Buildings are continuously recognized as being responsible for significant amount of carbon emission to the environment. A good way to reduce this emission is through the choice of appropriate materials. However, selection of buildings materials is typically based on a number of factors, some of which can either be cost or environmental related. The selection process becomes complicated when designers are faced with several material options of building elements and each option can be supplied by different suppliers whose selection criteria may affect the budgetary and environmental requirements of the project. In order to help decision makers select the most appropriate materials, this paper proposes a decision support system which integrates a modified harmony search algorithm, building information models and supplier performance rating. To illustrate the decision support system, this paper presents a case study of a building in Michigan. The system is capable of producing the cost and environmental implications of different material combinations or building designs.