AIVC - Air Infiltration and Ventilation Centre

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mechanical ventilation

Uncontrolled ventilation in connection with mechanical exhaust. Hallitsematon ilmanvaihto koneellisen ilmanpoiston yhteydessa.

Notes that if the exhaust air flows in an apartment building are adjusted to the same value in similar apartments, the pressure conditions may not be the same in these apartments. 

The use of tracer gas for determining ventilation efficiency.

The local ventilation efficiency of a mechanical ventilation system may in general terms be defined as "providing air in those parts of a room where it is required". In this paper different definitions of the local ventilation efficiency and methods for measuring it are discussed. Presents results from measurements of ventilation efficiency. A test room was mechanically ventilated and nitrous oxide used as a tracer gas. A number of sensors were placed in the room with the aim of determining the variations in the air change rates within the room.

Study of the internal climate in selected rooms of a Berlin school. Studie uber raumklimatische Umbegungsbedingungen in ausgewahlten Raumen eines Berliner Mittelstufenzentrums.

Reports findings of investigations carried out by West German Federal Ministry of Health in July 1978 into the internal climate in the one third of the rooms in a representative West Berlin school which are located in the building core. These rooms have mechanical ventilation and artificial lighting. Gives results of measurements of room temperatures, air change rates, (measured using N2O as a tracer gas), concentration of carbon dioxide and acoustic performance of the rooms.

There will soon be 50,000 FTX systems in single-family houses in Sweden. Snart 50,000 FTX system i Svenska smahus.

A market review of inlet/exhaust ventilation with heat recovery in single family houses. Traces recent developments in new house production. Tabulates review on several criteria including manufacturer, type, flow rate, frost protection, position of heat exchanger, type approval. Review covers over 40,000 units installed.

The effect of reduced ventilation on indoor air quality and energy use in schools.

Indoor air quality in an air conditioned California high school has been measured over a variety of ventilation rates ranging from 13.3 cubic feet of outside air per minute for each classroom occupant to approximately 1.5 cfm per occupant.< Parameters measured include outside air supply rate, the occupants' subjective perception of indoor air quality, airborne microbes, carbon dioxide, carbon monoxide, nitrogen oxide, sulphur dioxide and ozone in two classrooms, a halland outdoors.

The Ekono building - cost effective energy design.

Discusses energy saving measures taken in the Ekono office building, headquarter of Ekono consulting engineers, situated near Helsinki. Describes the use of hollow slabs for intermediate floors, tight window construction, the extract air window system, efficient lighting and computer control of ventilation. It is planned to control ventilation by monitoring the concentration of carbon dioxide in the building. Reports measurements of infiltration rate with nitrous oxide as a tracer gas using both constant concentration and decay rate techniques.

Air flow variation of HVAC caused by stack effect and opening a window.

Unopenable, fixed windows have been widely used in high-rise buildings in Japan, but the energy crisis has forced a reconsideration of the merits of natural ventilation with openable windows. However opening windows inhigh-rise buildings, has the disadvantage that open windows causes air flow variation of a mechanical system due to stack effect.< Reports results of a computer simulation of this problem. Describes computer program to calculate air flows in a building. Describes example building, giving air leakage and HVAC system characteristics.

The case for controlled ventilation of houses

Fresh air requirements in individual rooms of an occupied house vary between 0.5 and 2 air changes per hour depending on the number and activity of the occupants. The most common method of ventilation control is by opening windows but measurements show that even quite moderate window opening results in air change rates greater than 2 air changes per hour throughout a house.< Reports measurement of the energy cost of window opening in a test house with a heat loss coefficient of 5 kWh/K day. Finds in a low energy house,controlled ventilation is essential.

Air-to-air heat exchangers : saving energy and improving air quality.

Describes the use of mechanical ventilation coupled with heat recovery devices in residential buildings to maintain acceptable indoor air quality and conserve energy. Gives tables showing the energy saving possible with a heat exchanger.

Ventilation rates

Treats investigations in office building where 1) flow rates of supply air, return air and ventilation between main office area and adjacent rooms were measured with an anemometer. Return air rates remained constant but ventilation rates varied widely during measurement periods. 2) CO2 was used as tracer gas to determine ventilation rates in offices. Calculates alterations in gas concentrations in rooms adjacent to stairwell and changes in outdoor air concentrations. During air conditioning, ventilation rates in the room were 4-5 room air changer per hour.

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