However, also in this case, substantially higher costs impede the use of speed-controlled compressors in simple household refrigerators.Another possibility is to op- timize heat transfer at the evaporator and condenser, because the maximum efficiency of refrigeration processes is deter- mined by their temperatures. Increasing the evaporator temperature by 1 °C typically leads to a reduction of power con- sumption of 3–4%,decreasing the condenser temperature by 1 °C reduces power consumption by 2–3% (Dalkilic and Wongwises, 2010).