Carli, Inc works to optimize the energy efficiency of buildings by developing detailed computer models of the building (including its heating and cooling systems and all building components). Based on building architectural drawings we generate computer models of the new or existing buildings and perform hourly energy use calculations and simulate how the building will respond on an hour-by-hour basis to the local climatic conditions. Various energy efficiency measures (EEMs) are analyzed for electricity and fuel use and based on the analyses cost-effective strategies are identified. The EEMs may include efficient lighting and daylighting, assemblies for roofs, walls, and windows, optimum features of HVAC systems, central plant optimization, cost-effective controls and passive solar strategies.

Choice of building simulation models is made depending on the size and complexity of the building and building systems. For smaller buildings, models like Energy-10 are considered suitable, as it does not require a high level of effort for creating input data and analysis. The program analyzes energy performance of small commercial and residential buildings, provides quick strategies, and aids in exploring EEMs. The ranking of EEMs is sometimes very helpful in making the decision about the suitability of a particular energy efficient option.