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L’étude des déplacements d’air au niveau des airpaths est particulièrement compliquée, autant au niveau théorique que pratique. Ce rapport a pour objectif de proposer une nouvelle méthode pour mesurer in-situ l’étanchéité à l’air d’un airpath. Ce rapport se divise en quatre parties. Dans un premier temps, nous développons le concept d’incertitudes de mesure et de loi de propagation. Ce concept est primordial dans la description d’une méthode de mesure puisqu’il informe sur sa fiabilité. Pour illustrer ce concept, nous développons brièvement le cas de la « fan pressurization method ». Dans un second temps, nous faisons une review des méthodes de mesure développées dans d’autres articles. Cette review reprend autant des méthodes de mesure in-situ que des méthodes de mesure de laboratoire. Dans un troisième temps, nous décrivons en détail la méthode de mesure proposée et le calcul d’incertitude qui lui est lié. Dans un quatrième temps, ce rapport conclut sur les prochaines étapes pour la validation de la méthode de mesure proposée.

Within the context of more stringent buildings codes, mastering airtightness is of importance to achieve energy efficient buildings. Unintended air leakage through the building envelope, which is due to bad design and poor workmanship, not only increases energy consumption, but also leads to moisture disorders, affecting building durability and occupants health. This moisture risk is present in particular for lightweight structures such as timber frame buildings, which are sensitive to air leakage. It is therefore necessary to better understand and to assess the impact of unintended air transfers on the hygrothermal field and the heat flux in the vicinity of an airtightness defect. To this end, two numerical models are developed, dealing with Heat-Air (HA) and Heat-Air-Moisture (HAM) transfer respectively. The HAM model is firstly validated in 1D using numerical benchmarks from literature. Then, temperature measurements in a cellulose insulation layer subjected to moist air flow are compared with the models outputs, and good agreement is obtained. The HAM model provides a better prediction of the temperature field compared to the HA model. Following this 2D experimental validation of the HAM model, it is applied to a complex defect geometry, including porous insulation materials and thin air gaps. This defect is meant to be realistic, as it is drawn from a measurement campaign aiming to identify typical envelope leakage points encountered in timber frame buildings. Long term simulations are performed under transient temperature and humidity conditions, in case of air exfiltration and air infiltration. This study helps identifying tendencies towards moisture risk: infiltrating air flow dries the assembly whereas exfiltrating air flow humidifies it. A methodology to assess heat fluxes through the defect is presented. Finally, a simplified approach is derived from the detailed HAM-model, to take into account the contribution of airtightness defects on the total heat loss on the building scale. It is shown that the additional heat loss induced by an airtightness defect may be described by a specific heat loss coefficient. In addition, the coupling between air flow and envelope has a significant impact on total heat flux calculations. The influence of moisture transfers on observed tendencies is also discussed., Dans un contexte de durcissement des règlementations thermiques, la maîtrise de l'étanchéité à l'air des bâtiments est essentielle pour atteindre les objectifs de consommation énergétique. Les fuites d'air parasites à travers l'enveloppe, dues aux défauts de conception ou à une mauvaise mise en oeuvre, mènent à une surconsommation énergétique, mais aussi à des pathologies liées à l'humidité, mettant en péril la durabilité du bâti et la santé des occupants. Le risque lié à l'humidité est particulièrement présent dans les cas des enveloppes légères à ossature bois, sensibles aux transferts d'air. Il est donc nécessaire de mieux comprendre et de quantifier l'impact de ces transferts d'air sur le champ hygrothermique et sur le flux de chaleur au niveau d'un défaut d'étanchéité. Dans ce but, deux modèles numériques traitant les transferts couplés 'air-chaleur' et couplés 'air-chaleur-humidité' sont développés. Le second modèle est d'abord validé en 1D à l'aide de benchmarks numériques. Ensuite, des mesures de température dans un isolant en ouate de cellulose traversé par un flux d'air humide sont comparées avec les sorties des modèles. Une bonne concordance mesures-modèles est obtenue. Le modèle 'air-chaleur-humidité' s'avère plus précis pour prédire le champ de température que le modèle 'air-chaleur'. Suite à cette validation 2D du modèle couplé 'air-chaleur-humidité', celui-ci est appliqué à une géométrie de défaut complexe, mettant en jeu des isolants poreux perméables à l'air en contact avec des fines lames d'air. Ce défaut se veut réaliste, puisqu'il est issu de campagnes de mesures nationales qui ont permis d'identifier les points sensibles des enveloppes à ossature bois vis à vis des fuites d'air parasites. Des simulations sont réalisées avec des conditions aux limites variables en température et humidité sur des temps longs (quatre ans), en exfiltration et en infiltration d'air. Ces études permettent de dégager certaines tendances vis-à-vis des risques liés à l'humidité. Ainsi, l'exfiltration provoque une humidification significative de l'assemblage tandis que l'infiltration mène à un séchage. Une méthodologie pour évaluer les flux thermiques à l'échelle du défaut est également proposée. Dans une dernière partie, une approche simplifiée est proposée pour prendre en compte l'impact des défauts d'étanchéité à l'air sur la déperdition thermique à l'échelle bâtiment. La perte thermique supplémentaire générée par un défaut d'étanchéité peut être caractérisée par un coefficient de perte thermique propre au défaut, et le couplage du flux d'air avec l'enveloppe a une influence significative sur l'évaluation du flux déperditif total. Enfin, l'influence des transferts d'humidité sur les tendances observées est discutée.

