Heating, cooling, ventilation, and the air that keeps buildings habitable.
HVAC engineering is the branch of mechanical engineering concerned with heating, ventilating, air conditioning, and refrigeration — controlling temperature, humidity, air movement, and air quality so buildings stay comfortable, healthy, and efficient.
HVAC engineering designs the systems that condition indoor air: furnaces and boilers for heat, chillers and air conditioners for cooling, fans and ductwork for ventilation, and the controls that tie them together. The work begins with a heating and cooling load calculation — quantifying how much heat a space gains in summer and loses in winter — and ends with selected, sized, and laid-out equipment, ductwork, and piping that meet that load efficiently.
The discipline rests on applied thermodynamics, fluid mechanics, heat transfer, and psychrometrics (the study of moist air). An HVAC engineer must balance comfort, indoor air quality, first cost, and energy use, all while complying with mechanical and energy codes. Refrigeration — the vapor-compression cycle behind every air conditioner, chiller, and cold-storage system — is a core part of the field, governed by both equipment standards and EPA refrigerant-handling rules.
Quantifying sensible and latent heating/cooling loads (Manual J, ASHRAE) and analyzing moist-air properties on the psychrometric chart.
Duct design and sizing (Manual D), diffusers, VAV boxes, air balancing, and fan selection for required airflow and static pressure.
The vapor-compression cycle, DX systems, chillers, cooling towers, and refrigerant piping — including EPA Section 608 handling rules.
Boilers, pumps, chilled- and hot-water piping, and steam distribution sized for heat transfer and pressure drop.
Outdoor-air requirements (ASHRAE 62.1), exhaust, filtration, energy recovery, and pressurization for healthy, code-compliant air.
An HVAC engineer designs heating, ventilation, air conditioning, and refrigeration systems for buildings. They calculate heating and cooling loads, select and size equipment, design ductwork and piping, apply psychrometrics for humidity and air-quality control, and produce mechanical drawings and energy-code documentation that comply with ASHRAE standards and the mechanical code.
An HVAC engineer designs and sizes systems and performs the calculations and documentation (often as a licensed PE), while an HVAC technician installs, maintains, and repairs that equipment in the field. The engineer decides what equipment is needed and how the system is laid out; the technician makes it run.
Psychrometrics is the study of the thermodynamic properties of moist air — dry-bulb and wet-bulb temperature, humidity, dew point, and enthalpy. HVAC engineers use the psychrometric chart to separate sensible from latent loads, determine supply-air conditions, and design for humidity control, which is essential for comfort, energy efficiency, and avoiding mold or condensation.
HVAC design follows ASHRAE standards — 90.1 for energy efficiency, 62.1/62.2 for ventilation and indoor air quality, and 55 for thermal comfort — alongside the International Mechanical Code and local energy codes. Load and duct sizing commonly use ACCA Manuals J, D, and S, and refrigerant work is regulated by EPA Section 608.