Example - for a 3-bedroom, 2,000-sq.ft. home, with an exhaust-only ventilation strategy, and a target ventilation rate of 50 CFM you would need to install a 50 CFM fan with an adjustable-speed DC motor for continuous operation.
Quick Answer. Trenches were built during World War I to protect stalemated troops on both sides from artillery and rifle fire. Although the war began with rapid movement of the German army, when the Allied forces stopped the Germans, both sides dug trenches to help avoid losing territory they had gained.
One of the key purposes of a military staff is to provide accurate, timely information (which includes the results of contingency planning) on which command decisions are based. A goal is being able to suggest approaches or help produce well-informed decisions that will effectively manage and conserve unit resources.