Biomass stoves and boilers bonus: what changes from August 3rd

From gas to pellets, goodbye to all incentives

The crackdown is one of the effects of the RED III directive which comes into force on 3 August 2026, which imposes new standards for renewables in buildings and more stringent requirements for the use of pellets and biomass in general, with the aim of reducing the impact of fine particles.

Until today, it worked like this: anyone who abandoned gas for a biomass generator, be it a boiler, a stove or a thermo fireplace, accessed the building bonuses or the Conto Termico contribution regardless of the starting point. The intervention fell within the scope of energy saving, both as a Home Bonus (or Renovations) and as an Ecobonus, therefore with a 50% deduction for the first home or 36% for the others. In the case of the Thermal Account, the virtual incentive percentage reached up to 65% of the total cost.

From August 3rd this approach changes radically. From now on the benefit survives only for those who replace a biomass system with another biomass system, therefore for those who already have a wood-burning stove or boiler and renew it, or for those who dispose of coal or diesel boilers.

In any case, for those who replace an LPG or natural gas generator, the door remains ajar but narrow: the incentive only applies if the new biomass appliance does not exceed 1 mg/Nm³ of primary particulate emissions, a very low value which effectively selects only the highest technological range appliances.

Squeeze on particulate emissions

In fact, with the directive the technical requirements to which the incentive remains linked also change. The biomass boilers must have five-star certification and a useful thermal efficiency of at least 87%, accompanied by a thermal storage of at least 20 dm³ for each kW of installed power.

Previously, the concession was also possible with a four-star certification and without the obligation of such a large storage tank. The Directive, however, aims to limit the combustion of materials that generate fine dust in urban areas, aligning community standards on air quality. Hence the new restrictions: the European orientation excludes public subsidies for the transition from a fossil fuel such as methane (which does not generate dust locally) to systems that increase the emission of particulate matter in the area.

When the incentive is saved

The legislation does not completely cancel bonuses for biomass, but drastically restricts their field of application only to specific efficiency interventions, i.e. those that provide for “type by type” replacement, or in the case of the transition from coal or diesel to biomass. To maintain access to benefits, the installation must meet the following requirements:

• 5 Star Certification: the new generator (stove or boiler) must have the highest environmental certification required by Ministerial Decree 186/2017;
• High thermal efficiency: the new models must guarantee an efficiency of no less than 87%;
• Minimum emissions: in cases of exemption linked to exceeding the gas, the production of primary particulate matter must remain less than 1 mg/Nm³.

Only certified pellets

Furthermore, the rules are also more restrictive in terms of the type of biomass that can be used to be entitled to benefits. In fact, it is not enough for the stove to be 5-star: the pellets burned must be certified in ENplus A1 quality class (the highest on the market), and the owner is obliged to keep the purchase invoices of the bags for fiscal and maintenance checks.

In the event of checks, in addition to the loss of the incentive, fines provided for by regional air regulations may be incurred. The objective of the restriction, on the other hand, is precisely to facilitate the transition from gas to electric and ensure better air quality.

Comparison table

A summary of the innovations brought by the RED III directive in force from 3 August 2026: