Overview
It Incorporates models of:
- 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
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 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
Summary
- 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.
Gallery
