With the current electricity problems facing South Africa and the rise of the green building initiative internationally, energy-efficient buildings have become much more popular.Architects form an integral link in the design of these energy efficient buildings. Energy-efficient building design strategies therefore, require both architects and engineers to work closely together in optimising the building design.However, this is not always practical in real world terms. Architects must therefore, be able to perform a preliminary thermal analysis if energy efficient design strategies are to succeed.Existing tools do not however cater for architects to do a fast preliminary thermal analysis during the initial design phase.They also often require fixed computer systems. A need therefore exists for a simplified mobile thermal design application for architects.