List of Approved non-default leakage rate

LEED claims the forced default is 2%, and cannot be changed. This may not be true. Trane was allowed to use a leakage rate of 0.5% for new R-123 chillers, which is completely ridiculous. It is ridiculous because leakage rate has a huge impact on the calculations. More than any of the other factors. Trane seems to claim you can still use their 0.5% rate. http://www.trane.com/Commercial/EnergyIaqEnvironment/8_2_1_LeedAndGreenBuildings.aspx Trane's alternative calculation tool: http://www.trane.com/Commercial/Uploads/Xls/2282/EAc4Calculator_LEED-V3_protected.xls

The Trane 0.5% leakage could only be used for R-123 chillers. It would not automatically apply to all Trane equipment. Small sized HVAC units will not comply with the credit regardless of the refrigerant type, assuming you are using standard refrigerants (R-410a). The reason is that the refrigerant charge per ton is always higher with smaller tonnage equipment. For R-410a the charge has to be about 1.98 lbs/ton to drop below 100 for the calculated impact. Refrigerant HFO-1234yf has ZERO ODP and 4 GWP. This is a replacement for R-134a, a refrigerant used in car A/C systems. While approved for car use, and starting to be used in non-mobile applications in Europe, this is a long way from being used in small scale building A/C systems in the U.S. The USGBC EAc4 equation did not consider that the method would prevent small scale systems from qualifying and would nearly always allow all large commercial equipment to qualify. In other words, they developed a tool to give a LEED point for large scale projects at the expense of the smaller LEED projects. The USGBC did not invent the calculation method. They borrowed it. The calculation method was developed in 1993 based on a study of chillers using R22, R123 and R134a. It was not a study based on any other HVAC equipment type or refrigerants. Because leakage rate is the determining factor in the calculations, and lower OPD & GWP refrigerants generally require higher charges per ton you can easily figure out that newer environmentally responsible refrigerants will never be green in LEED, but environmentally less responsible refrigerants will always be considered green in LEED. Unfortunately, the above is the way it is with LEED and EAc4. The one-size-fits-all equation doesn't make environmental sense.