English

Traffic emissions have a significant impact on urban air quality, which particularly concerns street canyons, i.e. spaces with limited air exchange. Traffic emissions in street canyons create high concentrations of air pollutants. Based on measurements carried out for selected routes and model experiments conducted in a wind tunnel, it is shown that a roadway’s urban structure has a significant impact on concentrations of pollutants from traffic emission which enter buildings by means of mechanical and natural ventilation systems.

Many buildings in Sweden are in need of renovation in order to meet the current standards of energy use in buildings. Particularly challenging are old listed buildings, the majority built before 1950, because the renovation is restricted to the parts that do not change the appearance of the building. This paper presents experiences gained during the renovation of a listed building where aging of materials, movements and settlements during the building operation have left trails in form of air leakage paths that are difficult to cover by renovation.

A voluntary certification for very low energy buildings has been implemented in 2013 in France, which requires among other the ventilation systems to be controlled by an independent technician. To ensure the expertise of these technicians, a certification scheme has been implemented for the airtightness measurement of ductwork. This certification will soon be required for the ventilation system controls.

When one intends to evaluate buildings energy efficiency their airtightness is a fundamental parameter. Airtightness is linked to undesirable and uncontrolled ventilation and, therefore, should be minimized. Quantitative characterization of expected leaks of common building elements would be useful for practitioners that intend to improve building enclosures for airtightness optimization. The most well accepted experimental procedure to evaluate in-situ buildings’ airtightness is the fan pressurization method, typically making use of a “blower door” device.

In recent years there has been much emphasis on improving the energy performance of Irish buildings. Much of this impetus stems from our requirements to implement provisions in the Energy Performance Building Directive (EPBD, 2002/91/EC, 2010/31/EU), and international targets to reduce CO2 emissions by 2020. In Ireland, residential buildings account for 27% of Ireland’s CO2 emissions after transport. As a large proportion of the Irish building stock has already been built home owners are encouraged to retrofit existing buildings to improve the energy rating.

Variable air volume (VAV) ventilation systems reduce fan power consumption compared to constant air volume (CAV) systems because they supply air according to the airflow demand. However VAV ventilation systems do not take fully into account the potential energy savings as the control strategy operates the terminal boxes and the air handling unit (AHU) independently without pressure integration. The pressure in the main duct is maintained at a constant static pressure (CSP) which corresponds to the pressure required under the design full load condition.

The framework of the research presented in the paper is a project oriented to promote the use of concrete solutions in buildings based on maximizing the benefits of its thermal inertia for cooling periods.

The constructive solution developed has one configuration for summer (cooling mode). This configuration is similar to a ventilated facade that is formed by a thermally insulated outer layer of concrete, an intermediate air layer and an inner layer of concrete. The inner layer is cooled at night by forced ventilation using an outdoor - outdoor scheme.

The airtightness test of the building is one of a few building envelope measurements used in practice, which is quantitative, not just qualitative as e.g. infrared thermography. The so-called blower-door test result may be a measure of the building design and construction quality and could also be used for the energy demand for heating and cooling analyses.

As the benefit of natural ventilation in reducing operational cost is well recognised, the concept of natural ventilation is becoming more received by residents and designers alike.

The energy efficiency and energy consumption of mechanical ventilation systems depend mainly on the heat and cool recovery efficiency and the operational costs of electric energy for air handling unit fans.

For free pre-heating of fresh air in winter and pre-cooling in summer and to protect the heat exchanger in the air handling unit against freezing earth-to-air heat exchangers (EAHEs) are used. For large demand of fresh air multi-pipe systems are used to diminish total pressure losses and provide required amount of thermal energy.