Use the workflow from left to right. Enter your design conditions first, then define zones and envelope properties, calculate the 24-hour peak, review the load breakdown, and finally select equipment.
Project: choose the location and indoor/outdoor design conditions.
Zones: enter floor area, height, occupants, windows, and envelope values.
Loads: run the 24-hour design-day calculation and inspect the peak hour.
Equipment: compare preliminary capacity matches and airflow.
Report: print/save the engineering summary and JSON project data.
Design Assistant
Project & design basis
This version uses a transparent component heat-balance model and a 24-hour design-day simulation. It is an engineering-development tool, not a certified ASHRAE Standard 183 implementation.
Zones / rooms
Each zone is calculated independently. Total equipment selection is based on the coincident building peak.
Envelope assemblies
Engineering Suite
Advanced preliminary design tools. Values are transparent estimates and should be verified by the responsible engineer.
The current model remains transparent; schedule factors are used as preliminary modifiers.
Psychrometrics
Enter conditions and calculate.
Ventilation & Airflow
Run the load calculation to populate airflow checks.
Preliminary Duct Sizing
Preliminary only — verify with the project duct design method.
Project Save / Load
Save a complete editable project snapshot locally, then restore it later.
Design Readiness
Run the calculation to populate detailed checks.
Design-day load result
—Peak cooling BTU/h
—Peak heating BTU/h
—Cooling tons
—Cooling kW thermal
—Design airflow CFM
Cooling loadHeating loss
Peak cooling components
Peak heating components
Zone peak table
Design QA / readiness
—Design readiness
—Zones
—Missing / review items
Peak calculation details
Use this section to understand where the peak cooling number comes from.
Equipment selection
Equipment is filtered by calculated capacity. Actual manufacturer performance must be checked at project entering/leaving conditions, altitude, ambient limits, refrigerant conditions, and certified rating data.
Airside checks
—Required CFM
—CFM / ton
—Sensible heat ratio
—Latent load
Design Scenarios / Sensitivity
Preliminary sensitivity view. It estimates how selected envelope changes affect the current peak; verify final scenarios with a full recalculation.
Better wall insulation
—
Approx. cooling change
Better glazing
—
Approx. cooling change
Exterior shading
—
Approx. cooling change
Fan / Coil Preliminary Check
Run the load calculation first.
Calculation Audit Trail
No calculation has been executed yet.
Engineering report
Calculation basis & limitations
This application uses a transparent, hourly design-day component model: envelope conduction, solar fenestration, occupants, lighting, equipment, ventilation and infiltration, plus heating transmission/air losses. It is intended for engineering development and preliminary sizing. A production-grade compliance engine should use validated climate design data, detailed constructions and fenestration, schedules, psychrometric calculations, and a validated Heat Balance or Radiant Time Series implementation, with QA against an accepted reference calculation.
Request a Consultation
This preliminary result is a starting point, not a final specification. Send it to our engineering team for review and an actual quotation.
HVAC System Designer PRELIMINARY
Zones → AHU → coil → fan → ducts → terminals. Use validated manufacturer and project data for final design.
System Flow
Zones 0 zones
→
Return Air 0 CFM
→
Mixed Air 0 CFM
→
Cooling Coil 0 tons
→
Supply Fan 0 CFM
→
Terminals 0 CFM
Air System Inputs
Preliminary Results
Selected Load0BTU/h
Required Airflow0CFM
Outdoor Air0%of supply
Cooling Capacity0tons
Mixed-Air / Coil Check
Mixed Air DB—°F
Coil ΔT—°F
Approx. Coil Load—BTU/h
Fan Input—kW*
*Preliminary fan input assumes 1.5 in.w.g. total static pressure. Replace with an actual system static-pressure calculation before equipment selection.
Design Review
Enter or load project data, then calculate the system.
Zone Airflow Allocation
Zone
Cooling Load
Required CFM
Share
No zones loaded.
NAD Toseeh Paydar · HVAC Engineering Advisor · Internal Project Model