ductwork airtightness

The 2002 Energy Performance of Buildings Directive (EPBD) already indicated the potential importance of airtightness. With the 2010 EPBD recast and its ambitious 2020 targets, there is even more pressure on these aspects since for most European climates and countries, good envelope and ductwork airtightness levels are necessary to achieve nearly zero-energy buildings.

Various studies demonstrate a significant impact of ductwork leakage on the fan power consumption of ventilation systems. They have shown that the total energy used by fans can be reduced by 30-50% by improving the airtightness of the ductwork system. However, most of those studies focused on non-residential and multi-family buildings. This study focuses on single-family dwellings; specifically houses.  

This paper summarizes the most recent results of the French database of ductwork airtightness. This database was created in 2016. It is fed through measurements performed by qualified testers according to a national scheme regarding ductwork. Measurements are mainly performed in building applying for the Effinergie + label which requires class A for ductwork airtightness. Therefore, results discuss in this paper only apply to the buildings of the database and cannot be generalized to all new buildings in France.

A ductwork system that has limited air leakage, within defined limits, will ensure that the design characteristics of the VAC system are sustained. It will also ensure that energy and operational costs are maintained at optimal levels. 

Does the UK have any requirements regarding ventilation ductwork airtightness and how does the UK assess the installed performance of ducted mechanical ventilation systems? 

In France, the current regulation on the energy performance of buildings (RT 2012) does not require ductwork airtightness measurement when the default-value is used in the regulatory EP-calculation. Thus, measurements are only mandated when a specific airtightness level is used in EP-calculations or required by a voluntary certification scheme. In such case, measurements have to be performed according to a national scheme regarding ductwork airtightness measurement.

This paper proposes a methodology to assess fan energy use savings when improving ductwork airtightness. This methodology is based on new standard FprEN 16798-5-1:2016. Unlike the classical "cube law", it considers pressure drops at air terminal devices separately from the pressure drops in the rest of the system.

This paper gives a quick overview of the PRAXIBAT programme led by the French Agency for Energy and Environment to improve building professionals skills to achieve low- or nearly zero-energy buildings. It looks more specifically at the initiatives targeted at ventilation systems installers, with practice-oriented trainings in quasi-real conditions.