Free Engineering Simulation Tutorial - Opensource Software & Simulation Guides

The PMV / PPD thermal comfort calculator on this page implements the Fanger comfort model exactly as defined in ASHRAE Standard 55 and ISO 7730 — the two internationally recognised benchmarks for evaluating the thermal environment of occupied buildings. Rather than judging comfort from air temperature alone, the model performs a full heat balance on the human body using six variables and returns two indices: the Predicted Mean Vote (PMV) , which places the average thermal sensation on a scale from −3 (cold) to +3 (hot), and the Predicted Percentage of Dissatisfied (PPD) , which estimates how many occupants will be uncomfortable. Figure 1 PMV PPD Calculation steps For HVAC designers, building-performance researchers and CFD analysts, PMV/PPD is the standard post-processing metric that turns a temperature and velocity field into a defensible statement about occupant comfort. This calculator is validated against the worked cases in ISO 7730 Annex D, and it pairs natural...

Ventilation is the most underrated system in any building. Get it right and occupants stay alert, healthy and comfortable while energy bills stay low. Get it wrong and you get stuffy rooms, condensation, mould, sick-building complaints — or an HVAC plant burning electricity around the clock to fix a problem that a well-placed window could have solved for free. This guide compares natural ventilation and mechanical ventilation in buildings in depth: the physics that drives each, what ASHRAE Standard 62.1 requires, energy implications, HRV and ERV heat recovery, hybrid mixed-mode design, and how CFD is used to prove a design works before it is built. Figure 1. Two ways to deliver fresh air. Natural ventilation uses wind pressure and buoyancy through openings; mechanical ventilation uses fans, ducts and filters to deliver a controlled airflow regardless of weather. Table of Contents Why Ventilation Matters Natural Ventilation: How It Works Types of Nat...