The idea that intend temperatures can be reduced by ventilating the air-space between the ceiling and the roof (the attic) of a house, is widely acknowledged by Civil Engineers and Architects. This phenomenon was evaluated through three softwares (CASAMO-CLIM, COMFIE and SPIEL) which were designed for the analysis of the thermal performance of buildings, by comparing the results of all three.
The "Passivhaus Darmstadt-Kranichstein" is a 4 unit terrace house with an extremely low total annual energy consumption of less than 32 kWh/m² of living area, thereof about 12 kWh are needed for room heating /Feist 1994/. The determinig factors for the low consumption are the superinsulation, airtightness of the thermal envelope in combination with a highly efficient VAV ventilation system, and an improved window construction. The "Passivhaus" therfore is a typical example of an improved low energy house.
Computational fluid dynamics has been used for assessing the thermal comfort and air quality in an office ventilated with a displacement system for a range of supply air conditions. Thermal comfort is predicted by incorporating Fanger's comfort equations in the airflow model. Indoor air quality is assessed according to the predicted contaminant concentration and local mean age of air. The performance of the displacement ventilation system is then evaluated based on the predicted thermal comfort and indoor air quality.
The technology of chilled ceilings is currently a favourite issue among HVAC technicians. In this article the author describes the advantages of this system.
Indoor climatization requires temperature and humidity control. The physical processes affecting the heat and vapour balance comprise heat and vapour diffusion across the envelope, ventilation, water evaporation or condensation, metabolic heat and vapour generation, solar and auxiliary heating.
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