4 - Airtightness

Stimulation of good building and ductwork airtightness through EPBD

Building and ductwork leakage are detrimental to energy conservation, comfort, hygiene, and building damage
Good envelope and ductwork airtightness allows one to better control of the ventilation airflow rates. Therefore, it makes it possible to minimize energy use while maintaining a good indoor environment. To provide a rough idea, studies report that envelope leakage can increase the heating needs by 5 to 20 kWh/m²/year in a moderate climate (2500 to 3000 degree-days) given today’s levels of airtightness. Regarding ductwork, the SAVE-DUCT project has shown on a sample of 42 systems in Belgium and France that 20% of the air flowing through these systems was leaking out of the ducts.

Because of the large energy impacts of envelope and ductwork leakage, many low-energy labels (PassivHaus, Minergie-P, Effinergie, etc.) include specific requirements on these aspects.

Where are the leaks ?
Envelope leaks are typically located as described in the figure below. Leakage air passages can be easily identified by depressurising the building with a fan and using an infra-red camera. The fan (de)pressurisation also allows one to quantify the leakage according to the European standard EN 13829.

Ductwork leakage are typically located at connections with duct components, air handling units, and air terminal devices. These are more difficult to identify on site as ducts are often hidden in areas that are difficult to access (technical shafts, drop ceilings, etc.).

How are envelope and ductwork airtightness addressed in the regulations of the member states ?
Airtightness issues are tackled very differently in the EPBD implementations by the member states. For instance, the UK has chosen to set a minimum envelope airtightness requirement and to require compulsory testing for some buildings. In many other states, there are no minimum requirements but default values for airtightness are used in the EP calculation. In this last option, the significance of the penalty varies widely between the states and better airtightness can only be used in case test results are available.

Objective of ASIEPI
The objective of ASIEPI is to give a clear picture to policy makers regarding the way better envelope and ductwork airtightness is stimulated in the member states, including indications - where available - on the impact of the measures taken to transform the market. The following questions will be addressed:

  • What are the different strategies implemented in the Member States?
  • What is the impact of envelope and ductwork leakage on the energy performance?
  • Which control measures are taken depending on building size or usage (if any)?
  • What is done in case of renovation?
  • How effective are those strategies?
  • How is training organized? What kinds of training schemes are available in Europe?
  • What kind of actions has been successful, including evolution of the regulation, support of pilot projects, training, research and development?
  • Which tools can be used to help owners, designers, builders, and craftsmen build tighter?
  • What kind of equipment for testing is available? For large buildings? For very airtight dwellings? Cost issues?
  • How to carry out measures in multi-unit complexes (e.g. apartments)? Which possibilities for costs optimisation?

Once collected, this information will be structured and synthesised to allow dissemination among policy makers as well as other key market actors. If appropriate, specific suggestions can be added (e.g. more cost-effective testing schemes and procedures).