ventilation

Enhancing the energy efficiency of buildings imposed by global warming and by the perspective of fossil fuel dwindling requires new technical solutions, more efficient. The race for efficiency directly affects ventilation and air tightness of buildings, the main potential causes of heat loss in homes. If heat recovery is emerging as an effective solution to meet energy performance and indoor air quality in climates with harsh winters, some other solutions appear to be very efficient in moderate climates.

Most European standards and national regulations about ventilation rates are based on indoor air quality assumptions in terms of contamination. On the other hand, indoor air humidity is important for human health as well. In case of high flow rates during the heating seasons in cold climates, the indoor air humidity tends to low values.

Recently, in order to reduce energy consumption in the building sector, many air-conditioning systems have been proposed and applied to real buildings. Of particular note, air-conditioning systems that treat sensible and latent loads separately have been assessed as efficient in hot and humid climates. In this study, a highly efficient desiccant system combined with a cogeneration system and a heat pump desiccant system has been developed.

Cold storage is a way to deal with peak cooling loads. Cold storage integrated with building structures is independent of the approach used for building cooling – it can be used with passive cooling as well as mechanical cooling. High thermal storage capacity in a narrow temperature interval makes phase change materials (PCMs) a suitable medium for cold storage in built environments. A set of experiments was performed with the aim to investigate performance of PCM cold storage in building structures under various ventilation strategies.

Tracer gas measurements are an unparalleled means of measuring air recirculation, leakage, and air flow rates in air handling systems [1-5]. However, such measurements are subject to significant measurement uncertainty in field conditions. A common problem is imperfect mixing of tracer gas.

Reduction of infiltration in the Equinox House, a residence under construction in Urbana Illinois, has been characterized through a series of blower tests as different joints and seams in the building were sealed. Equinox House is constructed with 30 cm thick SIPs (Structural Insulation Panels) wall and roof panels consisting of a Styrofoam core and oriented strand board sheathing on interior and exterior surfaces. Blower door tests were performed as each type of seam in the house was sealed.

It is estimated that people in the developed world spend more than 85-90% of their time indoors. Of this, most is spent in homes. To minimize health risks from pollutants occurring in homes, exposures should be controlled. The most effective way to achieve this is to control sources of pollutants and to reduce emissions. Often, especially in existing buildings, this strategy is difficult to implement, in which case exposures are controlled by providing sufficient, presumably clean, outdoor ventilation air to dilute and remove the contaminants.

The use of supply jet flows is the most common type of air distribution for general ventilation. Usually the supply flow rate is constant or slowly varying (VAV-systems) to cope with a varying load. A novel air distribution method, with the potential to reduce stagnation and to increase the ventilation efficiency, is to introduce rapid flow variations (pulsations). This paper reports on a fundamental study of this type of air distribution.

This study copes with the problem of ventilation in existing educational environments in terms of indoor air quality (AIQ), comfort and energy consumption. In accordance with international regulations, densely occupied environments such as school classrooms need high air change rates in order to provide sufficient fresh air. Nevertheless, in Italian schools, it is rare to see mechanical ventilation systems or natural systems that are mechanically controlled. This means that it is necessary for the users to control air changes by opening or closing the windows.

To clarify the indoor climate in Japanese college classrooms, an air-conditioned, mechanically ventilated classroom of a university was surveyed. Temperatures, humidity and carbon dioxide (CO2) concentration in winter and summer were measured before, during and after lessons. The airtightness of the room and the airflow rate of the ventilation system were also measured. In winter, at an outdoor air temperature around 0 ºC and with the thermostat temperature of the air conditioners set to 30 ºC, the vertical difference in room air temperature exceeded 10 ºC.