Methodology and Standards

Standards referenced

Standard	Used for
ASHRAE Fundamentals 2021	Load calculations (RTS, Ch. 18), psychrometric properties, heat transfer
ASHRAE 90.1-2022	Equipment efficiency thresholds and compliance scoreboard
ASHRAE 62.1-2019	Ventilation requirements (Multi-Zone equation, Ev correction) and compliance scoreboard
ASHRAE 15-2022	Refrigerant safety classifications and compliance scoreboard
ASHRAE 170	Healthcare ventilation compliance scoreboard
NEC 430	Motor circuits — FLA, MCA, MOCP (feeds the electrical coordination export)
SMACNA HVAC Duct Construction Standards 2006	Duct sizing, fitting equivalent lengths — V2 (distribution release, targeted early 2027)
IMC (International Mechanical Code) 2021	Code-required ventilation rates, exhaust — scoreboard on the V2 roadmap
IFGC 2021	Fuel gas piping and combustion air — V2 roadmap
NFPA 90A / 90B / 96 / 99	Air-handling installation, kitchen exhaust, healthcare facilities — scoreboards on the V2 roadmap

Standards marked V2 back calculation engines that exist in the codebase today but are parked as Coming Soon in the launch build. At launch, compliance scoreboards are ASHRAE-only: 90.1-2022, 62.1-2019, 15-2022, and 170.

Calculation methods

Cooling and heating loads

AIM Works supports three calculation methods, selectable per project:

• RTS (Radiant Time Series, ASHRAE HOF 2021 Ch. 18) — the default for new projects. Clear-sky solar from Spencer declination and the published ASHRAE monthly clear-sky constants; sol-air conduction; mass-aware radiant time factors. Cooling loads are swept across the cooling season, and each zone is reported at its own peak month and hour — south glass that peaks in September is sized for September, not July. Zone supply airflow comes from the room sensible load; ventilation outdoor air is reported separately as a coil-level load.
• CLTD/CLF (Cooling Load Temperature Difference / Cooling Load Factor)
• Simplified (peak design block load)

All three are altitude-corrected. Honest limits, stated plainly: these are design-day peak loads, not 8,760-hour energy simulation, and the month sweep varies solar by month while holding ambient at the summer design condition (conservative for shoulder months — disclosed in the method metadata).

Ventilation

ASHRAE 62.1-2019 Multi-Zone equation. Vbz = Rp × Pz + Ra × Az per zone; Voz = Vbz / Ez. System-level Vot computed using the multi-zone Ev correction factor. Per-unit demand-controlled ventilation (CO2-based) inputs and building pressurization / relief-air checks are included.

Hydronic pipe sizing (V2 — not available at launch)

Darcy-Weisbach equation with Colebrook-White friction factor. Velocity, head loss, and pump head computed for each segment. Four network topologies supported: Direct Return, Reverse Return (Tichelman), Primary/Secondary, and Ring Main (Hardy-Cross). The engine is built and tested, but the distribution workflows are parked as Coming Soon in the launch build — targeted for the V2 release in early 2027.

Duct sizing (V2 — not available at launch)

Equal friction method. SMACNA-tabulated equivalent lengths for fittings. Same availability as hydronic pipe sizing: built, but parked for the V2 distribution release.

Psychrometrics

Magnus formula for water-vapor saturation pressure; Sprung's wet-bulb approximation; altitude-corrected atmospheric pressure. State points, mixing, and coil analysis following ASHRAE Fundamentals, at sea level or altitude. IP units at launch; SI display is on the roadmap.

Equipment selection

Block-load capacity matching with engineering safety factors. Chiller, boiler, and DX equipment efficiencies meet or exceed ASHRAE 90.1-2022 §6.4.1 minimum thresholds. Refrigerant compliance per ASHRAE 15-2022 occupancy classification and quantity limits.

Motor circuit data (electrical coordination)

NEC 430 — motor full-load amps, MCA (× 1.25), and MOCP rounded to standard breaker sizes per NEC 430.52. AIM Works does not do electrical design: this data feeds the one-way motor-schedule coordination export for the electrical engineer.

Maturity labels: validated, advisory, reference

Every module in AIM Works carries a maturity label alongside its method:

• Validated — the calculation is checked against a published worked example (ASHRAE handbook or equivalent), with the citation shown. This label is earned per citation, never assumed.
• Advisory — a real calculation built from published methods, suitable as a design starting point, with its assumptions and limitations disclosed.
• Reference — a checklist or scoping tool keyed to your project data. It is never presented as an engineered result.

The label, method, assumptions, and limitations appear on each module's workspace and ride into the exports — the calc package includes the full maturity register for every computed module, so a reviewer sees the trust level of every number in the deliverable, not just in the app.

What AIM Works does not do

• No annual energy simulation, 8,760-hour modeling, or EUI results — loads are design-day peaks.
• No gbXML export.
• IP units only at launch; SI display is deferred to a later release.
• No electrical or plumbing design — only one-way coordination exports for those disciplines.
• No construction documents — the DXF export is true-scale traced geometry, not a drawing set.
• At launch, distribution sizing (duct and pipe), specialty mechanical calculations, and the IMC / IFGC / NFPA scoreboards are parked as Coming Soon.

Why this matters

Every calculation in AIM Works displays the method and standard used inline. Reviewers can verify what's behind every number without opening a separate documentation file. This transparency is a core design principle, not an afterthought.

Outputs are advisory; engineering judgment by the user remains required, and all calculations must be reviewed and stamped by a licensed Professional Engineer before construction.

For deeper questions about methodology, contact support@getaimworks.com.