Natural Ventilation Solutions

Natural ventilation, unlike mechanical fan ventilation, simply uses the natural pressure differential force of air movement, wind and buoyancy to deliver a steady supply of fresh air for building ventilation and cooling.

Natural Ventilation Solutions

Mistrale Software Selection

Natural ventilation System design involves a number of complex parameters making system specification and design a more than healthy challenge.  In support of our Mistrale system we have therefore developed, in conjunction with the University of Strathclyde, an intuitive and user friendly software package that enables natural ventilation terminal selections to be made with relative ease.

The software is used for calculating the ventilation product sizes to achieve a required level of fresh air input in a target room within a naturally ventilated building. The tool models simple building configurations, consisting of one or more neighbouring rooms, on up to three floors. Both summer and winter conditions can be assessed and different methods to create the natural air flows can be explored.

Exact dimensions for specific products with real CE values, in conjunction with any windows, extract terminals or boost extract fans can easily be determined.

Key Features:

  • Provision of clear guidelines for the establishment of space loads whether from occupants, lighting, transfer or solar.
  • 6 types of typical building models are available ranging from 1-3 storeys in height. Inlet, transfer and exhaust ventilation units are selectable for each area
  • Fresh air requirements per person are illustrated and are input into the design automatically. This data is variable floor by floor.
  • Various inside and outside temperatures can be input for both summer and winter conditions together with directional and dynamic wind speeds
  • Mixed mode feature included to mimic inclusion of an exhaust boost fan facility
  • Over or under heating data is provided so that coil selections for units can also be included
Mistrale Software

Ventilation may enter and leave via one face of the building, or it may pass through the room in a cross flow ventilation scheme. There is the option for air to pass to or from a common atrium, or tower, either directly, or via a corridor. The tool takes account of the combined effects of external wind pressures on air flow through openings into the building, and internal temperature differences that create buoyancy driven flows within the building. Air flow rates are calculated for each external opening, and the direction of flow indicated on a schematic diagram. The ventilation rate in the target room, in air changes per hour is calculated for each room.

The net heating or cooling load is also calculated based on the ventilation flow into the room and the quantity of heat required, after allowing for internal gains, to bring that air up to the specified room temperature. This is not a dynamic calculation, just an indication of steady state ventilation load, assuming required plant capacity is available.

Users can establish specific target design parameters with the software allowing easy comparison of the current calculated flows with the actual targets.

An export feature finally allows the results of one or more cases to be summarised as a series of project schedules, and saved or printed as a pdf.

For any assistance with sizing and selection please contact our natural ventilation team at our head office