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With increasing mean and extreme temperatures due to climate change, it becomes necessary to use—not only future typical conditions—but future heatwaves in building thermal simulations as well. Future typical weather files are widespread, but few researchers have put together methodologies to reproduce future extreme conditions. Furthermore, climate uncertainties need to be considered and it is often difficult due to the lack of data accessibility. In this article, we propose a methodology to re-assemble future weather files—ready-to-use for building simulations—using data from the European Coordinated Regional Downscaling Experiment (EURO-CORDEX) dynamically downscaled regional climate multi-year projections. It is the first time that this database is used to assemble weather files for building simulations because of its recent availability. Two types of future weather files are produced: typical weather years (TWY) and heatwave events (HWE). Combined together, they can be used to fully assess building resilience to overheating in future climate conditions. A case study building in Paris is modelled to compare the impact of the different weather files on the indoor operative temperature of the building. The results confirm that it is better to use multiple types of future weather files, climate models, and or scenarios to fully grasp climate projection uncertainties.

International audience; Heatwaves are responsible for many deaths due to hot weather. Natural ventilation is promoted as a cooling solution to reduce the impacts of climate change because of its energy-saving potential. This paper addresses the prediction of heat-related health risk situations in naturally ventilated dwellings, where indoor thermal conditions depend on external climate and occupant behaviour. Thus, the operating limits of a dwelling vary according to its dynamic thermal response to indoor and outdoor stresses. To secure a building design, a method to improve the prediction of heat-related health risks is proposed that links predicted percentage dissatisfied (PPD) and wet-bulb globe temperature (WBGT) indicators to distinguish a moderately warm situation from a heat stress situation (WBGT>29°C). Simulations are performed for a dwelling during the 2015 heatwave in Paris (France) to test the method. In the example, natural ventilation was found to reduce the indoor temperature, but there remains ambiguity regarding the ability of natural ventilation to provide moderate conditions. According to the scope of the ergonomic standards, "moderate thermal environment" and "heat stress" temperature ranges are not contiguous. Bridging of this gap requires establishing thermal comfort ranges and heat stress thresholds adapted to people according to their acclimatisation level and their sensitivity to heat.

A national survey on indoor environmental quality covering 567 residences in mainland France was performed during 2003–2005. The measured parameters were temperature, relative humidity, CO 2 , and the indoor air pollutants: fourteen individual volatile organic compounds (VOC), four aldehydes and particulate matter PM 10 and PM 2.5. The measured indoor concentrations were analyzed for correlations with the building characteristics: type of dwelling, period of construction, dwelling location, type of ventilation system, building material, attached garage and retrofitting. The median night time air exchange rate (AER) for all dwellings was 0.44 h −1 . The night time AER was higher in apartments (median = 0.49 h −1 ) than in single-family houses (median = 0.41 h −1 ). Concentration of formaldehyde was approximately 30% higher in dwellings built after 1990 compared with older ones; it was higher in dwellings with mechanical ventilation and in concrete buildings. The VOC concentrations depended on the building characteristics to various extents. The sampling season influenced the majority of the indoor climate parameters and the concentrations of the air pollutants to a higher degree than the building characteristics. Multivariate linear regression models revealed that the indoor–outdoor difference in specific humidity, a proxy for number of occupants and their indoor activities, remained a significant predictor for most gaseous and particulate air pollutants. The other strong predictors were outdoor concentration, smoking, attached garage and AER (in descending order).

International audience; In order to improve the knowledge of the indoor environment quality of energy-efficient buildings, a 3-year follow-up study was carried out in two wooden-framed low-energy single-family houses in France. Several indoor air indicators and indoor environmental parameters were measured during seven weeks in total from the pre-occupancy stage up to three years of occupancy. Questionnaires were used for each investigation to record the family activities and perceived comfort of occupants. The ventilation systems presented some shortcomings, including the failure to reach the designed exhaust air flow rate and induced occupant dissatisfaction. Regarding the measured pollutants, both houses didn't present any specific indoor air pollution. The variability of indoor air quality over time was explained by the high emissions from the new building materials, products, and paints during the first months after completion and then more episodically by human activities during occupancy. Regarding the thermal comfort and even if occupants were globally satisfied, overheating and under-heating were observed. According to our results and in order to guarantee the health and the well-being of occupants in these buildings, it would be useful to integrate the solar shadings at the very first stage of the building design, to design more quiet, user-friendly and robust ventilation systems and to implement mandatory inspection as well as frequent maintenance by professionals and finally to promote the labelling of low-emitting construction and decoration products, furniture and consumer products.

