Consider a 200,000-ft2 enclosed parking garage that can hold 1,000 cars.

a. Determine the size of the supply/exhaust fans to ventilate this garage if 1.5 cfm/ft² are required. Assume a fan pressure of 1.5 in. of water and a fan efficiency of 0.75.

b. Using the design method, determine the needed cfm/ft² to ventilate the garage if at peak hour 30 percent of the cars are moving (assume the worst-case scenario for emissions: winter and cold start). Assume that the acceptable CO level to maintain is 25 ppm. Size the supply/exhaust fans. Discuss the energy saving if the garage is operated 12 hours/day, 7 days/week, and 50 weeks/year. Is it worth to retrofit the ventilation system if the energy price is $0.08/kWh (the cost of fans and their drives can be estimated as the cost of motors multiplied by 2.5)?

c. Discuss any other means to reduce the energy cost in ventilating the garage.