Procedure to select combined heating and hot water systems: An expeditious cost optimality approach

The European Union has proposed a common methodology to identify energy-efficient measures with the minimum global cost throughout the lifecycle. It is known that the energy impact of a specific measure is influenced by other measures in the same package, which affect its profitability. For this reason, the cost-optimal package cannot be a simple combination of individual cost-optimal retrofitting measures. Thus, to define a cost optimal solution, the energy performance and the global cost of a large number of packages need to be calculated and analysed. To overcome the expensive computational effort of this type of study, this work proposes an expeditious procedure for selecting the optimal energy source for heating and domestic hot water (DHW) service generation as a function of the following variables: energy needs and costs, initial investment, primary energy conversion factors and efficiency of energy systems. The method was applied to a reference dwelling in the Portuguese building stock. With the expeditious cost optimality approach, once an energy system configuration has been determined, an estimation of the cost-optimal package can be established as the sum of the most profitable options for each element. (AU)