Here's the problem with most online "AC calculators": they multiply your floor area by a single number and call it a day. But a 15×12 bedroom with two shaded north windows and a well-insulated wall needs a completely different air conditioner than the same size room with big west-facing glass under an uninsulated roof — sometimes twice the capacity. Floor area alone can't see that difference. The calculator below can, because it uses the real component heat-gain method from ASHRAE and ACCA Manual J — the same physics HVAC engineers use. Enter your room's actual construction and get a genuinely accurate cooling load, ready for a real purchase decision. Figure 1. A real cooling load is the sum of heat entering through every surface — walls, windows, roof — plus solar radiation through glass, air leakage, and heat from people and equipment. Accurate AC sizing means adding all of these, not guessing from floor area. Table of Contents The R...
Most fire deaths are caused not by flames, but by smoke. Toxic gases and loss of visibility disable occupants long before fire reaches them — which is exactly why predicting how smoke and heat move through a building is one of the most valuable things a fire safety engineer can do. The best tool for that job is free, open source, and built by the US government: FDS — the Fire Dynamics Simulator . This guide explains what FDS is, its capabilities and application areas, how any user can get started, and how it helps prevent fire disasters in buildings. Figure 1. What FDS models: a fire generates a rising thermal plume, hot smoke banks down under each ceiling, and occupants must escape before visibility and temperature become untenable. FDS predicts these smoke and heat flows hour by second across the whole building. Table of Contents What Is FDS (Fire Dynamics Simulator)? Capabilities of FDS Application Areas Smokeview, BlenderFDS & Companion T...