Updates to Hourly Weather and TDV Data
The CA weather data and time-dependent valuation (TDV) factors have been updated for the 2013 Title 24 Standards. The new weather files have been recalculated using data from 1997-2008. Old files were based on data from 1950-1980 and are no longer valid due to weather trends shifting over time in many locations. The new weather files also use much improved satellite based solar data.
Overview of the 2013 Title 24 Weather Data
The new weather data set consists of 86 location specific weather files and 16 generic climate zone files. The 86 location specific weather files are intended for use in all code compliance simulations. The 16 climate zone weather files are simply the files for a single selected “reference location” for each climate zone, copied and renamed for easy reference. The 16 climate zone weather files are expected to be used for CASE analyses and other research activities.
Location specific weather files will more closely match the weather for actual building sites and reduce problems that may arise from design sizing being based on weather data which may be significantly different from the “climate zone” weather data. Compliance software tools should allow users to select the weather data that is closest to their actual project site. The CBECC-Com software will prompt users for the project zip code, and it will automatically select the nearest weather file in the same climate zone.
The weather data set consists of several file types:
- Design Day Weather Files - (DDY file format) Design day files are used for performing peak HVAC system sizing calculations.
- Annual Weather Files - (EPW file format) Annual weather files are used for performing the simulations to determine annual energy and TDV consumption and peak demand.
- Informative Weather Files - (STAT and AUDIT file formats) These files contain general information about the weather data including hottest/coldest months, peak temperature and humidity conditions, and various other summary metrics.
The weather files are included in the CBECC-Com installation and can be found in the C:\Users\(your username)\Documents\CBECC-Com 2013 Data\EPW\ folder on your computer.
Overview of the 2013 Title 24 TDV Data
The concept behind TDV is that energy efficiency measure savings should be valued differently depending on which hours of the year the savings occur, to better reflect the actual costs of energy to consumers, to the utility system, and to society. Prior to 2005, the value of energy efficiency measure savings had been calculated on the basis of a “flat” source energy cost. In the 2013 TDV update, the hourly TDV factors are also correlated with the statewide typical weather files used in building simulation tools. This is important because in California hotter weather tends to be correlated with increased demand on the electrical system, increasing the cost of energy during those hours.
The new TDV data consists of 16 sets of TDV factors, one for each CA climate zone. For each climate zone, TDV factors are defined for each fuel type (electricity, natural gas, and propane). Compliance software tools should utilize the TDV data based on the climate zone location of the project site. The CBECC-Com software will automatically select the appropriate TDV data based on the project's zip code.
Download the 2013 TDV Data
The TDV materials are available for download here.
- TDV Data Files - Download the TDV files. Included in this zip file is the full set of TDV files.