mdwom

This mode is intended for a grouped mixed mode system where openings are controlled from the maximum dry bulb temperature of a Zone Group. This 'maximum group temperature' is the largest dry bulb temperature in all the zones belonging to the group. The apertures are closed as the maximum group temperature exceeds a cut-off value, so mechanical cooling can be introduced through Internal Conditions. This mode requires the following parameters.

 

Parameter

Description

Zone group

The name of the zone group whose maximum dry bulb temperature will control the aperture.

Lower limit

The aperture will be closed if the controlling dry bulb temperature is below this value.

Upper limit

The aperture will be fully open if the controlling dry bulb temperature is above this value.

Cut-off

The aperture will start to close as the maximum group temperature rises above this value. The aperture will be fully closed at one degree above this value.

Upper wind speed

The aperture will start to close when the wind speed exceeds this value. The aperture will be fully closed at 0.5m/s above this value.

 

For example, the automatic control function mdwom could have the parameters set as follows:

This would define the following strategy for aperture opening. As the maximum group temperature in zone group 'Offices' rises above 22C the aperture would start to open. The aperture would be fully open at 24C and remain fully open until 25C when it would start to close. At 26C and above the aperture would be closed. The aperture will also close if, at any time, the outside temperature is greater than the group maximum temperature. The aperture starts to close when the two temperatures are equal and will be fully closed when the outside temperature is one full degree above inside. The wind speed will also start to shut the aperture as it increases above 5m/s and be fully closed at 5.5m/s. For a full description of how final aperture opening values are calculated please see the section: Aperture Type Functions.

 

odwom