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NZB2021 ‘Doors Open Days’ – sharing experiences from low energy buildings to meet nearly zero building standards by 2021 (NZB2021)

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The project implemented a "Doors Open Days" campaign in 10 EU-Countries. The campaign consisted of specific days during which both public and private actors could visit new and refurbished houses and public buildings. Through the Open Days, visitors got non-commercial hands-on-experience with nearly zero energy buildings. The objective of this campaign was to give hands-on-experience with nearly zero energy buildings to the general public and public authorities and to convince them that the Net Zero Energy Building (NZB) challenge can be met. This was achieved by the transfer of a best practices campaign from Belgium ‘Ecobouwers Opendeur’ to 9 new EU-countries. The Belgian forerunner campaign model was further developed and adapted to the regional contexts of the partners. A web platform was set up to acquire buildings for the ‘Open Days’, organise subscriptions and give both general and specific information on NZB’s and the EPBD requirements. Five international visits of carefully selected opinion makers to NZB’s were organised between countries. The programmes of the international visits were tailored according to the needs and challenges of the visiting teams.


  • 25,870 people took part in the two ‘Open Days’ campaigns of 2013 and 2014 visiting 1,440 exhibited buildings (houses and public buildings). 92,5% of the visitors were satisfied by the information heard on the Open Days. 76,5 % of the visitors said they would implement good practices for their home.
  • We estimate that the project will entail a carbon emission reduction of 46,800 ton and an energy saving of 217,120 MWh by 2020.
  • A 32-page European brochure in 8 languages for decision makers on good examples of promoting NZEBs has been printed; more than a million regional brochures announcing the Open Days have been distributed.
  • 899 different media reports on the Open Days were published. A web platform in 8 languages supporting the Open Days and providing detailed information on EPBD and NZB’s attracted up to 4,260,000 visitors.
  • The project disseminated the common European challenge and the way to meet the EPBD requirements: 10 mini-documentaries translated into 8 languages showing energy efficient solutions from all over Europe were viewed by more than 6000 people.
  • The experiences of 39 opinion makers on international sites visit to NZBs will be communicated to the broad public (19 contributions).
  • 50 European good examples were translated into 8 languages and presented on the web platform. 
  • The project could count on a broad platform of 82 stakeholder partners supporting the campaign and helping to communicate the projects' objectives and the Open Days.                                                                                                                                                    

Lessons learned

  • Exhibitors are proud and motivated to open up their houses. All partners shave made the best benefit of this group of active volunteers.
  • Personal contacts by phone and e-mail are by far the most efficient way to acquire exhibitors. The Passive House Associations have been valuable partners in most countries as well.
  • Public and private buildings ask for a different approach because the target groups are different.

Partners and coordinator

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Bond Beter Leefmilieu Vlaanderen vzw
Contact point: 
Benjamin Clarysse


Key documents

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In brief

01/08/2012 to 31/03/2015
Contract number: 

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