Overview

The aim of this app is to calculate and visualise incident solar radiation falling on surfaces or solar flux passing through spatial regions. This can be done for any instance in time or over any period of the year. This data can then be used to quantify solar radiation, sun exposure, shading, overshadowing, rights-to-light or even the visibility of points in the model. You can also do volumetric analysis and use that data to optimise forms or generate site-specific solar envelopes.

In addition to spatial information, you can also view the detailed shading mask and solar radiation at any point in the model. A shading mask is simply a map of which parts of the sky dome are visible from a particular point and which are obstructed by opaque objects in and around the site.

The other key aim was to see if I could implement dynamic sky radiance/luminance mapping for use with the shading. The degree of shading at any point is usually quantified by the percentage of the sky that is occluded. However, the luminous distribution over the sky dome is typically quite uneven and varies significantly over short time periods. With this app, you can experiment with a range of different sky conditions and quantify shading based on the percentage of actual sky radiance that is occluded.

Why a Simple Block Model

The use of a really simple block model is actually quite important here. This app is all about being able to quickly and easily set up a site condition and get some immediate analytical feedback. Moreover, it's about design and using highly dynamic calculations to gain some insight into the way results change when the model changes. This means being able to readily create detailed scenarios entirely from scratch and then experiment intuitively with different design options and analysis conditions. When used creatively, multiple merged blocks can pretty closely approximate the majority of built forms.

I will obviously support arbitrary CAD/BIM geometry with more complex shapes and forms in the future. However, with this app, I really wanted the focus to be on the dynamic relationship between the model and the results, without needing a site file to import or having to first learn a quirky new 3D drawing system before being able to actually do or see anything.

Interesting Features

The following are some of this app's interesting features:

• Using simple axially-aligned blocks to make editing simpler and more intuitive, as well as being able gto optimise ray-tracing for close to real-time shading calculations,
• Performing some simple real-time constructive solid geometry (CSG) to union multiple intersecting axially-aligned blocks into a single solid,
• Dynamically updating both a WebGL shading mask within the 3D context of the model and a 2D SVG shading mask to show real-time shading and sky effects,
• Updating more than a thousand or so individual SVG path elements to show a dynamic 2D sky distributions can be quite slow, so this version actually renders the shading and dynamic sky distribution to a WebGL canvas beneath the 2D SVG Sun-path diagram, which is significantly faster,
• Overlaying sky radiant distributions of the CIE Standard General Sky types that update dynamically whenever the date, time or location changes,
• Being able to select different sky subdivision methods and subdivision angles to directly compare how accurate the sky segmentation really needs to be, and
• The ability to display both shading and sprayed rays in a colour that reflects the obstructing object.

© Dr. Andrew J. Marsh, 2020.