ASHRAE Journal - March 2011 - 38

As shown in Table 2, the efficient fryBaseline Efficiency Case ers have a marginally lower nameplate Double- Doublerating. However, they have significantly Flattop Fryer Sided Sided Fryer A Fryer B Grill lower energy consumption during idle Grill A Grill B and the various cooking duties. Another Quantity 2 4 1 1 1 2 EEM was to eliminate one fryer in the low-energy QSR because three efficient Nameplate Rating (kBtu/h) 90 122 96 143 120 120 fryers provided sufficient production capacities. Idle 0.24 0.11 0.14 0.11 0.04 0.03 Besides the hooded cooking appliancDuty Level, Light 0.34 0.39 0.28 0.27 0.16 0.16 Energy Input es, the other large group of appliances is Medium 0.46 0.58 0.42 0.38 0.47 0.31 in the unhooded category. Table 3 pres- (% of Nameplate) Heavy 0.65 0.94 0.57 0.48 0.91 0.59 ents the unhooded appliances, quantity, Production nameplate input, and usage factor dur33.0 69.2 58.1 78.4 134.2 81.9 Capacity (lb/h) ing cooking. Those appliances that remained the same from the baseline to Table 2: Baseline and energy-efficient hooded appliances. efficiency cases are not listed in Table 3. As shown in Table 3, the coffee brewer was changed to an The overall power consumption of the walk-in cooler and airpot brewer, which has a lower energy input than a standard freezers were reduced from total of 2,130 W to 1,460 W coffee brewer. In addition, the coffee is stored in a portable, using the following measures: the insulation was increased insulated carafe, which eliminates the need to have separate to 5 in. (127 mm) thick from the standard 3.5 in. (89 mm) coffee warmers (this is the second change). The third ap- thick, evaporator fans with electronically commutated mopliance change occurred in the holding cabinets by going tors were used in the efficient case, along with switching to to a more energy-efficient model; and the fourth appliance compact fluorescent lights, and strip curtains on the outer change was with the half-size convection oven, which has a doors. Additional measures included in these savings are higher nameplate input, but a much lower energy use factor, electronically controlled expansion valves and demandresulting in an overall lower energy use for the oven. based defrosting, and a desuperheater to recover waste refrigerant heat.

Refrigeration

Table 4 presents the baseline and energy efficiency parameters for the smaller (nonwalk-in) refrigeration equipment, including reach-in units, under-counter units, a refrigerated prep table and ice machines. Table 4 shows the efficiency improvements made to the reach-in refrigerator and freezer, under-counter units and the refrigerated prep table. With regard to the ice machines, there was not a direct efficiency improvement in the units themselves, but the condensers have been moved from being integral with the ice-making equipment to being mounted remotely outside of the building. One benefit this provides is that less heat is rejected to the space, which can save on cooling energy required to condition the space.
Baseline Quantity 1 3 1 1 Appliance Coffee Brewer Holding Cabinets Coffee Warmer ½ Size Convection Oven Input, Each
(kW)

Mechanical System
Kitchen exhaust airflow is the key factor that determines the size and energy consumption of restaurant HVAC systems. High efficiency hoods and demand controlled ventilation (DCV) are two EEMs that allowed the exhaust airflow to be reduced by 60% to 75%. Table 5 shows the hood style, overall length, depth, and airflows of the hoods. The baseline HVAC system shown in Figure 2 uses two constant air volume (CAV) packaged rooftop units (RTU); one each for the kitchen and dining zones. Since these RTUs are designed to handle a maximum of 25% of outside air when in cooling mode, they are often oversized to accommodate all of the supply air required to compensate
Efficiency Case

Use Factor
(Fu,idle)

Quantity 1 3 – 1

Appliance Airpot Brewer Holding Cabinets Coffee Warmer ½ Size Convection Oven

Input, Each
(kW)

Use Factor
(Fu,idle)

3.9 2.5 1.0 5.5

0.09 0.35 0.09 0.20

1.75 1.5 – 12

0.09 0.05 – 0.05

Table 3: Baseline and energy-efficient unhooded appliances.
38 ASHRAE Journal ashrae.org March 2011

ASHRAE Journal - March 2011

Table of Contents for the Digital Edition of ASHRAE Journal - March 2011