Calculation of initial and long-term heating costs for a nearly zero energy single-family building over 30 years

In practice, during the design stage of a building, only the initial costs are taken into account. These costs are also discussed with the customer and optimised with the aim of reducing them. It is the global costs over a longer period that show the real difference in the total expenses of living in a particular house, however. In this study, one newly built, nearly zero energy single-family building was studied in detail using a comparative global cost calculation methodology. The most popular insulation materials, construction types, types of windows, and types of floor construction in Latvia are included in the calculation of the costs. The results demonstrate that initially cheaper building means lower global costs during the analysed 30-year operating period due to initial costs are significantly higher than all other costs including energy costs, meaning that changes in construction type and building materials affect the initial cost more than the long-term energy costs. In parallel, different modern heating systems (including heat pumps) were included in the analysis to calculate and compare heating expenses. The results show that almost all the heating systems have the same energy costs regardless of fuel type for the 30-year period, however, the initial costs of these systems vary due to the different used technologies. Therefore, only the sum of the initial and long-term energy costs provides objective information about heating systems that are optimal in the long-term.