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The energy efficiency ratio (EER) of a particular cooling device is the ratio of output cooling energy (in BTUs) to input electrical energy (in watt-hours) at a given operating point. EER is generally calculated using a 95 °F (35 °C) outside temperature and an inside (actually return-air) temperature of 80 °F (27 °C) and 50% relative humidity.
Energy conversion efficiency (η) is the ratio between the useful output of an energy conversion machine and the input, in energy terms. The input, as well as the useful output may be chemical , electric power , mechanical work , light (radiation), or heat .
A realistic indication of energy efficiency over an entire year can be achieved by using seasonal COP or seasonal coefficient of performance (SCOP) for heat. Seasonal energy efficiency ratio (SEER) is mostly used for air conditioning. SCOP is a new methodology which gives a better indication of expected real-life performance of heat pump ...
Energy efficiency was a lower priority when energy was cheap and awareness of its environmental impact was low. In 1975 the average fuel economy of a car in the US was under 15 miles per gallon [ 6 ] Incandescent light bulbs, which were the most common type until the late 20th century, waste 90% of their energy as heat, with only 10% converted ...
HSPF is defined as the ratio of heat output (measured in BTUs) over the heating season to electricity used (measured in watt-hours). [1] [2] It therefore has units of BTU/watt-hr. The higher the HSPF rating of a unit, the more energy efficient it is. An electrical resistance heater, which is not considered efficient, has an HSPF of 3.41. [3]
A new energy label, introduced in 2010, is based on the energy efficiency index (EEI), and has energy classes in the range A+++ to D. [11] The EEI is a measure of the annual electricity consumption, and includes energy consumed during power-off and standby modes, and the energy consumed in 220 washing cycles. For the washing cycles, a weighted ...
In Europe, the seasonal efficiency of refrigeration equipment, chillers and air conditioners is often rated by the European seasonal energy efficiency ratio (ESEER) which is controlled (among others) by the Eurovent Certification Company. [1] A similar standard in the United States is the integrated energy efficiency ratio (IEER).
It is a dimensionless ratio of useful energy output to energy input, expressed as a percentage. For example, a 90% AFUE for a gas furnace means it outputs 90 BTUs of useful heating for every 100 BTUs of natural gas input (where the rest may be wasted heat in the exhaust). A higher AFUE means higher efficiency.