Chvac is a Windows desktop program for commercial HVAC load calculations that computes peak heating and cooling loads, determines building tonnage, room CFM requirements, and runout/main duct sizes, and provides full psychrometric calculations for air quantities. It supports both the RTS and CLTD calculation methods and complies with ANSI/ASHRAE/ACCA Standard 183-2007. Projects can be built from manual inputs or directly from floor plans created with Drawing Board, and the software imports/exports gbXML for BIM interoperability. Chvac links with Energy Audit, PsyChart (direct air handler data import), HVAC Solution, and transfers data to EnergyPro and eQUEST to streamline analysis and documentation workflows. It automates ASHRAE 62 ventilation compliance, allows different indoor conditions per room, handles extensive envelope inputs per room (30 walls, 30 windows, 12 roofs), operates in English and metric with conversion, and supports virtually unlimited rooms including optional grouping under VAV boxes.

Key Features

Peak load, airflow, and duct sizing Commercial heating/cooling loads with airflow and duct calculations.

• Calculates peak loads; determines building tonnage and room CFM.
• Calculates runout and main trunk duct sizes; computes CFM with psychrometrics.

Standards and methods Validated methods and code-related functions.

• Uses RTS or CLTD methods; complies with ANSI/ASHRAE/ACCA Standard 183-2007.
• Automates ASHRAE Standard 62 ventilation compliance.

Data input and BIM/interoperability Flexible modeling and data exchange.

• Manual data entry or directly from Drawing Board floor plans.
• Imports/exports gbXML; transfers to EnergyPro and eQUEST; links with Energy Audit, PsyChart, HVAC Solution.

Room-level flexibility and scale Handles complex commercial buildings.

• Different indoor conditions for each room; virtually unlimited rooms.
• Optional grouping under VAV boxes; extensive per-room envelope elements (30 walls, 30 windows, 12 roofs).

Units, outputs, and reporting Global usability and documentation.

• Calculates in English and metric; convert projects between units.
• Spreadsheet output file; numerous color pie charts and bar graphs.

Benefits

Code-aligned, defensible designs Produces calculations consistent with standards and ventilation compliance.

• ANSI/ASHRAE/ACCA 183 compliance and ASHRAE 62 automation support review and permitting.
• Psychrometric integration documents CFM and coil conditions rigorously.

Efficient workflows across tools Reduces re-entry and speeds analysis.

• gbXML I/O and links to EnergyPro, eQUEST, PsyChart, and HVAC Solution streamline handoffs.
• Build from Drawing Board plans or manual inputs to fit existing processes.

Scales to complex commercial projects Models large buildings and varied conditions.

• Unlimited rooms, VAV grouping, and extensive envelope inputs suit diverse facilities.
• Per-room indoor conditions capture realistic operational variability.