COMBUSTION AIR , as defined in the Mechanical Code, is the total amount of air provided to the space which contains fuel-burning equipment; it includes air for fuel combustion, for draft hood dilution and for ventilation of the equipment enclosure. Its applicability to live/work is that in buildings of unusually tight construction, combustion air may be required to be ducted in from outside air sources to accommodate needs of gas appliances such as range, water heater, space heater, etc. One other application of this term to live/work: space or water heating equipment which is located in and draws its combustion air from a bedroom or bathroom is not permitted under the mechanical code. In a large open space such as a live/work unit, it is arguable that a gas appliance not in the sleeping area shall draw its combustion air from the common atmosphere of the space. One way to avoid this problem is to use a direct vent heater which draws its combustion air from outside. Another may be to provide calculations to substantiate an assertion that there is sufficient air infiltration into the space combined with its large volume to easily meet both combustion air needs of the appliance and the fresh air needs of the occupants-- who are also able to exert free will and open their windows.