Application of Thermal Comfort Indices to Outdoor Urban Settings using Rayman Model

Università degli Studi di Parma Facoltà di Ingegneria APPLICATION OF THERMAL COMFORT INDICES TO OUTDOOR URBAN SETTINGS USING RAYMAN MODEL

Parma, 23 Maggio 2011

Ing. Filippo Fontanesi

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PMV-PPD predicted mean vote PMV is defined in terms of thermal load, measured as the net metabolic heat produced at the skin surface less the total sensible heat loss when a human is exposed to the environment. PPD predicted percent dissatisfied



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PET physiological effective temperature PET was developed as an index which takes into account all basic thermoregulatory processes (Höppe, 1993) and is based on a thermo-physiological heat balance model called Munich energy balance model for individuals (MEMI) (Höppe, 1984;1999).

PET is defined as the equivalent air temperature at which, in a typical indoor condition (without wind and solar radiation) the heat budget of the human body is balanced with the same core and skin temperature as under the complex outdoor conditions to be assessed.

Assumptions for the indoor reference climate: • mean radiant temperature equals air temperature (Tmrt=Ta) • air velocity 0.1 m/s • water vapour pressure 12 hPa (50% rh at Ta=20°C) • work metabolism 80 W (light activity) • clothing 0.9 clo



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PET physiological effective temperature The advantages of using PET are: • It is an universal index and is irrespective of clothing (clo values) and metabolic activity (met values) • It has a thermophysiological background and so it gives the real effect of the sensation of climate on human beings • It is measured in °C and so can be easily related to common experience • It does not rely on subjective measures • It is useful in both hot and colder climates



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PET physiological effective temperature



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SET* standard effective temperature Because ET* depends on clothing and activity, it is not possible to generate a universal ET* chart. A standard set of conditions representative of typical indoor applications is used to define:

SET* is defined as the equivalent air temperature of an isothermal environment at 50% rh in which a subject, wearing clothing standardized for the activity concerned, has the same heat stress (skin temperature tsk) and thermoregulatory strain (skin wettedness w) as in the actual environment.



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Tmrt mean radiant temperature Tmrt is the uniform temperature of an imaginary enclosure in which radiant heat transfer from the human body equals the radiant heat transfer in the actual nonuniform enclosure.

Kipp & Zonen, CNR 1: Instrument setup for measuring the three-dimensional short- and long wave radiation field affecting human beings. Delta OHM, HD32.10



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RayMan Model Modelling of Mean Radiant Temperature within urban structures Estimation of Thermal Indices Date and time Geographic data longitude (..°..’E) latitude (..°..’N) altitude (m)

Geo factors topography buildings data, vegetation data import of fisheye-photo albedo

Required data air temperature (°C) relative humidity RH (%) wind velocity (m/s) cloud cover personal data clothing activity

Output sunshine duration (h) shade Mean Radiant Temperature (°C)


(clo) (W)

Human Energy Balance

Thermal indices Predicted mean vote PMV Physiological equivalent temperature PET (°C) Standard effective temperature SET* (°C)


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References ASHRAE Handbook—Fundamentals, American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc., Atlanta, 2001. Matzarakis, A.; Rutz, F.; Mayer, H., 2000: Estimation and calculation of the mean radiant temperature within urban structures. In: Biometeorology and Urban Climatology at the Turn of the Millenium (ed. by R.J. de Dear, J.D. Kalma, T.R. Oke and A. Auliciems): Selected Papers from the Conference ICB-ICUC'99, Sydney, WCASP-50, WMO/TD No. 1026, 273-278.

PMV Fanger, P. O., 1972. Thermal Comfort, Analysis and application in Environment Engineering. New York. McGraw Hill. ISO Standard 7730: Moderate Thermal Environments - Determination of the PMV and PPD Indices and Specification of the Conditions for thermal comfort, International Organisation for Standardization, Geneva, 1994. PET Höppe, P., 1999: The physiological equivalent temperature - a universal index for the biometeorological assessment of the thermal environment. Int. J. Biometeor 43, 71-75. Matzarakis, A., Mayer, H., Iziomon, M., 1999: Applications of a universal thermal index: physiological equivalent temperature. Int. J. Biometeor 43, 76-84. SET Gagge, A. P., Fobelets, A. P., Berglund, L. G., 1986: A standard predictive index of human response to the thermal environment. ASHRAE Trans 92, 709-731. RADIATION FLUXES VDI, 1994. VDI 3789, Part 2: Environmental Meteorology, Interactions between Atmosphere and Surfaces; Calculation of the short- and long wave radiation. Beuth, Berlin.



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Application of Thermal Comfort Indices to Outdoor Urban Settings using Rayman Model

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