BS EN 16212-2012 pdf download.Energy Efficiency and Savings Calculation , Top-down and Bottom-up Methods.
For different cases, e.g. refurbishment of dwellings or new dwellings, different baselines are defined. With appropriate baseline choices the calculated additional savings can represent the effect of policy measures. These issues are elaborated on In Clause 6.
In top-down calculations no distinction is made as to the cause of increased penetration of high efficiency boilers. Therefore top-down methods do not need specific baselines and provide only total savings.
4.4 Type of data used
Top-down calculations generally rely on statistical figures at aggregated level. e.g. energy consumption and production in sub-sectors of industry, or total fuel use of cars and the distance driven by the cars.
Bottom-up calculations normally ask for detailed data, such as the number of subsidised boilers or the appliances sold in each label category. These data are mostly, but not necessarily, of a non-statistical nature.
In some cases, the difference in aggregation level between top-down and bottom-up saving calculations becomes very small. For instance, top-down diffusion indicators on solar water heaters may show the same aggregation level as bottom-up analysis of subsidy schemes for solar heaters.
4.5 System boundaries
The system boundary defines the object of assessment arid the calculated energy savings. In this European Standard, the system boundary is restricted to energy use by end-users, ranging from a large group (e.g. a sector) to a specific element (e.g. washing machines).
Although end-user actions can only be camed out inside the system boundary, if those actions result in electricity savings, there will usually be extra savings in the power supply system outside the boundary. These extra savings result from lower demand, leading to lower conversion and transmission losses. In order to capture these savings resulting from the end-user action, electricity savings may be optionally expressed in primary units, using a conversion factor (see also 5.3.3.2 and 6.2.2.6).
When calculating energy savings, the use of energy as raw materials. non-energy uses” are often excluded and only the savings related to a reduction in the energy used for purposes such as heat, light or power are considered,
NOTE Examples of non-energy uses are; petrochemical feedstocks, asphalt. lubncants.
In general, with top-down methods the system boundaries are determined by the statistical definition of the energy consumption figures used (see Annex A). For bottom-up methods. the system boundaries can vary considerably. ranging from almost all end-use when calculating the saving results of a comprehensive audit scheme, to the energy use of a single appliance type in households when calculating the savings of a subsidy scheme for that particular appliance.
5 Top-down saving calculations
5.1 Energy efficiency Indicators
5.1.1 General
Energy efficiency indicators relate energy consumption to a driver, preferably a physical output or the number of energy using systems. The change in the Indicator value over a period of time is used to calculate top-down energy savings. Subclauses 5.1.2 and 5.1.3 consider the applicability of indicators for top-down energy savings calculations.
5.1.2 Structure effects and disaggregation
At a high aggregation level the energy consumption trend can incorporate the effect of structural changes, thereby influencing the calculation of savings. Therefore, indicators should be corrected as far as possible for structural changes, in order to be used for the calculation of energy savings.
One way to eliminate the so-called structure effects due to structural changes is by disaggregation of activities. For instance, instead of analysing the ratio between energy consumption and drivers at the overall industry level, the analysis can be done at the level of cement or steel production. For households, separate analyses for space heating. hot water use and app4iances can be done, provided that reliable data is available. Indicators at a lower aggregation level are distorted less by structure effects in the calculation of energy savings.
The indicator can also be corrected for factors that mask actual energy savings. For instance, energy use for space heating may be corrected for the shift from room heating to central heating which will lead to extra energy consumption and, possibly, negative observed energy savings. By correcting for increased energy demand due to the shift to central heating the indicator will typically provide positive energy savings.
Due to restricted data availability it is not always possible to correct for factors that are considered structure effects. Statistically based indicators represent aggregated changes in consumption for groups of end-users, measuring either their total energy consumption or parts thereof. As well as applying at the national level. indicators can cover smaller geographical units, such as regions or cities, if statistical data is available.BS EN 16212-2012 pdf download.