Designing passive solar commercial buildings is commonly viewed as a high-risk venture. Although passive concepts have been applied successfully to residential buildings for some time, there have been very few passive solar commercial buildings to date. Owners, architects, and engineers alike have been cautious in applying untried passive concepts when large construction budgets were at stake.On the other hand, some solar advocates and innovative designers claim that passive solar concepts may be only an extension of known bulding design theory with the potential of cutting building energy use in half and saving millions of barrels of imported oil.This paper will present key lessons learned to date (in the design process) about passive solar commercial buildings.