HVAC Loads

Pro

A full heat-balance load engine, validated against EnergyPlus, running directly on your Revit model.

Overview

HVAC Loads is not a spreadsheet wrapped in a Revit window. It is a full heat-balance physics engine, computing space-by-space heating and cooling loads directly on the model: conduction through the envelope via transfer functions, surface-by-surface solar with real shading geometry, and hour-by-hour heat balance across all twelve monthly design days. There is no gbXML export, no external tool, and no re-entered geometry: the spaces, walls, roofs, and windows already in your model are the inputs. The engine has been validated room-by-room against EnergyPlus 25.1 on a published, reproducible reference building, with the reference set to the conventions the engine documents about itself: cooling within 2.4% (conservatively above), design heating within 2.1%, and a median room at +0.2%. See the Validation page for the full study and downloadable reproduction package. Results are saved into the Revit project itself, so the whole team works from the same numbers.

Key features

• Heat-balance engine: transfer-function conduction, surface-by-surface solar with shading, and exact per-component attribution, so you see exactly what drives each space’s peak
• Validated head-to-head against EnergyPlus 25.1: cooling within 2.4%, design heating within 2.1%, median room +0.2% (full study on the Validation page)
• Simplified mode for early design: estimates glazing so schematic models without windows, or even walls, still produce credible loads
• Design weather from the built-in map of 10,000+ ASHRAE stations, with full monthly design-day data
• Construction Builder and Fenestration Builder included: assemble walls, roofs, and layer-by-layer glazing with an NFRC simple-glazing window engine
• Ground-coupled slab-on-grade and below-grade surfaces, exposed floors, and roof solar handled explicitly
• ASHRAE 62.1 ventilation rates computed per space, with state-amendment options, in the loads report
• Building- and space-type libraries with schedules, so inputs are set once and reused across the project
• Results embedded in the Revit project and presented in report views ready for review and documentation

How to use it

1. 1

   Open your Revit model with spaces placed (or just separation lines, in Simplified mode).

2. 2

   Click HVAC Loads on the RIME ribbon (HVAC panel).

3. 3

   Pick your weather station on the Sites map and confirm design conditions.

4. 4

   Assign constructions and space types; review occupancy, lighting, equipment, and ventilation inputs.

5. 5

   Run the calculation and review the space-by-space breakdown, peak-hour attribution, and 62.1 ventilation tab.

6. 6

   Save to the project so results travel with the Revit file.