Step 1: Energy analysis and action planning

The first step is always to know the state of the building. A thorough energy diagnosis should be made: analyze historical consumption (utility bills), existing thermal insulation, efficiency of systems, critical issues (e.g., air infiltration, unevenly heated areas), and strengths. An energy technician will perform thermographic surveys, measurements, and calculations to define current energy needs and hypothesize improvement interventions.

The diagnosis will reveal the actions needed to bring the building up to the NZEB standard. Typically, at a minimum, combined interventions will be needed on the envelope (coat, fixtures) and systems (switch to heat pump, photovoltaics). Planning must be integrated: it is not enough, for example, to install solar panels if the building then dissipates heat; conversely, coat and fixtures reduce requirements but to get to near zero, renewable energy must also be produced. So the output of the diagnosis will be a package of coordinated interventions.

It is essential to estimate the costs and expected savings. This estimate will feed into a preliminary project that will be the basis for applying for funding. For example, let’s say that for the Ozieri Middle School, the diagnosis recommends: thermal coat (estimated cost €200k), replacement of windows and doors (€100k), new heat pump central heating plant (€80k), 50 kW photovoltaic system (€70k), LED lighting makeover (€50k). Total investment ~500,000 €. Calculated energy savings are 85% on thermal and 50% on electrical, bringing the building to NZEB class A4. With these figures, the municipality can move to the next step: seeking funds to cover the expense.

Step 2: Finding incentives (Conto Termico 3.0 and co-financing)

Once the plan of interventions toward NZEB has been defined, the municipality must identify funding channels. This is where the Conto Termico 3.0, which finances much of the work, comes into play:

• For municipalities ≤15,000 inhabitants, CT3.0 may cover 100% of eligible costs because the ultimate goal is an NZEB building (maximum incentivized intervention category)myenergy.co.uk.. In the hypothetical case of Ozieri (which is >15k ab, but suppose it was <15k), the €500k could come entirely from the GSE. If the municipality is larger, it will still get 65% (325k €) from the GSEmyenergy.co.uk..

• The Conto Termico also provides an additional contribution for the diagnosis and APE required for the project (100% for PA)biblus.acca.it, so initial design costs can also be reimbursed.

Often, however, given the scale of NZEB interventions, a mix of funds may be needed. For example:

• Regional POR ERDF calls: Sardinia periodically publishes notices for public building efficiency. Sorso and Bono got ~2.5M€ and ~2M€ respectively from such notices for their schoolsunionesarda.itunionesarda.it. These grants can be added to the Conto Termico. In the case of Sorso, in fact, 1.4M€ had been booked on CT2.0 and the rest from ERDF fundsunionesarda.it.

• PNRR funds: if the building is school, check funding from the Ministry of Education (mission 4). Many Sardinian municipalities have won PNRR school calls with amounts between 1 and 3 million for integral renovations targeting NZEB. For example, the Province of Sassari is upgrading some high schools with PNRR funds targeting sustainable buildings. A municipality can allocate the PNRR share to cover structural or earthquake-proof parts, and use the Conto Termico for the energy part (since they are not cumulative on the same cost, but can be separated by workings).

• Extra GSE subsidies: the Conto Termico 3.0 allows cumulability with other non-repayable subsidies up to 100%myenergy.co.uk.. This means that if, for example, a regional call for proposals finances 60% of expenses and CT3.0 40%, you can go up to 100%. Or, if CT3.0 already gives 100%, no more funds are needed.

• ESCo and project financing: in the absence of calls for tenders, a municipality can agree with an ESCo to carry out NZEB interventions. The ESCo advances the costs, collects the Conto Termico and a portion of the savings in utility bills for a certain period. This model (energy performance contract) has been used in projects such as Sassari smart cityinfobuildenergia.itinfobuildenergia.it. In small municipalities it is less common, but it is a viable way forward if other financing is not obtained.

In practice, step 2 culminates in the submission of applications: the application for Conto Termico reservation (attaching diagnosis, project and resolutions) and/or application to any regional/PNRR calls. Ideally, the CT reservation should be made close to the start of work, but a regional funding decree can be obtained in the meantime and then the CT added. Bottidda and Sorso demonstrate how to combine sources: Bottidda 500k ERDF + 315k CT2.0lanuovasardegna.it, Sorso 2.49M ERDF + 1.4M CTunionesarda.it. Both municipalities thus cover 100% of the costs. Your municipality can replicate these models.

Step 3: Coordinated execution of NZEB works.

Once the funds are secured,the work to transform the building into NZEB iscarried out. This phase typically takes 6-12 months (for an average-sized school). Some crucial tips:

• Contract the work to qualified firms: NZEB upgrading touches many aspects (construction, window and door fitters, plumbers, electricians, photovoltaic installers). It is good to do an integrated contract or well-coordinated lots. The firm (or RTI) must have experience in efficiency upgrading, to avoid misunderstandings (e.g., the roofer must connect with the person replacing the windows and doors, the electrician must know how to install columns and storage systems, etc.).

• Experienced construction management: appoint a construction manager with energy expertise, who will check the proper installation of insulation, the correct installation of heat pumps, the calibration of the VMC, etc. A small mistake (unresolved thermal bridges, poorly adjusted system) can jeopardize the achievement of the NZEB standard.

