Ulf Larsson

Thermal analysis of super insulated windows (numerical and experimental investigations)

Windows are crucial for peoples experience of the indoor climate, especially in the Nordic countries with cold climate and short days during the winter. This paper reports the first results from an ongoing research project focused on an improved integration of windows with the indoor air climate and peoples perception of the windows. The thermal performance of a well-insulated window has been investigated both numerically and experimentally in a full scale test room. The window under consideration is a low-emissive triple-glazing window with two closed spaces filled with the inert gas krypton. An oxidised metal with low emissivity factor coats one pane in each space. Experimental and numerical investigations on the thermal performance of the window have been conducted for different winter cases. Temperature data obtained by direct temperature measurement using thermocouples and through numerical analysis are presented. The heat transfer through a window construction depends on three mechanisms i.e., conduction, convection and radiation. In this paper the convection-conducting mechanisms have been closely investigated. The numerical predictions agree well with the results from the measurements.

Experimental investigation of downdraught from well-insulated windows

Since the climate in the Nordic countries is cold for several months a year, windows are crucial in building envelopes. The current trend to reduce heat losses by building components has resulted i ...

Comparison of ventilation performance of three different air supply devices: a measurement study

ABSTRACT People today spend a significant part of their time in an indoor environment, whether it be home, school, vehicle or workplace. This has put greater demands on indoor environment, in terms of both air quality and thermal comfort. The main objective of building ventilation is to take care of pollutants and lower their concentration, but it is also used to cool or heat indoor air. The aim of this paper was to study the behavior of three different ventilation supply devices, i.e. mixing supply device, displacement supply device and confluent jet supply device, in an office room. Different cases have been studied experimentally with different airflow rates, supply air temperature and supply devices. The results shows that mostly that we can expect, but the results show a very small difference in ventilation efficiency between the different systems and in theory there should be a larger difference.