Direct Solar Irradiation

11. Viewing Direct Solar Irradiation along a Path

The city landscaping team has a new shipment of flowers, and they must decide where to plant them. They already have a general idea along a new pathway, using planters that reach two meters high so they can be seen from afar. These plants are very fragile and burn easily in the direct sun.

To find the ideal spot, we first have to recreate the path with line segments that you can import or draw with the SketchUp tool (we will be using the one we’ve used before to explain sampling points). We then proceed to the sampling of line or multi-line into points for example every 5m.

Then, we need to emulate the planters. To do so, we can create a 3D buffer. Click on Extensions > Edit > Buffer

Select the name of the layer containing your sampled pathway and the geometry of the samples (ConstructionPoints). Next, you have the choice to create Round buffers or Mitre buffers (ie, with sharp corners). Select its size : we want 2m because we want to know the conditions at the top of our pedestals, not at ground floor.

Next, we would like to know how much direct solar radiation each pedestal top would receive throughout the year. Create the appropriate sun paths.

Our plants are here to stay, so let’s create sun paths for the entire year. Go to Extensions > t4su > Select > SelectRoofFaces  and select your buffer layer.

We are finally ready to calculate the direct solar irradiation. Click on Extensions  > t4su > Sun views > SunViewFactor.  Select your buffer layer in the drop-down list, which still has the “rooftops” selected, as well as your Sunpath layer. You also have the choice of the type of sky. Let’s take the sky will give the highest radiation results : “Pure”. If you click on Extensions > t4su > View > PickUpEntity, you can select each buffer to see the new attributes that have been added. Click on Extensions > t4su > View > ColorFaces  and select DirectSolarIrradiance:Float as your classification criteria. You shouldn’t need more than four or five classes. The results show that areas close to intersections generally receive slightly more radiation. It would be best to place the plants along the narrowest streets.

Result of the Direct Solar Insolation along a Path, with Legend.

Pinpointed Areas with Least Direct Sunlight, 2m above Street Level.

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