English

Airtightness of buildings is necessary to obtain healthy, sustainable and energy efficient buildings. Measuring the airtightness of a building has become more common lately, much due to the higher energy use in leaky buildings. The airtightness of a building can for example be measured in order to attain a certification, or on demand from a developer. In some studies, there have been large seasonal variations in airtightness. In most cases, the buildings are more leaky in wintertime, but there are also some investigations that show the opposite.

Numerous studies have investigated the application of multi-zone demand-controlled ventilation for office buildings. However, although Swedish regulations allow ventilation rates in residential buildings to be decreased by 70 % during non-occupancy, this system is not very common in the sector. The main focus of the present study was to experimentally investigate the indoor air quality and energy consumption when using multi-zone demand-controlled ventilation in a residential building. The building studied was located in Borlänge, Sweden.

In low energy buildings and passive houses due to very low heating demands integrated heating and ventilation (VAV or DCV) systems are used to provide proper indoor climate conditions – thermal comfort and indoor air quality. Dynamic changes of indoor conditions result in permanent changes in air flow.

Demand controlled ventilation (DCV) is seen more and more as a promising way to limit the energy consumption due to ventilation in buildings. However DCV is always a compromise between decreasing the ventilation flow rates and assuring the indoor air quality (IAQ). Ventilation requirements are usually expressed as required air flow rates in the ventilation standards and regulations. Up to now, no consensus for an absolute criterion of IAQ exists in the international scientific community.

Mechanical positive input and extract ventilation are common strategies employed in English houses, generally because they provide adequate indoor air quality and specifically because they are effective at minimizing mould growth and its associated negative health consequences. Air is either exclusively supplied or extracted (never both) by a mechanical system at a prescribed airflow rate designed to ensure adequate indoor air quality.

We propose a new approach for measuring air infiltration rates in buildings. The method belongs to the class of tracer gas techniques but, unlike conventional CO2 based methods that assume the outdoor ambient CO2 concentration is constant, the proposed method recognizes that photosynthesis and respiration cycle of plants and processes associated with fuel combustion produce daily, quasi-periodic, variations in the ambient CO2 concentrations.

The present study aims at investigating carbon dioxide (CO2) concentrations inside elementary schools’ classrooms and how students’ productivity is affected. Measurements were conducted in 9 naturally ventilated schools of Attica from April to May 2013. Monitoring lasted for 7 hours per day, for a period of one to five days per school. CO2 concentrations were monitored simultaneously in the inside and the outside environment of the classrooms. Indoor concentrations of CO2 in almost all schools were higher than the ASHRAE threshold limit values.

Cooking devices are a major source of contaminants in dwellings. They cause exposure to combustion products and vapors. The type and production rate of contaminants depend on the heating type (gas vs. electric cooking) and cooking process (frying vs.

In both, newly built and renovated buildings the building air-tightness has to be ensured. With a tight building envelope comes a low infiltration air-exchange. A minimum outdoor air exchange to ensure acceptable moisture and indoor air quality levels must be maintained. A model is introduced, that couples hygrothermal whole building simulation with a multi-zone air-flow simulation.

In the past, many churches were raised and in a church building no heating no heating system was installed, except a simple individual coal or peat stove, which could be rented by the churchgoers. The thick high stone walls of the church alleviated the fluctuations of the ambient air temperature and relative humidity. Accordingly, the indoor climate in the church building was quite stable. After the Second World War the living standard of the people increased and the increased prosperity also led to higher comfort demands in churches.