Top 10 Best Energy Calculation Software of 2026

EnergyPlus is a state-of-the-art, open-source whole building energy simulation engine developed by the U.S. Department of Energy. It models detailed energy consumption for heating, cooling, lighting, ventilation, HVAC systems, and more using advanced heat balance methods. Widely used for research, building design optimization, energy code compliance, and performance analysis, it supports complex geometries, schedules, and controls.

OpenStudio is an open-source software platform developed by NREL for whole-building energy modeling and simulation, serving as a graphical user interface and workflow tool for the EnergyPlus engine. It enables detailed modeling of building geometry, systems, schedules, and loads to perform energy audits, code compliance checks, LEED certifications, and design optimizations. With integrations like SketchUp for geometry and a vast library of standards-compliant measures, it supports advanced parametric analysis and retrofit evaluations.

eQUEST is a free, open-access building energy simulation software developed by UCLA's Department of Architecture, leveraging the DOE-2.2 engine to model whole-building energy use, costs, and peak loads. It features an intuitive CHEETAH wizard that guides users through inputting geometry, systems, schedules, and weather data for rapid schematic design analysis. Widely used for energy code compliance like ASHRAE 90.1 and California Title 24, it generates detailed reports, graphics, and optimization suggestions to support efficient building design.

DesignBuilder is a comprehensive building energy modeling software that uses the EnergyPlus engine to simulate energy use, thermal comfort, daylighting, and HVAC performance in buildings. It offers an intuitive 3D graphical interface for rapid model creation, supporting detailed simulations for compliance with standards like LEED, BREEAM, and Part L. Ideal for architects and engineers, it streamlines the transition from design to energy analysis with tools for optimization and cost estimation.

IESVE (Integrated Environmental Solutions Virtual Environment) is a comprehensive building performance simulation platform designed for energy modeling, thermal analysis, daylighting, and CFD simulations. It enables users to perform dynamic whole-building energy calculations, optimize HVAC systems, and ensure compliance with standards like ASHRAE 90.1, LEED, and BREEAM. The integrated suite of modules supports architects, engineers, and sustainability consultants throughout the building design lifecycle.

TRNSYS is a comprehensive transient system simulation program designed for modeling the dynamic behavior of energy systems, including buildings, solar thermal systems, and HVAC. It uses a modular approach where users connect pre-defined or custom components to build complex simulations. Widely used in research and engineering for accurate predictions of energy performance over time.

HOMER Pro is a specialized software for optimizing and simulating hybrid renewable energy systems, including solar PV, wind turbines, batteries, diesel generators, and grid connections. It uses advanced algorithms to find the lowest-cost system configurations while performing detailed techno-economic analyses, sensitivity studies, and risk assessments. Ideal for off-grid, microgrid, and remote power applications, it helps users evaluate system reliability, emissions, and financial viability over the project lifecycle.

RETScreen is a free Clean Energy Management Software suite developed by Natural Resources Canada, designed for performing pre-feasibility and feasibility studies on renewable energy, cogeneration, and energy efficiency projects. It enables users to model energy production and savings, conduct financial analyses including IRR and payback periods, and calculate GHG emission reductions using built-in climate data, product catalogs, and incentive databases. The tool supports a wide range of technologies such as solar PV, wind, hydro, biomass, and district energy systems.

The System Advisor Model (SAM) is a free, open-access software tool developed by the National Renewable Energy Laboratory (NREL) for simulating the performance and financial metrics of renewable energy systems. It supports detailed modeling of technologies such as photovoltaic (PV), concentrating solar power (CSP), wind, geothermal, biomass, and fuel cells, providing hourly energy production estimates, cost projections, and cash flow analyses. Users can incorporate site-specific weather data, incentives, and financing structures to evaluate project viability.

PVsyst is a leading professional software for the simulation, sizing, and performance analysis of photovoltaic (PV) systems, supporting grid-connected, off-grid, and water-pumping configurations. It provides precise energy yield predictions by integrating extensive meteorological databases, comprehensive component libraries for modules and inverters, and advanced modeling of losses including shading, soiling, and thermal effects. Used extensively by solar engineers worldwide, it generates detailed reports for project optimization, financial viability, and bankable studies.