English

Air infiltration holds a central role in building energy consumption and is associated to several building physics phenomena. Air infiltration in buildings due to wind-induced pressure is a complex process, strongly influenced by the turbulent nature of wind. This extended summary highlights the findings of a series of studies with focus on unsteady wind and its impact on air exchangesin buildings. The focus is on wind gustiness and its relation to air infiltration under natural conditions.

The airtightness just after the end of a building phase is assumed to be relevant criteria for high energy performance. Testing on site the initial performance of the airtightness via the blower door test has become nowadays a common practice but generally implemented before the occupation of the building. But a lot of questions are still remaining targeting the sustainability of the performances.

Wind pressure and thermal forces are driving forces for pressure difference on the building envelope. In European and German standards infiltration is calculated using wind speed, temperature difference and wind pressure coefficients resulting from upstream and downstream flow on the building envelope. This long term measurements shall present measured pressure differences on the building envelope in comparison to those calculations

With lower air leakage in modern homes, ventilation of homes has become more important than ever before. It seems however that we are getting it very wrong. A lack of ventilation can cause building sickness, with degradation of the physical building and also poor air quality which has a big impact on the occupants themselves. Our statistics show that designers and contractors are still not getting it right, leaving us with a generation of poorly ventilated housing stock.

The objective of present work was to develop the metric that assess the performance of solutions securing high indoor air quality in low-energy (modern) residential buildings. This was achieved by summarizing data on the levels and types of gaseous pollutants and particulate matter in low-energy buildings and comparing them with the existing exposure limits for pollutants.

Because buildings are responsible for 40% of energy use and 36% of Greenhouse Gas (GHG) emissions in the EU, energy efficiency in buildings has become a priority to drastically reduce the energy use in buildings. Consequently, a number of policy measures have been implemented in European Member States to drive the market towards Nearly Zero-Energy Buildings, including the Energy Performance of Buildings Certificates (EPCs), which are the most visible instrument of the Energy Performance of Buildings Directive (EPBD).

There have been many new sensors introduced on the market claiming that they can perform accurate measurements of Indoor Air Quality. Many of them are low-cost sensors that can be applied at the mass scale. The subsequent question is what is and should be considered to be the metric of Indoor Air Quality. No consesus on this matter has yet been achieved. Few metrics have been proposed in the past including most known CO2 and TVOC concentrations but actually only CO2 concentration has been widely used in the applications related to built environment and HVAC.

Building airtightness tests have become very common in several countries, either to comply with minimum requirements of regulations or programmes, or to justify input values in calculation methods. This raises increasing concerns for the reliability of those tests.

There are four key sources of uncertainty in airtightness testing: