Large refrigeration and air-conditioning systems used in commercial buildings were evaluated to determine if greenhouse gas emissions could be reduced from both the indirect greenhouse gas emissions from energy usage, and from direct greenhouse gas emissions from high-global warming potential refrigerant leaks. Supermarkets were the primary business type to use both large amounts of energy and emit significant amounts of refrigerant. Energy conservation measures and refrigerant leak reduction measures were assessed for technical feasibility and cost-effectiveness. Measures that were both commercially available and cost-effective were recommended for inclusion into the California Building Code Title 24. Greenhouse gas reductions of 1.2 million metric tonnes of carbon dioxide equivalents can be achieved annually by applying the assessed measures, at a cost savings of between $15,000 and $75,000 annually for each facility, depending upon the size of the supermarket, with larger supermarkets saving more money.