leakage rate

This issue has always been a little confusing and has become a bit more muddled in light of recent rulings made by GBCI that further defined the allowable values for leakage rate (Lr). Here's the low-down:

*The "default" value of 2% should never be used. Ever. This is a LEED-NC concept that was never appropriately aligned for the EBOM rating system. If a project team is unable to calculate their actual leakage rate for a building that is currently occupied with operational equipment, they would not meet the minimum requirements for the prerequisite. Likewise, do not use manufacturer specifications for anticipated leakage rates. Anything can happen once a piece of equipment is installed and operational, so the manufacturer's estimates may not accurately capture the actual performance.

*Bottom line - always use the actual calculated value for leakage rate of each piece of HVAC equipment in the project building with more than 0.5 pounds of refrigerant. You can calculate these values by tracking how much additional refrigerant has been added during maintenance activities throughout the performance period.

*There is only one caveat to this rule: If the actual measured leakage rate of a piece of equipment is less than 0.5%, you must use the minimum default value of 0.5% in your calculations for Lr. You cannot use 0% in your calculations; if you do, the reviewer will adjust your calculations and report the updated Refrigerant Impact per Ton. This minimum default value is specified in the Rating System language for EAp3, so it's pretty much set in stone. This requirement has recently been enforced much more consistently and the reviewers are on the lookout for incorrect calculations, so make sure you use the correct values.

Jason -
Can you direct me to "the recent rulings" by GBCI that you refer to in this comment stream regarding the allowable values for leakage rate? I've looked in the addenda (up through 11/3/10), the CIRs, and the reference guide but have not found anything that says you cannot use the 2% leakage rate as a default. On page 223 of the Reference Guide, Sample Calculation 2, describes a scenario that uses actual leakage rate and the 2% default - indicating it would be ok for us to do so as well.

As I understand it, EPA only requires an owner of appliances that contain 50 or more pounds of refrigerant to tracking the amount of refrigerants, which may mean the some organizations will not have this information at their fingers tips and I do not see where it says you should track your leakage rate for the performance period (which as it could be as short as 3 months).

On the other hand, if you have appliances that are less than 50 pounds but more the 0.5 pounds and have not had to put refrigerant in them over the past year, then you could accurately say your annual leakage rate is 0%, but you would use the LEED required minimum of 0.5%

Thanks for providing this valuable information. I guess Im just looking for the actual documentation from GBCI before we head down the actual leakage rate route.

Per page 221 of the LEED-EBOM Reference Guide, "Refrigerant Leakage Rate (Lr) must be based on actual leakage rates experienced in the project building..." The suggestion that project teams can use a default of 2% and not even bother tracking leakage from their equipment is misleading and incorrect. I can tell you unequivocally that the review team will send the credit back to you and ask for clarification if you do not use actual leakage rates and provide some documentation substantiating your claim.

Your note about using 0.5% Lr when you have not had to recharge any equipment is correct - that is exactly how you should manage that scenario.

Thanks for getting back to me Jason. I really appreciate it. We'll move forward by tracking our leakage rate.

Thanks again!

My question is how do you change the default rates to .5%?? The field cannot be edited directly and is based on the refrigerant added and the days since refrigerant last added column.

It looks like if I use .05% of the total refrigerant in the lbs of refrigerant added column and 365 in the days since refrigerant last added colum, the leakage rate changes to .5%. Is this what I should be doing?

Kim, there's been an ongoing battle with GBCI and USGBC over the usability of the EAc5 credit form. My guess is that you may not be upgraded to the most recent version of the form. You can request a form upgrade by calling or emailing GBCI customer service. Once you have Version 4.0 of this form, the field for Lr is an editable field that you can adjust.