Renovating in Luxembourg: what order should the work be done in?

In Luxembourg, the order of an energy renovation is determined by looking at the home as a whole. An assessment, coordination between insulation and heating, and the stages of the Klimabonus scheme: useful pointers before starting work.

Replace the windows, insulate the walls or replace the boiler? In Luxembourg, the order of works depends on the condition of the home and on how its systems work together. An accredited energy adviser can draw up a renovation plan and help schedule the stages, while the Klimabonus 2026-2030 grants have criteria and deadlines that should be checked before work begins.

An energy renovation is not a checklist of works to be carried out in the same order in every home. An uncomfortable window may draw attention without being the factor that accounts for the greatest heating needs. And installing new equipment without examining the insulation and radiators can lead to an unsuitable choice. The first useful decision is therefore to look at the home as a whole.

Start with the home, not a fashionable measure

Feeling cold near a window is not enough to determine which intervention will have the greatest effect on consumption. Heat loss can occur through different parts of the building envelope — the roof, walls, windows or floors — and the extent varies from one building to another. Ventilation, airtightness and the heating system also matter in the assessment.

An article by Futura reports, drawing in particular on an Engie executive and data from the company’s simulators, that users do not always choose the measures that address their home’s priorities. It also cites an estimate attributed to Ademe, according to which windows account for 10 to 15% of heat loss, compared with up to 30% for the roof. These proportions are not an assessment of a home in Luxembourg: on their own, they cannot determine the order of works in any particular home.

The broader point is this: an estimated share of heat loss for a type of building does not tell you which intervention will be most appropriate in your own home. The condition of the existing insulation, the layout and the existing heating system all affect the decision. A coherent renovation aims to reduce the building’s energy needs while planning how air will be renewed and heat distributed.

In Luxembourg, an accredited adviser helps plan a renovation pathway

Klima-Agence describes a process in which an accredited energy adviser plays a central role when a project includes several measures. The adviser visits the home, draws up a renovation plan and then produces a list of the selected works. The companies’ quotes can be reviewed with the adviser before applying for preliminary approval. After the work, the process includes, among other things, a final report and an application to the Single Housing Aid Office for payment of the grants.

Requirements vary depending on the nature of the project. Klima-Agence’s page states that, for insulation measures undertaken separately, eligibility must be certified by an accredited energy adviser or an accredited tradesperson. For a plan covering several interventions, it specifies the involvement of an accredited adviser and describes the planning and monitoring stages. It is therefore useful to check which process applies to the planned works rather than assume that any quote or audit will be sufficient.

This approach is also useful in practice: it makes it possible to discuss how the works fit together before signing. If insulation reduces heat requirements, the heating capacity needed may change. If the windows are replaced or airtightness improves, air renewal must also be considered. The aim is not to automatically delay urgent work, but to avoid a standalone project making subsequent stages more complicated or costly.

Insulation and heating: decisions that are linked

Replacing a boiler with a heat pump is not a decision to be made solely on the basis of the grants available. The sizing and operation of the equipment depend in particular on the home’s needs and its heat distribution system. In a poorly insulated building, needs may remain high; radiators and the temperatures required must also be taken into account. This is why an overall assessment can help compare an immediate replacement with a scenario in which the building envelope is improved first.

This does not mean there is a universal rule requiring complete insulation before any changes are made to the heating. Technical constraints, the condition of a boiler and the possibility of carrying out the work in several phases vary from one home to another. The purpose of the assessment is precisely to define a suitable sequence rather than apply a general rule.

The performance of existing equipment also deserves attention. Futura’s article mentions maintenance of the heating circuit and the possible build-up of deposits in radiators. This is worth discussing with a professional if the system is not heating well; the article does not establish that it will guarantee savings or that it should be a priority for every household.

The 2026-2030 grants do not replace an assessment

According to information published by Klima-Agence, the Klimabonus scheme is changing for the 2026-2030 period. For applications for preliminary approval submitted by 30 June 2027, grants for renovation of the building envelope are temporarily increased by 15 to 20%. The grant for energy advice is also increased, until the same deadline, by 300 euros for a single-family house and 500 euros for a multi-family house.

For heat pumps installed in existing buildings, the page announces a temporary increase of 2,000 euros for installations ordered by 30 June 2027. However, this information is not enough to establish the amount to which a particular household would be entitled: the criteria, procedures and deadlines vary depending on the measure. Klima-Agence’s page recommends checking the applicable conditions and preparing the project before starting work.

Preliminary approval should not be confused with a grant that is automatically guaranteed. The stages described by Klima-Agence distinguish between project preparation, the application, carrying out the work in compliance with the requirements and payment of the grant. Before committing, households can consult the agency’s grants simulator and seek the free, independent advice presented on its website.

A useful first step

To prepare for an appointment, it is useful to gather the available information about the heating, insulation already installed, windows, bills and planned works. The aim is to give the adviser an overall picture, not to carry out an assessment yourself. Households considering several interventions can then ask how the work should be sequenced, which quotes need to be checked and when to apply for preliminary approval.

The right order is therefore not found on a bill or in a list of measures said to be priorities. It is determined by the home, its equipment and the rules governing grants in force. For Luxembourg residents, Klima-Agence’s resources provide a local starting point; advice or figures from a French scheme cannot serve as a national rule.