A new method for assessing the grid interaction of a building's electricity consumption and generation is presented. It consists of the Grid Support Coefficients GSC(abs) and GSC(rei). GSC(abs) "weights" the electricity consumption profile with a time-resolved reference quantity which expresses the availability of electricity in the public grid (here: stock electricity price, residual load, cumulative energy consumption or fraction of wind and PV in the electricity mix). GSC(rel) relates GSC(abs) to the worst and best achievable values on a scale of -100 to 100 in order to increase the comparability of the results. The new evaluation method is applied to analyze the electricity consumption and/or production of 52 different energy supply systems in buildings, where detailed monitoring data are available. These examples include twelve heat pumps or chillers in office buildings, 38 heat pumps in residential buildings and two combined heat and power units (CHP) in multi-family buildings, all located in Germany. The in-depth analysis shows that the analyzed present-day buildings predominantly consume electricity at times with a low or average electricity availability. Optimal scheduling of all heat pumps could flatten the residual load significantly. In order to achieve this, thermal storages several times larger than the ones currently installed would be required. (C) 2015 Elsevier Ltd. All rights reserved.