Installation of a new domestic hot water (DHW) production system

Changing your domestic hot water system

The use of domestic hot water varies from company to company. In some cases, it is used for sanitary installations and cooking, while in others, hot water is used for manufacturing or to assist in the production of materials or services. As a result, it is important to put in place the right solution, tailored to the specific situation.

Below is an approach that shows the stages and benefits of changing your domestic hot water (DHW) production system.

Definition of requirements for the domestic hot water system

Analysis of the current situation

• Determine the parameters of the installation, e.g. age, general condition, temperature level, consumption, and associated costs, etc.

• Define current domestic hot water consumption. The following elements provide a reliable assessment of the situation:
  • meter readings
  • monthly drinking water bill
  • consumer inventory (flow rate, temperature, schedule, etc.)
• Determination of the hot water demand of the different building functions for business operation
• Analysis of whether certain existing consumption points can be removed
• Assessment of whether the company produces waste heat that could be recovered for domestic hot water production
• Identification of any specific requirements for hot water supply (temperature level, quantity, etc.)
• Analysis of possible technical solutions and any that may be excluded

Identifying the domestic hot water system best suited to requirements

Decentralised or centralised system

• If consumption is low, check whether using cold water is not sufficient or encourage the installation of electric water heaters – e.g. for hand-washing facilities in an office building.
• Where consumption is high, a centralised solution is preferable. In this case, you need to define the power of the system (flow rate, temperature, schedule, etc.)

Definition of the solution

• Based on the requirements analysis, the solution is defined in collaboration with a qualified professional (heating installer) or a consulting engineering office.
• Take account of the existing heating system.
• It is important not to overlook the potential energy savings that can be made by recovering waste heat and combining the main heat production unit with solar thermal collectors.
• See the “Installation of a new heat production unit” measure.

Note: a permanent circulation pump must be incorporated into sanitary networks above a certain size.

Verification of the project with regard to operating permits

• When adapting existing facilities, and particularly when setting up new facilities, check the nomenclature for classified establishments.

Drafting specifications and requests for tenders

Subsidy application

Government subsidies

Fit 4 Sustainability programme

The Fit 4 Sustainability programme provides co-financing for environmental audits and action plans on one or more topics selected by the company (energy, GHG, waste, water, etc.).
Aid of up to 60%, 70% and 80%, depending on the size of the company, for the fees associated with carrying out an environmental study (energy audit and/or carbon footprint assessment) and a detailed, costed action plan to reduce its consumption/GHG emissions (medium- and long-term investments, ROI, etc.) – open to SMEs and large companies (except those that must carry out studies required by the environmental authorities, including mandatory energy audits)
For questions: Luxinnovation

SME Packages – Sustainability

• Financial Aid for small and medium-sized enterprises covering up to 70% of eligible costs for the implementation of a project aimed at reducing the environmental impact. The eligible project budget must be in a range from 3.000 € to 25.000 € excl. VAT.
• For more information:
  • Chambre des Métiers for craft companies
  • Chamber of Commerce for businesses in the non-craft sectors

Aid for environmental protection

The law of 8 December 2025 on the renewal of the aid scheme for environmental and climate protection provides for the granting of investment aid to SMEs and large companies established in Luxembourg, with an establishment authorisation, and carrying out projects that contribute to environmental or climate protection.

This aid is intended to support:

• Energy production from renewable sources
• Renewable hydrogen production
• High-efficiency cogeneration
• Storage (electricity, heat, biogas) under specific conditions

The following maximum rates apply:

Regardless of their size, companies can receive aid upon request if they meet the conditions described in Article 8 of this law, provided that the aid exceeds €50,000 for SMEs or €100,000 for large companies.
They may also participate in regular calls for projects, which will be announced below when they become available. When aid is granted through a competitive process, the aid rate may reach up to 100% of eligible costs.
The General Directorate – State Aid and Company Financing will verify the eligibility of applications.

• For support or questions regarding the process, please contact Luxinnovation.

SME aid scheme – Aid for miscellaneous investments

Subsidies for small and medium-sized businesses , up to 10 % or 20 % of the amount of miscellaneous investments aimed at promoting the modernisation and competitiveness of the Luxembourg economy.

• Verification of company eligibility and costs: Ministry of the Economy (Department for Support to SMEs)
• Any questions?
  • House of Entrepreneurship of the Chamber of Commerce
  • Chambre des Métiers (Chamber of Trade)

N.B. State subsidies cannot be combined for the same project.

Application for subsidies from electricity and natural gas suppliers

Since 2015, natural gas and electricity suppliers have been required to make energy savings for consumers under the obligation scheme. Since then, energy suppliers have been offering support and advice, as well as subsidy programmes for consumers to implement energy efficiency measures.

The following suppliers offer this service for companies:

• Enoprimes Enovos + SUDenergie
• SUDenergie
• Sudstroum

N.B. Energy supplier subsidies can be combined with any state subsidy for the same project.

After completion of the works

If the heat production unit is changed, the installation must be inspected by an official from the Chambre des Métiers

Inspection of all new heating installations running on diesel, solid fuel or gas by the Department for the Inspection and Approval of Buildings (SCRB) of the Chambre des Métiers.

Planning maintenance and periodic inspection of the installation