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Chvac - Commercial HVAC Loads

Version 8 Is Officially Released!

Commercial Load Calculations Done Right

Chvac has been an industry leader in commercial load calculationsoftware since 1979. Try Elite Software's flagship program today

and see why so many professional engineers are choosing Chvac. Get bothChvac and EnergyPro (which Chvac links to) and you'll have the most powerful,user-friendly commercial load calculation/energy analysis combo on the market.

Features

Calculates Peak Heating & Cooling LoadsDetermines Building Tonnage and Room CFM Requirements, and RunoutDuct SizesUses either the RTS or CLTD calculation methodChvac complies with the ANSI/ASHRAE/ACCA Standard 183—2007Computes CFM Air Quantities With PsychrometricsCalculates from Manually Entered Data or Directly from Floor PlansCreated with Drawing Board (sold separately)Imports and exports gbXML filesNew! Allows Different Indoor Conditions for each RoomLinks with Energy Audit ProgramLinks with PsyChart program. The PsyChart program can import Chvacsystem data directly into its Air Handler Model window.Links with HVAC Solution program.Transfers data to the EnergyPro and eQUEST programs (more on usingeQUEST with Chvac)Allows 30 Walls, 30 Windows, and 12 Roofs per RoomAutomates Compliance with ASHRAE Standard 62Calculates in both Metric and English UnitsConverts any project from English to Metric units and vice-versaAllows Simultaneous Infiltration and VentilationCalculates Runout and Main Trunk Duct SizesSelects Equipment from ARI/GAMA DatabasesAllows Virtually Unlimited Number of RoomsRooms May be Optionally Grouped Under VAV BoxesPrints Numerous Color Pie Charts and Bar GraphsCreates Spreadsheet Output File

Overview

Chvac quickly and accurately calculates the maximum heating and cooling loadsfor commercial buildings. The cooling loads can be calculated with either theCLTD method or the new RTS (Radiant Time Series) method. The program allowsan unlimited number of rooms which can be grouped into as many as 100 airhandling systems. Chvac automatically looks up all cooling load and correctionfactors necessary for computing loads. In addition, it can look up outdoor designweather data for over 2000 cities located around the world. There is also provisionfor editing the weather data as well as adding data for other cities. Comprehensivereports list the general project data, detailed room loads, air handler summaryloads, outside air loads, total building loads, building envelope analysis, tonnagerequirements, CFM air quantities, chilled water flow rates (if applicable), andcomplete psychrometric data with entering and leaving coil conditions. Otheroutstanding features include ASHRAE Standard 62 analysis, automatic buildingrotation, 360 degree wall orientations, tilted glass, exterior shading, internaloperating load profiles, variable indoor design temperatures, people diversity,pretreated outside air, seasonal infiltration and ventilation rates, reheat loads,duct gains and losses, and return air plenums.

Five Versions Available

There are five versions of the Chvac program; 2 room capacity ($295), 10 roomcapacity ($395), 50 room capacity ($595), 100 room capacity ($995), andunlimited capacity ($1495). Keep in mind that a room is a single space, and thatrooms can be grouped into air handling systems which in turn make up thebuilding. Rooms can optionally be grouped under vav boxes as well (zones). This

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allows Chvac to compute diversified peak loads at four levels in one run of theprogram: room, vav box (zone), air system, and total building. The maximumnumber of air handling systems allowed for any version is the number of roomsallowed or 100, whichever is the lesser. Each Chvac version is exactly the samewith the exception of the room capacity and price. However, there is a generousupgrade policy. If at any time you decide to obtain a version of Chvac with greatercapacity than the original one you obtained, all that is required is to pay thedifference in price between the two versions.

Advanced Features

Chvac contains many, many advanced features. Here are just a few of itscapabilities.

