Energy Indicators for Sustainable Development ... - IAEA Publications

number of people and on ownership levels of electric appliances. As the number ofpeople in a household declines, energy use per household declines, while the energyuse per capita increases. Energy use for water heating and cooking, and for manyappliances tends to vary with the household size and the number of people perhousehold.For developing countries with large rural sectors or large numbers of homes withoutaccess to electricity, the share of homes connected to the electricity grid is animportant factor in total household energy use. The shares of homes using differentkinds of combustible renewables and waste (CRW) are also important.(c) Limitations of the Indicator: When energy use by end use is not known, energyuse per household can be used as an energy-intensity indicator, but it does notmeasure energy efficiency developments very well. Some important conclusions canbe drawn, however, if the average winter temperature, ownership of energy-usingappliances and dwelling size are known. In a country with cold winters and a highpenetration of central heating systems, a low total use of energy for all purposes,relative to total home (floor) area and the severity of winter climate, probably impliesefficient heating practices. Conversely, high energy use relative to floor area in acountry with mild winters might imply inefficiencies. However, since energy-usehabits vary so much, both among countries and among end uses, few conclusionsabout efficiency can be drawn from the indicator on residential energy use perhousehold.The measurement and interpretation of energy intensities are complicated bydifferences among products within a category, such as size (e.g. refrigerator capacity),features (freezer compartments in refrigerators) and utilization (hours per year a stoveis used).(d) Alternative Definitions/Indicators: None.(e) Measurement of Efficiency: To describe energy efficiency developments,intensities should be expressed as energy use per unit of disaggregated energy service.The inverse of these intensities would then reflect energy efficiency — for example,litres of refrigerated volume at a given temperature divided by electricity use forrefrigeration, lumens of light per watt of power consumed, or computer tera-flops persecond divided by power consumption for the computer, etc. In practice, these kindsof disaggregated data are not available. For some household equipment, specificenergy requirements can be calculated from survey data on equipment efficiency andusage time per year for the equipment.Activity (Services Provided): Ideally, output units would be in energy servicesdelivered, such as lumens of lighting, number of meals cooked, area and time heated,litres of hot water provided, litres refrigerated, kilograms of clothes washed, etc. Inpractice such data are rarely available, even for individually metered homes. If dataseparating residential energy use by main end use are available, floor area should beused as the activity measure for space heating, air conditioning and lighting; numberof persons per household, for water heating and cooking; and ownership levelsmeasured as number of devices per household, for important electric householdappliances.65