torsdag 23 oktober 2014

Direct Replacement of Exhaust Air Limitation

Measure 1: Direct Replacement of Exhaust Air Limitation The economic justification for this measure was made by comparing equipment first cost and energy cost differences between an exhaust-only hood system versus an equivalently performing short-circuit hood system for a 10’ section of cooking line. An exhaust-only hood provides adequate capture and containment in this hood section with 1,500 cfm of exhaust air. The replacement air is assumed to come from the room in both cases. An equivalently performing 10’ short-circuit hood would have to exhaust 3,000 cfm with 1,500 cfm of replacement air being directly injected into the hood and the remaining 1,500 cfm coming from the room.  The basis of comparison used the costs of the hoods, the cost of the exhaust fans, and the cost of the addition makeup air unit required for the short-circuit system. The energy comparison used the brake horsepower difference between the exhaust and makeup air fans. The difference in brake horsepower was then converted to KW and multiplied by 15-year hourly energy cost data.  The systems were assumed to operate from 11 am to 11 pm everyday to simulate a typical restaurant serving lunch and dinner. Climate Zone 12 was used as the source of the energy costs but the energy savings are not associated with climate and would apply to all climate zones. Other metrics like the amount of ductwork, fire-proofing insulation could also be compared but since there is no component of a short- circuit hood system that is smaller and thereby costs less over an exhaust-only hood system, the comparison is limited to this small set of essential equipment to justify the costs.  Equipment cost data has been provided by a kitchen hood vendor.

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