Within the context of more stringent buildings codes, mastering airtightness is of importance to achieve energy efficient buildings. Unintended air leakage through the building envelope, which is due to bad design and poor workmanship, not only increases energy consumption, but also leads to moisture disorders, affecting building durability and occupants health. This moisture risk is present in particular for lightweight structures such as timber frame buildings, which are sensitive to air leakage. It is therefore necessary to better understand and to assess the impact of unintended air transfers on the hygrothermal field and the heat flux in the vicinity of an airtightness defect. To this end, two numerical models are developed, dealing with Heat-Air (HA) and Heat-Air-Moisture (HAM) transfer respectively. The HAM model is firstly validated in 1D using numerical benchmarks from literature. Then, temperature measurements in a cellulose insulation layer subjected to moist air flow are compared with the models outputs, and good agreement is obtained. The HAM model provides a better prediction of the temperature field compared to the HA model. Following this 2D experimental validation of the HAM model, it is applied to a complex defect geometry, including porous insulation materials and thin air gaps. This defect is meant to be realistic, as it is drawn from a measurement campaign aiming to identify typical envelope leakage points encountered in timber frame buildings. Long term simulations are performed under transient temperature and humidity conditions, in case of air exfiltration and air infiltration. This study helps identifying tendencies towards moisture risk: infiltrating air flow dries the assembly whereas exfiltrating air flow humidifies it. A methodology to assess heat fluxes through the defect is presented. Finally, a simplified approach is derived from the detailed HAM-model, to take into account the contribution of airtightness defects on the total heat loss on the building scale. It is shown that the additional heat loss induced by an airtightness defect may be described by a specific heat loss coefficient. In addition, the coupling between air flow and envelope has a significant impact on total heat flux calculations. The influence of moisture transfers on observed tendencies is also discussed.; Dans un contexte de durcissement des règlementations thermiques, la maîtrise de l'étanchéité à l'air des bâtiments est essentielle pour atteindre les objectifs de consommation énergétique. Les fuites d'air parasites à travers l'enveloppe, dues aux défauts de conception ou à une mauvaise mise en oeuvre, mènent à une surconsommation énergétique, mais aussi à des pathologies liées à l'humidité, mettant en péril la durabilité du bâti et la santé des occupants. Le risque lié à l'humidité est particulièrement présent dans les cas des enveloppes légères à ossature bois, sensibles aux transferts d'air. Il est donc nécessaire de mieux comprendre et de quantifier l'impact de ces transferts d'air sur le champ hygrothermique et sur le flux de chaleur au niveau d'un défaut d'étanchéité. Dans ce but, deux modèles numériques traitant les transferts couplés 'air-chaleur' et couplés 'air-chaleur-humidité' sont développés. Le second modèle est d'abord validé en 1D à l'aide de benchmarks numériques. Ensuite, des mesures de température dans un isolant en ouate de cellulose traversé par un flux d'air humide sont comparées avec les sorties des modèles. Une bonne concordance mesures-modèles est obtenue. Le modèle 'air-chaleur-humidité' s'avère plus précis pour prédire le champ de température que le modèle 'air-chaleur'. Suite à cette validation 2D du modèle couplé 'air-chaleur-humidité', celui-ci est appliqué à une géométrie de défaut complexe, mettant en jeu des isolants poreux perméables à l'air en contact avec des fines lames d'air. Ce défaut se veut réaliste, puisqu'il est issu de campagnes de mesures nationales qui ont permis d'identifier les points sensibles des enveloppes à ossature bois vis à vis des fuites d'air parasites. Des simulations sont réalisées avec des conditions aux limites variables en température et humidité sur des temps longs (quatre ans), en exfiltration et en infiltration d'air. Ces études permettent de dégager certaines tendances vis-à-vis des risques liés à l'humidité. Ainsi, l'exfiltration provoque une humidification significative de l'assemblage tandis que l'infiltration mène à un séchage. Une méthodologie pour évaluer les flux thermiques à l'échelle du défaut est également proposée. Dans une dernière partie, une approche simplifiée est proposée pour prendre en compte l'impact des défauts d'étanchéité à l'air sur la déperdition thermique à l'échelle bâtiment. La perte thermique supplémentaire générée par un défaut d'étanchéité peut être caractérisée par un coefficient de perte thermique propre au défaut, et le couplage du flux d'air avec l'enveloppe a une influence significative sur l'évaluation du flux déperditif total. Enfin, l'influence des transferts d'humidité sur les tendances observées est discutée.

