Commercial HVAC replacement and installation in Vancouver.

Rooftop units cool close to half of all commercial floor area in the country, so most replacement decisions are packaged-unit decisions. Once a unit is past 15 years, the useful question is not whether to replace it but what to replace it with.

There are three honest answers. A like-for-like swap gets the building back to normal fastest and keeps engineering cost down. A high-efficiency unit of the same type costs more up front and earns it back through run hours — the DOE spec that created this class targeted up to 50% less energy than the standard in place at the time, and a federal minimum finalized in 2015 has since raised the floor for every new unit. A heat pump rooftop unit adds reverse-cycle heating and comes in dual fuel, all-electric, and cold climate versions.

Price at least two of the three. The gap is usually smaller than owners expect, and it is far easier to compare before the old unit fails.

No two roofs price the same, and the equipment is rarely where a quote goes wrong. These are the lines that swing hardest between two bids on the same building. If a number looks low, one of these is usually missing rather than cheaper.

The most expensive way to buy a commercial rooftop unit is to wait until it dies in August. Replacement on failure removes every choice worth having: you take what is available, at the price it is available, with no time to check whether the size still fits the building. Federal guidance is blunt about this — facility managers routinely delay until the unit fails, and proactive replacement usually beats both replacement-on-failure and a reflexive like-for-like swap at end of life.

Start with the load, not the nameplate. Twenty years changes occupancy, plug loads, lighting heat, and often the envelope. A unit sized for the building as it was two decades ago can be oversized today, which shows up as short cycling, poor humidity control, and comfort complaints no service call ever fixes. The load calculation is a few hours of work that decides the largest line on the quote.

Then decide the fuel question once, deliberately. Heat pump rooftop units are strongest where winter heating runs mild to moderate, and the practical constraints are electrical capacity, physical room on the roof, and the existing gas line. Those are answers a site visit produces in an afternoon. If the answer is no, a high-efficiency unit of the same type is a good outcome, not a consolation prize.

Two buildings on the same block can price very differently. The split is rarely about the equipment. It is about what has to change around the equipment, and how much of that can be confirmed before the crane is booked.

A quote written from a phone call is a guess with a number attached. The site review exists to turn the unknowns into fixed lines, and there are only a handful of them.

The first is the load: what the space demands now, on today's schedule, with today's equipment in it. The second is the roof: curb dimensions, structural capacity for the new unit's weight, and whether an adapter or a new curb is the honest answer. The third is infrastructure — electrical capacity at the panel, feeder routing, and the state of the gas line if you are keeping gas heat. Federal heat pump guidance names those same three as the infrastructure questions that decide whether a heat pump is realistic at a given site, alongside equipment availability and contractor familiarity with the technology.

The fourth is access. Crane reach, staging space, which stalls close and for how long, and whether the lift happens before the building opens. The fifth is controls: what the new unit needs to talk to, and who owns the point mapping.

Answer those five and the quote stops being an estimate. Skip any of them and you will meet it again as a change order.

The install is one morning. The consequences run for the next decade and a half, and they land in two places: what the unit costs to run, and what it costs to keep running.

On the run side, the numbers are not small. Federal analysis has put the annual energy waste of an old, inefficient rooftop unit at roughly $900 to $3,700 apiece. Across a roof with four or five units, that is a line item, not a rounding error, and it is why the efficiency tier deserves more attention than a rushed replacement usually gives it.

On the service side, the decision you make now sets the shape of your fleet. Roofs replaced one unit at a time, on failure, end up with a mix of ages, control platforms, and refrigerants that no service contract covers cleanly. Owners who plan the sequence end up with fewer variables to manage.

If you own more than one unit, the highest-leverage move is to stop treating replacement as an emergency. Walk the roof once, write down the age and condition of every unit, and rank them. The ones past 15 years are candidates whether or not they are currently complaining.

From there, phasing is a budget exercise rather than a crisis. Replace the oldest and hardest-working units first, in a shoulder season when losing a zone for a day costs nothing. Book the crane once for two or three units instead of three times for one. Standardize on a control platform so the next unit integrates in hours instead of days. Every one of those moves is cheaper when it is scheduled.

Procurement follows the same logic. Equipment availability is one of the factors federal guidance names in deciding what is actually deployable at a site, and availability is something you can plan around when you have months and cannot when you have days. If you are considering a heat pump anywhere on the roof, do the electrical capacity study once for the whole building rather than per unit. It is the same panel either way, and the answer changes which units are candidates.

Lifetime cost is mostly decided in the first week of a project.

Two bids are only comparable when they scope the same work. Ask for these five in writing and the differences between contractors become obvious in about a minute.