05CH11231, the CEC under the Califoarnia Energy Commission contract No. EPC-15-037 and Aereco SA under Contract No. FP00003428. The contribution of Cerema is funded by the French Ministries in charge of sustainable development, transports and urban planning, and by the Région Auvergne Rhône-Alpes.

a b s t r a c tIn this study we estimate the air leakage distribution of single-family dwellings in Catalonia and use a statistical analysis of an airtightness database for single-family dwellings in France to identify the building characteristics that have the greatest influence on airtightness. The most significant variables are found to be the structure type, the floor area, the age of the building, the number of stories and the insulation type. A multiple linear regression technique is then applied to establish a predictive model for deriving an estimated value of airtightness from these characteristics. To estimate the infiltration airflow, a stochastic simulation of the building characteristics was performed per census tract using real data on the distributions of building variables taken from the census information. The model is then applied to determine the power law coefficient and the airtightness distribution. The predicted flow coefficients are combined with the AIM-2 model and given meteorological conditions to determine the infiltration airflow. Two sets of meteorological conditions are considered: average conditions and extreme conditions for each season.

Historic building restoration and renovation requires sensitivity to the cultural heritage, historic value, and sustainability (i.e., building physics, energy efficiency, and comfort) goals of the project. Energy-efficient ventilation such as demand-controlled ventilation and heat recovery ventilation can contribute to the aforementioned goals, if ventilation concepts and airflow distribution are planned and realized in a minimally invasive way. Compared to new buildings, the building physics of historic buildings are more complicated in terms of hygrothermal performance. In particular, if internal insulation is applied, dehumidification is needed for robust and risk-free future use, while maintaining the building’s cultural value. As each ventilation system has to be chosen and adapted individually to the specific building, the selection of the appropriate system type is not an easy task. For this reason, there is a need for a scientifically valid, systematic approach to pair appropriate ventilation system and airflow distribution solutions with historical buildings. This paper provides an overview of the interrelationships between heritage conservation and the need for ventilation in energy-efficient buildings, regarding building physics and indoor environmental quality. Furthermore, a systematic approach based on assessment criteria in terms of heritage significance of the building, building physics (hygrothermal performance), and building services (energy efficiency, indoor air quality, and comfort rating) according to the standard EN 16883:2017 are applied.

As ventilation systems become more sophisticated (or "smart") standards and regulations are changing to accommodate their use. A key smart ventilation concept is to use controls to ventilate more at times it provides either an energy or IAQ advantage (or both) and less when it provides a disadvantage. This paper discusses the favorable contexts that exist in many countries, with regulations and standards proposing "performance-based approaches" that both enable and reward smart ventilation. The paper gives an overview of such approaches from five countries. The common thread in all these methods is the use of metrics for the exposure to an indoor generated parameter (usually CO2), and condensation risk. As the result, demand-control ventilation strategies (DCV) are widely and easily available on the market, with more than 20-30 systems available in some countries.

The French air leakage testers' scheme led to the development of a national database, which includes about 219,000 airtightness measurements, mainly from residential buildings built since 2010. This paper first presents the measurement methodology and the requirements of the testers' scheme regarding the reliability of the data included in the database. Different analyses are then presented, to:-give a general overview of the new French building stock;-analyse several factors, including insulation, ventilation systems, and main building materials, that may significantly impact building leakage measurement results;-identifying levers to improve the practices of building construction stakeholders and testers. These analyses reveal influential factors, such as the main material of the building, the thermal insulation technique and the type of ventilation system. The most frequently identified leaks and the most influential leaks have been identified, in order to improve building airtightness. The common use of last-minute correction has also been identified, despite the impact on airtightness durability. Finally, these analyses confirm that the multi-point testing method fits well with the French context, buildings and climates.

Given that airtightness is recognized as an essential issue for low-energy dwellings, today it is often included in energy performance (EP) calculations, frequently through single-zone models with uniform air leakage. Because more consideration is often given to EP than to indoor air quality issues, air leakage through internal partitions is often disregarded. Therefore, additional studies are needed to check these assumptions.In the present study air leakage through the building envelope and through internal partitions is investigated. This paper presents the methodology used in an experimental study, conducted to measure multizone air leakages, using the guarded zone pressurization technique. We developed a detailed innovative database with 456 exterior and internal partition wall air leakage measurements, taken in 23 detached houses. For each wall, the database includes general information on the building, special requirements, the building's main characteristics, measurement protocol, type of wall, measurement input data and measurement results (CL, n, q50 and the reliability index developed). Then an analysis of this database is provided. The analysis reveals most important relationships. For instance, internal partition wall air leakage is not related to the envelope's airtightness level; instead, the type of building structure has greater influence. Through this study, we underline the impact on building airflows of more detailed modelling of internal and external air leakage in multizone approaches, with consequences on indoor air quality (IAQ) bedrooms where people spend most of their time. As a conclusion, we propose air leakage values and dispersion input data for multizone IAQ models.

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