L'installation efficace et durable des fenêtres demande une bonne étanchéité à l'air et une bonne gestion de l'eau. Dans ce numéro, on explique le rôle joué par le degré d'étanchéité à l'air et l'emplacement du plan d'étanchéité à l'air de l'interface mur-fenêtre dans les infiltrations d'eau de pluie. C'est le deuxième numéro d'une série de Solutions constructives sur les détails d'installation des fenêtres.

International audience

Results of air quality measurements are presented for a group of low-leakage houses located in Saskatoon, Saskatchewan. Houses were tested for formaldehyde, nitrogen dioxide, radon, and humidity levels. The median level of formaldehyde was 0.09 ppm, slightly lower than the guideline of 0.1 ppm. Elevated levels of formaldehyde (>50 ppb). Those houses lacking a mechanical ventilation system had considerably higher incidences of elevated formaldehyde concentrations than those incorporating mechanical ventilation., Trans. Indoor Air Quality in Cold Climates : Hazards and Abatement Measures: 29 April 1985, Ottawa, Ontario, Canada

Venting the fire region of a building to the exterior significantly reduces smoke problems caused by a fire. This is often achieved by means of a smoke exhaust shaft with dampered openings on each floor. In the event of fire, the dampers at the top and on the fire floor are opened to exhaust smoke to the exterior. The performance of the smoke exhaust shaft is seriously affected by any extraneous air leakage through closed dampers located on the non-fire floors. Tests have been conducted before and after fire exposure to measure the air leakage characteristic of proprietory fire dampers currently used for smoke shaft application. The pre-fire test ratios of leakage area to damper area were generally below 2.5%. After exposure to the standard time-temperature, the ratios were generally below 4%. Restricting the maximum furnace temperature to 1000 degrees F (540 degrees C) considerably reduced the increase in leakage area ratio due to fire exposure., Reprinted from: ASHRAE Transactions, v. 90, 1984, Part 1B, p. 647-654. ISSN: 0001-2505

