HVAC Engineering StudioManual J/D/S · ASHRAE 62.1/90.1 · Design Tools · 3D Viewer · Simulators · Calculations

Applied HVAC Engineering Professional Program

Manual J simplified cooling load: envelope conduction, solar gain, occupant loads, equipment, and lighting. Outputs tons and BTU/hr.

Heating loss by component: walls, ceiling, floor, windows, and infiltration. Enter 99% design temps. Outputs MBH and BTU/hr.

Rule-of-thumb tonnage sizing using ft²/ton zone factors and construction efficiency adjustments. Gives min/max range.

Rule-of-thumb heating and cooling load by climate zone and insulation quality, recommended nominal tonnage, and a balance-point check for whether supplemental or cold-climate heat is needed.

ACCA Manual D equal friction method. Inputs: CFM and friction rate. Outputs round diameter, standard size, velocity, and pressure drop.

Supply CFM from BTU/hr load and ΔT. Adds ASHRAE 62.1 minimum outdoor air by space type. Outputs CFM/ton and OA flow.

From dry-bulb and RH: wet-bulb, dew point, humidity ratio, enthalpy, and specific volume using Magnus formula.

ASHRAE 62.1 outdoor air requirements by space type. People and area components, zone OA flow, CFM/person and CFM/ft².

Commercial chiller plant capacity: building loads, diversity, redundancy. Outputs tons, kW, kW/ton, CHW GPM, and cooling tower sizing.

Boiler output from heat loss + DHW loads with piping loss and redundancy. Fuel type, AFUE, annual fuel cost, and hot water GPM.

ACR copper pipe sizes for liquid, suction, and discharge lines. Supports R-410A, R-32, R-22, R-134a, and R-407C. Velocity check included.

Fan and motor sizing from CFM and total static pressure. BHP, motor kW, W/CFM efficacy, altitude correction, and standard motor size.

Hazen-Williams pipe sizing for chilled/hot water systems. Velocity check, friction loss, pump head, glycol correction, and BTU/hr capacity.

Instantly convert between BTU/hr, tons of refrigeration, kW, MBH, and kcal/hr. Live 5-way conversion with reference table of common HVAC equipment capacities.

ASHRAE CLTD/CLF/SCL commercial zone cooling load: envelope by orientation and construction mass, glazing solar/conduction, internal gains, ventilation. Outputs tons and full breakdown.

ERV/HRV sensible and latent effectiveness: pre-conditioned supply air temperature, energy recovered, and estimated main coil load reduction. AHRI 1060-based.

Educational overview of NFPA 92 smoke control concepts — stairwell pressurization, zoned/atrium smoke management, and general design criteria. Not a fan-CFM calculator.

Convert between US DOE SEER2/HSPF2 seasonal efficiency ratings and dimensionless COP — includes a typical peak/rated COP range and efficiency-tier context.

Interactive pass/fail tracker for the instrument-verified checks (airflow, refrigerant charge, static pressure, controls) that confirm an installed system matches its design.

Why a cooling coil does two different jobs at once — dropping dry-bulb temperature (sensible) and condensing moisture out of the air (latent) — and why two coils with identical total BTU/hr capacity can leave a space feeling completely different.

Why relative humidity changes with temperature alone even when the actual moisture in the air never does — and why dew point, not RH, is the number that tells you how much water vapor is really there.

Why static pressure and velocity pressure trade off through a duct system — and why doubling a fan's speed doubles airflow but quadruples pressure and needs eight times the power.

Why a space can have a high air-changes-per-hour number from aggressive recirculation while still under-ventilating with the actual outdoor air ASHRAE 62.1 requires.

Why a fan sized only against the ductwork's pressure drop can fail to deliver its design airflow — external static pressure deliberately excludes the equipment's own internal filter, coil, and cabinet losses, but the fan has to overcome both.

Why an AHU sometimes skips the compressor entirely by opening its outdoor air dampers instead — and why a dry-bulb-only economizer control can be fooled by cool-but-humid air that actually carries more total heat than return air.

Why a fan curve only tells half the story — static pressure is what actually gets overcome pushing air through a duct system, velocity pressure exists only because the air is moving, and total pressure (their sum) is a genuinely different number from either one alone.

Why a Constant Air Volume system reduces cooling by reheating a fixed volume of already-cooled air — spending energy twice — while a Variable Air Volume system just delivers less air, which is why VAV has become the dominant choice for most modern multi-zone commercial buildings.

