COMMONLY USED COMPUTER PROGRAMS IN HVAC

The usual need to look up values from various tables and charts makes the conventional hand calculation
quite laborious, time consuming and prone to errors and inaccuracies because of the tendency to simplify
truncate or interpolate tabulated values. Listed below are the suggested applications and methodology of
two computer programs Elite CHVAC and TRACE 700 that may be used in the cooling and heating load
calculations.

Elite CHVAC

CHVAC is a commercial Heating, Ventilation and Air Conditioning software platform developed by Elite
Software. This computer program calculates the maximum heating and cooling loads in commercial and
industrial buildings.

Listed below are capabilities of CHVAC:

  • Calculates peak heating and cooling loads
  • Calculates both heating & cooling airflow CFM requirements
  • Calculates run out and main trunk duct sizes
  • Automates compliance with ASHRAE Standard 62
  • Provides overall building envelope report
  • Spreadsheet file compatibility
  • Performs complete psychrometric analysis
  • Prints bar graphs and exploded pie charts
  • Exterior shading handles overhangs, fins, & glass tilt
  • Uses exact ASHRAE CLTD procedures
  • Built-in design weather data for hundreds of cities
  • Analyzes up to 12 months per calculation
  • Calculates 24 hours per design day
  • Allows unlimited number of zones per project
  • Zones may be grouped under 100 air handlers
  • Zones may be optionally grouped under VAV boxes
  • Allows 12 walls, 12 windows, and 5 roofs per zone
  • Allows simultaneous infiltration and ventilation
  • Allows different summer and winter air rates
  • Allows varying indoor conditions within a project
  • Allows 6 master roof types,8 master wall types, 8 master partition types, and 20 master glass types
  • Allows glass to be tilted from 0 to 180 degrees
  • Allows for roof and wall color effects
  • Provision for both VAV and constant volume systems
  • Proper handling of return air plenum loads
  • Accounts for people diversity in total building load
  • Computes supply fan horsepower and heat gains
  • Accounts for both draw-thru and blow-thru fans
  • Calculates reheat requirements if necessary
  • Computes supply and return duct gains and losses
  • Allows direct specification of supply CFM quantities
  • Allows specification of minimum supply air quantities
  • Allows heating only, cooling only, or both
  • Excess supply air can be handled as reheat, reserve capacity, or by adjusting the leaving coil conditions
  • Leaving coil conditions can be specified with a desired dry bulb temperature or a relative humidity
  • Calculates chilled and hot water coil flow rates
  • Allows for pretreated outside air
  • Allows heating and cooling safety factors
  • Lighting & equipment watts along with no. of people can be entered directly or on a per square foot basis
Calculation Method

CHVAC performs calculations using the CLTD/CLF procedures described in the ASHRAE Handbook of Fundamentals. The programs use exact CLTD and MSHGF table values where possible, otherwise direct
calculations are made. This calculation technique allows the programs to calculate for any building
orientation and still produce output results that can be easily verified by hand.

Program Input

CHVAC is a true Windows program that uses all the latest data entry techniques such as toolbars, hyper linked help, and form tabs. All input data is checked at the time of entry so that no improper data can be entered. Five types of data are requested: general project data, outdoor design data, building material data, air handler data, and specific zone data. The general project data includes the project and client name, designer, building opening and closing hours, internal operating load schedules, and any desired safety factors. The outdoor design data includes the summer and winter outdoor design conditions (automatically looked up for you if a city reference is given) and the desired ventilation and infiltration rates. The building material data includes the definition of master building material types for roofs, walls, partitions, glass sections, and exterior shading. A user defined material library is available for saving the data on common material types. The air handler data includes the fan and terminal type, the desired heating and cooling supply air temperatures and data for duct heat gains and losses. The zone data includes the zone name, floor length and width, number of people, equipment watts, lighting watts, external shading data, and specific roof, wall, partition, floor, and glass data.

Program Output

The CHVAC program provides eleven types of reports,which can be selectively previewed onscreen or printed as desired. CHVAC supports all printers that work with Windows and numerous full color reports are available.The reports are: General Project Data, Air Handler Input Data, Zone Input Data, Detailed Project Zone Loads, Air System Zone Summary, Total Building, Air System, and Zone Load Profiles, Air System Total Load Summary, Air System Psychrometric Analysis, Overall Building Envelope Report, Pie Charts, Bar Graphs, and the Total Building Load Summary. Air system summary data can be exported to your favorite spreadsheet.

 

COMPUTER PROGRAMS HVAC

TRACE ® 700

The TRACE Load ® 700 program is a commercial Heating, Ventilation and Air Conditioning software platform developed by Trane’s CDS Group.

The Load phase of the program computes the peak sensible and latent zone loads, as well as the block sensible and latent loads for the building. In addition, the hourly sensible and latent loads, including weather-dependent loads, are calculated for each zone, based on the weather library. The building heating/cooling load calculations, used in the load phase of the program for annual energy consumption analysis, are of sufficient detail to permit the evaluation of the effect of building data such as orientation, size, shape and mass, heat transfer characteristics of air and moisture, as well as hourly climatic data. The Design phase of the TRACE program calculates the design supply air temperatures, heating and cooling capacities, and supply air quantities given the peak load files generated by the Load phase. For applications where the building design parameters are known, you can override the calculation of these values using optional entries to the System phase. This gives you the ability to simulate existing buildings
with installed equipment that may not be sized according to the loads calculated in the program’s Load Phase.

Beyond this, the calculations used to simulate the operation of the building and its service systems through a full-year operating period, are of sufficient detail to permit the evaluation of the effect of system design, climatic factors, operational characteristics and mechanical equipment operating characteristics on annual energy usage. Manufacturers’ data is used in the program for the simulation of all systems and equipment. The calculation procedures used in TRACE are based upon 8,760 hours of operation of the building and its service system. These procedures use techniques recommended in the appropriate ASHRAE publications or produce results that are consistent with such recommended techniques. The following are the program features:

Project Navigator View
  • Organizes entries by task to lead you through the modeling process
  • Displays the status of each modeling step
  • Accommodates up to 4 alternatives per project
Project Tree View
  • Organizes all rooms, systems, and plants in a hierarchical list
  • Displays all information about a system, zone, or room on 1 screen
  • Supports cut, copy, and paste to save entry time
Component Tree
  • Displays cooling set point for every room in the project on 1 screen
  • Makes it easy to check and edit your work

Task-oriented display guides you through the modeling process as follows:

Select weather information

  • Provides both design and typical weather data by location
  • Choose from 400 climate locations
  • Import standard weather files for a full-year (8760) analysis

Create rooms

  • Describe the construction, airflows, thermostat settings, heat sources, and schedules by room

Create airside systems

  • Choose from more than 30 methods of air distribution
  • Add energy recovery, economizers, and dedicated ventilation/makeup air

Assign rooms to systems

  • Create thermal zones and assign them to systems
  • Determine airflows, coil loads, and fan sizes for each airside system

If the only requirement is to calculate the cooling and/or heating loads and the project does not require energy analysis and economic evaluation, it is recommended that the Program Load ® 700 be utilized instead of Full TRACE 700.The only difference is that Trace Load ® 700 users only have access to the Load Design section (from Project Information to Assign Rooms to Systems). Full TRACE 700 users will have full access to the Load, Energy and Economic sections.

The advantage of using only Trace Load ® 700 is that all the added features and capabilities (applicable to load design) in full TRACE 700 program are also available to the Trace Load ® 700 users. Also, same file extensions and libraries will enable users of both programs to transfer archived files back and forth without any additional steps needed.

 

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