Estimation of solar radiation for Derna city climate conditions on inclined modelling radiant fluxes and mean radiant temperature in complex urban settings : application of RayMan model

Abstract EN

Radiant fluxes have the most significant effect on people’s thermal comfort, mainly during sunny conditions.

The effect of the absorbed radiant fluxes is parameterised by the mean radiant temperature (Tmrt).

The calculation of Tmrt is required in the human energy balance model, and thus for the assessment of thermal comfort using thermal indices.

The most accurate way to calculate Tmrt is by applying method based on six-directional radiation measurements.

This method, however, has disadvantage in terms of complexity and cost, particularly for analysing the variability of Tmrt in urban areas.

This has increased the demands for modelling methods.

RayMan is the most popular models used for thermal comfort research and urban planning.

RayMan is designed to simulate radiant fluxes including Tmrt and provide assessment of human thermal biometeorology for the urban areas.

The aim of this paper is to present an application of RayMan model for an urban setting in Bayda, Libya.

A validation of RayMan simulation has also been conducted in this paper.

The results show that using meteorological data of air temperature, air humidity and wind speed as well as data of urban morphology, the model is capable of simulating Tmrt and thermal comfort in complex urban settings.

Also, the model provides possibilities to show sun paths in fish-eye view, as well as shadow patterns of the buildings at period of the day.

The model’s results demonstrate benefits of RayMan in urban design and planning for the development of strategies to improve human thermal biometeorology and thermal comfort.