Refrigeration
16% of Domestic Electricity Use – Potential Savings: $60 per year
(Based on replacing a 15-year-old 15 cu ft refrigerator with a modern unit; the average Canadian refrigerator is 10 years old.)
A very old refrigerator could cost over $200/year to run! (.) Refrigerators run 24/7 to keep your food fresh. Often they are forced to work even harder, coping with children browsing for a treat. Opening the refrigerator as infrequently as possible and only briefly saves money.
Most people have combination refrigerator/freezer units. These keep everything conveniently close, in the kitchen. However, when cooking is happening, the kitchen is the warmest room in the house, making the refrigerator work harder. Also, the kitchen tends to be humid with water vapour from cooking. Both encourage condensation inside, costing energy and requiring frequent defrosting – even more energy.
A few units have no visible condenser (the grid of thin plumbing behind your refrigerator). Instead, they are “skin cooled” – the condenser is attached to the refrigerator’s outer skin, which gets warm when running. A traditional condenser seems purpose-built to catch dust bunnies, which eventually form an insulating blanket, reducing efficiency. Other modern units use a hidden, compact fan cooled condenser. Skin cooled units never need cleaning – other types must be cleaned regularly to run properly.
Location
For maximum efficiency, the refrigerator should be put in the coolest, driest room in the house – probably the basement. Of course, many would not accept the inconvenience. Another efficient alternative would be to have a refrigerator with no freezer in the kitchen. As these never freeze, they need no defrosting. That means that they don’t waste energy creating ice, and then more energy melting it. So, a moist location (a well-used kitchen), and snack-hunting kids have much less effect on energy use.
The freezer – less often accessed – can be kept in the cool basement where it works less hard and needs little defrosting. The freezer should be a chest model. These are more efficient (but less convenient) than uprights. When the door of an upright is opened, the cold, heavy, air slides out – you can feel the cold on your feet – and is replaced with warm moist air. The chest model loses little cold air when its door is opened.
Separate Refrigerator and Freezer
When I bought a new refrigerator (1989), the total energy use of a separate refrigerator and freezer was much less than that of combinations then available. Today, combinations have improved to the point where there is little difference. However, buying a chest freezer and placing it in a cool, dry place will reduce energy use by more than the data tables suggest. As a bonus, separate units provide more storage room.
Modern, Efficient Refrigerator/Freezers
Modern self-defrosting refrigerator/freezer combination units are more efficient for several reasons. They have better insulation. Old units were not well sealed, allowing moisture to penetrate the insulation and mould to grow, reducing effectiveness. Door seals are now magnetic, ensuring a tight seal so less moisture enters the cold compartments, and much less frost forms on the evaporator. Self-defrost operates by reversing normal refrigerant flow, so the evaporator becomes the condenser and vice versa. This warms the cold coils, melting accumulated frost. Then the normal cycle resumes. Older units defrosted on a set schedule, needed or not. The cycle reversed for a set time, enough to melt a heavy frost accumulation, even though there might be little present. Modern units sense the presence of frost, and time the defrosting accurately.
Each gram of vapour requires 3000 joules of energy to condense and freeze. To defrost, the refrigerator cycle reverses. Then each gram of ice takes around 350 joules of energy to melt! Forming and then melting one gram of ice (15 grams is one tablespoon) from moist air each minute requires about the same amount of energy as a 60 watt light bulb.
Super-Efficient Units
The Danish “Vestfrost” combination refrigerator/freezer uses half the power of a conventional combination unit (or 2/3 of the energy, adjusting for size difference). It uses better insulation, plus a variable speed compressor, which adjusts to the need for cooling.
California’s “Sun Frost”, makes ultra-efficient refrigerators and freezers designed to operate from solar panels and wind power. These have thicker insulation and completely separate refrigerator and freezer compartments, each with their own compressor. The freezer section seldom needs defrosting because it does not collect humidity from the frequently accessed refrigerator section. The refrigerator’s evaporator operates at a higher temperature than conventional combination units, collecting less moisture. This saves energy (condensing moisture warms the evaporator), and also slows the drying of stored vegetables, prolonging shelf life. “Sun Frost” uses 1/3 of the energy of a conventional combination unit.
Modern refrigerator/freezers use less than ½ the energy of models made just 15 years ago. Super-efficient units exist which could further cut today’s energy consumption by 30-50%. These are expensive, and will not become widespread unless the cost of electricity rises further.
Both the “Vestfrost” and the “Sun Frost” cost more than conventional units. But, where electricity is expensive, or where a large investment in solar panels and a wind turbines is needed, they are excellent investments. They also show that greater energy efficiency is possible – if we demand it!
Dump the “Beer Fridge”!
33% of Canadian homes own a 2nd refrigerator, typically 20 years old
Some people own a “beer fridge”. This is often an old unit, which should have been discarded. It may use over 4 times the power of a modern one because its door seals are tired, its insulation, poor to begin with, may be moist and mouldy, and its old-style compressor, inefficient. Unless it is under 15 years old, your “beer fridge” may be costing you $20-$30 per month. Is keeping 72 bottles of beer cold really worth $250 a year? How much beer could you buy for that? If you really need a beer fridge, buy a new one (with no freezer). You are likely to save the purchase price in electricity costs in 3-4 years!