ID#10448 made on
EAc4 - Enhanced refrigerant management
Rating System Family:
Building design + construction
Our project is connected to a district energy system which provides both heating and cooling for the building; no additional building-level cooling systems are installed. The district system draws hea...
Our project is connected to a district energy system which provides both heating and cooling for the building; no additional building-level cooling systems are installed. The district system draws heavily on deep lake cooling with a complement of refrigerant-based cooling. We also have walk-in refrigerators on the premises. We are not permitted to count the deep lake cooling with a refrigerant factor of zero, so because the walk-in refrigerators use refrigerants with a high impact (according to the LEED calculation), we exceed the impact limit of 100 for the credit even though the project?s cooling capacity is largely provided by refrigerant-free sources.
We propose a calculation methodology that demonstrates a design case reduction of the total refrigerant impact as compared to the baseline case:
• The baseline case is calculated by factoring the total cooling capacity of the building?s baseline case and a refrigerant impact of 100 per ton. The demand (during the simulated year) is 1496 kW for the baseline case and 1704 (483,9 tons) installed capacity, as per the EAp2 form and the EA Section 1.4 Tables respectively.
o total design case cooling capacity = 483.9 tons
o total refrigerant impact = 483.9 x 100 = 48390
• The design case factors the labeled capacity on the district energy system?s heat exchanger (district cooling exchanger) and the walk-in refrigerator equipment, and their respective refrigerants.
o total design case cooling capacity = 393.7 tons
o total refrigerant impact = 393.7 x 86 = 33798
• Total reduction in cooling demand = 393.7 / 483.9 = 81.36 (18.64% reduction)
• Total reduction in refrigerant impact = 33798 / 48390 = 69.85 (30.15% reduction)
The calculation confirms that the refrigerant impact reduction is in excess of that associated with the reduced cooling capacity. We would like this to be an ACP.
The applicant proposes an alternate approach to the enhanced refrigerant impact credit which allows credit for the portion of cooling that is provided by systems that contain no refrigerants.
It is acceptable for the applicant to document that the refrigerant impact for the project (including downstream and upstream systems) is less than a refrigerant impact allowance calculated based on the Baseline cooling capacity* from the EAp2: Minimum Energy Performance Baseline energy model. However, the allowance calculated based on the cooling capacity shall be limited to 75 per ton (versus 100 per ton allowed using the compliance path defined in the Rating System Language for Proposed equipment).
To calculate the Baseline case allowance, multiply the total Baseline cooling capacity from the EAp2: Minimum Energy Performance model by a refrigerant impact of 75 per ton (in this case 483.9 x 75 = 36,292).
To calculate the Proposed case refrigerant impact, complete the EAc4: Refrigerant Impact form for the proposed systems (including upstream and on-site equipment). [Note: for upstream equipment, enter the capacity of the upstream equipment by multiplying the equipment capacity by the proportion of building loads to total district energy cooling loads. For example, if the building loads represent 10% of the district energy cooling loads, multiply the capacity of each piece of upstream equipment by 10%].
If the total refrigerant impact for the proposed design (including upstream systems) is less than the Baseline refrigerant impact allowance identified above, the project shall be deemed to comply with this alternative compliance path.
If using this path, please ensure that energy simulation output files showing both the Baseline cooling and refrigeration capacities AND the Baseline cooling and refrigeration peak operating capacities are uploaded either in EAp2: Minimum Energy Performance or in this credit.
* For the purposes of this Alternative Refrigerant Impact calculation, all uncooled spaces must be excluded from the total Baseline cooling capacity reported unless the documentation demonstrates how passive cooling has been achieved for these spaces.
Related Addenda (Corrections & Interpretations)