Fruchill – the frugal fridge : Cool refrigerators with cold outside air to cut peak demand for electricity

Sammanfattning: To use electricity, especially during peak demand periods, to cool fridges makes cold air seem as an overlooked resource for reducing the electrical energy spent on operating household refrigerators. This thesis investigates whether an automatic device for supplementary cooling of a fridge using cold outside air can be retrofitted to a fridge in order to save energy. Prototypes were constructed to facilitate iterative optimization resulting in a POC design that reduces the energy consumption for a retrofitted refrigerator by 82-93% while maintaining the temperature inside the fridge at +4 °C. This is particularly valuable during peak demand periods. Modern materials designed for ducts and insulation together with mass produced fans, sensors and control electronics of high quality and at low cost make retrofitting of currently marketed refrigerators to a viable proposition. The individual household can reduce its cost for electricity and over some years reach payback of the installation cost. On a larger scale, retrofitting offers a contribution for energy consumers in general as well as grid operators who benefit from reduced peak demand and the costs associated with maintaining marginal capacity. A conservative estimate suggests that latitudes and altitudes with climate that permit economically justified retrofitting holds globally some 200-500 millions of refrigerators. The volume speaks for an interesting opportunity to use cold air as a valuable resource.