Impacts of street design parameters on human-biometeorological variables
Author
Summary, in English
Abstract in Undetermined
This study deals with a current problem of urban human-biometeorology on the micro-scale, which becomes more important due to the future increase of severe summer heat in Central Europe. The impact of street design parameters on the thermal comfort of citizens is analysed in an experimental way for typical summer conditions in Central Europe. The investigation is focused on the behaviour of mean radiant temperature Tmrt and physiologically equivalent temperature PET as the most important human-biometeorological variables for thermal comfort during these atmospheric conditions. To get quantitative results on how they depend on small-scale characteristics of urban street canyons, an investigation design is applied which is based on measurements of relevant meteorological variables - like air temperature Ta - by specific humanbiometeorological measuring systems. They were conducted in selected street canyons within different urban quarters of Freiburg, the warmest city in Germany, from 2007-2009. Tmrt and PET were calculated from the measured meteorological variables by well-tested approaches. The geometry of urban street canyons is characterised by (i) the sky view factor SVF determined from fish-eye photos, (ii) the ratio of building height H to street width W, (iii) the orientation to the sun, and (iv) the fraction of ctc (coverage by the street tree canopy). To eliminate the influence of slightly different weather conditions even on typical summer days, the results are not presented in form of absolute values for the human-biometeorological variables, but in form of ratios for the measured radiative flux densities and in form of differences for the measured and calculated temperatures. As the results for Tmrt and PET should primarily quantify universal patterns of the impact of street design parameters on human thermal comfort, they are only presented as mean values for the period 10-16 CET. The main results obtained from different analyses are: (i) SVF for the southern half of the upper hemisphere (SVF90-270) is more suitable to characterise the sites with respect to the thermal perception of citizens than SVF for the whole upper hemisphere (SVF1-360), (ii) in contrast to wide E-W oriented street canyons, narrow E-W oriented street canyons have larger spatial differences in Ta, Tmrt and PET, (iii) with respect to the orientation, these differences are larger in E-W than in N-S oriented street canyons, and (iv) an increase of ctc by 10 % leads to a decrease of Ta by only 0.2 °C, but to a reduction of Tmrt by 3.6 °C and of PET by 1.4 °C.
This study deals with a current problem of urban human-biometeorology on the micro-scale, which becomes more important due to the future increase of severe summer heat in Central Europe. The impact of street design parameters on the thermal comfort of citizens is analysed in an experimental way for typical summer conditions in Central Europe. The investigation is focused on the behaviour of mean radiant temperature Tmrt and physiologically equivalent temperature PET as the most important human-biometeorological variables for thermal comfort during these atmospheric conditions. To get quantitative results on how they depend on small-scale characteristics of urban street canyons, an investigation design is applied which is based on measurements of relevant meteorological variables - like air temperature Ta - by specific humanbiometeorological measuring systems. They were conducted in selected street canyons within different urban quarters of Freiburg, the warmest city in Germany, from 2007-2009. Tmrt and PET were calculated from the measured meteorological variables by well-tested approaches. The geometry of urban street canyons is characterised by (i) the sky view factor SVF determined from fish-eye photos, (ii) the ratio of building height H to street width W, (iii) the orientation to the sun, and (iv) the fraction of ctc (coverage by the street tree canopy). To eliminate the influence of slightly different weather conditions even on typical summer days, the results are not presented in form of absolute values for the human-biometeorological variables, but in form of ratios for the measured radiative flux densities and in form of differences for the measured and calculated temperatures. As the results for Tmrt and PET should primarily quantify universal patterns of the impact of street design parameters on human thermal comfort, they are only presented as mean values for the period 10-16 CET. The main results obtained from different analyses are: (i) SVF for the southern half of the upper hemisphere (SVF90-270) is more suitable to characterise the sites with respect to the thermal perception of citizens than SVF for the whole upper hemisphere (SVF1-360), (ii) in contrast to wide E-W oriented street canyons, narrow E-W oriented street canyons have larger spatial differences in Ta, Tmrt and PET, (iii) with respect to the orientation, these differences are larger in E-W than in N-S oriented street canyons, and (iv) an increase of ctc by 10 % leads to a decrease of Ta by only 0.2 °C, but to a reduction of Tmrt by 3.6 °C and of PET by 1.4 °C.
Publishing year
2011
Language
English
Pages
241-552
Publication/Series
Meteorologische Zeitschrift
Volume
20
Issue
5
Document type
Journal article
Publisher
E Schweizerbartsche Verlags
Topic
- Physical Geography
Keywords
- Atmospheric conditions
- Air temperature
- Absolute values
- Building height
- Central Europe
- Fish-eye
- Germany
- Human thermal comfort
- Mean radiant temperature
- Mean values
- Measuring systems
- Meteorological variables
- Micro-scales
- Physiologically equivalent temperatures
- Quantitative result
- Radiative fluxes
- Sky view factor
- Spatial differences
- Street canyon
- Street design
- Summer heat
- Tree canopy
- Urban street canyon
- Weather conditions
Status
Published
ISBN/ISSN/Other
- ISSN: 1610-1227