At Hermann-Rietschel-Institute systematic tests of the limits for the ventilation with openable windows are under way. The parameters temperature distribution and air velocity are the most attended values. Window ventilation in office buildings has limits in application. An open window can remove cooling loads out of the room. With one window and a room with a depth of 5 m, the maximum cooling load is about 20 to 30 W/m2. These limits are determined by air velocities within thermal comfort.
In predicting the thermal environment of an indoor space affected seriously by the outdoor weather like an atrium using natural ventilation, it is essential to grasp the impact of the external outdoor weather precisely. This report describes the result of the analysis of the outdorr and indoor region including solar radiation analysis considering the date and hour, latitude and longitude taking the atrium under construction in Kyoto as an example.
In the EU Joule project Nat Vent one of the work packages was dealing with controlled air flow inlets. During the last conference in Greece and overview was presented on availability, performances and application of controlled air flow inlets. At the presented poster an interactive IAQ computer tool was demonstrated. This tool has been improved and is now available. Some participating countries in the Nat Vent project have carried out special tests with the NatVent IAQ tool. The NatVent participants were asked to design a natural ventilation system according to their national requirements.
Predicting the movement of smoke in a naturally ventilated building is a difficult process for architects and design engineers alike. A software model developed by the Fire Research Station may provide a solution.
Natural ventilation is a sustainable, energy-efficient and clean technology that is well accepted by occupants. It can be used to provide fresh air for occupants as necessary, to maintain acceptable air quality levels and to cool buildings in cases where climatic conditions allow. The successful application of natural ventilation techniques and the effectiveness of natural ventilation are determined by the prevailing outdoor conditions and microclimate as well as by building design and building use.
Conventional evaporative coolers are high-pressure high-volume devices that deliver cool air by water evaporation wetted pads. Natural down-draft evaporative coolers, or "Cool Towers", are devices developed at The University of Arizona's Environmental Research Laboratory. Similar to conventional coolers, these devices are equipped with wetted pads and sprays at the top which provide cool air by evaporation but the air is moved by gravity flow saving the energy required by the blower. In arid regions, cool towers are useful for cooling buildings and outdoor private and public areas.
Natural ventilation in office buildings can sometimes offer other advantages than traditionalmechanical ventilation systems. Often natural ventilation systems are promoted at an earlystage by an architect, but perceived dificulties, e.g. to pre-determine the function of a naturalventilation system, can serve as a barrier and a mechanical system is often chosen instead.
Previous work by Linden, Lane-Serff and Smeed (1990) has developed a simple mathematical model for natural displacement ventilation of an enclosure. The work also introduced the experimental salt-bath technique, which uses salt solutions and fresh water to generate buoyancy forces that are analogous to those found in naturally ventilated buildings. The work claims that a good correlation exists between the predictions of the simple mathematical model and the results obtained using the salt-bath technique.
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