• Involve the school/office: if the building is a school, coordinate the construction site with the school leader, perhaps scheduling the most invasive work in the summer. Also, informing users (students, staff) about what is being done and why, makes them participate and more tolerant of any temporary inconvenience.

• Energy testing: in addition to standard technical testing, it is useful at the end of construction to perform an air tightness test (blower door test) and thermographic verification to ensure that the envelope is well insulated. These tests are not mandatory but strongly recommended to certify NZEB quality.

• Systems activation and training: when everything is installed, the systems need to be commissioned and adjusted. It is important that those who will then manage the building (the municipal maintenance man, the school manager) receive training on the new system: for example, how to properly set up air conditioning with heat pumps, use of smart thermostats, maintenance of VMC filters, etc. A poorly managed NZEB is likely to underperform.

During execution, the municipality can already start benefiting from the Conto Termico advance payments (if booked): upon reaching certain SAL (work progress status), it can receive the scheduled installments from the GSEmyenergy.co.uk, which help pay the contractor’s SALs. For example, a 50% down payment on completed coat and fixtures, and balance upon completion of work.

Step 4: Final testing, monitoring and obtaining incentive

Once the work is completed, administrative closure is carried out:

• The building’spost-operam APE is prepared: this document will certify the new energy performance. If all has gone well, the building will now be class A3 or A4 (NZEB). In the case of Sorso, the Azuni school is expected to go from a very low energy class to an A4 NZEB due to the integrated interventionsunionesarda.co.uk.. Bottidda plans precisely to certify the town hall in class A4lanuovasardegna.it.

• All the final certifications and documents are collected: declarations of compliance of the systems, data sheets of PV panels, heat pumps, etc., certificates of disposal of old boilers, “after” intervention photos. These will be used for reporting to the GSE and other financing agencies.

• You submit the application for the Conto Termico balance (if there is a reservation) or the application for direct access (if you were not reserved) through PortalTermico, attaching invoices and documentsmyenergy.co.uk. The GSE verifies within a few months and then disburses the final contribution. In Sorso, for example, the municipality will receive the 1.4 million booked on CT2.0 from the GSE once the school is completed and accounted forunionesarda.co.uk.. With CT3.0 it will be similar, only with higher percentages for small entities.

• It is also possibly reported to the regional/ministerial entity if there has been other co-financing (by submitting test, APE and final project report).

Now the school or town hall is officially a functioning NZEB building. But the journey doesn’t end there: the full-scale monitoring phase begins. It is recommended to install tools to monitor actual consumption (many times this is required by the grant itself). That way the municipality can verify that the expected results are materializing: for example, comparing the new (drastically reduced) bills with the old ones, checking that the PV system is producing as estimated, that the automated systems are optimizing use.

Excellent feedback comes from users: teachers and pupils will report more comfortable environments, no more freezing cold or too hot classrooms. In City Hall, employees and citizens will notice a pleasant indoor climate and the disappearance of perhaps noisy old splits or electric heaters under desks. Such qualitative feedback is tangible evidence of the success of the NZEB transformation.

Real-world example: NZEB transformation of Sorso school.

We have mentioned Sorso several times because it is a real case in point. Let’s summarize it as a concrete example of NZEB transformation with incentives:

• Background situation: 1950s elementary school, large leakage, old systems, high annual consumption.

• Planning: municipality does NZEB diagnosis and design (envelope + systems + PV), cost ~3.9 million.

• Funding: gets 2.49 million from Sardinia ERDF call and books 1.4 million from Conto Termicounionesarda.itunionesarda.it. 100% covered.

• Work: started in 2023, includes coat, insulated roof, new window frames, 100 kW photovoltaic system, electric heat pumps, LED lighting, control systemsunionesarda.co.ukunionesarda.it. The building on completion will be NZEB: self-sufficient for a large part of needs thanks to PV, no more diesel or gas, improved comfort.

• End state: emissions reduced to near zero, energy bills virtually zero, historic building brought back to life and in line with 2025 standards. A feather in Sorso’s cap and a replicable model.

Similarly, your municipality can move from theory to practice: identify a candidate building (perhaps the most energy-intensive school or city hall if very inefficient), study how to make it NZEB, and follow the steps described by taking advantage of Conto Termico 3.0. In no time, you could inaugurate the first NZEB building in your area.

Conclusion and call to action

Turning an old school or town hall into an NZEB building in north-central Sardinia is no longer a pipe dream, but a reality within reach thanks to available incentives. We have seen that the process requires design and organizational effort, but the results amply repay the effort: near-zero utility bills, comfort for users and employees, a calling card of innovation and sustainability for the local community.

The Conto Termico 3.0, in particular, proves to be a decisive tool, financing up to 100 percent of the interventions in small municipalities and in any case a large part in larger municipalities. Combining it with other funds (regional, PNRR) can fully cover costs, as the cases of Sorso, Bottidda, Bono show. There are no more excuses for procrastination: every careful administration can and should consider NZEB upgrading of its building stock.

If you want to embark on this path of transformation in your municipality, Twin Plus is here to help you every step of the way. From initial diagnosis to executive design, from managing GSE incentive paperwork to construction management, we provide our experience to make NZEB successful. Contact us today for a free assessment of your building: we’ll tell you which interventions are cost-effective and how many incentives you can get. Together, we will turn your school or town hall into a model of energy efficiency that all of Sardinia can be proud of. The future of Sardinia’s public buildings is near zero-let’s start building it, one project at a time.