Does EnergyPlus calculate TDV in units of J TDV or kBtu TDV?
In the documentation for the FuelFactors object Source Energy Factor field, there are some instructions on how to calculate TDV. In particular, there's a value of 0.293 mentioned for electricity and 0.01 for natural gas. These are also present in the 5ZoneTDV.idf example file, along with some schedule objects to reference the CSV files where the TDV factors are stored. My question is what these numbers actually mean and how they were derived? These values only seem to be mentioned in relation to EnergyPlus and Energyplus is the original source of these two numbers.
For a little background, I'm trying to reproduce some TDV calculation results and I have failed repeatedly trying all sorts of plausible variations to the calculation. I'm not sure if the person who made the calculation made a mistake, if I am making a mistake, if there is a difference in TDV units, if I'm not working with the correct IDF, etc. I've used a procedure to calculate TDV in the past, but I've never known for sure what each part of the calculation is intuitively doing and where all the constants come from.
The calculation method for TDV has never been super clear and I'd like to be able to say something other than "I don't know how the TDV calculation works, but this is the formula." if I'm going to be using TDV in published research. I'm pretty sure the 0.293 and 0.01 in EnergyPlus are for converting the TDV factors from their units of kBtu/kWh and kBtu/therm in the CSV files to Joules/Joules, which would mean that the annual TDV calculation would be in units of J TDV rather than kBtu TDV, but I'm not sure. I thought I would ask the creators of the 5ZoneTDV.idf example file and clear up one of the many opaque portions of the TDV calculation that I don't fully understand yet.
Ha ha. I was using 2019 TDV factors, but the other source was using 2022 TDV factors, which got released last month. Phew! The results I've been giving people for years aren't wrong. : )
Can you share how to get 2022 TDV factors ? I tried download spreadsheet from CEC website (TDV_2022_Update_Model_ada.xlsb) but macro returns error
@ngkhanh It's been a while, but the only place I was able to find this information was by installing CBECC-Com because the TDV values have to exist somewhere in the files to calculate with them, along with the paired EPW files. I also had to look at the IDF file CBECC-Com feeds to EnergyPlus for the simulation start weekday and holidays because TDV varies significantly between weekends and weekdays. Then to test I got everything right, I checked my own IDF simulation and TDV calculations against the total energy use and TDV CBECC-Com came up with.
@ngkhanh Finding information to actually calculate with TDV was such a struggle because, like you, I wasn't able to find clear instructions. The CEC has some resources online and Energy and Environmental Economics, Inc.: E3 had something to do with making it, but even finding the raw TDV hourly values was a struggle. At the end of the process, the only reason I thought my calculation of TDV was correct outside of CBECC-Com was because my calculations matched CBECC-Com and there were code compliance ramifications if CBECC-Com was wrong.
Anyways, I wish you the best, and good luck!
@Mitchal Dichter Thanks you so much for your detailed instructions - I got TDV and Source Energy factor from this macro spreadsheet (cec_link it takes me 3-5 min to get exported timeseries data- remain input should be similar to TDV idf example. I will check if I got same results as CBECC-Com with exported data