Designing the refrigeration layout for an HVAC system in a small office requires a few steps. First, the size of the office needs to be determined in order to calculate the required cooling capacity. This can be done by measuring the square footage of the office and using a cooling load calculator. Second, the type of refrigeration system needs to be chosen. This can be a split system, a packaged system, or a rooftop system. Third, the refrigerant type needs to be selected. This should be based on the type of system chosen and the local regulations. Fourth, the refrigerant piping needs to be designed. This includes the piping layout, the pipe size, and the insulation. Finally, the refrigerant controls need to be installed. This includes the thermostat, the expansion valve, and the compressor. Once all of these steps are completed, the refrigeration layout for the HVAC system in the small office is ready for installation.