Air infiltration is the uncontrolled leakage of air into a house, that results from pressure differentials across its envelope induced by wind and inside-to-outside temperature difference. It is recognized as one of the major energy losses in residences but is difficult to estimate. Infiltration rates can be measured using the tracer gas method which requires expensive equipment and long preparation time, but it is difficult to use on a large scale for routine tests. A more simple method is to use the fan pressurization method to conduct air leakage tests and then translate the result into infiltration rates using an infiltration-air tightness correlation. This paper introduces such a correlation for houses in a suburban area. A preliminary study of the proposed correlation has been reported previously. The final result is now presented.

Schools, as a group, are the third largest users of energy in buildings in Canada. The Division of Building Research, National Research Council of Canada therefore welcomed the opportunity in the autumn of 1975 to participate with the Carleton Board of Education in a program to reduce energy use in schools. A major problem encountered initially was the lack of data on air infiltration for school buildings. A program of air leakage measurements in schools was therefore carried out. Results of the measurements were then applied to a simplified model of a school building, from which air infiltration and its contribution to total heating consumption could be calculated., Also presented at the 1st Air Infiltration Centre Conference held on October, 1980, UK

Measured space heating and total energy-consumption values are presented for a one-year monitoring period for a group of 27 low-energy houses in Saskatoon, Saskatchewan, Canada. The average space heating energy consumption for the 27 houses was 43.7 kJ/m.degrees C-d (2.1 Btu/ft[2].degrees F-d) for the period from May 1980 to May 1981. The total energy consumption averaged 365 MJ/m[2] (32,200 Btu/ft[2]); and space heating energy consumption averaged 228 MJ/m[2] (20, 100 Btu/ft[2]). These low-energy houses have a number of energy-conserving features -- air tightness, controlled ventilation, air-to-air heat exchangers, use of south windows for passive solar gain, and high insulation levels -- that distinguish them from conventional housing stock.

The values given by current methods of estimating air change rates in houses may be many times, more or less, the actual rate. Because the air change rate has such a great effect on the energy use pattern of houses, this uncertainty is particularly important to the field of energy auditing. Considering the various laboratory methods and specialized field techniques, it was hypothesized that a simple humidifier could be used to provide a steady concentration of tracer gas to measure the air change rates in existing houses. The method is based on the assumption that if the indoor humidity of a house is maintained at a constant level and if the only source of moisture is a humidifier, its total water output can be related to the amount of infiltration air. Several experiments using simple free- standing humidifiers were conducted in four unoccupied houses near Ottawa. During the experimental period the humidifier output was recorded and calculations made of the corresponding air change rates required to absorb that water. From the recorded data, it was discovered that another internal source of moisture had contributed to the moisture level of the indoor air. A method has been found to estimate this unknown quantity of water and its effect on the humidifier performance. It is now believed that the humidifier method can also be used in occupied houses. This paper presents the theory, outlines the major constraints and analyses the observed results from the experiments in which water vapour was used as a tracer gas to measure the air change rates in houses., Proceedings, Building Science Conference "Design and Rehabilitation of Building Envelopes": 04 March 1982, London, Ont., Canada

The purpose of the study was to identify the air tightness levels of a group of houses in the Saskatoon area. Included were houses of different ages, construction styles and methods of achieving air tightness. The note describes the houses, the test method and the results, and discusses the last in terms of house age, the contractor, construction style, and the effects of special air tightness techniques.

The operation of an air exhaust system or fuel-burning appliance removes air from the house, creating a negative pressure in the building. If too much air is removed and the negative pressure becomes large enough, the natural flow of gases up the furnace chimney can be reversed. The flow of combustion products into the home can create a danger of carbon monoxide poisoning. The digest describes a study conducted to determine the relationship between carbon monoxide poisoning and the air tightness of a house.

