# NZEB Renovation Definition in a Heating Dominated Climate: Case Study of Poland
### Potential Indicators of the NZEB renovation Definition: Results of a Survey  
In order to create the NZEB renovation definition, it is crucial to determine its potential indicators. A survey was carried out among 17 building energy efficiency experts during 2017 on potential approaches and indicators that could be used for the NZEB definition of existing single-family houses in Poland. This number of informants was deliberately limited as it was especially important to address the question with experts having not only theoretical, but also practical, knowledge on the issue. The results of the survey were the starting point for the definition of NZEB renovation for single family buildings. Table 2 shows that 7 out of 13 indicators have scored 10 or more votes and are most relevant from the point of view of the definition. At the same time almost all indicators have received negative votes. In order to state which requirements are most important the number of \"No\" votes was subtracted for the \"Yes\" votes. The result (last Table 2 column) clearly shows that now only two indicators (bold + green) have scores higher than 10. The rest score below 8, down to -4. It shows that, in the opinion of the experts, only the index of energy needed for heating Q\({}_{\rm H}\) and energy efficiency of renovation improvement (i.e., the percentage reduction of the primary, non-renewable energy Q\({}_{\rm P}\) demand) are found to be highly important. What is interesting is the index of non-renewable, primary energy demand Q\({}_{\rm P}\) of the building after renovation is found to be less important, scoring 10 compared to 13 for energy needed for heating Q\({}_{\rm H}\). This is probably because of the comparison of energy consumption before and after renovation seems to be a more reliable methodology than the use of only one value after modernization. \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multirow{2}{*}{**Country**} & **Energy** & **Primary** & **Final** & & & **Thermal** & \\  & **Need for** & **Energy** & **Energy** & **CO\({}_{2}\)-** & **Summertime** & **Air** & **Transmittance** & **Systems** \\  & **Heating** & **Demand** & **Demand** & **Emissions** & **Comfort** & **Tightness** & **of Fabrics** & **Efficiency** \\  & **Q\({}_{\rm H}\)** & **Q\({}_{\rm P}\)** & **Q\({}_{\rm F}\)** & & & & **Elements** & **Elements** \\ \hline \multicolumn{2}{c}{Austria} & & & & & & & \\ \multicolumn{2}{c}{Belgium (Brussels)} & & & & & & & & \\ \multicolumn{2}{c}{Germany} & & & & & & & & \\ \multicolumn{2}{c}{Ireland} & & & & & & & & \\ \multicolumn{2}{c}{Slovenia} & & & & & & & & \\ \multicolumn{2}{c}{Portugal} & & & & & & & & \\ \multicolumn{2}{c}{Slovak Republic} & & & & & & & & \\ \multicolumn{2}{c}{Italy} & & & & & & & & \\ \multicolumn{2}{c}{France} & & & & & & & & \\ \multicolumn{2}{c}{Luxembourg} & & & & & & & \\ \multicolumn{2}{c}{Sweden} & & & & & & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Indicators of NZEB renovation definition used in EU countries [15; 16; 17; 18; 19; 20; 21; 22; 23; 24; 25; 26; 27; 28; 29]. According to the findings of the survey, the definition of NZEB renovation should only include two indicators:  
* The energy need for heating Q\({}_{\rm H}\), expressed in kWh/(m\({}^{2}\) year); and
* The percentage of reduction of primary non-renewable energy demand Q\({}_{\rm P}\), (including heating, ventilation, domestic hot water (DHW), and auxiliary systems for the case of residential buildings), determined in relation to the energy demand of building before renovation. According to the EC recommendation 2016/1318 [11] Q\({}_{\rm P}\) should also include energy used for cooling and lightning although this was deliberately excluded in the study. Most of the existing SFH do not use cooling and lighting as it is calculated in non-residential buildings.