Extract text from Design day weather files (DDY)
To convert DDY Weather files to another format, you need EnergyPlus or other Data software.
To convert other file formats to the "Simulation Weather Data" file type, you need software like EnergyPlus or a similar tool.
A .DDY file is a Design Day Weather data file used to simulate peak HVAC system sizing in building energy models. They define the 'worst-case scenario' weather conditions, such as the hottest summer day or the coldest winter day, for a specific geographic location. These files are essential for accurate simulation engines like EnergyPlus and eQUEST.
The fundamental problem with .DDY files is their highly specialized structure. They use a proprietary ASHRAE (American Society of Heating, Refrigerating and Air-Conditioning Engineers) text format, often structured similarly to an EnergyPlus Input Data File (IDF). Because they are not standard spreadsheets, viewing or editing the peak temperature and humidity parameters requires specialized simulation software. If you simply want to extract the weather parameters for a report or custom analysis, you must convert the file.
The best target formats for a .DDY file are CSV or TXT for spreadsheet analysis, or .epJSON for modern EnergyPlus workflows. Converting to a spreadsheet format allows you to quickly read the data without launching a heavy simulation environment. Be aware that converting the file away from its native structure means you cannot plug it back into an older version of EnergyPlus without reformatting.
Generic converters rarely understand the niche syntax of building simulation files.
Convert.Guru analyzes your DDY file, detects the exact format, and lets you read the text inside.
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If you want to convert DDY file to CSV, JSON, XML, YAML, YML, TOML, INI, CFG, CONF, DAT, DB or SQL, you can use EnergyPlus or similar software from the "Building Energy Simulation Data" category. In the File menu, look for Save As… or Export….
To convert DBF, XML, SQLITE, XLSX, SQL, TSV, ACCDB, YAML, MDB, CSV, ODS or JSON files to DDY, try EnergyPlus or another comparable tool in the "Building Energy Simulation Data" category.
The history of Convert.Guru began over 25 years ago in California with Tom Simondi’s file-format database. A former contributor to Space Shuttle development and a software pioneer of the 1980s, Simondi established a trusted resource for file type analysis that was even referenced by Microsoft Windows XP. Today, we use modern technology to process and convert thousands of file formats while continually improving our DDY converter.