What does “nearly zero energy building” (NZEB) mean?

An NZEB building is a highly energy-efficient building with very low energy requirements (near zero, in fact) and covered to a significant extent by renewable sources. In practice, these are buildings constructed or renovated in such a way as to minimize heat loss, use very efficient technological systems, and produce some of the energy they consume on-site. The result is that the primary energy consumption of an NZEB is extremely low compared to a conventional building.

This concept was introduced at the regulatory level by the 2010 European EPBD directives and implemented in Italy: from 2019 all new public buildings must be NZEB, and from 2021 the rule applies to any new constructionss.camcom.it. Major renovations of existing buildings should also tend to the NZEB standard. In Sardinia, the region has implemented these obligations through regional energy regulations and CAM (Minimum Environmental Criteria) for public buildings.

But what are the parameters for defining an NZEB? In summary:

• High-performance envelope: high thermal insulation (walls, roof, floors), high-performance fixtures, elimination of thermal bridges. NZEB building requires little energy for heating and cooling because it retains indoor temperature well.

• Efficient systems: heat pump air conditioning systems, mechanical ventilation with heat recovery, LED lighting and automatic control. The few remaining consumptions are met with state-of-the-art equipment.

• On-site renewable sources: installation of photovoltaic, solar thermal, mini-wind, or other renewable systems to produce electricity and heat on-site. Ideally, an NZEB produces almost all the energy it consumes on an annual basis (it is not required to be off-grid or totally self-sufficient, but very close).

• Control and monitoring: smart devices to optimize consumption, smart meters, building management system. This ensures that the building functions as planned in the design phase.

In quantitative terms, the national decree defines very low thresholds of non-renewable primary energy requirements for NZEBs, differentiated by climate zone. Sardinia is in temperate climate zones (B, C, D depending on location): here an NZEB will have a very low energy performance index, e.g. <15-30 kWh/m²year for heating (indicative values). Simply put, an NZEB building consumes up to 80-90% less energy than a traditional building from the 1980s.

Why NZEBs are the future of public housing (including in Sardinia)

Near-zero energy buildings represent the future for several reasons, and this is particularly true for Sardinian public buildings:

• Climate regulations and targets: as mentioned, the law already requires new public buildings to be NZEB. In addition, Europe is pushing for zero-emission buildings by 2050. This means that even for existing PA buildings there will be progressive regulatory pressure to upgrade them to NZEB. By adapting now, you can keep up with future mandatory standards.

• Economic savings in the long run: an NZEB has minimal energy consumption, so heating, cooling and electricity bills are very low. This is crucial for Sardinian municipalities, which often have limited budgets: think of how many public resources would be freed up if every school or municipality had nearly zero energy costs. The initial investment to implement an NZEB is paid back over the years by the savings achieved. For example, the municipality of Bottidda estimates a 96% reduction in CO₂ emissions and proportionally in consumption by turning the town hall and library into NZEBlanuovasardegna.it. Less operating expenses mean more funds for other citizen services.

• Virtuous example and awareness raising: NZEB public buildings become showcases of sustainability. An NZEB elementary school in a town in Sardinia is not only comfortable for children, but also educates new generations about the importance of energy conservation. The public also has a duty to set a good example for the private sector: municipalities that renovate historic buildings to NZEB standards show that it is possible to combine architectural tradition and technological innovation.

• Comfort and room quality: we often focus on energy numbers, but an immediate benefit of NZEBs is the huge improvement in indoor comfort. More stable temperatures, no drafts, cleaner air thanks to the VMC, optimized natural lighting: these are all aspects that make it pleasant and healthy to be inside an NZEB building, whether it is a school, a hospital or a municipal office. This positively impacts the productivity, learning and general well-being of the occupants.

• Adapting to the Sardinian climate: Sardinia experiences very hot summers and mild but wet winters. NZEBs, with their insulation and efficient systems, are climate resilient: they stay cool in summer (without having to spend a fortune on air conditioning) and warm in winter with little energy. They can also incorporate rainwater harvesting systems, green roofs, and natural shading, helping to mitigate extreme weather effects. In rural areas or smaller islands, near-zero buildings combined with renewables and storage can ensure continuity of services even in the event of blackouts or emergencies, increasing local energy autonomy.

Ultimately, focusing on NZEB in public building means reducing costs, improving services and hitting environmental targets. It is a strategic choice that every enlightened administration should adopt. It is no coincidence that many funding calls (such as ERDF or PNRR funds for school construction) give award scores to projects that achieve the NZEB standardqualenergia.co.ukqualenergia.it, precisely to steer investment in that direction.

Examples of public NZEBs in Sardinia

Although the concept is relatively new, we are beginning to see the first concrete examples of NZEB or quasi-NZEB public buildings in Sardinia:

• “Azuni” Primary School in Sorso: Thanks to the funding obtained, this school will be transformed into NZEB by 2026. As described in other articles, thermal insulation, thermally insulated window frames, 100 kW photovoltaic panels and eliminated fossil fuels will be implemented, making the building virtually self-sufficient for most of its energy needsunionesarda.co.uk.. It is one of the first examples of an NZEB school in northern Sardinia and may serve as a pilot project for other similar realities.

