The AIVC 2023 workshop “Towards high quality, low-carbon ventilation in airtight buildings” organized in collaboration with NILIM and BRI of Japan was held on 18-19 May 2023 in Tokyo, Japan.

Participation was possible online and in person and the event drew over 100 participants – researchers, engineers & architects, industry representatives and international organizations from 16 countries.

The programme included 30 presentations grouped into 5 sessions: “Opening”, “IEA-EBC Annexes”, “Quality assurance of ventilation and heat recovery systems”, “Airtightness” & “Role of ventilation in infection control”.

The airtightness session at the workshop consisted of 7 presentations; it dealt with the promotion of airtightness, measurement issues and durability.

Towards a better airtightness.

Kiyoshi Hiwatashi (Taisei Corporation, JP) presented a “Proposal to promote airtightness in non-residential buildings in Japan”. While a few years ago lots of new residential buildings were being tested in Japan, there is now no requirement on tests at commissioning as it is estimated to be too complicated and costly compared to the energy savings associated to the Japan’s climate.

Valerie Leprince (Cerema, FR) presented trends in building and ductwork airtightness in different countries. This presentation was a summary of 7 Ventilation Information Papers published by the AIVC on national trends regarding airtightness. This presentation showed that in some countries almost all new (residential) buildings are now tested and pointed out a need for a reliable protocol for airtightness test that allows to perform the test in any condition and provide repeatable results.

Measurement issues

As stressed above, the reliability of test is necessary when airtightness tests become obligatory; however, ISO 9972 has several issues which were highlighted by Benedikt Koelsch (Cerema, FR) in his presentation “ISO 9972: An overview of difficulties with the current standard”. An on-going project in Cerema aims at improving the standard, making it more reliable, more repeatable and usable in any conditions including testing high and large buildings.

This specific subject of airtightness testing of large buildings was addressed in the presentations of Takashi Hasegawa (Eikan-Shoji, JP) “Airtightness of large buildings in Japan: current situation and a proposal for the future” and Iain Walker (LBNL, USA) “Airtightness testing of large buildings”.

Yuichi Takemasa (Kajima Technical Research Institute, JP) in his presentation “Measurement for exterior wall airtightness of high-rise buildings using stack effect/individual air conditioning and outdoor air entering through entrance doors” proposed a smart method to evaluate airtightness of high-rise buildings using natural stack force. The method consists of measuring the pressure difference between inside and outside in different heights (from bottom to top) and to open a door (with a known size) at the bottom and then close it to open one at the top. The shift of the pressure along the height of the building allows to calculate the leakage area (assuming an equal repartition of leakage on each floor).

Durability of building airtightness

Having requirements on new building airtightness only makes sense if the airtightness lasts in time. Valérie Leprince (Cerema, FR) presented the AIVC Technical note TN71: Durability of building airtightness to summarize studies performed on this subject both in laboratory and through on site measurements. Main conclusion was that in some cases airtightness deteriorates during the 2 first years after completion and then tends to stabilize (a deterioration of 20% is observed in average); nevertheless, reasons behind this deterioration are still under investigation.

The recordings and slides of the workshop are now available online here.