The air distribution in a room is investigated using computational fluid dynamics. Four common methods of supplying air to a room are compared. The effect of air change rate on the ventilation effectiveness for contamination is small, however the effect of room heating or cooling load can be very significant. It was found that air turbulence has a major influence on the air movement, air velocity and dispersion of contaminants in the room.
Existing regulations concerning the design and construction of residential buildings which are naturally ventilated via courtyards and lightwells have origins in daylighting rather than in aerodynamics. The design of narrow, high-sided courtyards which achieve healthy . conditions for occupants, has long been a problem and a subject of various guidance and research, although many doubts and gaps in knowledge still remained. The work described below resolves these problems, and the coherent theory developed may lead to clearer guidance on the design of courtyards for natural ventilation.
Computational fluid Dynamics (CFD) is a powerfizl tool for analysing problems of air movement and has been increasingly widely used in applications in buildings. The emphasis has often been on its development as a replacement for the experimental approach, however, further work is needed to develop confidence in applying CFD to problems of air flow in buildings.
In the framework of a CEC demonstration project on humidity controlled ventilation, detailed measurements are carried out in 18 apartments in Namur, Belgium.The paper gives a brief description of the building, of the airtightness of the apartments and of the ventilation provisions. The largest part of the paper deals with the major outcomes of the study.
The importance of natural ventilation, typically restricted to residential buildings application, is rapidly increasing also within the commercial buildings. This is mainly due to the energy savings expected from a reduction of the use of the forced ventilation. Moreover, the remote control of the indoors, provided by means of the intelligent buildings features, allows an easier management of the environmental quality. Furthermore, the indoor air quality is also directly affected by the air exchanges obtained by natural ventilation.
The BRE method of predicting water vapour conditions in houses is based on two generalised moisture admittance parameters a and p. Previous laboratory experiments suggested that it is possible to determine these coefficients for an unfurnished room with wooden panels, using measurement periods of six hours under dynamic equilibrium conditions. The present study explores the possibility of using such conditions to determine a and P in-situ for the living-room and bedroom of a furnished flat of conventional construction.
The momentum balance on a centrifugal fan, supplemented by a complete energy balance for rigorous interpretation of power-pressure interactions, relates these variables to flow rate and fan speed. Non ideal behaviour is modeled by direct mechanical interpretation and by engineering correlation, leading to more general expressions than provided by the fan laws. First attempts to fit these expressions to measured data show promise but reveal limitations of current practice in the data collection and reporting process.
A new miniature mechanical ventilation system with both supply and extract air and an air-to-air heat exchanger has been developed in Great Britain and Denmark. The system which is intented to ventilate a single room has the dimensions of a shoe box and can be placed/installed on the inside wall in an existing air vent. The system can operate with two air flows, 40 or 70 m³/h. At the low speed the noise is insignificant, intended to be "not disturbingN in sleeping rooms.
Several demonstration buildings were constructed in order to find technical solutions to energy saving and better indoor air quality in the 1980's in Fiand. Warm air heating systems were installed in two multi-storey residential buildings and in several single family homes. Heat recovery units were installed in many buildings. During renovation, mechanical supply air and heat recovery units were installed in two multi-storey residential buildings. Studies on energy consumption and performance of air conditioning systems were carried out in the demonstration buildings.
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