There is a lack of software tools for rapid, accurate, and cost-effective building energy modeling and simulation. While some platforms for energy modeling exist, they do not openly integrate with other systems and are not structured for supporting portfolio-scale energy efficiency (EE) program management and modeling. As a result, cities, utilities, and private organizations are limited in their ability to cost-effectively develop and manage portfolio-level building improvement and investment strategies. The lack of integrated tools is significantly hindering the wide-scale adoption of energy efficiency technologies across the United States. Establishing an open portfolio management platform with a next-generation building modeling and simulation engine that connects with external systems will unlock investment in energy efficiency technologies across the United States. The platform will connect building owners, program managers, and financial institutions to data management and modeling tools and will increase efficacy and reduce costs of EE programs by supporting an accessible, and competitive, EE marketplace of building technologies, financing, and software solutions. Maalka will develop a series of open application programming and user interfaces for connecting users to a next generation energy modeling and simulation engine. The interfaces will serve as the core of our open platform to facilitate automated portfolio-level energy modeling and insight generation. Upon this platform, we will develop interfaces for managing data collection, analysis, and integration with external customer management systems.