Why refrigerant never leaves the rooftop in a DX system and never leaves the chiller plant in a chilled water system — and why only chilled water, never refrigerant, travels through the building to serve many zones from one central source.

Why Bypass Factor (a coil's own physical design) and Sensible Heat Ratio (the space's load) aren't two names for the same thing — and why matching a coil's BF to a space's target SHR, not just sizing on total tons, is what correct equipment selection actually requires.

Why a unit's SEER rating (efficiency averaged across a whole cooling season) can look great while its EER (efficiency at one fixed 95°F condition) is unremarkable — and why heat pumps need a third number, HSPF, just for the heating season.

Why a compressor that can only run at 0% or 100% overshoots and undershoots the building's load on every cycle — and why adding a low stage, or continuous modulation, is what actually closes that gap.

Animated P-h diagram for the vapor-compression cycle. Adjust evap/cond temps, superheat, and subcooling — watch state points shift and COP update live. Supports R-410A, R-32, R-22.

Interactive psychrometric chart with animated process lines. Simulate heating, cooling/dehumidification, humidification, and air mixing between plotted states.

Multi-zone thermostat simulation over a 24-hour day. Set setpoints and occupancy per zone, then watch the HVAC system cycle as outdoor temps change and internal gains build up.

Animated SVG duct tree from AHU to diffusers. Color-coded velocity bands flag over- and undersized ducts. Shows CFM, velocity (fpm), and pressure drop per segment.

Two-chiller plant with cooling tower and primary/secondary pumps. Vary building load 0–100% and watch the sequencing logic stage equipment on/off. Tracks kW/ton efficiency.

Animated AHU cross-section with airflow particles through mixed-air dampers, preheat, cooling coil, supply fan, and reheat. Temperatures update at every section in real time.

Interactive 3D walkthrough of a 3-story commercial building. Explore AHUs, VAV boxes, chiller plant, boiler, hydronic piping, ductwork, and BAS controllers with ASHRAE references.

Split-screen interactive designer for a complete central-plant commercial HVAC system. Explore a 3D building — rooftop AHU, DOAS/energy recovery, cooling tower, mechanical-room chiller/boiler/pumps, VAV boxes with reheat, ductwork, diffusers, and BAS sensors — alongside a connected system diagram (airside loop + chilled/condenser/hot water loops + controls). Click any component or node to cross-highlight across both views, and toggle to a top-down Floor Plan with duct/pipe runs. Covers ASHRAE 90.1, 62.1, 15, and 55.

Split-screen 3D building viewer + live system schematic. Click any device — AHU, VAV, DDC, chiller, boiler, pump — to cross-highlight across both panels. Covers BACnet controls, CHW/HHW piping, and air distribution per ASHRAE 90.1.

Dedicated 3D deep-dive into a central chiller plant room — two 300-ton water-cooled chillers, primary/secondary CHW pumping with the decoupler bypass line, condenser water loop, and rooftop cooling tower. Built to match this studio's Chiller Plant Sequencing Simulator.

Interactive 14-section ASHRAE reference guide covering psychrometrics, cooling/heating load calculations, duct sizing, refrigeration cycle, chillers, VRF systems, ASHRAE 62.1 ventilation, and energy codes. First 3 free to preview.

Interactive 39-chapter illustrated guide covering system fundamentals and psychrometrics, residential and multi-family systems, commercial and industrial plants, VAV and chilled-water distribution, ventilation and energy recovery, BAS controls, equipment schedules, and troubleshooting. First 3 free to preview.

Interactive 30-chapter guide following a single 45-story high-rise case study through a complete 17-phase HVAC engineering workflow — Basis of Design, central plant, airside/ductwork, hydronic risers, smoke control, BAS architecture, data center cooling, energy management, ASHRAE Guideline 36 sequences, and commissioning. First 3 free to preview.

Zoomable 17-sheet single-family residence HVAC construction drawing set — Manual J/Manual S load calculations, heat pump balance point sizing, floor/attic/roof plans, installation details, and control/wiring diagrams. Sheets 1-3 free to preview.

Complete residential HVAC system design: Manual J room-by-room load calculation, Manual S equipment selection, Manual D duct sizing, airflow schedule, wiring diagram, and a permit-ready design package with schematic and spec templates.

20 fillable rows for rooftop units, air handlers, and VAV boxes — CFM, cooling tonnage, heating MBH, and electrical characteristics — with automatic building totals.

A single-family residence carried from Manual J load calculation through equipment selection, duct design, ventilation, controls, and a finished commissioning checklist.