Saving energy in new and old buildings

Energy-efficient buildings are important if the energy transition is to succeed While energy-efficient building became standard practice some time ago, the energy-efficient refurbishment of older

buildings is till lagging behind. dena provides a broad range of information services to support homeowners in the implementation of energy-efficient refurbishment.

Energy-efficient refurbishment

Energy transition for buildings

Energy-efficient refurbishment has many benefits for private homeowners. Moreover, increasing the energy efficiency of older buildings is a crucial factor in reaching the climate targets.

A building’s energy efficiency is a crucial factor in the construction of new builds or the refurbishment of older buildings. The German Energy Saving Ordinance (EnEV) and the Renewable Energies Heat Act (EEWärmeG) define many different energy standards that investors must adhere to in the construction of new builds.

Refurbishment offers significant potential

On the other hand, there are approximately 18 million existing residential buildings. Around three quarters of them were constructed before the First Thermal Insulation Ordinance was introduced in 1979. The majority of older buildings are unable to fulfil current energy standards. Efficiency potential is particularly high in these buildings, as the energy consumption in older buildings is frequently up to five times higher than in modern efficient houses.

This makes it particularly important to refurbish older buildings if the energy transition targets are to be reached. Above all, building owners must receive information and targeted funding in order to motivate them to carry out energy-efficient refurbishment. dena becomes involved at this point: among other things, it provides information on the benefits and opportunities of energy-efficient refurbishment.

The benefits of modern insulation, windows, heating and ventilation

Energy-efficiency measures achieve more than just reducing the energy costs. An efficiently heated house without draughty corners also provides a more pleasant living environment. The measures involved in energy-efficient refurbishment include the insulation of outside walls, the roof and the cellar, replacing windows (thermally insulated glass) and efficient heating systems for heating and hot water. It is also worth considering the use of renewable energies. Modern ventilation systems contribute to an improved room climate while filtering dust and pollen out of the air.

Competent advice on energy

Not all measures need to be carried out at once, of course. It is perfectly reasonable to complete refurbishments step by step. After all, there is no standard solution which can be applied to all buildings. Each house is unique and needs to be considered individually. Competent advice and good planning by an expert are important in order to guarantee the quality and cost effectiveness of the measures.

A detailed energy-efficiency analysis is conducted during qualified on-site advice on energy. A professional energy consultant reviews the requirements, recommends  suitable measures that suit the specific building, and provides an initial overview of eligible funding programmes. Qualified energy consultants are listed in the Energy Efficiency Expert database.

What the government does to support the energy transition in the building sector

The government subsidises energy-efficient building and refurbishment, for instance through KfW and the Federal Office for Economic Affairs and Export Control (BAFA).

Projects on the topic

Efficient House Database

dena created the efficient house database to showcase successful buildings. It allows owners to view energy-efficient buildings and obtain inspiration for their own construction project. Experts can draw attention to themselves with their efficient houses.


  • Project start: 2009
  • Around 1,300 registered efficient houses: 60 percent are refurbishments; 40 percent new buildings
  • Two thirds of the buildings correspond to  efficient house class 70 or better

Database of Energy Efficiency Experts for Government Funding Programmes

Investors can consult the Database of Energy Efficiency Experts for Government Funding Programmes to find experts in the area of energy-efficient building and refurbishment.


  • Project start: 2011
  • Funding bodies: Federal Ministry for Economic Affairs and Energy, KfW Group, BAFA
  • Number of listed experts: over 13,700
  • Number of network partners: 23
  • average queries per month: 56,000

Campaign “zukunft haus” (“future house”).

What was originally conceived of as a portal for informing and motivating owners in 2003 has now developed into an extensive campaign and a mainstay for stakeholders from the industry and politicians, as well as for the press.


  • Project start: 2003
  • Over 9,000 newsletter subscribers
  • Approx. 30,000 press reports with a total reach (circulation) of 1.2 billion
  • Turnover of more than 6.3 million information brochures
  • Free hotline: over 100,000 questions on energy efficiency in buildings
  • Website: (consumer) information tailored specifically for a particular target group; over 8 million visitors on central internet platform

Efficient House Pilot Project

The “Efficient House" pilot project by dena has focused on the energy-saving refurbishment of residential buildings since 2003, and of municipal buildings since 2007, with a special focus on schools, to create high standards of energy efficiency.


  • Project duration: 2003 - 2014
  • energy-saving refurbishment and assessment of over 400 residential and non-residential buildings in Germany
  • over 300,000 m2 of living space refurbished
  • CO2- annual reduction of over 3.7 million tonnes in residential buildings
  • average reduction in energy consumption of 80 percent during the pilot projects
  • 98 of the investors recommend energy-efficient refurbishment

"The Building Transition" Refurbishment Campaign

“The Building Transition” is the first nationwide, cross-sectoral refurbishment campaign. The campaign provides owners of detached and semi-detached houses with detailed information on all aspects of energy-efficient modernisation, and helps them locate qualified energy experts.


  • Campaign start: 2014
  • Number of partners: 24
  • Number of sponsors: 2
  • Number of regional cooperation partners: 16
  • Regional information events for homeowners: approx. 330
  • media reports triggered by the campaign: approx. 1,600
  • social medial reach: roughly 800,000 persons