3.3.4 Prototype D

Prototype D is a mixed use building with a clear specification. Prototype D is the case study building used in the User's Manual for ASHRAE Standard 90.1-2007 to demonstrate the use of the Performance Rating Method (PRM). The building has seven above-ground stories and an underground garage. The building’s footprint is 150 ft x 90 ft with the long axis oriented due east-west. The first floor contains retail spaces with large display windows that have overhangs projecting 10 ft on the south, east, and west exposures. The second and third floors contain offices that have similarly oriented overhangs, although the overhangs project only 5 ft. Above the offices are apartments on floors four through seven. To provide more daylight and fresh air, the four floors of apartments have two 20 ft x 30 ft notches taken out of the floor plan; therefore, these levels have 1,200 ft² less floor area than floors one, two, and three. The building also has an unconditioned stairwell.

Figure 3.3.4-1: "Prototype D Floor Plans"

Figure 3.3.4-2: "Prototype D Exterior View"

Prototype D is a steel-framed building with steel stud walls with R-7 insulation in the cavities and ⅝ in. sheetrock. The windows are single glazed with clear glass in all areas except the offices, which have single-pane windows with gray glass. All windows have thermally broken metal frames. Only the windows on the residential levels are operable.

A fluorescent electric lighting system is used throughout the commercial sections of the building. Lighting power density is 1.38 W/ft² in retail areas, 1.16 W/ft² in office areas, 0.25 W/ft² in the underground parking, and 0.5 W/ft² in stairwells. The perimeter zones of the office have automatic daylight dimming controls.

Retail spaces are served by a four-pipe fan coil system so that they can be independently shut down if the stores’ operating hours differ significantly. A variable air volume (VAV) air-handling system served by the same centrifugal chiller and a boiler provides space conditioning in the office levels. The apartments are heated and cooled by four-pipe fan coil systems, which are also served by the chiller and boiler. The underground parking is ventilated during retail business hours.

A 160-ton, chiller with a rating of 0.6 kW/ton and a 2,250,000 Btu/h boiler serve all of the heating and cooling loads in the building.