Report Number




Energy Efficiency; Buildings; Energy Consumption


Achieving annual net zero energy use in homes has been demonstrated as feasible in dozens of monitored projects in the United States.[1] In particular, very low energy use homes in Europe have been proven within the Passivhaus approach.[2] Achieving 'nearly zero energy buildings' (NZEB) has also been established as a vital objective over the next decade within the European Union (EU) (Boermans et al., 2011). However, reaching this result at the lowest possible cost remains a key challenge around the world. Balancing renewable power generation with energy efficiency will be vital in Europe as anticipated by Voss, Musall and Lichtmeß.[4] We describe new energy optimization software, EnergyGauge: CostOpt developed to address this need. The model performs detailed hourly sequential simulations showing how to achieve very low or zero energy home designs at the lowest possible cost in a variety of climates. The model can be used either for optimization of new or existing homes, which often have very different costs for various envelope measures. We have adapted the model to run in European climates and demonstrate it here simulating existing homes in 31 representative locations. A key result of our investigation is that energy reductions of 70-100% are economically feasible for existing EU residences. Finally, we illustrate how exclusion of lighting and appliances results in sub-optimal solutions, particularly for electricity use which has a disproportionate impact on greenhouse gas emissions. The results have important implications for the NZEB target established by the EU.

Date Published



Published in: Proceedings of the 7th International Conference on Energy Efficiency in Domestic Appliances and Lighting

Local Subjects

Buildings - Energy Consumption; Buildings - Energy Efficiency


FSEC Energy Research Center® Collection



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