When François Lévy was asked to design a country home on a substantial piece of land, he immediately faced an issue: locating the building in a spot which required as little re-grading as possible while being able to reap the benefits of solar energy. The most desirable location —given site access and a range of mature oaks— would have left the building sitting slightly out of grade. And, if he had chosen the most obvious building orientation (long and narrow with broad elevations facing north and south), part of it would jut out of the ground and some crucial trees would be lost.
He approached the solution beginning with one extreme: if the building were placed for optimal photovoltaic collection, what would regrading look like?
Using the Site Model tool in Vectorworks Architect, he was able to determine that this approach meant 340 cubic yards of cut and fill, an expensive prospect.
On the other extreme, he tested placing the house parallel to site contours, which reduced cut and fill to about 100 cubic yards. Though a huge improvement in terms of site impact, it meant losing three significant oak trees and having poor photovoltaic collection and shading due to being 50 degrees off optimal azimuth.
“I tried a variety of different orientations between the two extremes of optimizing for minimal contour disturbance and maximum shade, at first in 10° increments,” Lévy said. “I was able to quickly accomplish each iteration by rotating the Site Model, Heliodon, and trees, but leaving the house and its Site Modifiers in place. Recalculating the cut and fill quantities was literally a click of a button, and running a solar animation only took a few minutes. Within an hour or so I had found a happy compromise.”
He was able to iterate and find a solution between the two extreme positions. The proposal would require 289 cubic yards of cut and fill, but it would lose no major trees and be only 15 degrees from south azimuth.
“The angle of sunlight impinging on a surface (insolation) graphed against orientation or azimuth is a sinusoidal curve; the peak of the curve is maximum insolation. Notice that within a few degrees of the optimum azimuth the sine curve is quite flat, especially in summer when there is the greatest solar gain. In other words, rotating the orientation ten or fifteen degrees from due south has minimal impact on solar collection (and therefore the general effectiveness of roof shading),” Lévy explained.
Lévy’s project exemplifies the advantages of using a BIM software like Vectorworks Architect. Being able to quickly iterate building orientations allowed him to find the optimal compromise as well as provide justification to the client and builders.
Discover how Lévy leverages the power of BIM for small-scale projects with a FREE webinar by him.