MacroFlo

• Demonstrate how to reduce the need for air conditioning using natural / mixed-mode strategies
• Analyse all aspects of bulk airflow: infiltration, natural ventilation, facade design, mechanical ventilation
• Simulate air flow processes over different periods – from a single day to as long as a year
• Evaluate feasibility of strategies such as: single-sided ventilation, cross-ventilation, whole-building ventilation, chimneys, opening controls

MacroFlo simulates air flow driven by wind pressure and buoyancy forces (and mechanical air movement if used in conjunction with ApacheHvac).

MacroFlo uses a fast multi-zone thermo-fluid solver to simulate interaction between air flows, pressures and thermal conditions.  It models large air volumes and simulates air flow between these, through building elements such as windows and doors.

It enables you to easily define the size of window or door openings and how they will open and close.

It Incorporates models of:

• external wind pressure based on empirical data
• stack effect (buoyancy)
• flow characteristics of cracks
• flow characteristics of large openings
• two-way flow
• resistance due to grilles and wall friction
• Rayleigh instability

Input Data

• Building geometry passed automatically from ModelIT:
  • Room dimensions and connectivity
  • Co-ordinates of windows, doors and holes used as MacroFlo openings
  • Assignment of opening properties to windows and doors using a simple and efficient editing process based on opening types
• Opening properties:
  • Wind exposure
  • Crack dimensions and flow characteristics
  • Free opening area
  • Timing and degree of opening
  • Opening controls, expressed as functions of weather variables and conditions in any room
• Hourly wind speed, wind direction and external air density from weather file
• Data from ApacheSim and ApacheHvac building simulation and system thermal parameters can be used

Analysis Options

• MacroFlo’s flexible input structure allows analysis of problems involving any combination of infiltration, natural ventilation and mechanical ventilation.

Outputs

• Studies using MacroFlo can provide:
  • evaluation of natural ventilation solutions
  • evaluation of ventilation control strategies
  • an understanding of the performance of double-skin façades
  • analysis of room temperature statistics in naturally ventilated buildings
  • predictions of air velocities through openings
  • analysis of HVAC systems where the building is used as a return air pathway
• For each opening MacroFlo calculates:
  • Volume flows in and out
  • Mass flows in and out
  • Effective free area for air flow
• Aggregated air flows for each room are also available
• The effect on building and system thermal performance, and the weather data used to drive the simulation can be viewed
• MacroFlo results are displayed by the Virtual Environment program Vista
• Results are accessed via graphical views of the building, allowing interrogation of data at a hierarchy of levels: building, room, surface, opening
• Vista displays graphs, tables, monthly summaries, ranges or user-specified synopses
• Multiple results can be displayed simultaneously or aggregated
• Metric and imperial units are available
• Graphical and numerical data can be exported to Excel, Word and other applications.