High Performance This guide on All That Glass Can Do begins with a closer look at thermal and energy performance. When it comes to glass, the top demand from owners and designers are systems that allow projects to feature large expanses of glass while meeting energy code requirements. Energy code requirements The national energy codes are becoming more stringent, cycle after cycle, according to Tom Culp, owner of Birch Point Consulting and energy code consultant for the NGA. Culp describes it as a rough “zone shift” in each updated edition. “Every three years, in our normal work at ASHRAE, IECC, California Title 24, we see steady advancement and uptake in energy-efficient technologies while also being practical and cost-effective,” he says.