TL;DR · 30-second read
The Short Version
Comfort Systems USA installs the heating, cooling and electrical systems inside large buildings, including data centers: the warehouse-sized computer buildings that run artificial intelligence and the internet.
Its stack of signed but unfinished work nearly doubled in a year, to about $17.8 billion. That is almost five times what it took in from customers in its latest three months. Its profit per share jumped 69%.
The surprise is where the wait is. Companies racing to build data centers are lining up for the pipefitters, sheet-metal workers and electricians who keep those computers from overheating.
Comfort Systems USA (NYSE: FIX), the Houston-based mechanical and electrical contractor, reported third-quarter 2026 net income of $489.0 million, or $13.91 per diluted share, up from $291.6 million, or $8.25, a year earlier, in an earnings release filed with an 8-K on October 22. Revenue rose to $3.77 billion from $2.45 billion, operating cash flow reached $1.01 billion, and backlog (signed work not yet performed) climbed to $17.81 billion from $14.06 billion at the end of June and $9.38 billion a year earlier.
BigGo Finance, covering the October 23 earnings call, framed the results around surging data center demand. Alongside the results, the company raised its quarterly dividend by $0.10 to $1.00 per share. In a separate 8-K, it said Chief Financial Officer Bill George will retire after the 2026 annual report is filed, with Chief Accounting Officer Julie Shaeff named as successor.
Executive Summary
The headline numbers are large on their own: a 69% rise in earnings per share, roughly 54% revenue growth and a backlog that has nearly doubled in twelve months. Chief Executive Brian Lane described “extraordinary results across every metric” and said the company believes it is “well-positioned to grow organically” through year-end and into 2027.
The more telling figure is the relationship between backlog and revenue. Comfort Systems added roughly $3.75 billion of backlog in a single quarter while also completing $3.77 billion of work. That implies new awards of around $7.5 billion, close to double what it billed. When customers sign work faster than a contractor performs it, the contractor’s crews become a queue that new projects have to join.
For anyone building, financing or leasing data center capacity, that matters. The heating, ventilation and air-conditioning (HVAC), piping and electrical fit-out is what turns a building shell into usable, coolable computing space. Comfort Systems’ numbers suggest that part of the build is being booked further and further in advance.
The Backlog Is Outrunning the Work
Backlog is a contractor’s order book: the value of contracted work not yet performed. At Comfort Systems it grew about 90% year over year, from $9.38 billion to $17.81 billion, while quarterly revenue grew about 54%. The company also reports a same-store figure, which strips out businesses acquired over the past year. On that basis backlog still rose from $9.38 billion to $17.39 billion, so the expansion is overwhelmingly organic rather than bought.
Coverage gives another view. A year ago, backlog equaled about 3.8 quarters of the company’s then-current quarterly revenue. It now equals about 4.7 quarters. Within the latest quarter, backlog rose by roughly $3.75 billion even though the company performed $3.77 billion of work. By our arithmetic, that implies about $7.5 billion of new work entering the book in three months. Even after setting aside the up to $0.42 billion that came with acquired businesses, awards ran close to twice revenue, a book-to-bill ratio near 2.
That is the mechanism behind the idea that data center owners are waiting in line. Comfort Systems has not said its crews are fully booked, and some of the stretch likely reflects larger, longer-duration contracts signed earlier in a project’s life. Both readings point the same way: developers are committing to mechanical and electrical contractors earlier and in larger blocks. The company’s own cautionary statement lists “undertaking contractual commitments that exceed the Company’s labor resources” and “shortages of labor and specialty building materials” among its risks. On this evidence, the pace at which the backlog converts depends on crews and materials, not on customer appetite.
Why AI Data Centers Run Through the Mechanical Trades
A data center’s computing hardware turns nearly all the electricity it draws into heat. AI accelerators, the specialized chips used to train and run AI models, pack far more power into each rack than conventional servers. Removing that heat takes a whole plant of equipment:
- chillers, cooling towers, pumps and air handlers;
- increasingly, liquid-cooling loops that carry coolant close to the chips;
- large-bore piping connecting all of it, which has to be fabricated, installed, pressure-tested and commissioned on site.
