Commercial HVAC replacement and installation in Sunnyvale.

Most buyers are choosing between three things, not ten. Keep repairing the unit you have. Swap it for the same kind of unit on the same curb. Or change the system type while the roof is already open.

The age question decides more than it looks. DOE's guidance is blunt about rooftop units past 15 years: they waste real money every year compared with newer equipment, and most owners still wait for a failure before acting. Waiting is the expensive version. A failure in August turns a planned purchase into whatever is on a truck.

The third option only makes sense at replacement time. Changing from gas heat to a heat pump unit, or resizing tonnage, is cheap to decide now and expensive to revisit later.

No two roofs price the same, so ignore any number given before someone looks. These are the lines that actually move an installed price, ordered roughly by how often they surprise people.

The equipment decision deserves more attention than the crane day. DOE's rooftop unit work is the clearest evidence here. The department challenged manufacturers to build units that cut energy use by up to 50% against the standard of the time, then paid for third-party field verification so owners were not buying on a data sheet. More than twenty models now beat that specification, and a national minimum efficiency standard finalized in 2015 raised the floor under everything sold since.

That history matters to you in one practical way. The cheapest unit a supplier can quote is usually the one that just clears the floor. The step above it is a real product with measured savings behind it, not a marketing tier. Ask for both prices on the same quote, and ask for the annual energy difference in writing.

Decide the fuel question at this moment too, not later. DOE's heat pump rooftop guidance walks the same checklist a good contractor will: climate, electrical capacity, physical constraints, gas lines, and whether local crews install and service that equipment well. A heat pump unit that arrives without the panel capacity to run it is a schedule problem, not an equipment problem.

Before you set a budget, work out which of these two projects you have. The equipment is often identical. What separates a one-morning swap from a phased job is the roof, the power, and the schedule you have to protect.

A quote written from a nameplate photo is a starting number, not a price. Somebody has to get on the roof.

The site review confirms four things in order. First, the load the space needs today. Occupancy, plug loads, and the envelope all change over twenty years, and the old nameplate only records what someone assumed back then. Second, the physical fit: curb dimensions, the condition of the framing under it, clearances, and whether a crane can reach the unit using the lot you actually have. Third, the services. Electrical capacity at the panel, feeder size, the gas line if the unit keeps burning gas, and refrigerant line runs on a split system. DOE lists these same infrastructure items — electrical capacity, physical constraints, and gas lines — as the ones that decide whether a heat pump unit is even practical at a given site.

Fourth, the refrigerant handling plan. EPA rules under Section 608 of the Clean Air Act govern how refrigerant is handled and recycled when this equipment is serviced or removed. That is the installing contractor's job, and it belongs in their scope rather than a footnote.

A rooftop changeout in Sunnyvale is permitted work. California building departments treat mechanical upgrades and repairs as permit-required, along with the electrical work that comes with them, and re-roofing sits on that same list with its own permit. Build the review and the inspection into your schedule rather than into the week you hoped to start.

That shared list points at a real sequencing decision. If the roof membrane is near the end of its life, doing the re-roof and the unit set as one coordinated project is usually cheaper and less disruptive than craning a new unit onto a roof you plan to tear off in two years. Ask your roofer for the membrane's remaining life before you sign the mechanical scope.

Two questions shape how this project feels more than the equipment does. Who pays, and who gets inconvenienced.

On the money side, the split between capital cost and operating cost is where owners and tenants usually disagree. The owner writes the check for the unit. The tenant pays the power bill. DOE's figure for what an old, inefficient rooftop unit wastes — $900 to $3,700 a year — is real money, but it lands on whoever holds the meter. If your lease separates those two parties, say so early, so the efficiency tier gets decided by someone with a stake in it.

On the operating side, the question is what the building can tolerate. A single-unit building has no cushion. A building with several units can often stage the work zone by zone and keep people comfortable throughout.

The strongest argument in DOE's guidance is about timing, not technology. Most facility teams delay a rooftop replacement until the unit stops holding the space, needs constant service, or fails outright. Replacing proactively usually beats replacing on failure, and it often beats a last-minute like-for-like swap, because a failure removes every choice you would have wanted to make.

Planned replacement buys you three things. You can compare equipment instead of taking whatever is available. You can schedule the crane for a low-traffic day instead of the first day it is free. And you can bundle the work — roof, curb, controls, electrical — instead of paying a separate mobilization for each piece.

Across a portfolio, the same logic scales. Rank units by age and service history, replace the worst two or three each year, and standardize on one or two models so parts and controls stay simple. DOE's Advanced RTU Campaign ran exactly this play with more than two hundred organizations across more than 43,000 units, with combined reported savings of $37 million a year. The lesson is not the size of that number. It is that this works far better as a program than as an emergency.

Two quotes are only comparable when both spell out the same five items. If one leaves a line blank, that line is not free — it is just not priced yet. Ask before you compare.