Why I can't open Early Power Estimators (EPE) tool in the latest version of Microsoft* Excel?

Description

Due to the legacy design of the Early Power Estimator (EPE) worksheets, which include VBA macros, ActiveX components, and embedded DLL files, errors may occur when opening the Excel file on newer Windows platforms or when using Microsoft* Office 365, in both 32-bit and 64-bit versions.

When the spreadsheet is opened, several actions occur in the background.

Excel extracts the embedded DLLc files to the user's %TEMP% directory.
A script then decompresses the DLLc files into standard DLL files.
The script subsequently loads and executes the DLL files, which is used by the Excel macros.

Why the issue occurs:

To extract and execute the required DLL files, the Excel macros rely on a set of commands provided by Microsoft .NET and Microsoft Visual C++ runtime libraries, depending on the specific version of the Excel worksheet.

In newer versions of Microsoft Windows and Microsoft Office 365, these runtime components are no longer bundled together by default, and some legacy functions used by older scripts have been deprecated or replaced with newer implementations. As a result, scripts designed for earlier environments may fail when attempting to call these functions. Note: In some systems, some of these are already installed automatically by other 3rd party software tools during installation.

Additionally, the legacy script design does not support symbolic linking or modern handling of the user's %TEMP% directory, which can cause issues when extracting and accessing temporary files.

Modern systems also enforce stricter security controls, including:

- ActiveX restrictions in newer versions of Microsoft Excel
- Trust Center policies that block code execution from untrusted locations
- Operating system security policies in Microsoft Windows that may prevent DLL execution from the %TEMP% directory if such restrictions are enabled

As a result, if any of these conditions are triggered, users may encounter errors such as “Unable to find or load DLL files.”

For example, errors may appear related to the zlib.dll file (the 32-bit or 64-bit version used depends on the installed Excel architecture).

Resolution

To workaround this issue

PART A: Unblocking the Excel and Enable Macros/ActiveX

1. Unblock the Excel File
• Right-click the EPE Excel file → Properties → Check Unblock under Security.
• Click Apply → OK.

2. Enable Macros and ActiveX
• Open Excel → File → Options → Trust Center → Trust Center Settings:
Enable Macros.
Enable ActiveX controls.
Leave other settings as default (Safe Mode can remain enabled or disabled).

3. Check whether you can now open the EPE excel sheet. Else proceed to PART B.

PART B: Installing the necessary Microsoft .NET and Visual C++ runtime libraries.

Microsoft .NET installation

Go to your Installed apps settings and find for .NET. It is recommended to have both .NET Runtime and ASP .NET installed in your system. If you already have a version installed on your machine then proceed to the next step( you only require 1 version each), otherwise refer to this location to download Download .NET 8.0 (Linux, macOS, and Windows) | .NET

Example:

Microsoft Visual C++ Installation

As different EPE Excel sheet relies on specific Visual C++ version, you will need to install multiple versions of Visual C++ for both 32bit and 64bit. This is because even though Excel is running on 64bit, existing scripting might have dependency on 32bit functions as well.

Recommendation to install C++ version for both 32 bit and 64 bit as below Latest Supported Visual C++ Redistributable Downloads

Visual Studio 2017-2026
Visual Studio 2015 (in older Microsoft release, it might show as C++ V14 or 2015-2022 version)
Visual Studio 2013
Visual Studio 2012

Example

After installing both 32 bit and 64 bit, do restart the system and then try launching the EPE excel sheet again.

In some rare occurrences, you might need to install Visual Studio C++ 2010 , Visual Studio C++ 2008 and Visual Studio C++ 2005. Do refer to PART C first as the issue might not be due to Visual C++ but symbolic link.

PART C: Symbolic Link issue workaround (optional)

If installing the .NET and Visual C++ runtime libraries still does not help in resolving the error opening EPE Excel, you should check whether your %TEMP% file folder is the same as what reported in the error when opening the EPE excel sheet. If the folder path are different between %TEMP% and the path reported by Excel sheet, it means that they are using symbolic link folder. In this case user should copy the .dll files generated out from the %TEMP% when they opened the excel sheet and copy it over to the Windows SySWoW folder (%windir%\SysWOW64).

To access your %TEMP% folder , just type %TEMP% into your explorer and it will open your folder location (%TEMP% is set in windows environment variables)

From the %TEMP% folder, there are multiple *epe* DLL files if you open different EPE excel sheets. Copy all of these .DLL files into your Windows SysWOW64 folder and try launching the EPE excel sheet again.

Example, if using Cyclone® V EPE excel sheet, these are the 4 files required in red box in %TEMP% to be copied over

NOTE 1: The SysWOW64 folder is selected because it is part of Windows’ default search locations when required DLL files cannot be found. Alternatively, you can add a custom directory to the Windows Environment Variables (PATH) so that Windows will also search that folder when looking for the DLL files.

NOTE 2: Adding the %TEMP% folder into the system environment variables will not have any effect as latest Microsoft Windows have blocked the DLL searching mechanism to prevent search %TEMP% folder as part of the security to prevent remote execution from DLL.

Additional Information

If all fails, alternatively install Process Monitor from Microsoft to analyze the DLL failure/error

1. Download Process Monitor from this location Process Monitor - Sysinternals

2. Close all excel sheets that is open in Windows.

3. Launch the Process Monitor , then select Filter. Set to Process Name and EXCEL.exe and click Add.

4. After adding the filter, ensure that capturing is started

5. Then open any of the EPE excel file,and wait till you get the DLL (eg. epe_zlib_32bit.dll) error then press pause on the Process Monitor.

6. Then use Find and search for the dll error stated in the excel(eg. epe_zlib_32bit.dll)

It will give you a list of things, but important is to check the details on createfile, open, close , query, those are the functions that are in the zlib dll file.

Example

Good case scenario where no error occurred.