Best Vabi Alternative for HVAC System Software

Vabi vs Hysopt

Vabi is trusted for quick, static heating and cooling load calculations — but real system design needs more than static estimates. Hysopt goes further with dynamic HVAC system simulation, full hydraulic design and balancing, and control strategy validation — so your system works exactly as intended once installed.

What’s the Difference between Vabi and Hysopt?

Vabi is well-known for reliable static energy calculations. It gives engineers a clear baseline for heating and cooling loads — essential for early-stage sizing and compliance checks.

‍But here’s the catch:
Vabi doesn’t test or optimise the actual HVAC system design that will deliver those loads in practice.

Hysopt fills that gap. It uses static loads as a starting point, then adds dynamic thermal, hydraulic and control simulation to help you right-size, balance and verify your entire system — long before it’s built.

Features

Hysopt

Vabi

Heating & Cooling Load Calculation

Included

Core feature

Dynamic HVAC System Simulation

Thermal, hydraulic & controls

Not available

Hydraulic Network Design & Balancing

Detailed balancing

Not included

Control Strategy Validation

Simulated logic

Not available

Energy & CO₂ Optimisation

Proven savings

Static only

Reports & Deliverables

System sizing, balancing, CO₂ data

Static load reports

Why HVAC Engineers Choose Hysopt

1. Beyond Static Loads

Vabi gives you load numbers — Hysopt turns them into a working HVAC system with dynamic flows and control logic tested upfront.

2. Find Hidden Oversizing

Manual static calculations often oversize systems. Hysopt’s simulation and balancing engine fixes this before it wastes energy.

3. Prove Real Savings

Hysopt delivers clear, data-backed CO₂ and energy savings reports — not just estimates.

Who Benefits from Switching to Hysopt?

HVAC Engineers & Designers

Take Vabi’s static loads and turn them into fully optimised system designs.

Commissioning Teams

Reduce costly balancing and control headaches onsite.

Energy & Sustainability Managers

Meet net zero goals with proven savings instead of rough estimates.

Switching from Vabi to Hysopt is Easy

Switching from Vabi is easier than you think. Hysopt offers onboarding support for existing projects:

• Import static loads to build dynamic models
• Simulate thermal flows, hydraulic balancing and control logic
• Generate clear, actionable design and savings reports
• Onboard with help from real HVAC simulation specialists

Capabilities

Hysopt

Vabi

Dynamic Thermal & Hydraulic Simulation

Built-in

Not included

Control Strategy Modelling

Validated

Not available

System Balancing & Optimisation

Proven

Static only

CO₂ & Energy Savings Reports

Clear & automated

Estimates only

Frequently asked questions

Is Hysopt more accurate than Vabi?

Yes — while Vabi gives static heating and cooling load estimates, Hysopt uses a physics-based engine that connects load calculations directly to dynamic thermal, hydraulic and control simulation. This makes your system design more precise and realistic from day one.

Can I design and optimise my entire HVAC system in Hysopt?

Yes — Hysopt covers everything from load calculation and sizing to full hydraulic network design, balancing and control strategy validation. This removes the need for separate static tools like Vabi and ensures your entire system is checked for real-world performance.

How does Hysopt help avoid oversizing compared to Vabi?

Vabi only provides static demand numbers, which can lead to conservative oversizing. Hysopt dynamically simulates flows and controls so you can right-size every pipe, pump and valve — cutting unnecessary energy use and installation costs.

Do I still need Vabi if I have Hysopt?

No — Hysopt fully replaces Vabi by providing integrated load calculations and the dynamic system simulation that static tools cannot deliver. You get one workflow that handles design, sizing, balancing and performance proof in one place.

Ready to see the Difference?

Make the switch from Vabi to Hysopt today — and deliver HVAC systems that don’t just meet load estimates but perform exactly as promised.

Talk to an expert Start your free trial

Still comparing?

Explore other Hysopt comparisons

Discover the Hysopt software

Discover our innovative simulation and calculation software, completely tailored to HVAC engineers.
Join the ranks of leading professionals already using Hysopt to deliver remarkable results.

Discover Hysopt