How energy efficient can commercial and multifamily buildings become in the near future if first cost is not considered? The paper describes how building energy simulation modeling was used to try to answer this question. The first step was to assemble a list of energy efficiency measures that can be included in the design of non-residential buildings. The list included both commonly used and cutting edge energy efficiency measures with the goal of being comprehensive, at least for measures that can be modeled. Input was sought from many people to ensure that the list of measures did not exclude any important ones.