A pilot survey was undertaken from September 2009 to June 2011 in 310 schools and day-care centres distributed in all regions of France including overseas departments. This experimental survey was carried out as part of the preparation of the mandatory control of indoor air quality in public buildings. Three parameters were measured in 896 classrooms or child playrooms: benzene, formaldehyde and carbon dioxide (CO2). The last enables the determination of degree of air 'stuffiness' during children occupancy as well as the night-time air change rate. The level of air stuffiness was represented by a score from 0 (no stuffy air) to 5 (extremely stuffy air), which depends on both the occurrence and intensity of CO2 concentration. Moreover, a simple audit of each building was undertaken in order to describe its characteristics, the equipment, user behaviour and outdoor environment. Results show varying levels of air stuffiness from one room to another: low or no air stuffiness was recorded in 30% of rooms, medium to high air stuffiness in 48% of rooms, and very high to extreme air stuffiness in 21% of rooms. The air in day-care centres was generally found to be less stuffy than in schools, because of more favourable ventilation conditions and lower children density per square metre. At the opposite, the air in elementary schools was found to be generally more stuffy than in the other establishments. Air change rates were estimated from the decay of CO2 concentration by an automated method. The observed carbon dioxide values were low at a median level around 0.2 air changes per hour (ac/h) in day-care centres and 0.1 ac/h in nursery or elementary schools. Mechanical ventilation systems were installed in all the day-care centres and used for 60% of the time. They were also installed in the monitored nursery and elementary schools where they were used, on average, for 20% of the time. The most common mechanical systems were based on exhaust ventilation or balanced ventilation directly in the rooms.

Worldwide, public policies are promoting energy-efficient buildings and accelerating the thermal renovation of existing buildings. The effects of these changes on the indoor air quality (IAQ) in these buildings remain insufficiently understood. In this context, a field study was conducted in 72 energy-efficient dwellings to describe the pollutants known to be associated with health concerns. Measured parameters included the concentrations of 19 volatile organic compounds and aldehydes, nitrogen dioxide, particulate matter (PM2.5 ), radon, temperature, and relative humidity. The air stuffiness index and night-time air exchange rate were calculated from the monitored carbon dioxide (CO2 ) concentrations. Indoor and outdoor measurements were performed at each dwelling during 1 week in each of the two following seasons: heating and non-heating. Moreover, questionnaires were completed by the occupants to characterize the building, equipment, household, and occupants' habits. Perspective on our results was provided by previous measurements made in low-energy European dwellings. Statistical comparisons with the French housing stock and a pilot study showed higher concentrations of terpenes, that is, alpha-pinene and limonene, and hexaldehyde in our study than in previous studies. Alpha-pinene and hexaldehyde are emitted by wood or wood-based products used for the construction, insulation, decoration, and furnishings of the dwellings, whereas limonene is more associated with discontinuous sources related to human activities.

International audience; The evaluation of indoor air quality (IAQ) in buildings is complex because IAQ involves a broad spectrum of substances and agents that vary over time and space. To address this complexity, IAQ indexes are used to describe, classify and improve IAQ by providing easy-to-understand and comprehensive rankings of IAQ levels in buildings. Although many IAQ indexes have been proposed all over the world, their relevancy regarding the evaluation of IAQ levels has not been fully studied in a large number of dwellings. In this study, six measurement-based IAQ indexes proposed for use in the USA, France, Taiwan, and Hong Kong were evaluated. The calculation of IAQ levels was based on nine indoor parameters measured in 567 French dwellings, i.e., indoor air temperature, relative humidity, and concentrations of formaldehyde, total volatile organic compounds, radon, carbon monoxide, carbon dioxide, PM2.5, and PM10. A factorial analysis using the multiple correspondence analysis and the hierarchical cluster analysis methods was performed to determine whether the calculated IAQ levels of different indexes in the studied dwellings were repeatable across all indexes. The results showed that three of the indexes tended to provide only positive IAQ ratings, while the other three indexes were more discriminating. Three classes of IAQ levels in dwellings, along with indoor parameters associated with each class, were identified. All of the indoor parameters were associated with the classification of IAQ 2 levels, while the formaldehyde concentration and relative humidity were the key parameters to identify the dwellings with the best IAQ.

