temperature control, during winemaking is crucially important, as outlined in temperature. Although it has been widely and systematically practised only since the 1960s and 1970s, its efficacy was appreciated as long ago as Roman times (see die). See refrigeration for details of how wine may be cooled at various points in its life. In cool wine regions or particularly cool years, a fermentation vessel may need to be heated to encourage alcoholic fermentation, most easily by circulating warm water in equipment also designed to carry cooling cold water or, in smaller cellars, simply by closing doors and installing a heater or two. Some form of heating may also be required to encourage malolactic conversion.