AIVC - Air Infiltration and Ventilation Centre

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Development of indoor climate classes to assess humidity in dwellings

The knowledge of indoor air humidity in the design phase is important to decide on the appropriate moisture control measures to prevent moisture problems in building components. Because of the uncertain nature of most of the factors affecting the indoor humidity, its accurate prediction in the design phase is not possible. To overcome this problem, the concept of Indoor Climate Classes has been introduced and used in Europe since its early development in the Netherlands in the 1970s up to its recent introduction in a European Standard on the hygrothermal performance of building components.

The hygrothermal behaviour of rooms : combining thermal building simulation and hygrothermal envelope calculation

The hygrothermal behavior of a building component exposed to weather is an important aspect of the overall performance of a building. Today the hygric transport phenomena through a building envelope are well understood and a realistic assessment of all relevant effects can be carried out by one of the numerous models and computer programs, that have been developed in different countries over the last years. The calculation of the hygrothermal performance of a part of the envelope is state-of-the-art, but until now, the total behaviour of the actual whole building is not accounted for.

Ocular, airway, and dermal symptoms related to building dampness and odors in dwellings

The aim of that study is to establish the relationship between symptoms and report of building dampness and odors.A questionnaire was then sent to the inhabitants of 231 multi-family buildings of Stockholm, containing more than 4800 dwellings, with questions about : personal factors, symptoms, population density in the apartment, water leakage, odors, and signs of high indoor air humidity.A combination of odor and high humidities was linked to high occurrence of the symptoms : humidity in building is therefore associated to Sick building Syndrome.

Breathing freely in schools - results and model approaches concerning the air quality in classrooms (In German)

Carbon dioxide concentration, indoor air temperature and relative air humidity are studied in 7 schools with natural ventilation systems, during 58 days on one year. The results show that the level of 1500 ppm of CO2 is exceeded in 39 days. A software programme was developed to calculate the CO2 concentration level according to the number of pupils and the ventilation rate.
Health problems may result from a too low ventilation rate.

Effects of temperature and humidification in the office environment

In this paper, the links between temperature and Sick Building Syndrome symptoms on the one hand and temperature and workers'perceptions of air dryness in environments with and without humidification on the other hand are evaluated .The average intensity of symptoms and perceptions of dry air relative to room temperature in humidified and non-humidified conditions are studied. The results are presented then analysed .

Numerical prediction of indoor air humidity and its effect on indoor environment

This paper describes a numerical model that takes into account the indoor air moisture and its transport by the airflow, within an enclosure. That model is a potential useful tool for correctly estimating the indoor environment in steady and homogeneous thermal conditions.

Indoor air humidification, sick building syndrome symptoms, and perceived indoor air quality in the office environment

Dryness is still one of the major complaints concerning indoor air quality in office buildings and respective nonindustrial environments. Dampness in buildings in terms of excess amounts of water in the solid parts, and the harmful consequences have been discussed vigorously in recent years. Indoor air humidity, which means water vapour in the indoor air, has been given less attention.

Low winter humidity indoors has a negative effect on the performance of office work

Thirty subjects (17 female) were exposed for 5 hours in a climate chamber to clean air at 5%, 15%, 25% and 35% RH at 22 °C, in balanced order. Another 30 subjects (15 female) were similarly exposed to air polluted by carpet and linoleum at 18, 22 and 26 °

Influence of temperature and humidity on the perception of odours Einfluss von temperatur und Feuchte auf die Wahrnehmung von Geruchsstoffen

Experiments were operated to estimate the influence of temperature and humidity on the perception of odours in the air by trained and untrained persons .

Moisture transport across imperfect hydraulic contact interface - A parametric study

Material properties, water vapor permeability, sorption/suction isotherm and moisture diffusivity, are prerequisite for application of all hygrothermal models. Based on the experimental results and well-determined material properties, a numerical model was validated. This model was then used to analyze the sensitivities of the moisture flow across imperfect hydraulic contact interface with respect to these three material properties.