Abstract
Direct comparison of building energy performance levels between countries is usually not possible due to differences in climatic conditions, calculation methods, primary energy (PE) weighing factors and input data. This paper aims to analyse performance requirements and calculation methodology for residential Nearly Zero Energy Buildings (NZEBs) in Oceanic and Nordic climate zone countries according to European Commission (EC) recommended values, focusing on Denmark, Estonia, and Finland. Performance levels for each country are compared with European Commission (EC) recommended values (EU 2016/1318) using normalization and benchmarking through detailed computer simulations. The study is based on two representative buildings: a Danish single-family house and an Estonian apartment building, both designed to meet national NZEB requirements. The buildings were modelled using national and standardized (EN 16798–1:2019) methodologies, including country-specific climate and input data. The simulated performances were compared with EC threshold values, modified, and re-calculated to meet the NZEB PE targets of each country. To match the recommended energy performance, on-site renewable energy production using photovoltaic panels was increased or decreased accordingly. Results show that Estonian requirements for NZEB fulfil the EC NZEB recommendation. In the warmer, Oceanic climate zone it was however impossible to fulfil EC NZEB even with Estonian NZEB. This indicates that PE recommendations are too strict for colder Oceanic locations, represented in this paper by the Copenhagen climate.
Highlights
In heating dominated countries, the design of building envelope as well as ventilation and heating systems require higher attention in design practices to provide good indoor climate at low energy consumption [1]
Flexibility is needed to account for the impact of climatic conditions on heating and cooling needs and on the costeffectiveness of packages of energy efficiency and renewable energy sources measures” [4], meaning that each country is free to implement its own Nearly Zero-Energy Building (NZEB) levels and performance assessment methodology
This paper aims to analyse performance requirements and calculation methodology for residential NZEBs in Oceanic and Nordic, climate zone countries, focusing on Denmark, Estonia, and Finland
Summary
The energy efficiency requirements for buildings in Estonia are defined through the maximum allowed PE consumption and are set in the national regulation [7]. Heat losses from building envelope, thermal bridges, ventilation heat losses, system efficiency calculation method, and onsite electricity production are accounted for using specific pre-determined values given in detail in the regulation [11]. [dimensionless] and ܣ௧ is the net heated building area, [m2] The latter equation accounts for the total energy consumed by the building, which includes the consumed renewable energy, which is produced on-site. The Estonian building regulation gives an additional requirement for the buildings: maximum allowed PE use without accounting (subtracting) the onsite produced and consumed renewable energy from the building’s total energy use. The requirement is defined as “EPI B” value and is calculated according to the following equation (for a building with on-site renewable electricity production):. The fraction of locally produced electricity accounted in the PE calculations is 45% for single family buildings with ܣ௧ lower than 120 m2, 40% for detached houses with ܣ௧ between 120 m2 and 220 m2 including terraced houses, and 55% for apartment buildings
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