Le fonctionnement d'un ventilateur d'extraction ou d'un appareil de combustion provoque un appauvrissement en air à l'intérieur de la maison et crée une dépression dans le bâtiment. Si on extrait trop d'air, la dépression peut devenir assez importante, pour inverser l'ascension naturelle des gaz dans la cheminée de la chaudière. Le refoulement des produits de combustion dans la maison peut créer un risque d'oxycarbonisme. Ce Digeste présente une étude de la relation existant entre l'étanchéité à l'air d' une maison et l'oxycarbonisme.

This note describes a system in which interior cladding serves as an air flow barrier, and a vapour barrier is provided by interior painting, wall-papering or a vapour barrier film that is factory-applied to the interior cladding elements.

Possible build-up of pollutant levels in low-energy houses is increasingly under investigation. Field data are presented on the indoor formaldehyde (HCOH) concentrations in a group of 33 relatively new low-energy houses., Ventilation Strategies and Measurement Techniques : Proc 6th AIC Conference: 16 September 1985, Het Meerdal Park, The Netherlands

The National Research Council of Canada has taken measurements of the air leakage characteristics of the exterior walls of eight multi-storey office buildings located in Ottawa, Canada. Varying in height from 11 to 22 stories, with curtain wall construction and fixed glazing, they were built during the sixties and early seventies. The results of the measurements are reported in this paper. A method for calculating infiltration rates caused by stack action has been developed and is applied to heat loss calculations using the measured wall leakage values., Les auteurs présentent des valeurs mesurées d'étanchéité à l'air pour huit tours de bureaux (murs-rideaux et vitrages scellés). Ces valeurs sont de beaucoup supérieures aux valeurs mentionnées dans norme industrielle. Une équation permettant de calculer la vitesse totale de pénétration due à l'appel d'air est appliquée aux édifices à l'aide de valeurs mesurées de l'étanchéité à l'air des murs. Les auteurs examinent également le rôle que joue la pénétration de l'air dans la perte globale de chaleur, y compris la transmission et la ventilation mécanique., Reprinted from ASHRAE Transactions, vol. 82, part 1, 1976, p. 122-134., Réimprimé du "ASHRAE Transactions, vol. 82, part 1, 1976, p. 122-134"., 1976 ASHRAE Semi-Annual Meeting, February 1-5, 1976, Dallas, Texas, USA, 1st AIC Conference: Air Infiltration Instrumentation and Measuring Techniques, October 6, 1980, Berkshire, UK

Methods for improving the thermal characteristics and airtightness of the house envelope and basement are outlined, with some examples of features that will affect actual performance. The factors that influence ventilation rates are discussed including the effect of fans and chimneys on the air pressure differences and direction of air leakage through the house walls and ceilings. An understanding, by all concerned, of the interactions between the house enclosure, the equipment and services installed and the occupancy pattern is suggested as the best route toward energy conservation., Proceedings, "Building Toward 2001": 01 November 1981, Toronto, Ont. Canada

Over-all air leakage characteristics have been measured in several supermarkets and an enclosed shopping mall, all constructed between 1954 and 1979. Measured in three categories: tight, average and loose, air leakage rates for all the test stores constructed in recent years were in the loose construction category.

Fan pressurization tests on two unoccupied houses were conducted once every two weeks for a period of a year (May 1982 to July 1983) to determine the seasonal variation in airtightness. Both houses are of insulated wood frame construction. House No. 1 was built with more insulation than is required by the local building code, and a polyethylene vapor barrier was applied with special care to improve its airtightness. House No.2, a less air tight house, was built with various wall construction features and a polyethylene vapor barrier in only two walls. Indoor relative humidity, indoor and outdoor air temperatures, and moisture content of the stud and top plates of the wood framing were measured at the time of airtightness testing to determine whether a correlation exists between these factors and house airtightness. The results indicate that air leakage varies throughout the year, with the minimum value in late summer and fall and the maximum value in winter and early spring. The difference is more pronounced in the leakier house. There is also indication of a rough correlation between envelope airtightness and indoor humidity ratio., Measured Air Leakage of Buildings: 02 April 1984, Philadelphia, PA, USA

