In this tutorial, continued from last session in checking the site’s obstruction/overshadowing. You could use the same example file as in that one (link).
We would like to understand how surrounding buildings would affect our site using shading mask overlaid on a sun path in order for us to start the design process. What we can check for with overlaid sun path diagram . .
- Any shading from surrounding buildings already? (E.g. we might locate some functional uses there without having to create a new shade).
- Any exposed area? (i.e. very hot in summer time and therefore extra shading is critical).
- Implication – building orientation, glazing placement, or other functional allocation in which this information could be useful for
HOW-TO
We’ll create a representative point on a site to check for obstructions – This is similar to when a person takes a fisheye camera (which has a 180 degree field-of-view), place it at one location on a site looking up and take a photo of the hemispherical sky dome.
1 | CREATING A POINT OBJECT
In 3d editor, click on point icon and click again to place it on a site. You can select a center of your site as a starting point (can be on any zone). It would be easier if you create point from plan view (View > Plan or hit F5).
A point will be visible in both 3d Editor and Visualise view.
2 | CHECKING FOR OBSTRUCTION USING OVERLAID SUN PATH
Make sure a point is selected.
Go to Menu Calculate > Sunpath Diagram.
A sunpath overlaid with shading from surrounding building would show up. This is a view from your site looking up to the sky – similar to what a fisheye lenses would see but the obstructions will be grayed out.
3 | SEPARATING ZONE & SHADOW COLOR
From step 2, we can see that the overlaid shadow mask is in the same color, and that is gray, which is a default shadow color in Ecotect. It would be more informative in some cases to separate the surrounding buildings in different zone (layer) and make it case different shadow color.
First, go to Zone management tab on the right, you’ll see zones labeled obs_xxxx. This is for all the surrounding buildings in each direction. Click ‘zone management’ button at the bottom. Zone management window shows up. There are many parameters you can edit within each zone.
Use a different color for each obstruction zone. Then, you can change each zone’s (layer) color for easy visualization. The 3d Editor view would by default show you the zone color.
Under Visualise tab, the objects can be displayed using zone color as well. Under visualize tab setting, change the ‘Surface Display’ color to Zone Color.
Based on this chart, optimal shading is critical on the south side even though we have some obstruction but those houses only block diffuse part of the sky but not the sun which is the major source of heat gain into a building.
Analysis
The overshadowing in pink shows that we have taller building on the east so it blocks some of the morning sun all year long. This is good for locations where shading is required all year because this means that we might be able to locate some uses on the east side without having to create a lot of shading.
Overshadowing from north and south sides (yellow and green) are from lower obstructions, allowing some diffuse light from the sky to come through.
Towards the west (orange) which is critical for afternoon use, at later hours, there are some shading from nearby buildings.
An important thing to note is that this shaded mask only represents the overshadowing from the point that you have placed on your site (in this example, in the center) and may not apply to all areas of your site since the shading will vary depend on where you’re at. You can move the point to other places on your site or creating more points, especially if the site is large, to check for potentials and limitations of the site at different locations in terms of overshadowing.
Note:
This is only an initial test on a blank site. Conditions change when you start to put a building on-site. A 2-storey vs a 5-storey building has different exposure to the sun and different overshadowing pattern from surrounding buildings. Once you have some design options with varying heights, it can be useful to transfer it to Ecotect to see how the shading requirements would change under different massing options.
No comments:
Post a Comment