Comfort Systems’ 10-Q shows the business reported through Mechanical and Electrical segments, which covers both the cooling plant and much of the power distribution that feeds it.
Those trades sit on the critical path, the sequence of tasks that sets a project’s completion date. A building can be enclosed and its generators delivered, but it cannot host paying tenants until cooling and electrical systems are installed and commissioned. That makes skilled pipefitters, sheet-metal workers and electricians a gating resource, alongside the better-known constraints of chips and grid power.
Three groups of buyers are affected:
- hyperscalers, the largest cloud operators, which build their own campuses;
- colocation providers, which lease space to many tenants;
- developers building to suit.
For each of them, a contractor with nearly five quarters of revenue already under contract is one whose availability has to be secured early.
Is Scarcity Showing Up in Margins and Cash?
Net margin, meaning profit as a share of revenue, rose to about 13.0% from about 11.9% a year earlier, by our calculation from the reported figures. Rising margins at a contractor during a demand surge are consistent with stronger pricing, but they do not prove it. Project mix, productivity on repeat work and overhead spread across more revenue can all contribute, and the release does not break the improvement down.
The cash figures are more striking. Quarterly operating cash flow of $1.01 billion was roughly twice net income. Nine-month operating cash flow of $2.54 billion was more than three times the $717.8 million recorded in the same period of 2025. At contractors, cash running ahead of earnings often reflects customers paying on schedules that lead the work, which is one sign of negotiating leverage. That benefit can reverse as large projects move into later phases, and the company has not said which factors dominated.
The board raised the quarterly dividend to $1.00 from $0.90, which signals management’s confidence that this level of cash generation is not a one-quarter event.
What Could Interrupt the Queue
A long backlog is valuable only if it converts at the margins it was priced at. The company’s cautionary language names the main exposures:
- incorrect estimates when bidding fixed-price contracts;
- commitments that outrun labor resources;
- shortages of, or cost increases in, labor and specialty materials.
At $17.81 billion, even small estimating errors are large in dollar terms.
Concentration is the other question. If data centers are driving much of the growth, Comfort Systems’ results become more closely tied to the capital-spending plans of a relatively concentrated group of large buyers, whose budgets can shift with financing conditions and chip supply. The finance leadership change, by contrast, looks orderly. George is a co-founder and has been CFO since 2005, and will stay through the 2026 annual report. Shaeff has been chief accounting officer since 2005, and the company describes the appointment as part of its succession plan.
Background
Comfort Systems USA was formed in 1997 and has grown through a long-running acquisition program into one of the largest US building-services contractors. It now operates 211 locations in 155 cities, providing heating, ventilation, air-conditioning and electrical contracting services to commercial, industrial and institutional customers. It reports results through Mechanical and Electrical segments and trades on the New York Stock Exchange under the ticker FIX.
Mechanical and electrical contractors sit between the equipment makers that build chillers, switchgear and cooling units and the developers and operators that own data centers. AI computing has driven a wave of data center construction and raised the heat output of each rack. As a result, installing cooling and power systems has become a larger and more complex share of each project, and the skilled labor that does it has become a planning constraint in its own right. Source: Comfort Systems Posts Record $17.8B Backlog, EPS Jumps 69% to $13.91 as Data Center Demand Surges, BigGo Finance’s coverage of Comfort Systems USA’s third-quarter 2026 earnings call. Primary sources: Comfort Systems USA Reports Third Quarter 2026 Results (Exhibit 99.1 to Form 8-K, October 22, 2026); Form 8-K filed October 22, 2026: third-quarter results and dividend; Form 10-Q for the quarter ended September 30, 2026; Comfort Systems USA Increases Quarterly Dividend (Exhibit 99.2 to Form 8-K, October 22, 2026); Form 8-K filed October 22, 2026: CFO retirement and succession; Bill George to Retire After 30 Years of Service; Comfort Systems to Promote Julie Shaeff to Chief Financial Officer (Exhibit 99.1).Sources