is Happi

Happi is a three-year EU-funded project that paves the way for the renewal of 3.300 leases around six different housing associations in Sonderborg. The project will include investigations of how to energy refurbish the homes best, what technologies and methods will be used, and how these major renovations will be funded, so they do not result in increased expenses for residents. 

By 2029, the Sonderborg area should be 100% carbon neutral. An important step in the major transformation is the energy renovations of both rental and private homes. Housing associations in Sonderborg, which accounts for approx. 20% of the total housing stock in the municipality, has already completed comprehensive energy renovations. Thus, housing associations managed to reduce their carbon footprint by 44%. The Happi project ensures the next step in the development, where 3.300 homes will be energy renovated for approx. 114 million DKK. The renovations will result in annual energy savings of electricity and heat of more than 11 million kWh and in a further reduction of the carbon emissions by 1.640 tons per year.

Happi is funded with 7.5 million DKK by the EU and behind the project are Sonderborg’s ProjectZero and the municipality’s six housing associations in a close collaboration with EUC Syd and Danish Energy Management & Esbensen. The aim of Happi is to prepare the comprehensive energy innovations in the 56 different apartments of the six housing associations.

It is a big task. Therefore, it is divided into several sub-processes and tracks. As an example, one of the tasks must investigate how the renovations can be funded, so the residents do not experience increased expenses. For example, one option could be through joint financing, borrowing, and purchasing across the six housing associations, in order to achieve better prices, interest rates, and terms. Another very important track is dialogue with and involvement of the tenants in the renovation process because it is them and their houses all of which the project is about. Happi must therefore find new, good methods to involve the citizens in the decisions regarding their homes’ energy consumption and indoor climate. A third track is focused on educating the technical staff in the housing associations which consists of approx. 150 persons in energy renovations and energy savings, so that they can ensure knowledge and sound energy-efficient decisions on a daily basis in each housing association. In addition, as part of the Happi project, and energy plan must be prepared for each of the six housing associations. The energy plans shall specifically point out how each individual housing association and department plan their renovations. It can be quite different. From the placement of exterior lightning, windows and doors to insulation of outer walls and installation of solar cells on the roof. The energy plans should also point to efforts on good energy behavior in the housing associations. However, regardless of the effort, the purpose is the same: To optimize energy in the housing associations and thereby both take care of the environment and lower the heat bill as well as the total expenses in the association.

When the Happi project has been completed in 2021, it will not only mean that 3.300 rental apartments in Sonderborg are either fully occupied with or fully finished with energy renovations. It will also mean that valuable knowledge and experience has been gained which can be used in planning energy renovations of housing associations in Denmark and the rest of Europe. All knowledge and experience will be collected and documented systematically and can be followed closely on this page. 

Preparations of energy renovations in 3.300 rental homes across six different housing associations through innovative financing/funding methods and involvement of residents. 


The Consortium in the Happi projects consists of 9 partners from the Sonderborg area. All six housing associations in the municipality of Sonderborg are engaged in the project. Additionally, EUC Syd, Danish Energy Management and ProjectZero as well.