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.
Introduction. A tomb is a house, chamber or vault for the dead. The original purpose of a tomb was to protect the dead and provide the deceased with a dwelling equipped with necessities for the afterlife. Tombs probably arose from the prehistoric practice of burying the deceased in their own homes.