Blind controls
EOLIOS designs or rectifies the sizing and regulation of your blinds:
- Study of anemometer positioning
- Site audit with portable anemometer
- Designing blind control laws
- Numerical modeling of extreme winds
- Design of natural ventilation control systems
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Blind control sizing
EOLIOS brings its experience in urban aeraulics and large structures to bear on the efficient regulation of awnings. This regulation is crucial to the preservation of outdoor awnings.
Indeed, the awning is an effective protection to protect yourself from the sun. The blinds are motorized and regulated from anemometers causing the blinds to rise automatically if a wind threshold is exceeded.
European standard 89/106/CEE “Construction products” specifies the performance requirements that must be met by external blinds fitted to buildings. She asks to indicate at what speed of wind the awning can withstand. A classification into four classes has been determined so that the consumer can easily tell the difference.
Each class has its own maximum wind speed given in Beaufort or km/h (see table below).
Cold aisle / hot aisle design
The Beaufort scale is an empirical measurement scale, with 13 degrees (0 to 12), of the average wind speed over a period of ten minutes used in maritime environments. An anemometer constantly analyzes the intensity of the wind. As soon as the tolerance threshold is exceeded, the blind goes up automatically. It is essential to choose an environment without obstacles and air disturbances to have accurate data.
Analysis of correlated wind speeds
As you might expect, the wind measured by the anemometers is not consistent with the wind arriving at the blinds, and can lead to premature destruction of the blinds.
Indeed, the wind speeds are specific to each point of the roof and the facades of the building. Thus, the air speeds at the level of the anemometers are not necessarily correlated with the speeds on the facade where the blinds are located. Local phenomena modify the distribution of the flows which can disturb the functioning of the measuring systems.
Our studies take into account all the geometric details necessary to solve the problems. Several levels of scales, building (district), terrace (area), windbreak (particular elements) are refined separately so as to increase the resolution in the study areas.
Analysis tables will take up the profiles of the wind speeds at the level of the blinds or in critical zones and will be compared to the measurement point of the anemometer. Example :
Depending on the results of the analyses and the final placement of the anemometers, a reprogramming law will be proposed, taking into account the most unfavorable winds for the blinds.
On-site wind measurement :
We can carry out smoke tests in order to understand and situate the particular trajectories of the wind at the level of the blinds and the anemometers (terrace and roof area). We then generally produce a series of diagrams making it possible to explain the main lines of the wind on site, the specific aeraulics per floor and the behavior of the anemometers with respect to the blinds. These smoke analyzes are returned by video so that the operator obtains a general understanding of the impact of the wind on the building (for a single wind) in relation to the anemometers. The blinds subject to the most critical tearing are identified.
At the same time, we are taking measurements with a portable anemometer at the level of the blinds and the anemometers so that the operator can study the returns from the BMS. This also allows a more precise understanding of airflow effects in physically accessible areas.
The positioning of each anemometer is audited and the site effects are explained according to the observations. Simultaneous anemometric readings are taken so as to note the scale factors between the accessible blind zones and the anemometer zones.
EOLIOS generally visits the site twice for two similar audits for different winds. These audits are therefore dependent on weather conditions and can only be scheduled 48 hours in advance. If the site’s security conditions allow it, the EOLIOS engineers can evolve independently.
Beyond the simple measurement report, EOLIOS will recommend, in view of its experience and its understanding of the site, the modification of the location of the anemometers. We will also alert the operator, if the new positioning of the anemometers may include wind origins for which its results may be obsolete.
We would like to point out that this measurement and analysis campaign enables us tooptimize the operation of the anemometers, but cannot provide an exhaustive analysis of the phenomena, as only the accessible zones can be studied. As an option, we can also carry out numerical studies to gain a more detailed understanding of aeraulic phenomena.
Video – Study of the effects of wind in cities – La Défense
