Location, especially for apartments in multi-unit structures, is important. Ground floor units tend to be cooler year round while top floor apartments tend to be warmer. Windows with a southern exposure to the sun will allow your apartment to collect natural heat in winter. Another amenity, the enclosed hallway in an apartment building, can help lessen utility costs by buffering temperatures between outdoors and indoors. An enclosed porch on a house acts in the same fashion.
Landscaping can also enhance the efficiency of a house or apartment.
Trees shading west or east walls help reduce cooling costs. Evergreens on the north side of the dwelling can block north winds in winter, making January and February a bit more comfortable. South facing walls should have no shading or seasonal shading with trees that shed leaves in winter, so that the winter sun can warm up the south side. Heat flows out of your rental in winter and into it in summer. Ask the owner what levels of insulation are in the walls, ceiling, and floor.