Abstract
The buildings’ energy performance requirements in Estonia are based on cost-optimality analysis according to the EPBD and pre-defined building performance simulation (BPS) input data from EN 16798-1:2019. Previous studies have shown that the real electricity use of office building tenants differs from the currently used input data in BPS in Estonia – less in total energy use, but more in the shape of the profiles. The aim of this work is to investigate what is the impact of these differences on the cost-optimal solutions, which are identified based on BPS and the self-consumption of the photovoltaic panel (PV) systems. This study describes the energy performance and construction cost analysis of a new office building in Tallinn, Estonia. BPS based on the EN 16798-1 and a model derived from measurements in a real building were conducted and cost-optimal building solutions identified. The variables were building envelope insulation thickness, air handling unit size and effectiveness, electrical lighting control principles and PV system nominal power. The calculated energy use of the building with the two different sets of input data differed significantly. However, the set of cost-optimal solutions identified with EN 16798-1:2019 input data had minor differences from the set of solutions identified with the more realistic model. The decrease of net present value over 20-year period for cost-optimal solution was 11-14 €/m2 compared to the designed building.The realistic office tenants’ electricity model increased the calculated self-consumption of the PV system from 95% to 100%.
Highlights
Building energy calculation have to correspond to the minimum requirements [1], [2] in Estonia
building performance simulation (BPS) based on the EN 16798-1 and a model derived from measurements in a real building were conducted and cost-optimal building solutions identified
The best primary energy (PE) difference and extra cost combination was for AHU size measure (Figure 6) as the PE difference was similar to the lighting control measure, but the extra cost was more than 25 times smaller
Summary
Building energy calculation have to correspond to the minimum requirements [1], [2] in Estonia. New buildings have to achieve NZEB level that has energy performance certificate (EPC) rate 100 kWh/m2y. These requirements as well European Parliament directives [3], [4] sets, that simultaneously achieving the energy efficiency in a building, there is a need to focus on cost-optimality. Energy efficiency should not be achieved if the cost-optimality suffers. The energy efficiency should be calculated accurately, so the building solutions will be cost-optimal in practice. Some studies [5], [6] shows that real electricity use in office buildings differs from the electricity use calculated by currently used input data in BPS
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