The company’s largest commercial revenue source is electricity-related work at data centers, which Bieber called Willdan’s fastest-growing area. Burton brings expertise in building HVAC systems, energy controls technology and commercial energy procurement. It has also joined two Willdan utility programs, according to management. Gross profit dollars increased 28%, although gross margin declined 150 basis points because performance engineering and commercial project revenue includes more equipment and subcontractor costs. For the first half, contract revenue increased 19% to $386 million and net revenue grew 16% to $210 million.