In the 1920s, some interior lighting fixtures were manufactured as gas and electric combinations. Victorian era gas lights were being phased out and electricity was still considered new and unpredictable by many. However, as public confidence in this innovation, many fixtures were exclusively electric. Cloth-covered electric wires allowed for the suspension of lighting, such as chandeliers, which were developed in 1915. Both wall sconces and chain-hung fixtures were popular in the 1920s.
Your 1920s era house may be in the Craftsman or Mission style. This architectural design was naturalistic and characterized by local wood and stone building materials as well as an artistic departure from the prevailing opulent Queen Anne style. Angular light fixtures in square or rectangle shapes were crafted of iron or brass, while linear iron chandeliers hung from thick chains.
A more elaborate cousin of the Mission style lighting of the 1920s is the colorful art glass fixture. Characterized by amber or creamy glass shades with tapering trapezoidal faces atop iron or brass lamps, art glass table fixtures and sconces provided a warm and distinctive soft light. Curving stained or colored glass lampshades were also used in this era.
Some Tudor and Queen Anne homes featured lighting updated for electricity or in gas/electricity combination in the 1920s. For these more traditional home designs, chandeliers and sconces were available in silver finishes with parchment shades and even frosted glass domed ceiling fixtures embossed with patterns of grapes or flowers. While less distinctively associated with the design of the era than the Mission fixtures, these were authentic of the period, as well.