Th. Frank

Gypsum Board in Fire — Modeling and Experimental Validation

The thermal behavior of a commercially widespread gypsum board (810 kg/m 3) under fire condition has been investigated. For this purpose two 12 mm thick gypsum boards are subjected to the standard fire ISO 834 and the temperature distribution within them is measured by means of thermocouples placed at different depths in the samples. The results hereof are used to validate a numerical model based on the density, thermal conductivity, and effective heat capacity of the gypsum board as functions of temperature. The effects of dehydration/calcination and decomposition on these properties are determined by using thermogravimetric analysis, conductivity measurements after different heat treatments, and differential scanning calorimetry under air flow, respectively.

Analysis of Thermal Comfort Near Cold Vertical Surfaces by Means of Computational Fluid Dynamics

Cold surfaces may cause thermal discomfort due to down draught and/or infrared radiation exchange. In this paper a cold vertical surface of 3m height in a room (3 × 3 × 5m3) was investigated using computational fluid dynamics (CFD). Also calculated were a parameter that expresses thermal discomfort for the whole human body – the predicted percentage of (those people) dissatisfied – and parameters of local discomfort such as air speed and draft risk. Five cases with different heat loads (0–80Wm−2) and with/without furniture were simulated, each case with three different temperatures of the cold surface (17.5, 15, and 10°C). The mean operative temperature was approximately 20°C in all cases. It was found that with respect to thermal discomfort, draught was more critical than reduced operative temperatures or radiation asymmetry. An increase of the heat load in the room leads to higher down draught air speeds. Therefore, experiments performed in empty rooms tend to underestimate the maximum air speed that occurs in real, furnished rooms with heat loads. A set of correlations for maximum air speed within the occupied zone is proposed. Additionally, this study shows that CFD is a valuable technique to complement and broaden knowledge gained in laboratory experiments in the field of thermal comfort.

The influence of thermal and solar radiation on the energy consumption of buildings

Abstract By application of weather-resistant infrared 8 /smm to 14 /smm mirror coatings to the building envelope, the heat consumption can be reduced by up to 20% for single-family houses and by up to 12% for apartment and office houses in central Europe. This paper gives a review on the various theoretical and experimental aspects of this statement. This discussion includes visible and i.r. properties of the atmosphere, the solar radiation and the building envelopes as well as the other modes of heat consumption of houses. The predicted saving of heating energy was realized for test cabins in field experiments which served as a basis for parametric computer studies on actual buildings. The manufacture of weather-resistant i.r.-mirror coatings on metal and glass facades is discussed.

A Humidity Dependent Vapour Retarder in Non-ventilated Flat Roofs. In Situ Measurements and Numerical Analysis

The influence of a humidity dependent vapour retarder on the annual moisture distribution in thermally insulated flat roof constructions has been investigated by means of long term in situ measurements and two numerical simulation methods. It is shown that the simple Glaser method is not suitable to predict the moisture distribution in this type of construction under real climatic conditions and that only a transient hygrothermal analysis is able to reproduce the measured temperature and relative humidity. Based on both measurements and transient numerical simulations, the role of the vapour retarders for this type of constructions has been evaluated.