ID#1865 made on
EAc4 - Enhanced refrigerant management
LEED BD+C: New Construction, LEED BD+C: Core and Shell, LEED BD+C: Schools
EA Credit 4 has been restructured between LEED-NC 2.1 & 2.2 to take into account the global warming impacts of HVAC equipment. The premise is that HFC refrigerants, preferred for their low ozone d...
EA Credit 4 has been restructured between LEED-NC 2.1 & 2.2 to take into account the global warming impacts of HVAC equipment. The premise is that HFC refrigerants, preferred for their low ozone depletion potential, are less efficient than their CFC and HCFC counterparts, and thus cause more emissions from electricity generation. The formula developed guides applicants to utilize systems and refrigerants that optimize global warming and ozone depletion reductions, and uses the ratio of refrigerant to cooling capacity as a measure. We believe that refrigerant charge is a good indicator of Ozone Depletion Potential, but not of Global Warming Potential. Our experience with numerous projects, including supermarket and school projects, all of which use packaged rooftop units and ductless split systems, has created confusion and conflicting rewards in the goal of using less refrigerant. Case in point, the Trane 5-ton standard efficiency packaged rooftop unit has a refrigerant charge of 1.88 lbs/ton (meets the criteria of the credit as written) and uses 1.05 kW/ton, while the Trane 5-ton High Efficiency has a refrigerant charge of 2.5 lbs/ton (does NOT meet the criteria of the credit) and uses 0.95 kW/ton. The high-efficiency unit uses 10% less electricity, but still does not meet the credit despite a reduction in emissions due to less electricity used. This example is typical of major HVAC manufacturers of packaged rooftop units, and not simply an anomaly. Furthermore, supermarkets are heavy users of refrigeration equipment, and almost always utilize remote condensers and heat rejecters to prevent excess heat loads within the sales area. The refrigerated cases and freezers are connected to the condensers through refrigerant lines, typically using the HFC refrigerant R404a. The constraints of the building type and the distance between the heat rejection equipment and the cases necessitates using large amounts of refrigerant, sometimes up to 6 lbs/ton, and cannot possibly meet the criteria of the credit. The mere existence of this equipment precludes supermarket buildings from receiving this credit, despite the use of environmentally friendly refrigerants and waste heat recovery technology to assist in dehumidification and hot water heating. Similarly, the credit does not directly address the use of ductless split systems. This type of unit is most effective for conditioning spaces that are difficult to reach with traditional ductwork, and by nature must use refrigerant to connect the condensing unit to the fan coil unit. The quantity of refrigerant is indicative of the distance between the two and not necessarily of the efficiency of the unit. In the context of the supermarket building type: 1) Should we specify less efficient HVAC equipment that meets the credit instead of pursuing increased energy efficiency? Does that meet the intent of the credit? 2) Can we exclude the refrigeration equipment from this calculation? If not, what is the best practice recommended to achieve this credit, as the current criteria are unreachable? 3) Can the limit for ductless split systems be raised, or does achievement of this credit create a de facto requirement to eliminate use of these types of systems? Please contact Andrew Ellsworth at [email protected] or 412.362.2100 to obtain supporting documentation for this CIR in the form of charts, graphs and cut sheets. This information is critical to understanding the issue being raised.
The inquiry deals with the applicability of this credit for supermarkets. It should be noted that not all of the LEED credits apply to every projects, or are easily achievable for all projects. The credits applicable to a project are dependent on a number of factors including, but not limited to, building type, location, size, program and function. The specific building constraints of a supermarket need to be factored into any decisions for the systems selected. For example, in some supermarkets, non-refrigerant based secondary loops have been applied successfully both for cooling and heat recovery. It should be noted that larger refrigerant charges lead to the potential of larger refrigerant leaks, and the issues associated with emissions at source are not directly tied to this credit. This credit can also be awarded to projects that do not use any refrigerants. Per the LEED-NC v2.2 Reference Guide, page 213, this credit addresses only the direct atmospheric impact of refrigerant selection and management decisions. The indirect global warming impact of refrigerants in HVAC&R equipment is addressed in EAc1, which credits the energy savings associated with more efficient equipment. Applicable Internationally.
Related Addenda (Corrections & Interpretations)