Geometric Forms and Insolation Ii a Reassessment of the Relation Between Shape and Solar Irradiation

Abstract

This work re-evaluates the results of an old research on the relation of solar energy received by various forms and their geometric properties. In that past work, measured data of horizontal radiation was used to calculate the insolation on various forms in London, Athens, and Riyadh according to the solar model by J.K.Page et. al. of 1986. The ratio between the average insolation on a given form and on horizontal is named 'Form Insolation Index' [m-index], showing the percentage of the available solar energy received by the form. A major finding was the linear relationship between the m-index of a form and the ratio between its base size and its exposed surface [B/F]. The present research is a simplified repetition of the old one, extended also to Reykjavik and Lagos. The main difference from the past is that solar energy data on inclined planes was not calculated from horizontal but taken from datasets provided by the Photovoltaic Geographical Information System (PVGIS). The new output confirmed the linear relationship between m-index and B/F ratio. An unexpected finding was that new radiation values are higher than those measured 30 years earlier, an increase attributed mainly to the stronger direct component. © PLEA 2020 - 35th PLEA Conference on Passive and Low Energy Architecture Planning Post Carbon Cities, Proceedings. All rights reserved.