Handbook of air conditioning and refrigeration / Shan K

Trace 600 Input—External Loads
There are seven cards for external load input.
Trace 600 Input—Schedules
Card 19, load alternative description, will save separate files for each of the Load, Design, System,
and Equipment alternatives.
Card 20, general room parameters, determines the room number, zone reference number, room
description, floor length and width, construction type (a 2- to 12-in. (50- to 300-mm), light- or
heavyweight concrete construction), plenum height, R value of the acoustic ceiling, floor-tofloor
height, perimeter length, and duplicate floor and duplicate room/zone multipliers to save
input data for a similar floor or room/zone.
Card 21, thermostat parameters, lists input data of room design cooling and heating dry-bulb
temperatures and relative humidities; the highest and lowest room temperatures allowable to
drift up during low occupancy or nonoccupancy; cooling and heating thermostat schedules;
location of the thermostat; light, medium, or heavy room construction and the corresponding
2 to 8 h of time averaging; and carpet covering.
Card 22, roof parameters, describes the room number, alternate roof numbers, whether roof area
is equal to floor area, roof length and width, roof U value, roof construction type, roof direction,
roof tilting angle, and roof absorptivity �.
Card 23, skylight parameters (optional), covers the room number, roof number, length and width of
skylight, number of skylights or percentage of glass of roof area, skylight U value, skylight shading
coefficient, external and internal shading types, percentage of solar load to be picked up by return
plenum air because a portion of skylight is exposed to the plenum air, visible light transmissivity,
and the fraction of inside visible light being reflected on the inside surface of the glazing.
Card 24, wall parameters, lists the input data of room number; wall number; the length, height,
U value, and construction type of the wall; wall direction; wall tilting angle; wall absorptivity;
and ground reflectance.
Card 25, wall glass parameters, describes the room number, wall number, glass length and height,
number of windows or percentage of glass (of gross wall area), glass U value, shading coefficient,
external and internal shading type, percentage of solar load to return plenum air, visible light
transmissivity, and the inside visible light being reflected on the inside surface of the glazing.
In TRACE 600, card 26 specifies the load and operating schedules of the internal loads, fans, reheating,
and daylighting (optional). The operating schedule of internal loads and equipment affects
the design load (maximum block load), especially the annual energy use.
1. For the design load calculation of internal loads include people, lighting, and miscellaneous
equipment:
● TRACE 600 assumes that the internal loads are scheduled at 100 percent, 24 h/day during
cooling design months operation and at 0 percent, 24 h/day during heating design months, a
schedule of cooling only (CLGONLY).
● If the pickup, cool-down, or warm-up load is greater than the design load, the user should
consider oversizing the cooling capacity and heating capacity to handle the pickup loads.
● For the energy use calulation of internal loads, choose or create a schedule at which the internal
load varies 24 h/day.
2. For the outdoor ventilation air and infiltration loads:
LOAD CALCULATIONS 6.45
● TRACE 600 assumes that the design outdoor ventilation air and infiltration are scheduled at
100 percent, 24 h/day for both cooling and heating design months.