge The author would like to thank the Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP), for the financial support in this research, and The SB05 Support Programme, for providing accommodation and free registration for The SB05 Tokyo Conference.

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