|M.Sc Student||Bar-El Mi Chael|
|Subject||Analysis of the Conoitions to Obtaim a Pleasing Urban|
|Department||Department of Architecture and Town Planning||Supervisors||Mr. Milo-Emil Hoffman|
|Mr. Daniel Havkin (Deceased)|
The differences between the urban and the rural climate can be expressed (not necessarily.) in higher temperatures, more contamination, cloudiness and precipitation and less wind speed and radiation. Based on a field research in Tel-Aviv, the CTTC experimental-analytical model was first developed by Sharlin and Hoffman(1979-8O) for the prediction of the diurnal pattern of air temperature within the urban canopy layer (in calm steady weather) in a cluster located in the center of a homogenous neighborhood. A further theoretical development of Swaid and Hoffman (1987—89) conduced to a full analytical model confirmed with their field research results from Jerusalem and Tel Aviv and, with published results from Essen (FRG) considering three main factors:
1. The basic cluster temperature which is calculated considering being equal to the rural daily mean temperature.
2. Uprising of temperature due to solar irradiation absorption in the unshaded cluster surfaces.
3. Changes of temperature due to long-wave radiation from the cluster surfaces.
The analytical CTTC model’s formulation contains the climatic data, physical constants and factors which can “be controlled by the urban designer: the building material of the open area surface, the cluster’s orientation, height, width, depth and form (the existence or not of half-open colonnaded ground floor).
By checking these above mentioned design factors, this research is trying to develop an architectural- climatic design tool, for analyzing the urban canopy layer’s time depended temperature profile according to desirable comfort conditions for human users in the shade considering climatic data, human activity and clothes thermal insulation coefficients as described in Givony and Humphreys’ comfort evaluation models. In cases when discomfort is caused by the meteorological conditions, and the cluster relationships are not improving the situation, several steps are considered here in order to achieve comfort or improved conditions:
- Changing the surface paving material of the clusters open area.
- Creating half open colonnaded ground floor as part of the original cluster (loss of building area) and as an additional floor (change of height). Analysis of the thermal benefit of half-open-ground floor (in the above mentioned alternatives) in one or both sides of the open space between buildings is done.
- Change of cluster physical factors in order to increase (or decrease) the urban wind velocity.
- Change of partial shaded area by temporary means.
The output is a lexicon of 3-D “Design Envelopes” which gives the urban designer an evaluation methodology of the available options for improving the urban microclimate in the designed cluster including streets orientation. The numeric results enable specific consideration for every one of the assigned hours (0800, 1400, 2000).Further conclusions considering building density are possible.