2026 ISDE Rules for Insulation, Triple Glazing and New Frames Explained
The 2026 ISDE rules for homeowners cover several insulation measures, including glazing, frames and insulated doors. Because requirements and rates can change, check the current RVO page before ordering work. The information below describes the current conditions relevant to a renovation plan.
ISDE is a contribution to qualifying work, not a replacement for a technical design or a complete renovation quotation. Check the proposed build-up, existing openings and installation sequence separately from the subsidy calculation.
\nWho can apply and when
For an owner-occupied dwelling, the home must have been built before 1 January 2019, or its building permit must have been applied for before 1 July 2018. A building or installation company must carry out the work first. The homeowner then submits the application within 24 months. Keep invoices, product information and evidence of the installed measures for the application.
Rates apply to the qualifying area under the scheme. They do not determine whether a particular opening, frame or product is suitable for the building, so obtain a project-specific assessment before installation.
\nGlazing and frames
For glass measures installed in 2025 or later, the qualifying area is at least 3 m² and at most 45 m². HR++ glass must have a Ug-value of no higher than 1.2 W/m²K. Triple glazing must have a Ug-value of no higher than 0.7 W/m²K and must be installed with new insulating frames. Vacuum glass must also have a Ug-value of no higher than 0.7 W/m²K.
In 2026, the former Uf limit for frames has been removed. Do not use an old Uf threshold when checking a 2026 application. The current rates are €25 per m² for HR++ or vacuum glass without new frames, and €111 per m² for triple glazing or vacuum glass with new frames. These are subsidy rates, not a quotation for the work.
Insulated doors and combined measures
An insulated door qualifies only when it is combined with a qualifying glass measure. The current rate is €25 per m² for a door with a Ud-value of no higher than 1.5 W/m²K, or €111 per m² for a door with a Ud-value of no higher than 1.0 W/m²K. Confirm the applicable conditions and documentation with RVO before placing an order.
The insulation amount doubles when the homeowner completes more than one qualifying insulation measure, or combines insulation with a heat pump, solar boiler or connection to a heat network within 24 months. Combining insulation only with ventilation does not double the insulation amount. Plan the timing and retain the evidence for each measure.
Check the existing area and the documents
ISDE insulation support concerns qualifying work to existing parts of the dwelling. New area created by an extension or a new dormer does not qualify as existing-area insulation under this scheme. Ask the installer to describe the measured area and the product specification clearly on the invoice.
- Check the current RVO conditions and rates before signing the order.
- Confirm the glass type, Ug-value, frame situation and qualifying area in writing.
- Keep the invoice, payment record, product details and installation evidence.
- Submit the application within 24 months and report only qualifying existing-area work.
A well-prepared application starts with a project-specific check of the dwelling, the proposed measure and the current RVO rules. Technical suitability, installation quality and subsidy eligibility are separate questions, so resolve each one before work begins.
