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Carbon dioxide included in exhaled breath is often used as a tracer gas when estimation of ventilation aspect in buildings with occupants is performed. Carbon dioxide produced by occupants is the key for the estimation. JIS A 1406 and ASTM D6245-12 refer personal carbon dioxide production rate. However JIS does not take into account personal attribute like as body height and weight. On the other hand, ASTM does not take into account gender difference and based on average westerner adult data.

Adopting natural ventilation as a retrofit strategy for cooling, due to the low impact nature of the installation, is attractive due to the cooling potential of untreated outdoor air for large periods of the extended cooling season, particularly in northern climates. In line with this it is important to characterise the performance of natural ventilation components in low energy buildings in successfully transferring the cooling potential of outdoor air to the occupied zone.

The trend towards more nearly zero energy buildings and much more airtight buildings represents specific challenges for cooker hoods in residential buildings. 

There is a trend to perform more ventilation and air infiltration measurements in buildings, either to strengthen commissioning procedures or to learn from field data. This trend is stronger in nearly zero-energy buildings projects or programmes given the significant share of ventilation and infiltration losses on total building energy use.

An increasing number of countries (e.g. Czech Republic, Denmark, France, Germany, Ireland, Netherlands, Norway, Portugal, UK) include in their regulations either required or recommended minimum airtightness levels with or without mandatory testing. The number of tests performed on a voluntary basis is rapidly increasing either because of the energy penalty for untested buildings in the calculation method or due to the specific requirements of a given program. Furthermore, mandatory testing came gradually into force in the United Kingdom, Portugal, Denmark and France.

There exist several initiatives in different parts of the world to bring a stronger basis to ventilation requirements in relation to indoor air quality and health issues, for example, at LBNL in the US (Healthy efficient homes program), within the HealthVent project in Europe (2010-2012), at Health and Wellbeing project in Japan, Development of healthy and clean residential building standard in Korea (2008-2012) or within the French Observatory for Indoor Air Quality (running since 2001).

While it is generally accepted that ventilation-whether natural, mechanical or hybrid- is needed to provide acceptable indoor air quality and prevent building damage, there are debates about the actual performance of these systems and how deviations observed affect the overall building performance.

The current development in building energy efficiency towards nearly-zero energy buildings represents a number of new challenges to building design and construction. One of the major challenges is the increased need for cooling present in these highly insulated and airtight buildings, which is not only present in the summer period but also in the shoulder seasons and in offices even during occupied hours in winter. In most post-occupancy studies of high performance buildings in European countries elevated temperature levels is the most reported problem, especially in residences.

With the trend towards low-energy buildings, the importance and the interest for building air tightness is increasing. This implies an increasing number of tests, calling for increased attention to the quality of those tests including the way the test results are used to justify for programme or regulatory requirements. In turn, those tests put pressure on builders and craftsmen to reliably attain good airtightness levels. The project will review existing approaches and will analyse their pros and cons.