I'd give you that in its current marketed form it is astrological bullshit, but originally Vastu Shastra was a formal form of science [1] grounded on engineering principles and urban design. All persevering to obtain a 'calm' for the dweller.
One can still infer from the high precision N-S-E-W positioning of fairly huge ancient Hindu temples, historical remains of homes and dwellings, monasteries and other artefacts. Even the 1000+ step staircases in some of the forts and fortresses [2][3], transoceanic bridges [4] suggest the quality of math that was in play.
The choice and placement of stone, wood and metal w.r.t Sun, tropical climate and other ergonomic needs is simply mind blowing. Math has to be at the root of it.
Obviously not many records exist to substantiate the level of skill and academia prevalent at the time. I wish someone undertook a journey to research and substantiate just about "everything" that we have from Egypt to Indonesia (Hindu kingdoms spanned that far, yes!). At the risk of being shooed away by existing pride.
[1] http://en.wikipedia.org/wiki/Vastu_shastra
Even the wikipedia here, for example, says ... "while Vastu had long been essentially restricted to temple architecture..." which is completely wrong, and they defeat it in the third paragraph where they define "the Sanskrit word vastu means a dwelling or house with a corresponding plot of land" which is what Vaastu Shastra was all about, not temples alone.
[2] http://en.wikipedia.org/wiki/File:ChandBaori.jpg