# NZEB Renovation Definition in a Heating Dominated Climate: Case Study of Poland
### General NZEB Definition for Buildings Undergoing Major Renovations  
Legal requirements for renovated building are described in the amended Energy Performance of Buildings Directive (EPBD) [8] and the Energy Efficiency Directive (EED) [9]. According to the EPBD (Article 9), Member States should also create policies in order to support the renovation of buildings to Nearly Zero Energy Building (NZEB) levels. So far the NZEB requirements established by the European Commission only deal with new buildings to be constructed from 2021 onwards (and from 2019 for buildings owned and occupied by the public estate). For the purpose of the EPBD, the following definition of NZEB is used: \"nearly zero-energy building' means a building that has a very high energy performance. The nearly zero or very low amount of energy required should be covered to a very significant extent by energy from renewable sources, including energy from renewable sources produced on-site or nearby.\" No obligatory requirements on this regard have been introduced for NZEB renovations. According to the EED [9], Article 4 Member States should establish long-term renovation strategies for mobilizing investment in the renovation of national building stocks. Article 5 of the EED sets a 3% annual renovation goal for buildings owned and occupied by central government. Additionally, the package \"Clean Energy for All Europeans\", released by the European Commission in November 2016, identifies the important role building renovation as a way of meeting the \"Energy Efficiency First\" principle.  
A major renovation is defined in the EPBD Directive [10] thus:'major renovation' indicates the renovation of a building where:  
1. the total cost of the renovation relating to the building envelope or the technical building systems is higher than 25% of the value of the building, excluding the value of the land upon which the building is situated; or
2. more than 25% of the surface of the building envelope undergoes renovation.  
The EC recommendation 2016/1318 [11] states that the refurbishment under the NZEB requirements should come along with consequent energy performance requirements.  
According to the COHERENO project statement [12] the general definition on NZEB renovation can have one or more of the following features:  
1. The energy performance of the building after renovation fulfils the NZEB requirements for new buildings as they are defined at level of the EU MS and regions; and/or
2. The primary energy consumption of the building after renovation is reduced by 75% as comparing to the pre-renovation status; and/or
3. Potentially an additional primary energy minimum requirement of not more than 50-60 kWh/ (m\({}^{2}\) year) energy consumption [13] for heating/cooling, domestic hot water, ventilation energy consumption of auxiliary building's systems; and Potentially an additional minimum requirement for renewable energy share (proposed to be at least 50% of the remaining energy demand of the building as it is suggested in [14] taking into account the NZEB definition from EPBD; and
* Potentially an additional minimum CO2 requirement of no more than 3 kg CO2/(m2 year) as it is suggested in [14] based on the needs to meet the long-term decarbonisation goals for residential and services sectors as resulted from the EU 2050 Roadmap for a low-carbon economy.  
Country-specific definitions take advantage of one or more of the listed requirements, as discussed in the next section.