The air tightness of 63 houses built by nine builders in the Ottawa area in 1978 and considered to be representative of current construction was measured using a method involving air pressure difference. The results are presented in three tables and six figures. Various factors affecting air tightness, including design details and quality of workmanship, are discussed.

Les charges de chauffage et l'humidité relative des bâtiments en hiver sont affectées par les taux d'infiltration et de ventilation. Etant donné que les fenêtres et les portes constituent généralement la principale cause des fuites d'air dans les bâtiments, des réductions importantes de l'infiltration de l'air son réalisables, si l'on améliore l'étanchéité de ces ouvertures. La réduction du taux d' infiltration de l'air au travers des fenêtres cependant ne réduit pas l'exfiltration produite par les fissures et les matériaux poreux. Pour venir à bout des problèmes de condensation qui résultent de l'exfiltration les fissures et les matériaux poreux ne doivent pas être tolérés du côté chaud du bâtiment. Dans les bâtiments à plusieurs étages l'écoulement de l'air entre les planchers doit être restreint afin de réduire des différences de pression qui résultent de l'action de cheminée.

Three basic requirements of a wall are identified if problems (CBD 93) are to be avoided. A new approach to the use of precast concrete is developed which meets these three requirements.

Heating load and building relative humidity in winter are affected by over-all air infiltration and ventilation rates. Since windows and doors usually represent the major source of air leakage in buildings, significant reductions of overall air infiltration are achieved principally by increasing the air-tightness of these components. Reduction of the air infiltration rate through windows, however, will not reduce exfiltration through other cracks and porous condensation. To overcome condensation problems resulting from exfiltration, cracks and porous construction must be eliminated on the warm side of the structure. In multi- story buildings air flow between floors should be restricted to reduce pressure differences resulting from chimney action.

This Digest discusses air tightness and the distribution of pressure differences resulting from stack effect in buildings as they are designed at present. It also discusses ways in which pressure differences and air flow may be modified to alleviate associated problems by varying air tightness characteristics or by the operation of mechanical air supply and exhaust systems., Canadian Building Digest, CBD-107

It is the purpose of this Digest to discuss the implications of window air leakage, its characteristics and criteria. Much that is said may be applied to air leakage around closed doors.

L'auteur décrit les trois règles fondamentales à suivre pour l'érection des murs en éléments préfabriqués de béton afin d'éviter les difficultés mentionnées dans CBD-93F. Il explique une nouvelle méthode d'utilisation de ces éléments répondant aux trois conditions précitées., Digeste de la construction au Canada, CBD-94F

Le but du présent Digeste est d'évaluer les conséquences des fuites d'air qui se produisent autour des fenêtres, et de déterminer les caractéristiques et les critères de ces fuites. Une grande partie des observations qui seront faites s'appliqueront également aux fuites d'air existant autour des portes fermées.

This paper describes an experimental procedure for determining the air leakage characteristics of the exterior walls of buildings. The technique consists in pressurizing the building with the supply air system and recording the supply air flow rate and the resultant pressure differentials across the walls. The study of the results obtained makes it possible to establish an air flow coefficient and exponent for exterior walls. By applying this method to air flow rates and pressure differentials obtained using a computer-simulated building, it is possible to verify the procedure and confirm that the results obtained correlate closely with air flow characteristics used in the simulation. The air leakage properties of the exterior walls of four buildings, determined using this method, are also presented., Reprinted from ASHRAE Transactions, vol. 79, part 2, 1973, p. 40-48., 1973 ASHRAE Spring Conference, May 3-5, 1973, Minneapolis, Minnesota