Our Certifications at Durable Service Our team at Durable Service in Holdrege aims to have the finest heating and cooling service around. One of the ways we sustain our expertise and continue to learn about HVAC products is by earning industry certifications. Discover 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. Content areas include: residential, light commercial and commercial refrigeration. Achieving ICE Certification verifies a technician is experienced in the service and installation for the HVAC content area.