Applications MacroFlo

Overview

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

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

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

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 results analysis programs Vista and VistaPro
Results are accessed via graphical views of the building, allowing interrogation of data at a hierarchy of levels: building, room, surface, opening
Vista and VistaPro displays graphs, tables, monthly summaries, ranges or user-specified synopses
Results from MacroFlo include arrows showing airflow in and out of the building and wind rose settings for any time of the year
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

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 and window opening category.

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