So far, there is no clear definition of nZEB renovation. Therefore, in order to identify market actors and map the ‘front-runners’ that implement nZEB renovation for the housing sector in the target countries, a methodology should be elaborated.

To this end, the present study developed a set of harmonised criteria to track nZEB renovation – comprehensive and consistent enough to deal with all national approaches and existing definitions.

Based on these criteria, project partners will compile a list of existing nZEB renovations and subsequently will gather the relevant market actors within other project’s activities.

The set of criteria is directly linked to existing evaluation instruments (such as energy performance certificates, voluntary standards for low-energy buildings etc.) and thus, is aimed to become a practical tool for identifying nZEB renovation on each given market.

The report proposes a potential definition of nZEB renovation, which should have one or more of the following characteristics:
1. The energy performance of the building after renovation fulfills the nZEB requirements for new buildings as they are defined at level of the EU MS and regions or/and
2. The primary energy consumption of the building after renovation is reduced by 75% as comparing to the pre-renovation status or/and
3. Potentially an additional primary energy minimum requirement of not more than 50-60kWh/m²/yr energy consumption (GBPN, 2013) for heating/cooling, domestic hot water, ventilation energy consumption of auxiliary building’s systems and
4. 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 (BPIE, 2011) taking into account the nZEB definition from EPBD and
5. Potentially an additional minimum CO₂ requirement of no more than 3kg CO₂/m²/yr as it is suggested in (BPIE, 2011) 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.

Nevertheless, this definition for nZEB renovation seems to be more ambitious than most declared national nZEB approaches for new buildings.

The goal of the COHERENO project being to identify market actors that are currently undertaking nZEB renovations and enhance their collaboration, the criteria used to track these renovations should be open enough to identify not only few exemplary projects, but also a wider range of projects delivering consistent energy savings, that may not reach the highest possible levels but are close and can be improved.