Abstract
In the member states of the European Union (EU), nearly-Zero Energy Buildings (nZEB) are becoming mandatory building practice in 2021. It is stated, that nZEB should be cost-optimal and the energy performance levels should be re-defined after every five years. We conducted cost-optimality analyses for two detached houses, one terraced house and one apartment building in Estonia. The analysis consisted on actual construction cost data collection based on bids of variable solutions for building envelope, air tightness, windows, heat supply systems and local renewable energy production options. For energy performance analysis we used dynamic simulation software IDA-ICE. To assess cost-effectiveness, we used Net Present Value (NPV) calculations with the assessment period of 30 years. The results for cost-optimal energy performance level for detached house with heated space of ~100 m2 was 79 kWh/(m2 a), for the larger house (~200 m2) 87 kWh/(m2 a), for terraced house with heated space of ~600 m2 71 kWh/(m2 a) and for the apartment building 103 kWh/(m2 a) of primary energy including all energy use with domestic appliances. Thus, the decrease in cost-optimal level in a five-year period was ~60% for the detached house and ~40% for the apartment building, corresponding to a shift in two EPC classes.
Highlights
In the European Union, Energy Performance of Buildings Directive 2010/31/EU (EPBD) [1] obligates Member States (MS) to assure that minimum energy performance requirements for buildings are set to achieve cost‐optimal levels
That MS should take necessary measures to ensure that minimum requirements for energy performance are set for building elements that have a significant impact on the energy performance of the building when they are replaced or retrofitted, with a view to achieving cost‐optimal levels
As two new building categories were implemented in the building regulation, cost-optimal levels were calculated for small detached house and terraced building
Summary
In the European Union, Energy Performance of Buildings Directive 2010/31/EU (EPBD) [1] obligates Member States (MS) to assure that minimum energy performance requirements for buildings are set to achieve cost‐optimal levels. The cost‐optimal level is defined as “the energy performance level which leads to the lowest cost during the estimated economic lifecycle” [1] from two different perspectives: financial (looking at the investment itself at the building level) and macro-economic (looking at the costs and benefits of energy efficiency for society as a whole). It is stated, that MS should take necessary measures to ensure that minimum requirements for energy performance are set for building elements that have a significant impact on the energy performance of the building when they are replaced or retrofitted, with a view to achieving cost‐optimal levels. The analysis needs to include best available technical solutions and enable the assessment of nZEB performance levels and cost implications with very little extra effort [3]
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