- Ventilation naturally ventilated CLASSROOM
"The Minergie standard requires a controlled ventilation the buildings. This leads to ensure that new school buildings are now almost exclusively equipped with mechanical ventilation. " Minergie means mechanical, controlled ventilation, especially after the revision since the is the spring of 2009 came into force. Since the trend is not supported at all to lower power consumption, compact as possible buildings and energy efficient building by mechanical ventilation, it is exciting to show a way that works without much effort and consumption.
To date, in Switzerland, no such structures are revealed on the air wing as Minergie certified buildings have been realized. The new standard, which comes into force in 2009, it is theoretically not possible to certify such a building, because Minergie requires a mechanical controlled ventilation. This raises the question whether Minergie can ever be related to energy-efficient construction in or whether Minergie simply means a certain standard of building. The already realisieten projects (especially Luxemburg is) is almost entirely concrete structures. The difficulty with the lightweight construction is not enough to kompenzieren building mass to the additional requirement of temperature during the period of ventilation. However, simulations show that this even in light design may well be possible.
"The high density of people in specific classrooms are large quantities of air required. This opens up inevitably a tension between the objectives of air quality and the necessary power consumption for air support. A disproportionate to avoid high technical complexity, have frequently been unsatisfactory compromise. A natural ventilation concept using motorized ventilation windows (which in principle is also Minergie-compliant) provides a much better alternative and ensures that the low-energy school buildings keep their promise: best Raumkonfort with minimum energy consumption. Appropriate dynamic simulations help to explain why the concept works.
window ventilation for the school system well suited
school buildings have clearly defined to use and break times, which are extremely good for periodic airing. Students and teachers have the opportunity to regularly produce by opening the window contact with the environment, which can also be educational. With its capabilities for direct and immediate influence of users on their air space to enjoy natural ventilation concepts according to experience wide acceptance. the correspondingly high level of user satisfaction could, for example, in a large study by the Fraunhofer Institute demonstrated impressive. "
simulations In one simulation, the following responses are found:
_ How does the classroom during normal operation? _ How big is the heat loss with a forced ventilation?
_ How To offset the heat loss?
_ What heat output is needed or useful?
_ Which air exchange is achieved with the airing in the breaks?
_ How do the CO 2
concentrations of indoor air?
_ what could be achieved during the lessons as needed with additional vents?
Fig. 2, simulation model of a classroom
Figure 3, output
Figure 4, temperature variation
heating demand
"During the ventilation time is during the breaks on the air a lot of heat power to the External environment. This does not lead necessarily to a high power demand of the radiator. The reheating of the cold fresh air during and immediately after the break is essentially passive by enclosing using the stored heat in the building mass.
room comfort can already by opening fewer air wings according sia required minimum outside air flow rate of 15m
3 per person per hour can be achieved. energy consumption Despite the apparent advantage of mechanical ventilation, the heat from being able to back win of the exhaust air, cuts in school buildings, the natural ventilation concept as well as energetically much better. The consumption of the drives of the air wing is compared with that of the fans of a mechanical ventilation system can be neglected. The simulations show takes place at the window ventilation, the heating of fresh air in the room with the majority of heat from the building mass. This saved is the excess internal heat (of persons and sun), which is used to passively. As the natural ventilation is only when needed, unused rooms are not ventilated unnecessary. This not only saves additional energy but also prevents drying out the rooms in winter.
Conclusion The natural pauses air conditioning design with motorized air wing for the school system can are generally considered to be very suitable. The great advantage of airing in the breaks is that entering through the extremely high air exchange with high ventilation efficiency, air quality, especially after the break when the students in the classroom is very good and feels the air fresh by mild hypothermia. The CO
2 concentration peaks are relatively moderate, and connect each have only very short notice. " My experience has shown that the project contracting must decide at a controlled ventilation on ventilation windows, unfortunately against the Minergie. Although this ventilation type is very forward looking and yes to an environmentally conscious project contracting can be very exciting.
dominique.tschudin @ mac.com
Sources:
_ building ser magazine, March 2009, No. 3
_ Fraunhofer Society for the Promotion of Applied Research
., Munich
_ Minergie , Switzerland
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