OpenStudio Worth it 4.4/5 Free, open-source EnergyPlus front-end from NREL with a SketchUp plugin, a Measures library for parametric analysis, and Radiance daylighting support.

C.Scale Worth it 4.4/5 SaaS whole-life-carbon data platform used by architecture and engineering firms to run rapid embodied, operational, refrigerant, and landscape carbon (LCA) assessments from concept through construction, benchmark portfolios, source low-carbon products via EPDs, and auto-generate AIA 2030 DDx compliance reports. Grew out of EHDD's in-house carbon tool (EPIC) and is separately licensed to power Autodesk Forma's Embodied Carbon Analysis feature.

Dlubal RFEM 6 Worth it 4.2/5 Professional finite element analysis software with member, plate, shell, and solid elements; linear and nonlinear analysis; and modular add-ons for concrete, steel, timber, and glass design.

Ladybug Tools Worth it 4.0/5 Free open-source Grasshopper plugins for climate analysis, energy modeling, daylighting, CFD, and urban simulation, with a commercial cloud layer via Pollination.

EnergyPlus Worth it 4.0/5 Free, DOE-funded whole-building energy simulation engine with sub-hourly HVAC, lighting, and water modeling -- the engine under most commercial tools on this list.

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