International audience; To date little data exists on indoor air quality (IAQ) in French office buildings. Data is very fragmented and/or old (before 2000). Knowledge from studies carried out in other countries suggests that the type of indoor air pollution is likely to be specific in these environments. For example, computers, printers and photocopiers are now widely used at the workplace; these electronic devices emit pollutants such as volatile and semi-volatile organic compounds (VOCs and SVOCs), ozone, fine and ultrafine particles. Moreover, the use of cleaning products, potentially emitting VOCs, is common in offices. Finally, office buildings are often equipped with mechanical ventilation and air conditioning systems in comparison to dwellings. Poor maintenance can generate specific pollution. The impossibility to open windows in high-rise buildings should also be taken into account. In that context, the French observatory of indoor air quality (OQAI) launched in 2012 a nationwide survey in 300 office buildings. The main objective of this national survey is to characterize indoor pollution in the office building stock in France, and to describe systems in place. Moreover perceived comfort and health is investigated through questionnaires. Finally, since now a common approach between IAQ and energy savings is requested, energy performance in the office building stock is also studied. This should lead to a classification of buildings according to those criteria (IAQ, comfort, health, energy).

C'est en 2001, alors que les connaissances sur la pollution de l'air dans les bâtiments étaient encore rares et dispersées, que fut décidée la création de l'OQAI, observatoire entièrement dédié à la qualité de l'air intérieur. Sa mission : réunir, par le biais de campagnes d'études à l'échelle nationale, les connaissances nécessaires pour aider les pouvoirs publics à agir, inciter les professionnels à améliorer leurs pratiques et informer le grand public, sur la réalité de cette pollution et des risques pour la santé. En effet, la qualité de l'air que nous respirons chaque jour dans notre logement, au bureau, celle de nos enfants dans les crèches, les écoles ou les lieux de loisirs, fait l'objet d'une préoccupation croissante. Aujourd'hui, la qualité de l'air intérieur est devenue un thème central, présent dans tous les médias. L'Observatoire de la qualité de l'air intérieur a mis à jour de nombreux problèmes, dont la multiplicité des sources de pollution affectant le bâtiment, plaçant toujours l'humain au cœur de ses préoccupations. Les résultats de ces dix premières années de recherches et d'enquêtes de l'OQAI sont aujourd'hui rassemblés dans un seul ouvrage " Qualité d'air intérieur, qualité de vie ". Richement illustré et dans un format " livre d'art ", il propose un état détaillé des 10 premières années de recherches sur la qualité de l'air intérieur et tous les facteurs susceptibles de le dégrader, ainsi que les solutions à mettre en œuvre pour y remédier. Ce guide intéressera particulièrement les architectes et urbanistes, les collectivités et les pouvoirs publics, les associations et groupes d'opinions autour du Développement durable, un large public sensibilisé aux problématiques de la qualité de l'air intérieur des bâtiments, etc.

En preparation de la surveillance de la qualite de l'air dans les ecoles et creches decidee a l'occasion du Grenelle Environnement, une campagne pilote a ete engagee en septembre 2009. Une premiere phase s'est terminee a l'ete 2010. Elle a porte sur 160 ecoles et creches reparties dans 13 regions. Les autres regions francaises font l'objet d'une deuxieme phase de mesures depuis septembre 2010. Durant cette phase pilote, plusieurs parametres ont ete mesures : deux polluants chimiques (le benzene et le formaldehyde) et le confinement des salles de classe ou d'activites. En complement, un diagnostic simple de chaque bâtiment a ete realise. Les resultats montrent, si l'on se refere aux valeurs de gestion proposees par le Haut Conseil de la Sante Publique (HCSP), que la qualite de l'air est acceptable dans la plupart des ecoles et creches experimentees pour ces parametres. Neanmoins, quelques situations necessitent des diagnostics complementaires et des mesures correctives. En outre, 16 % des salles instrumentees sont insuffisamment ventilees (25 % dans les ecoles elementaires). Les maires et chefs d'etablissement ont ete informes des resultats et beneficient, le cas echeant, de moyens d'expertise pour tenter d'identifier les sources principales de pollution et mettre en place les actions necessaires.