Calculates Peak Heating and Cooling LoadsCalculates Both Heating & Cooling CFM RequirementsCalculates Runout and Main Trunk Duct SizesAutomates Compliance with ASHRAE Standard 62Provides Overall Building Envelope ReportCreates Spreadsheet File with Calculated ResultsPerforms Complete Psychrometric AnalysisPrints Bar Graphs and Exploded Pie ChartsExterior Shading Handles Overhangs, Fins, & Glass TiltUses Exact ASHRAE RTS or CLTD ProceduresBuilt-in Design Weather Data for Hundreds of CitiesAnalyzes Up to 12 Months Per CalculationCalculates 24 Hours per Design DayAllows Unlimited Number of Rooms per ProjectRooms May Be Grouped Under 100 Air HandlersRooms May Be Optionally Grouped Under VAV BoxesAllows 100 Walls, 100 Windows, and 100 Roofs per RoomAllows Simultaneous Infiltration and VentilationAllows Different Summer and Winter Air RatesAllows Different Indoor Conditions for each RoomAllows 20 Master Roof Types, 20 Master Wall Types, 20 Master PartitionTypes, and 50 Master Glass TypesProvides a User-Defined Library of Custom MaterialsProvides a List of your Favorite MaterialsAllows Up to 10 Internal Operating Load ProfilesAllows Full 360 Degree Wall and Glass OrientationsAllows Glass to be titled from 0 to 180 degreesAllows for Roof and Wall Color EffectsProvision for Both VAV and Constant Volume SystemsProper Handling of Return Air Plenum LoadsAccounts for People Diversity in Total Building LoadComputes Supply Fan Horsepower and Heat GainsAccounts for Both Draw-thru and Blow-thru FansCalculates Reheat Requirements if NecessaryComputes Supply and Return Duct Gains and LossesAllows Direct Specification of Supply CFM QuantitiesAllows Specification of Minimum Supply Air QuantitiesAllows Heating Only, Cooling Only, or BothExcess Supply Air Can be Handled as Reheat, Reserve Capacity, or byAdjusting the Leaving Coil ConditionsLeaving Coil Conditions Can be Specified with a Desired Dry BulbTemperature or a Relative HumidityCalculates Chilled and Hot Water Coil Flow RatesAllows for Pretreated Outside AirCalculates benefits of Heat Recovery Ventilators (HRV) for heating andcoolingAllows Heating and Cooling Safety FactorsLighting & Equipment Watts along with No. of People can be EnteredDirectly or on a Per Square Foot BasisSelects Equipment from the ARI/GAMA DatabasesCreates Custom Sales ProposalsCreates Spreadsheet Output File

Calculation Method

Chvac performs cooling calculations using either the CLTD method or the newRTS (Radiant Time Series) method. The RTS method is described in the latestedition of the ASHRAE Handbook of Fundamentals, while the CLTD method isfrom earlier editions of the Handbook. The RTS method is especially accuratebecause it calculates the delayed effect of radiant heat gains during each of thepast 24 hours in determining the current cooling load. That means, for example,that the program gives proper consideration to the effect of an external shadingdevice that shades a window in the morning in a room that peaks in the afternoon.

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The CLTD method, on the other hand, uses exact table values from the Handbookwhere possible, which means that you can verify the results by hand. You canactually switch back and forth between RTS and CLTD for any project. All youhave to do to switch between the two methods is to enter equivalent Master Datadefinitions for roofs, walls and glass and then change the Cooling CalculationMethod input to the other method.

Program Input

Chvac is very easy to use and includes a specific "dropdown" help window forvirtually every input, including a list of choices where appropriate. The programperforms extensive checks on the data you enter and alerts you to any problemsthat it finds, such as a wall having too much window area, or a leaving coiltemperature for an air handler outside of the expected range.

Five types of data are requested: general project data, outdoor design data,building material data, air handler data, and specific room data. The generalproject data includes the project and client name, designer, building opening andclosing hours, internal operating load schedules, and any desired safety factors.The outdoor design data includes the summer and winter outdoor designconditions (automatically looked up for you if a city reference is given) and thedesired ventilation and infiltration rates. The building material data includes thedefinition of master building material types for roofs, walls, partitions, glasssections, and exterior shading. A user defined material library is available forsaving the data on common material types. The air handler data includes the fanand terminal type, the desired heating and cooling supply air temperatures anddata for duct heat gains and losses. The room data includes the room name, floorlength and width, number of people, equipment watts, lighting watts, externalshading data, and specific roof, wall, partition, floor and glass data.

Program Output

Chvac provides several different types of reports which can be selectivelypreviewed on screen or printed. The reports are: General Project Data, Air HandlerInput Data, Room Input Data, Detailed Project Room Loads, Air System RoomSummary, Total Building, Air System, and Room Load Profiles, Air System TotalLoad Summary, Air System Psychrometric Analysis, Psychrometric Chart,Overall Building Envelope Report, Pie Charts, Bar Graphs, and the Total BuildingLoad Summary. Virtually all calculated data can be exported to a commadelimited text file that you can then import into your favorite spreadsheet programsuch as Excel.

