If your washing machine is undersized but your dryer is standard, consider drying two wash...

Ready for a chill? This standard air-conditioning system rating refers to the cooling capacity of a unit (in Btus per hour) divided by the power it consumes (in watts), at a given outdoor temperature. It is related to the Seasonal Energy Efficiency Ratio (SEER), which is a measure of a cooling system's efficiency over an entire cooling season. In both cases, the higher the number, the more efficient the unit. These ratios can help you compare the energy efficiency of your air conditioner to newer models, and decide if a replacement is due. Tip: Cooling equipment purchased before 1992 is likely to be extremely inefficient when compared to today's models.