Lʼarticle decrit les situations reelles de ventilation des habitations, ecoles et creches en France, telles quʼelles ont ete observees in situ ainsi que leurs impacts sur la qualite de lʼair interieur de ces espaces. La moitie du parc des logements a ete construite avant 1967. 35 % des logements sont equipes de VMC et 34,5 % de ventilation naturelle par grilles ou par conduits. Le comportement de lʼoccupant joue un role determinant sur la ventilation : lʼouverture des fenetres et la permeabilite a lʼair sont les postes preponderants du renouvellement dʼair par rapport aux systemes de ventilation tels quʼils sont mis en oeuvre. La moitie du parc des ecoles a ete construite avant 1970 ; alors que la moitie du parc des creches, apres 1995. 85 % des ecoles sont depourvues de systemes de ventilation, alors que 49 % des creches ont une VMC. Les niveaux de confinement de lʼair dans les ecoles et les creches sont preoccupants dans 1 salle sur 5, traduisant ainsi des conditions dʼaeration insuffisantes. Les creches sont moins confinees (1 salle sur 20) que les ecoles elementaires (1 salle sur 3).

http://www.aivc.org; International audience

National audience; Seminaire de lancement de projet - Colloque PRIMEQUAL - Aerosol et Particules

Le Centre Scientifique et Technique du Bâtiment (CSTB) a propose en 2007 un indice de confinement de l’air pour les salles de classe, fonde sur la mesure de la concentration en dioxyde de carbone (CO2). Sur une echelle de 0 a 5, cet indice, appele ICONE, reflete l’adequation du renouvellement d’air d’une piece a sa densite d’occupation. Il prend en compte a la fois les frequences de situation de confinement, mais egalement leur intensite. Applique a la surveillance reglementaire de la qualite de l’air dans les ecoles et lieux d’accueil de la petite enfance, cet indice s’est revele etre un outil pertinent et utile aux gestionnaires soucieux d’ameliorer les conditions de ventilation de leurs locaux. Le present article montre comment cet indice concu pour les ecoles peut etre applique a l’habitat, en insistant sur la specificite de ce lieu de vie, les conditions d’occupation des pieces etant tres differentes de celles des salles de classe. Selon l’etat d’occupation des pieces, l’etat des portes interieures et des fenetres, ouvertes ou fermees, l’indice de confinement est tres different d’un logement a l’autre. Les chambres sont systematiquement plus confinees que les sejours. Un indice de confinement relatif a l’ensemble du logement exige des mesures dans les differentes pieces. Aussi, en premiere approche, il est propose de se limiter au confinement de l’air dans la chambre principale du logement, en periode nocturne, sur une duree d’une semaine.

Dans les salles de classe, il est necessaire de renouveler l’air pendant la presence des enfants pour eviter un confinement de l’air trop important pouvant etre a l’origine d’effets sanitaires et d’une baisse de performance des ecoliers. En l’absence de systeme mecanique de ventilation, ce renouvellement de l’air necessite une ouverture reguliere des ouvrants, en veillant toutefois a limiter l’exposition aux contraintes exterieures (bruit, froid, etc.). Afin d’optimiser cette ouverture, le Centre Scientifique et Technique du Bâtiment (CSTB) a mis au point, dans le cadre du programme scientifique de l’Observatoire de la Qualite de l’Air Interieur (OQAI), un indicateur lumineux du confinement de l’air interieur, base sur la mesure en continu du dioxyde de carbone et un affichage tricolore immediat. Il permet ainsi d’alerter l’enseignant sur l’etat de confinement dans la salle de classe en temps reel. Cet indicateur a ete deploye dans 70 salles de classes d’ecoles maternelles et elementaires de trois regions francaises aux climats contrastes, de fevrier a juin 2010. L’etude a montre la bonne appropriation de cet outil par les enseignants. Neanmoins, des freins a l’aeration par ouverture des fenetres subsistent encore, tout comme l’arret de l’indicateur lumineux conduit rapidement a un retour aux pratiques qui precedaient son utilisation. En tout etat de cause, l’utilisation de l’indicateur lumineux a montre une reduction du confinement de l’air interieur (diminution de l’indice de confinement ICONE de 0,5 a 1,5 point). A ce titre, et meme s’il ne constitue pas une solution adaptee a toutes les situations et toutes les personnes, cet outil fait partie des moyens aujourd’hui disponibles de sensibilisation vis-a-vis de la qualite de l’air interieur dans les lieux d’enseignement.