Chvac and HVAC Solution Link

The Chvac load calc program calculates a great deal of the data needed to definea system in the HVAC Solution schematic diagramming program. Traditionally,this data has simply been transferred using a manual entry process. Now, thereis an automated process whereby HVAC Solution can import all the relevantChvac data system by system into the HVAC Solution software such that HVACschematic diagrams are automatically generated. See a video demo of thisprocess here and view more details on HVAC Solution here.

Links to Other Programs

Chvac not only calculates peak heating and cooling loads, it also aids inselecting HVAC equipment and analyzing building operating costs. Project datafrom Chvac can be exported to Elite Software's Energy Audit program as well asto the eQUEST program (see more info in this paragraph). In the future, we planto also provide a link to the Energy Plus program. Export to Energy Audit whenyou want to analyze residential and light commercial projects, essentially anyapplication which uses unitary HVAC equipment. Export to eQUEST when youwant to analyze large commercial projects that require precise modeling ofvariable loads, equipment, operating schedules, and control schemes. For justselecting unitary HVAC equipment, use the built-in Find HVAC Equipment featureof reading equipment performance databases published by the AmericanRefrigeration Institute (ARI) and the Gas Appliance Manufacturers Association(GAMA).

Import and Export of gbXML Files

Chvac now lets you import gbXML files from CAD drawing software such asAutoCAD MEP and many other programs. We give you extensive control over theimport process, including the ability to select which spaces, walls and windowsto include in the import (see screenshot below). If you are familiar with the datathat CAD programs typically write to gbXML files, you know that materialdefinitions are usually incomplete for purposes of load calculation, since they do

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not usually include data such as wall U-values or roof ASHRAE numbers. So onthe import dialog we let you select the default definitions for each kind of mastermaterial in the project.

Using eQUEST with Chvac for LEED Certification

Using the free eQUEST program with Chvac gives you a complete loadcalculation and energy analysis package. First, you enter your project in Chvacand let it determine your peak loads. Then, you export a ready-to-open eQUESTproject file from Chvac. Then you open that project in eQUEST, and enter anyadditional data you want to enter that is specific to eQUEST. Then eQUEST willlet you perform a detailed energy analysis. The eQUEST program can also beused to perform the calculations required for the energy portion of LEEDcertification, as described in an article in the September 2007 ASHRAE Journal(page 58 and following).

Drawing Board

A functional demo of Drawing Board is built into this version of Chvac. The built-in demo version of Drawing Board allows you to draw and save floor plans ofunlimited size, but HVAC calculations can only be made for two rooms of thefloor plan.

Update Information

Chvac version 7 users can update to version 8 for a substantial discount off thefull purchase price. See the Upgrade Pricing page for more information.

New Features in Version 8

Chvac version 8 can be installed on the same computer as version 7, and will notinterfere with version 7 at all. There is no problem in having both version 7 andversion 8 on your computer at the same time.

The following new features were added to version 8 that were not in version 7.

Export to EnergyPro. After opening a project, click "File | Export | Exportto EnergyPro." You must have EnergyPro installed for this feature to work.You can download a limited, functional demo of EnergyPro from here.Each applicable master data item now has an EnergyPro Code input,which you can use to map that master item to an EnergyPro material.Click the button beside any EnergyPro Code input and you'll see anEnergyPro Material dialog, which lets you select the mapped material fromdropdown lists. There is built-in mapping if you leave an EnergyPro Codeinput blank, but the user-defined mapping is easy to do, and is of coursemore precise.

Multiple items of equipment cooling loads for each room. Click thebutton beside either the Sensible Equipment or Latent Equipment inputson the Room Data window and a new Equipment Cooling Loads windowwill open. This window lets you enter as many items of sensible and/orlatent equipment loads for each room as you need, each with its ownquantity type, usage factor, operating profile, etc.. Click the button besidethe Item Name column and a new Typical Equipment Cooling Loads dialogopens. This dialog is filled with sensible and latent load information forvarious kinds of equipment listed in various tables in both the 2005 and2009 ASHRAE Handbook of Fundamentals.

Multiple items of lighting loads for each room. Click the button besidethe Lighting input on the Room Data window and a new Lighting Loadswindow opens. This window lets you create as many individual lightingload items as you need for each room, each with its own characteristics,such as Space Fraction, Usage Factor, etc.. Click the button beside theDescription column and a new Typical Lighting Loads dialog opens, whichlets you choose from several lists of lighting items that come from tablesin the 2005 and 2009 ASHRAE Handbook of Fundamentals.

