14

**Figure 5.** Success factors of implementation of PED and To-PED projects.

PED Towards PED **Figure 6.** Challenges and barriers for implementation of PED and To-PED projects.

A big challenge for successful implementation processes are legislation and regulations—an in-depth analysis of the particular legal barriers (on either local, national, or European levels) therefore seems to be highly relevant in particular for PED. Within the +CityxChange project, possible strategies to enable regulatory mechanisms have been studied [13].

#### **4. Discussion and Conclusions**

The analysis presented in this report was performed on data included in the first update of the PED Booklet (February 2020). The aim of this study is to evaluate trends, features, successes, or critical factors that contribute to development of PED projects in Europe.

There is a broad variety of projects addressing energy transition. While only 29 of 61 projects are planning to implement PEDs, all of them provide valuable approaches and strategies regarding actions towards the energy transition in the urban context. Most of the projects classified as Towards PEDs seem to include the possibility to develop into PEDs in a further step. However, the actual feasibility of many project designs is not yet assessable since a large share of the projects listed are in planning or early implementation stages. The PED Reference Framework, with its focus on energy functions and overall sustainability goals, provides an open framework—the results of the comparison between PED projects and Towards PEDs projects indicate that differences between the two groups are not categorical and the main issues and challenges of project implementation are similar. This therefore supports the assumption that projects with no self-declared PED ambition may be further developed to achieve PED status according to the PED Reference Framework. A further operationalization of the PED Reference Framework [5], which is currently under development, aims at a common PED definition that includes local differences and diverse approaches.

For this analysis it must be considered that not all countries have equally contributed to the Booklet yet. The Booklet is based on voluntary contributions from individual PED-related projects. Therefore, the results do not allow any interpretation about the level of PED efforts across Europe in general.

Nevertheless, these preliminary results highlight the importance of national programs and strong R&I involvement in the replication of PED strategies, as for example in Norway where ZEN Research Center on Zero Emission and Neighborhoods in Smart Cities is helping the spreading of pilot projects in line with the PED framework. Future investigations on the impact of climatic zones on PED mainstreaming will be also considered.

Projects that declared a PED ambition are mainly in their planning or implementation stage (93% versus 57% of To-PED). This suggests that most of PED strategies are still to be tested and optimized and a regular update of the Booklet cases and data analysis is needed. Efforts will continue to extend the data base, improve data quality, and assess these projects to identify good practice as well as critical issues at further stages.

Most projects with PED ambitions (66%) combine newly built neighborhoods with existing neighborhoods. This result is in good agreement with the framework that suggests the combination of new urban development areas with existing buildings. Only 7% of PED are developed in an existing neighborhood. The high complexity of a PED project requires deep interventions to fit with the new paradigm and might inhibit ambitions to apply PED ambitions to existing structures. The need for dealing with complex ownership structures or technological limitations, for instance regarding PV-instalment, in connection with other aspects of revitalization, for example, building protections and preservation of cityscape, are just two factors that need to be mentioned. Regarding the implementation of a PED ambition, it does not seem to be a common strategy to count only on existing neighborhood. However, for most European cities, transformation of the existing building stock is a key aspect for achieving the energy transition. Therefore, exploring, integrating and applying PED solutions and approaches to the existing urban structure seems to be a crucial challenge in the long run. An 8-step process to develop a PED is proposed by the JRC report [14].

A significant amount of PED projects involves a highly mixed land use (39%) while only 18% of Towards PED projects do. Multifunctional urban structures can be seen as a basic requirement for successful PED implementation since they support efficient use of energy and more opportunities for energy flexibility. A high percentage of PED mentioned commercial and social use of the land. Multifunctionality is also a crucial requirement for embedding PED strategies in integrated urban planning strategies aiming at high quality of life and sustainable local development. This is in line with the framework definition that requires social and economic sustainability.

Another feature of PED is their highly mixed combination of energy typologies. Fifty percent of PED projects integrate four to five energy sources, whereas 60% of To-PED projects use two or three. This is a reasonable result given the fact that PED projects have the ambition to have an annual positive energy balance produced from renewable sources. To satisfy this ambitious aim, the combination of multiple energy typologies is key to exploit changing energies' availabilities, consumptions with different weather conditions, or with the alternation of day and night and seasons. Photovoltaics is used in 71% of PED projects versus 30% of To-PED projects. Photovoltaics is a mature and suitable technology for decentralized and renewable energy production. Its profitability is already reached in some European countries and increasing diffusion in building rooftop is expected [15]. This explains why a high percentage of PEDs rely on photovoltaics solar energy as local production of renewable energy.

Stakeholders, citizens involvement strategies, integrated technology, and political support are considered main success factors for PED development. A successful PED implementation requires collaboration with citizens and final users right from initial planning stages to avoid their opposition to the change of paradigm that a PED aims to do in terms of social, economic and energy sustainability. Political support is a necessary factor to activate national programs and new funding opportunities. Furthermore, the technical complexity of a PED is the reason why integrated technology was mentioned as a main feature to its success.

The main barrier for a PED is the access to adequate funding and business models (Figure 6). PEDs are more expensive than traditional projects and they require multiple sources of financing and advanced business models. Innovations and changes introduced by PED projects require ad hoc regulations and a dedicated legal framework. This explains why legislation and regulations, together with existing governance structures within city administrations and a lack of cross-sectoral approaches, are often mentioned as main reasons for inhibited implementation processes (Figure 6).

Considering the issues discussed, key areas of action to be further explored can be summarized as follows:


Based on these preliminary observations, the next activities will focus on the following aspects:


**Author Contributions:** Conceptualization: C.G. and S.B.; methodology: S.B. and C.G.; software: S.B., S.T., and C.G.; validation: S.B. and C.G.; formal analysis: S.B. and C.G.; investigation: S.B. and C.G.; resources, S.B. and C.G.; data curation, S.B. and S.T.; writing—original draft preparation, S.B.; writing—review and editing, C.G.; visualization, S.B.; supervision, C.G.; project administration, C.G.; funding acquisition, C.G. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding.

**Acknowledgments:** The authors would like to thank all project representatives who provided data on the projects presented in the PED Booklet, which served as basis for this analysis. Furthermore, the authors would also like to acknowledge the support of SET Plan Action 3.2 Italian National Delegate Paola Clerici and the work of the PED Program Management, specifically Margit Noll, Hans-Günther Schwarz, Robert Hinterberger, and Susanne Meyer, and the contributions of the PED Program Stakeholders Group, specifically EERA JPSC, regarding overall conceptualization of the PED Program and the elaboration of the PED Framework, which is a fundamental basis for the analysis of the data provided.

**Conflicts of Interest:** The authors declare no conflict of interest.

#### **References**


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