SYSTEM DESIGN LOAD
The SYSTEM DESIGN LOAD Program
estimates design cooling and heating loads for commercial buildings
to facilitate HVAC system design. SYSTEM DESIGN LOAD advances
the art of HVAC load estimating by introducing the concept of
system-based design.
System-based design is a technique
which considers specific air-handling system features when performing
load estimating and system sizing calculations. This is important
because many systems have unique features which require special
sizing procedures. For example, consider Single Zone CAV, Multizone,
VAV, and Fan Powered Mixing Box systems. All contain different
components and operate in different ways. To provide high quality
system sizing data, the special features of each must be considered.
In the past, HVAC load estimating
programs calculated room loads and airflow rates, and system airflow
rates and coil loads without considering system specifics. This
data is useful for general studies and for preliminary design
when the system type is not known. SYSTEM DESIGN LOAD still offers
these capabilities, but also provides the option of going a step
further to tailor system sizing data to specific air handling
designs and controls.
In SYSTEM DESIGN LOAD, general
load estimating and system-based design start with the basics.
Access to design weather data for hundreds of cities is at your
fingertips. The ability to define specific wall, roof, and window
constructions. Features for defining building design, layout,
and operation in as much or as little detail as necessary. The
process then continues by allowing the user to specify the type
of system and controls used to deliver cooling and heating to
the building. As much or as little detail as desired can be used.
Sizing procedures then are tailored to the system choice to provide
high-quality output listings for room loads and airflow rates,
system coil loads and fan airflow rates, and component load details.
SYSTEM DESIGN LOAD FEATURES
- System-based design loads
for sizing and selecting system fans, central cooling and heating
coils, air terminal equipment, space heating coils, preheat coils,
and central chiller.
- Uses ASHRAE-endorsed Transfer
Function cooling load calculation procedure and ASHRAE clear sky
solar algorithms.
- Uses ASHRAE procedure
for heating load calculations.
- Permits scheduling of
cooling and heating equipment operation from 1 to 24 hours per
day.
- Performs complete psychrometric
analysis with conditions adjusted for altitude.
- Calculates zone and coil
loads for 12 monthly design cooling days, and 24 hours per day.
Searches for maximum zone and cooling coil loads.
- Analyzes sloped roofs
and skylights.
- Analyzes building orientations
at any of 16 principal exposures.
- Analyzes external shading
due to overhangs, reveals, and fins.
- Analyzes effects of common
interior shading devices in reducing solar and transmission loads
through windows.
- Analyzes effects of common
window framing in reducing solar loads and heat transmission through
windows.
- Analyzes effects of thermostat
throttling range on zone cooling loads.
- Analyzes morning pulldown
loads.
- Analyzes return plenum
loads.
- Analyzes the impact of
duct leakage.
- Computes supply and return
fan brake horsepower and heat gain.
- Analyzes draw-thru and
blow-thru fan arrangements.
- Analyzes dehumidification
controls, economizers, exhaust heat reclaim equipment and humidifiers.
- Permits hourly scheduling
of lights, occupancy, electric appliances, and other miscellaneous
sensible and latent heat gains or losses.
- Calculates true zone relative
humidity.
- Design weather for over
350 North American cities and over 200 international cities provided.
- Provides data for common
wall and roof constructions. Permits entry of other wall, roof
construction data.
- Provides data for common
windows. Permits entry of other window performance data.
- Comes with a built-in
transfer function coefficient generator.
- Storage for 1200 spaces
and 250 air systems, with up to 50 zones per air system and up
to 50 spaces per zone.
- Provides global editing
features.
- Permits rotation of building
easily.
- Outputs can be directed
to a file for use in word processors, spreadsheets, etc.
- Models all common air
conditioning systems including: constant volume, VAV, multizone,
dual duct, induction, mixing box, VVT, fan coils, PTACs, water-source
heat pumps, and radiant heating systems.
- Offers part-load performance
models for common fans such as: forward-curved, backward-inclined,
airfoil, and vane-axial. Part-load performance data for other
types of fans may be entered.
- Permits hourly scheduling
of thermostats, cooling and heating equipment, and fans.
- Permits seasonal scheduling
of cooling and heating equipment.
- Extensive use of presentation-quality
(VGA) graphical output.
HARDWARE REQUIREMENTS
- MS-DOS compatible microcomputer
- Minimum 540 kilobytes
of free conventional RAM.
- One hard disk & one
floppy disk drive.
- Color graphics monitor
recommended.
- Math coprocessor recommended.
- Compatible printer.