Load Preview window: Click the menu "Project | Load Preview" to openthis new window. It's similar to the window with the same name in Rhvac,but this one has over 90 columns of data available. You can choose whichcolumns to make visible. There is a corresponding Print Preview report.The Load Preview Layout dialog lets you choose one set of visible columnsfor the Load Preview window itself, and another set of columns for the PrintPreview version of it.

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Plenum-Room temperature difference automatic adjustment. Whenyou enter a return air plenum you can now specify that you want theprogram to automatically adjust your entered temperature differencebetween the rooms and the plenum until it converges on a solution. Youcan select the maximum number of iterations to perform for each plenum,as well as whether or not to round to the nearest whole numbertemperature. You can enter project defaults for these settings on theDesign tab of the General Project Data window, and you can override themfor each plenum on the Plenum Data window.

Pool latent loads. In each room you can now calculate the latent loaddue to indoor swimming pools. All you have to do is enter square footageof the water surface, enter the water temperature, select an activity factor,and select an airflow velocity. The program will then calculate a latent loadfor the swimming pool.

Sloped Ceiling Area Calculator dialog. This dialog lets you enterdimensions for a room's sloped ceiling, and calculates the resulting area ofthe ceiling. The area is copied to the roof's Width input, and the number 1is copied to the Length input.

Miscellaneous latent gains. On the Air Handler Data window you cannow enter miscellaneous supply and return latent equipment loads. Loadscan be positive or negative, and can occur on either the supply or returnside of the coil.

New Features in Version 7

The following new features were added to version 7 that were not in version 6.

RTS Calculation Method: You can now select to use either the CLTDmethod or the new Radiant Time Series (RTS) method for calculatingcooling loads. The RTS method is found in the latest ASHRAE Handbookof Fundamentals and is very accurate because it calculates the delayedeffect of radiant heat gains during each of the past 24 hours on the currentcooling load. You can easily switch back and forth between the twomethods simply by entering equivalent master roof, wall and glass data onthe Master Data window for both methods.

Easier and Better Glass Definitions: Now you can enter the width andheight dimensions for each window or skylight rather than having to enterthem for the master glass and then figure out the correct quantity to enteron the Room Data window. The Room Construction value of Light, Mediumor Heavy required for each glass in the CLTD method is now automaticallyassigned based on the selection you make for the entire room in the newRoom Type input.

Individual Ground Reflectance Values: You can enter a differentground reflectance for each component rather than having only one valuefor the whole project, which makes the results more accurate becausedifferent exposures around a building are likely to have different groundreflectances. Because the RTS method requires this input for roofs andwalls, each roof and wall now has a Ground Reflectance input, whichmakes it so each skylight and window is automatically assigned a groundreflectance value that is appropriate for its exposure.

Glass Number of Occurrences: You only have to enter data once for awindow or skylight that occurs multiple times in the same wall or roof.

Floor Slab Coefficient for Each Room: You can now enter the floor slabcoefficient for each room rather than having to use the same value for thewhole project.

Easier to Use Room Data Window: The Room Data window (formerly"Zone Data") has been redesigned to make it easier to enter all the data.You can change the number of visible roofs, walls and glass by clickingthe plus and minus buttons next to each group's scrollbar. Pressing Enterwhen on the last visible row of a component now makes the componentsscroll down by one so you can enter another item of the same type. If theType input of a component is set to zero, pressing Enter moves the cursorto the next group of inputs. All the important data is now on two tabsinstead of three.

More Roofs, Walls and Glass per Room: We've more than doubled theallowed number of roofs, walls and glass you can enter for a room.

Room Notes: You can save as many notes about a room as you want in

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the new "Notes About This Room" input on the Room Data window.

Easier Weather Data Selection: Both the Weather Database and theIndoor/Outdoor Design windows now let you select a city from a singledropdown list that shows all cities in the database.

Easier Weather Database Editing: It is now much easier to edit and addcities in the redesigned Weather Database window.

Screen shots Comprehensive Air Handler Data

Runout and Main Trunk Duct Sizing

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Built-in Custom and Favorite Material Lists

Easy Room Data Entry

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All Types of Exterior Shading

Import and Export of gbXML Files

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Drawing Board Window

Chvac includes a Drawing Board window, which operates at the demo level until you purchase a separate license for Drawing Board. The Drawing Boardwindow enables you to enter your room data by simply drawing the floor plan on the screen. Below is a screen shot showing a floor plan created from withinChvac.

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