This HVAC system type recommender helps narrow the field of system options for a project. Answer a handful of questions — building type, size, climate zone, zone count and control needs, design priority, and central-plant availability — and the tool ranks candidate systems — VAV on a central chilled/hot-water plant, fan coils with DOAS, VRF, packaged rooftop units, split systems, PTAC/PTHP, water-source or geothermal heat pumps, and gas unit heaters — showing the top three with pros, cons, and the points behind each rank.
It is a discussion starter, not a final design. The ranking reflects common engineering judgment about where each system fits best; the right choice for a given project still depends on detailed load, energy, and cost analysis.
Formula & Method
Score = building-type baseline (+8 best / +4 alternative)
+ size fit (+1) + climate fit (+1) + zone-control fit (+2)
+ priority fit (+2) + plant fit (+2 CHW, +1 HHW/steam, +1 standalone if no plant)
Rank by total (ties go to the baseline) → show top 3 with the score breakdown
The baseline is the system the AIM Works app’s system-selection step recommends for the building type and size: offices get a split system or small RTU under 5,000 ft², packaged RTUs up to 25,000 ft², and a VAV air handler on a central chilled/hot-water plant above that; schools and clinics get DOAS with fan coils, then VAV; retail and restaurants get RTUs; warehouses get RTUs, then unit heaters; hotels and multifamily get VRF, then DOAS with fan coils. Your other answers add smaller points, so they reorder the alternatives and overturn the baseline only when several point the same way. This is a rule-based screening matrix, not a design method, and every card shows the points behind its rank.
Frequently Asked Questions
How does the system type recommender work?
It is a rule-based scoring tool. The building type and size set a baseline that follows the same system-selection rules the AIM Works app uses; your answers on climate, zone count, priority, and central-plant availability then add smaller points where each candidate fits. The systems are ranked and the top three are shown with their pros, cons, a best-match label, and the score breakdown behind the rank. It is a starting point for discussion, not a final design decision.
When should I choose VAV versus VRF?
VAV with a central air handler is strong for larger multi-zone commercial buildings where good part-load efficiency, dedicated outside-air control, and economical zoning matter. VRF suits projects that need individual room control without a central air handler and excellent part-load efficiency, but it has refrigerant piping length limits and usually needs a dedicated outdoor air system for ventilation.
Does climate change the recommendation?
Yes. Climate affects both load profile and equipment suitability. Air-source heat pumps lose capacity in very cold climates, hot and humid climates push toward systems with strong dehumidification and dedicated outside-air handling, and mild marine climates open up simpler low-cost options. The tool weights each system's fit to the selected climate zone.
Is this a substitute for a full HVAC design?
No. The recommender narrows the field quickly, but final system selection requires load calculations, a life-cycle cost analysis, ventilation design per ASHRAE 62.1, energy code compliance per ASHRAE 90.1, and coordination with architecture and structure. Use the result to frame options, then validate the chosen system with detailed engineering.
Connect the calculation to the rest of the project.
AIM Works brings peak loads, ASHRAE 62.1 ventilation, equipment and plant sizing, compliance checks, Design Review, and engineering deliverables into one connected mechanical design workspace.
Peak loads (RTS or CLTD/CLF) and ASHRAE 62.1-2019 ventilation
Equipment and plant sizing against ASHRAE 90.1-2022 efficiency floors
Design Review that cites the check behind every finding
An AI co-pilot that drafts changes — you approve each one