Bottom-up methods allow assessing or estimating energy savings induced by single measures and expressed in energy metering units; subsequently they get added to energy savings achieved by other specific measures (i.e. bottom up). Doing so, one has to avoid double counting of energy savings. Assessment or estimation of energy savings will be based on the following data and methods:

• Bills received from suppliers and retailers
• Energy sales figures
• Sales figures on equipment and systems sold
• End-use load data
• Estimates based on simple technical appraisal without inspection
• Estimates based on extended technical appraisal after inspection

The European Commission had announced to present a harmonized bottom-up model until early 2008, but did not do so. Thus, the energieeffizienz monitoringstelle presented a national bottom-up methodology and has discussed these methods in a participatory process with all Austrian stakeholders affected by the ESD.