## 6 Conclusions  
The current trend in the majority of Danish energy retrofit applications and projects is that the retrofit process is driven by a reactive decision making, which is always accompanied by the lack of a cost-effective and energy efficient planning and the absence of a systematic screening and selection among improvement measures. The largest share of efforts put in any retrofit project is at the pre-retrofit design and implementation stages, where calculations, assessment, and evaluations of the retrofit options are carried out. On the other hand, what matters for any owner or building user in a retrofit project is to have a building of improved performance and to attain the savings promised at the design stage. However, there is an overall lack of commissioning of retrofitted building performance at the post-retrofit stage to assess the building performance after being retrofitted and to ensure that the savings are attained. \begin{table}
\begin{tabular}{c c c c} \hline \hline  & **School A** & **School B** & **School C** \\ \hline Design estimated heating savings relative error (\%) & \(-\)62.1 & 13.0 & \(-\)135.3 \\ Dynamic simulated heating savings relative error (\%) & 26.5 & 11.3 & 14.1 \\ Design estimated electricity savings relative error (\%) & \(-\)155.7 & \(-\)165.0 & \(-\)87.2 \\ Dynamic simulated electricity savings relative error (\%) & \(-\)17.3 & \(-\)16.2 & \(-\)29.2 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Energy savings relative error for design estimations and dynamic simulations compared to actual collected data in the three schools. Figure 10: A comparison between design estimated, dynamic simulated and actual reported (**a**) heating and (**b**) electricity energy savings for the three schools. In this work, three public schools were considered for post-retrofit evaluation. The schools have undergone a deep energy retrofit process by September 2018, with multiple energy conservation and improvement measures implemented targeting the building envelope and different energy systems. After the completion of the retrofit projects, the three schools' energy performance was monitored for a year on the holistic level, mainly electricity and heating consumption profiles. When considering the data collected, an overall evaluation of the retrofit projects was carried out to assess the technical impacts. It was shown that the respective energy savings in the three schools are within the following ranges (9 to 16%) for heating and (2 to 15%) for electricity consumption. In addition, a comparison was performed between the attained energy savings and the promised ones at the retrofit design stage. The average performance gap between the expected and real numbers for the three schools was around 61% and 136% for annual heating and electricity savings, respectively. On the other hand, an alternative approach was proposed and evaluated. In this regard, a calibrated dynamic energy performance model for each school was developed in EnergyPlus and employed in order to simulate the technical impacts of implementing the retrofit measures. The results of comparing the dynamic simulations with the actual data were much more satisfactory, as compared to the case of the design numbers. The performance gap between the real and simulated savings in the three schools was in the range of 16-29% for electricity and 11-26% for heating consumption. Based on the results of this post-retrofit evaluation study in the schools, it is concluded that the dynamic model simulations of the retrofit processes allow for reducing the performance gap between the expected and the actual energy savings, when compared to tabulated static approaches, which was found to be inaccurate with a large margin of error. This study highlights the added value of using the alternative dynamic modelling and simulation approach in predicting the expected impacts of retrofit projects, as compared to the static design numbers.