• Bottidda Town Hall and Library: The small municipality of Bottidda (SS) is upgrading the town hall and other municipal buildings by explicitly aiming for NZEB energy classlanuovasardegna.it. With an integrated €815,000 project, as seen, it will install insulation, photovoltaics+storage, heat pumps, LEDs and more. Once completed, Bottidda’s town hall will achieve the highest energy class (A4/NZEB) and boast a CO₂ emission reduced by 96%.lanuovasardegna.co.uklanuovasardegna.it. This is a virtuous example of how even a very small town can become a trailblazer in energy innovation.

• Newly constructed buildings: Some newly constructed public buildings in Sardinia are already NZEB by legal obligation. For example, the Municipality of Cagliari inaugurated a few years ago a new kindergarten designed with NZEB criteria (advanced insulation, geothermal system, integrated photovoltaics). Even in the health sector, new hospital facilities or wards are designed NZEB: think of the project (still in the early stages) of the new Sassari Hospital, which is to be nearly zero energy with state-of-the-art plant solutions.

• NRP projects: Several NRP-funded projects in Sardinia aim for deep renovations of school buildings with a jump of 2 energy classes or more, which will actually bring them close to the NZEB standard. For example, the 32 million notice for Sardinian schools requires an improvement of at least two classes and rewards consumption that is 20 percent lower than the normative NZEB requirementqualenergia.co.uk.. This means that many schools renovated with the NRP will in fact be NZEB or close to it (80% lower consumption than pre-intervention, etc.).

• Other examples: The municipality of Bottidda mentioned that it will create an energy community after making public buildings NZEBlanuovasardegna.it, also involving private individuals. Small towns such as Bottidda, Bono, Berchidda, Borutta (all B- starts with B curiously enough!) are also investing in similar projects. In southern Sardinia, the municipality of Serri completed the NZEB redevelopment of the municipal house a few years ago with the help of regional funds and CT2.0 (less well known, but a case study often cited at conferences). In short, from the north to the south of the island, NZEB projects are starting to pop up.

It is worth noting that an existing building can become NZEB through integrated upgrading. It is not always necessary to build from scratch; on the contrary, it is a great challenge (won in cases like Bottidda and Sorso) to demonstrate that even buildings from the 1960s-70s can, with the right interventions, achieve near-zero performance. This “energy regeneration” of Sardinia’s public heritage is a long but necessary path.

The town hall of Bottidda (SS) undergoing upgrading to become NZEBlanuovasardegna.itlanuovasardegna.it. Coat, thermal break windows, photovoltaics with storage, heat pumps and smart management systems will be installed, reducing CO₂ emissions by 96%.lanuovasardegna.it.

How Sardinian municipalities can facilitate the transition to NZEB

To accelerate the NZEB future, Sardinian municipalities and public agencies can adopt some strategies:

• Energy planning: include NZEB targets in their planning tools (SEAPs/SEAPs, three-year public works plans, etc.). For example, stipulate that every new municipal school or gymnasium should be NZEB, or that by 2030 50 percent of existing municipal buildings will be upgraded to Class A/NZEB.

• Training and outreach: make technicians, administrators and citizens aware of the benefits of NZEBs. Organize local conferences, take students to visit working NZEB buildings to experience the difference firsthand (e.g., when the school in Sorso is ready, it could become a destination for educational visits).

• Leverage incentives and partnerships: use all available funds (Conto Termico 3.0, POR FESR funds, PNRR, etc.) to finance the interventions needed to achieve NZEB standards. As we have seen, incentives cover much of the cost if projects are well designed. In parallel, consider public-private partnerships: ESCos performing the work in exchange for a share of the savings (energy performance contracts), energy companies willing to invest in public buildings. The Sassari-ENGIE case is an example of how a large municipality can move in partnership to decarbonize many buildingsinfobuildenergia.itinfobuildenergia.it.

• Design well and integrate technologies: a municipality should rely on experienced NZEB designers to maximize outcome and funding. Multidisciplinary skills are often needed (construction + facilities + renewables). In Sardinia we have excellence in the field (engineers and architects who have already designed NZEB in Mediterranean contexts). Involving them means having more effective projects. Also, think in a system perspective: an efficient NZEB with excess photovoltaics can power charging stations for municipal electric vehicles, creating synergy between sectors (building+mobility).

• Monitor and optimize: once an NZEB is implemented, the work does not end. Consumption and performance must be monitored. By installing monitoring platforms and actively managing buildings, anomalies can be detected and settings corrected to ensure that the building remains “near zero” indeed. Some Sardinian provinces (e.g., the province of Nuoro) have set up centralized monitoring systems for high schools to monitor consumption and improve managementprovince.nuoro.it.

Conclusion and call to action

NZEBs are no longer a futuristic concept, but an increasingly concrete reality even in Sardinia. They represent the inevitable future of public buildings: buildings that consume very little energy, respect the environment and save public money. Investing today to transform schools, offices and hospitals into nearly zero-energy buildings means preparing for a better tomorrow, aligned with climate goals and beneficial to local communities.

Sardinian municipalities and entities have a momentous opportunity ahead of them, backed by regulations and funding. The path to NZEB may seem complex, but with the right assistance it becomes achievable step by step. Twin Plus is ready to support Sardinia’s administrations in this transition: from the initial energy diagnosis to integrated envelope-plant design, to fundraising and post-intervention monitoring. We have the experience to turn your buildings into NZEB excellences, as demonstrated by our projects on the ground. Contact us to discuss your ideas: together we can define a roadmap to make your municipality a model of sustainability, combining technological innovation and enhancement of the local building stock. The NZEB future in Sardinia starts today, with the courageous and forward-looking choices of those who administer the present.