The vocabulary, without the trade-speak

A self-contained HVAC unit that sits on the roof.

A packaged rooftop unit contains the compressor, coils, fan and often the heating section in one cabinet sitting on a roof curb. It is the most common commercial HVAC configuration in New Jersey because it needs no indoor mechanical room.

A machine that makes chilled water for a building's cooling.

A chiller cools water that is then pumped to air handlers or fan coils throughout a building. Where a building has one it is usually the single largest electrical load on the site.

The fan and coil box that moves conditioned air.

An air handling unit contains the supply fan, filters and coils. It does not make heating or cooling itself; it distributes what the boiler or chiller produces.

The through-the-wall unit under a hotel room window.

A packaged terminal air conditioner is a self-contained through-wall unit serving one room. Most existing units heat with electric resistance, which is the most expensive way to produce heat.

A PTAC that heats with a heat pump instead of resistance.

A packaged terminal heat pump fits the same wall sleeve as a PTAC but produces several times more heat per unit of electricity. It is usually the highest-return substitution in a hospitality retrofit.

A refrigerant system serving many indoor units from one outdoor plant.

Variable refrigerant flow systems move refrigerant rather than air to distributed indoor units, allowing independent zone control across a building without ductwork.

A ductless heat pump serving one or more zones.

A ductless mini-split routes small refrigerant lines through a three-inch wall penetration instead of ductwork, which is why it dominates retrofits in older buildings that were never ducted.

Equipment that replaces air pulled out by exhaust.

In kitchens and industrial spaces, large volumes of conditioned air leave through exhaust hoods. Make-up air units condition the replacement air, and they are a significant and often overlooked load.

The metal box in the wall a PTAC slides into.

Sound sleeves are reused during a changeout, which keeps per-room work to hours. Coastal corrosion is the usual reason a sleeve has to be replaced.

Equipment switching on and off too frequently.

Oversized equipment satisfies demand quickly, shuts down, then restarts. Every cycle wastes energy on startup and purge, and it shortens equipment life.

A damper system that uses cool outside air instead of running cooling.

When outside air is cool enough, an economizer brings it in rather than running mechanical cooling. Seized economizer dampers are extremely common and produce no symptom other than a higher bill.

Running at partial output instead of all-or-nothing.

Modulating equipment matches its output to the actual load. Since buildings spend most hours well below design load, part-load behavior matters far more than peak efficiency.

Mixing the hot air trapped at a high ceiling back down.

In warehouses, heat collects at the ceiling while the floor stays cold, so the system runs longer to satisfy a thermostat at head height. Addressing it changes the heating numbers considerably.

A drive that varies motor speed instead of running flat out.

A variable frequency drive lets fans, pumps and compressors slow down when full output is not needed. Because power draw falls sharply with speed, the saving at part load is large.

How much heat you get per unit of energy put in.

Coefficient of performance is the ratio of heat delivered to energy consumed. Electric resistance heat has a COP of 1; a heat pump delivers several times that, which is the whole basis of the retrofit case.

Seasonal cooling efficiency ratings.

These express cooling efficiency across a season rather than at a single test point, which is why they reflect real operating cost better than a peak figure.

The calculation of what a building uses now versus after.

The energy model is not paperwork attached to the project — it is what determines the incentive. It is built from twelve months of real utility data rather than floor area and assumptions.

The category your account sits in with your utility.

Incentive programs band accounts by size and usage. Two buildings with identical equipment can land at different points in the incentive range purely because of which tier they fall into.

A bill component based on your highest peak draw.

Commercial accounts are billed partly on the single highest demand spike in a period, not only total consumption. This is why reducing peak load — the thing a chiller upgrade does — is worth more than it first appears.

The unit natural gas is billed in.

One therm is 100,000 BTU. Gas-side incentives are generally calculated from therms saved, in the same way electric incentives are calculated from kilowatt-hours.

What the building uses today, before any work.

The incentive is the gap between baseline and projected performance. The worse the baseline, the larger the incentive — which is why the oldest, most oversized plant produces the best economics.

The refrigerant in most equipment installed before 2025.

R-410A is legal to own, repair and recharge. What changed is that it is no longer manufactured into new equipment, and its price has moved with the federal phasedown.

The safety class of the refrigerants now replacing R-410A.

A2L means lower toxicity and mild flammability. New equipment uses A2L refrigerants such as R-454B and R-32, and they require different tooling, leak detection and technician training.

The A2L refrigerants in new commercial equipment.

Both have substantially lower global warming potential than R-410A. Neither can be mixed with R-410A, which is why a new outdoor unit cannot be paired with an old indoor coil.