Our Certifications at Durable Service Our team at Durable Service in Holdrege aims to have the best heating and cooling service around. One of the ways we maintain our expertise and continue to build knowledge about HVAC products is by earning industry certifications. Learn more about the certifications our technicians have received below. Industry Competency Exams (ICE) Industry Competency Exams, managed by NATE, measure industry-agreed standards of basic competency for entry-level technicians (one year of experience or less). Many students are required to participate in at least one exam before they can graduate. Topic areas addressed in these exams include: residential, light commercial and commercial refrigeration. Earning ICE Certification verifies a technician is experienced in the service and installation for the HVAC content area.