Towards Net-Positive Energy Urban Districts: A Pillar of the Energy Transition

In the current energy transition landscape, characterised by the dual requirements of accelerated decarbonisation and increased resilience to disruptions in the electricity system, the concept of positive energy districts (PEDs) is becoming increasingly relevant [1,2]. A PED is defined as an urban area or neighbourhood (group of dwellings) composed of buildings of various types, such as commercial or residential, which simultaneously implements demand management strategies, on-site renewable energy generation, and operational flexibility. As a result, it is able to achieve an annual balance of net-imported non-renewable primary energy, lower than the equivalent of the primary energy used, due to local production from renewable energy sources [3,4].

More specifically, the most widely used definition describes PEDs as ‘urban areas or groups of connected, energy-efficient and flexible buildings that produce near-zero net greenhouse gas emissions and actively manage surplus local or regional renewable energy production each year’ [3]. In their design, these districts are not conceived as energy islands isolated from the system but as smart nodes in the urban–regional energy system, capable of interacting with networks, transport, electric mobility, urban heating/cooling systems, and energy management ICTs [5].

In other words, it is about making the leap from a “zero-energy building” to a “neighbourhood” or “district” that produces more renewable energy than it consumes annually increasing the scale, synergy among buildings, shared infrastructure, storage, and smart management key elements. This approach involves a three-pronged strategy:

(1)

Intensive reduction in energy demand through increasing the efficiency of home appliances, enhancing building insulation, and optimising heating, ventilation, and air conditioning (HVAC) systems [5];

(2)

On-site renewable energy generation via the integration of solar photovoltaic, solar thermal, geothermal, heat recovery, biomass, etc., to cover residual demand [1];

(3)

Control, storage, and flexibility systems that allow for the adaptation of energy production, consumption, and export/import, optimising self-consumption and reducing the impact on central networks [4].

In this regard, the Joint Programming Initiative (JPI) Urban Europe programme (Positive Energy Districts and Neighbourhoods for Sustainable Urban Development) aimed to deploy and replicate 100 PEDs in Europe by 2025. A preliminary analysis of 61 European PED cases indicates that the concept is maturing, although it still faces technical, regulatory, and economic barriers [3].

The strategic role of PEDs is part of the logic of urban energy transformation: cities consume approximately two-thirds of the world’s energy and generate around 70% of CO₂ emissions [6]. Therefore, the scalability of the PED model is essential for achieving climate neutrality targets (e.g., by 2050 in Europe) and responding to the urgent need to decarbonise not only the electricity supply but also the heating/cooling, urban transport, and existing building sectors [7].

From an economic and resource perspective, PEDs offer several advantages:

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By generating local renewable energy surpluses and promoting district self-consumption, transport losses are reduced, and the overall system efficiency is improved [1].

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The intrinsic flexibility of these districts (through managed demand, storage, and integrated electric mobility) mitigates the impact of renewable variability and reduces the dependence on peak imports of energy from fossil sources [7].

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In terms of replicability, a neighbourhood or district that achieves a positive energy balance can serve as a demonstrator and accelerator of integrated solutions for other urban areas, leading to economies of scale and reduced techno-systemic risks [8].

Particularly in the transition scenario marked by the need to activate regulatory, financial, and organisational “hindrances” (bottlenecks), PEDs are established as urban innovation laboratories, where new business models, interaction with citizens, energy communities, and local governance are tested [9]. The fact that scientific initiatives such as IEA EBC-Annex 83 are dedicated to systematising definitions, methodologies, and tools for PEDs reinforces their relevance in the field of research and public policy [10].

Looking ahead, several factors shape their critical relevance: the growing electrification of consumption (vehicles, heat pumps, and air conditioning), the demand for emissions reductions in existing buildings (it is estimated that a high percentage of the housing stock in the European Union does not meet optimal energy efficiency standards), and the need to deploy distributed energy infrastructure without compromising the quality of urban life [1,11].

For these reasons, we prepared this Special Issue to serve as a guide, both documentary and procedural/design, to the success stories of positive energy districts, beginning with two reviews. In line with recent analyses by [12,13], international research emphasises that the success of positive energy districts depends on both technological factors and integrated governance and planning processes. While the first study identifies a framework of critical factors from the ideation phase to valorisation that includes coordination between actors, flexible planning, and citizen participation as keys to long-term sustainability, the second highlights the role of dynamic and renewable energy building envelopes in energy efficiency and distributed generation within PEDs. These advances reinforce the vision of PEDs as smart urban ecosystems, where technological and social integration is essential to achieving positive energy balances and climate resilience.

Next, a variety of topics and case studies are explored in the articles published in this Special Issue. In [14], the combination of different energy vectors in the context of multi-energy systems is presented as a crucial opportunity to reach CO₂ reduction goals. According to [15], the transformation of multi-story residences into zero-net-energy buildings is a challenge that can be successfully addressed through a holistic energy efficiency improvement plan. [16] remarks that nature-based solutions (NBSs) offer a promising framework for addressing urban environmental challenges while also enhancing social and economic resilience. [17] develop a techno-economic study, which addresses the pressing energy constraints in nations such as Bangladesh by proposing the implementation of photovoltaic (PV) microgrids. Hashemi and [18] study the importance of DC–DC converters for energy management systems in positive energy districts (PEDs), because they enable efficient conversion between different voltage levels and ease the integration of various renewable energy sources, energy storage systems, and loads. In [19] it is proposed a novel assessment framework for PEDs based on climate neutrality, which is aimed at bridging the gap between research-grade high-resolution analysis and practical policy-aligned application. Meanwhile, [20] conduct a case study focusing on the environmental, social, and economic benefits that PEDs offer. And [21] shows that combining PEDs and urban-industrial symbiosis (UIS) enables self-sufficient systems with near-zero emissions, thus providing a model for sustainable urban development.

In summary, positive energy districts are not only a promising experiment but also a structural vector for operationalising the urban energy transition. Their widespread implementation has a multiplier effect on efficiency, renewable generation, grid flexibility, and citizen participation. Addressing them with scientific rigour, integrated planning, and institutional support is essential to meeting the climate, energy, and sustainable urban development goals that mark this century.