WIT Press

A simplified method to select combined energy systems


Free (open access)


Volume 4 (2019), Issue 4



Page Range

311 - 319

Paper DOI



WIT Press


Sérgio Tadeu, Márcio Gonçalves, Nuno Simões & António Tadeu


The European Union aims to ensure that investment in energy efficiency measures is cost-effective. Thus,  the  minimum  energy  performance  requirements  of  buildings  must  follow  the  so-called cost-optimal levels. It is known that the impact of a specific measure on the energy performance is affected by others measures when implemented simultaneously, influencing its profitability. for this reason, the profitability of a given package of measures cannot result from the simple sum of potential benefits of each measure. consequently, to define a cost-optimal solution it is needed to run a great amount of combinations, implying an expensive computational effort. In order to help with the selection of the energy systems, this work proposes a simplified method for selecting heating and domestic hot water systems as a function of the following variables: initial investment, maintenance cost, energy needs and cost, and efficiency of energy systems. The proposed method is user-friendly and can assist various stakeholders: policy makers, energy experts, suppliers of products and services and building owners


Cost-optimal, energy retrofit, buildings, sustainability