Building and ductwork airtightness represent a key challenge towards very-low energy buildings and therefore towards the ambitious 2020 targets set in the recast of the energy performance of buildings directive. Results of the EU ASIEPI project (www.asiepi.eu, ) have shown that for most European climates, leaky envelopes and duct systems have a severe impact on the total energy use of the building, e.g., on the order of 10 kWh per m2 of floor area per year for the heating needs in a moderately cold region (2500 degree-days) and 0 to 5 kWh/m2/year for the ducts plus the additional fan energy use . Few European countries have taken steps to overcome this challenge, but whether good or bad, their experience is worth sharing to accelerate the market transformation needed on these issues .
Challenges for Nearly Zero-Energy Buildings
The EPBD recast  sets ambitious targets for year 2020 including the obligation for EU countries to implement regulations to increase the number of nearly zero-energy buildings (NZEB) in the next few years, and to generalize nearly zero-energy targets in new buildings and major renovations. Therefore, as illustrated in Figure 1:
- Because of the demonstrated energy impact of envelope and ductwork leakage, the implementation of the EPBD recast will for most climates automatically lead to specific attention to building airtightness (1);
- As a result of the increased attention for building airtightness, the need for appropriate, energy efficient, ventilation systems (2) will grow. Issues such as correct airflow rates, air quality, acoustics, draught, energy optimisation, economics, etc. will have to be handled. At present, we know that poor ventilation system performance is common in many European countries.
- Indirectly, the move towards nearly zero-energy buildings will lead to a greater need for ventilation systems, whether mechanical, natural or hybrid (3).
- In addition, there are tremendous challenges for the existing building stock. Although there will be in most countries more time for implementation and, in absolute terms, probably less severe targets, in addition to challenges similar to the new stock, there are specificities that considerably complexify the improvement of ventilation and airtightness.
What is TightVent Europe?
Since there are to a rather large extent similar challenges for the whole of Europe, the TightVent Europe platform aims at meeting the obvious need for a strong and concerted initiative to overcome these challenges. Indeed, sharing experience on practical issues such as specifications, design, execution, control, … and taking advantage of the lessons learnt from pioneering work will help improve airtightness quality while keeping in mind the need for adequate ventilation.
TightVent Europe has been initiated by INIVE EEIG (International Network for Information on Ventilation and Energy Performance) with the financial and technical support of the following founding partners: Building Performance Institute Europe, European Climate Foundation, Eurima, Lindab, Soudal, Tremco illbruck, and Wienerberger. Since November 2011, BlowerDoor GmbH and Retrotec have joined TightVent and thereby bring air leakage measurement expertise to the consortium (more information).
All partners are strongly interested in setting up a European wide collaboration and using the knowledge gathered through TightVent Europe for raising the awareness among all building professionals, for developing improved training courses, and for helping professionals in the development of quality management approaches. The partners also believe that there are areas that need further investigation (for example, the durability of seals, the integration of airtightness and ventilation issues in renovation projects, the variability of the energy impact with climate, etc.) where TightVent Europe can play a major role both in terms of research development and dissemination.
The target audience of the TightVent Europe activities is wide and ranges from the research community over designers, practitioners, supply industry to European, national and regional government policy makers. It includes:
- Policy makers
- Training centres (front-runners and associations/networks)
- Designers, engineers and builders, air leakage testers (front-runners and associations/networks)
- Research and technical centres
It is clear that awareness raising is key in the start up phase, whereas in time the emphasis should move to providing the appropriate support tools and getting the knowledge into the market.
 Directive 2010/31/EU of the European Parliament and of the Council of 19 May 2010 on the energy performance of buildings (recast). Official Journal of the European Union. 18 June 2010. L 153/13-34.
 Carrié, F.R., Andersson, J., and Wouters, P. 1999. Improving Ductwork – A Time for Tighter Air Distribution Systems, Report, EU Project SAVE-DUCT, Brussels 1999. ISBN 1902177104.
 Carrié, F.R., Rosenthal, B. 2008. An overview of national trends in envelope and ductwork airtightness, AIVC Information Paper VIP 29, August 2008, 6 pp.
 Carrié, F.R., Wouters, P., Heijmans, N., Rosenthal, B., Aurlien, T., Guyot, G., 2008. Ways to stimulate a market transformation of envelope airtightness. Analysis of on-going developments and success stories in 4 European countries, Web event, 12th December 2008
 Malmström, T.G., Andersson, J., Carrié, F.R., Wouters, P., and Demotte, C. 2002. Source Book for Efficient Ductwork in Europe. Report, EU Project SAVE-AIRWAYS, Contract n° 4.1031/Z/99-158. 2002.
 Publications and activities of the ASIEPI project. EU Project IEE-SAVE, Contract n° EIE/07/169/SI2.466278.
 Roulet, C.A., and Vandaele, L. 1991. Air Flow Patterns within Buildings Measurement Techniques. AIVC Technical Note 34, 284 pp. Available at www.aivc.org.
 Schild, P., Caillou, S., Millet, J-R., Mattsson, L. Å., Railio, J., Carrié, F.R. 2009. How to improve ductwork airtightness – Ongoing developments and success stories in Europe, Web event, 16th December 2009
 Schild, P.G. and Railio, J. 2011. Airtight ductwork – The Scandinavian success story. REHVA Journal, March 2011, pp. 26-29.
 Schild, P.G., and Mysen, M. 2009. Recommendations on Specific Fan Power and Fan System Efficiency, AIVC Technical Note 65, 42 pp. Available at www.aivc.org.
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