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.
Conditions in the trenches during WW1 were horrendous. Better trenches would be about seven feet deep and 4-6 feet wide. Sometimes sand bags would line the sides of the trench otherwise a kind latticework wall of hazel branches was used (a bit like hurdle fences).Planking would be laid in the base. On the lip of the trench would be sand bags and barbed wire.etter trenches would be about seven feet deep and 4-6 feet wide. Sometimes sand bags would line the sides of the trench otherwise a kind latticework wall of hazel branches was used (a bit like hurdle fences). Planking would be laid in the base.