Urban Canyon

A bioclimatic design approach is based upon incorporating the microclimatic requirements into the design to achieve higher comfort levels and lower energy consumption. The purpose of this study was to investigate the cooling effect of selected bioclimatic parameters on the outdoor air temperature of an open space. Several variables that attested earlier to enhance the outdoor environments were examined mutually to attain the impact that passive design has on the outdoor air temperature.
The computer simulation was found to be the most suitable tool for investigation according to the resources available. Three variables were tested initially, orientation, geometry and vegetation where the coolest parameter of each was incorporated into one scenario named the enhanced scenario. Three scenarios named the existing scenario representing a specific site conditions, the enhanced scenario combining the coolest parameters and a worst case scenario combining the warmest parameters, were compared together and evaluated.
The SW-NE orientation, the highest geometry of a height to width (H:W) ratio of 4, groups of trees and continuous grass revealed to be the coolest parameters incorporated in the enhanced scenario. The enhanced scenario was compared to the worst case scenario based upon an EW orientation, 0.5 H:W ratio and no vegetation which recorded the highest temperature levels. The results revealed a slight improvement in the outdoor air temperature due to the bioclimatic principles applied. The comparative results show cased a slighter improvement between the enhanced scenario and the existing scenario representing the site conditions of Dubai Knowledge Village due to the incorporation of a few principles only. The results of temperature and wind patterns recorded had contributed to understanding several outdoor behaviors which are useful for guiding an ecological design for small outdoor urban spaces.
One main conclusion was the existence of a threshold to the size of bioclimatic applications for them to achieve a significant improvement yet, an improvement was possible. However, the behavior of the outdoor parameters remains quite complex and unpredictable that requires further investigation.

Dhanmondi is one of the prime residential areas
of Dhaka City characterized by diverse road pattern with
primary, secondary and tertiary arteries, open spaces and
variation in porosity in urban fabric. Satmasjid road is the
primary road that runs through the Dhanmondi Residential
area and retains the character of the urban canyon of 30m-40m width and 20m-40m enclosure on both sides. There are vegetal canopy on road islands, robust open spaces and lakes alongside. The paper is based on the study conducted to understand the impact of urban canyon on the micro-climate of the surrounding area through a field survey along with the ENVI-met simulation model of the study area.

Urbanization generally influences the microclimate by changes introduced in land cover, the compact spatial structure of the metropolitan areas, the emission of pollutants, the modification of the physical properties of the surfaces, etc. The frequently observed steady increase of urban air temperatures around the world is considered to be a cumulative effect of all of the above mentioned parameters. Higher air temperatures, especially during the summer season, may have major implications for local air quality, heat stress, morbidity, mortality and energy demand. In this context, the present study investigates the capabilities of vegetation to attenuate microclimatic extremes. Specifically, we explored the diversity of microclimatic conditions in two parallel streets (in Vienna, Austria), one with trees, and the other one without. Simultaneously monitored data from two mobile weather stations was obtained for the selected study areas during hot and sunny days in August 2012. Using t...

This study gives a comparative analysis of available daylight planning tools and develops a rule-of-thumb method for determining street width to building height ratios, related to actual illumination levels inside urban buildings. Nine daylight planning tools for site planning and urban design decisions were identified, their characteristics compared, and the tools classified. Six of these tools were compared by applying them to a 200' x 400' (651 x 122 m) urban block at 40 degrees latitude. FAR allowed by the generated envelope was calculated for each tool and compared. A wide range of allowable building envelopes was found.

All prescriptive tools either specified or implied a street height to width ratio (H/W), but none provided a quantified basis for its proportion or exposure plane. A study was initiated to determine H/W in relation to average an minimum daylight factor within a building. A test was conducted using physical modeling in a mirror box artificial sky. Results of this test, plotting H/W against average daylight factor can be used as a preliminary design tool or as a way to determine zoning restrictions, while protecting daylight access.

GNSS has become one of the most widespread measurement technologies, widely used in GIS, mobile mapping applications and civil engineering. Utilisation of differential techniques offers cm-level positioning accuracy. Identified drawbacks are the requirement for line of sight to the satellites and accuracy dependent on the geometric distribution of the satellites. Especially the latter is paramount for any surveying or mobile mapping application in the urban environment. The utilisation of additional constellations (GLONASS, GALILEO or COMPASS) only partly mitigates the problem. Locata is an Australian terrestrial positioning technology, based on the pseudolite concept. It’s unique in its utilisation of the 2.4GHz ISM band and proprietary TimeLoc procedure, allowing for network synchronisation at the nanosecond level.

This paper focuses on the tight integration of GNSS with Locata, in order to address the described drawbacks and to provide cm level positioning in areas currently “difficult” for GNSS – such as urban canyons. This paper describes the intended deployment and utilisation of the integrated system in the typical urban environment where availability of GPS can be limited or even non-existent, depending on the time and location. The verification of the integration methods has been carried out using simulated GPS and Locata data. Also presented is an application simulation in a typical urban canyon environment (Canary Wharf, London, UK) using proprietary software developed at the University of Nottingham. Simulation of the proposed integration algorithms, using a real life scenario, has shown promising results with centimetre-level positioning accuracy on the moving platform. The algorithm provides code ambiguity estimation for both Locata and GPS on-the-fly, without prior knowledge of the position, providing predominantly 3D position on the cm level.

Recent years have seen an exponential increase of DVD equipped and navigation assisted cars. Nowadays a car trip can be both entertaining for passengers and computer assisted for drivers. In a further integration of automotive and information technologies, cars will be able to communicate to each other and to the Internet supporting safety, infotainment and pollution prevention applications. The research area which investigates topics, Vehicular Ad hoc NETworks (VANETs), is being widely investigated by both industry and academia. Position information plays a central role in many communication routing schemes designed for VANETs. This trend is justified by the feasibility of algorithms that route packets based on geographical proximity to the destination and by the widespread availability of navigation systems in cars. Geographical information is usually assumed accurate and precise. None of the algorithms available in literature, to the best of our knowledge, take into account possible position estimation errors. This paper is a first step in assessing the precision of a commercial GPS receiver for the support of vehicular communications. As we shall see, the performance of the receiver under investigation heavily depends on the type of urban area within this is employed. We believe that a strong understanding of the accuracy of such estimates is important to improve the performance and reliability of a vehicular network infrastructure.