Client Name - HMG



MEMORANDUM September 29, 2010

To: C&S Statewide team

Cc:

From: Cathy Chappell, Matthew Haro (HMG)

Doug Scott (Vacom)

Re: Stakeholder Meeting Notes, Wed. September 22, 2010

Attendees

Cathy Chappell, Matthew Haro, Erin Reschke (HMG); Doug Scott, Pranav Godbole (Vacom); Seran Thamilseran, Payam Bozorgchami (CEC); Stuart Tartaglia (PG&E); Steve Gayle (Source); Robert Eidson (Aztec-Energy); David Hinde, John Guerrieri, Scott Martin (Hill Phoenix); Knute Fredholm (RETA); Glenn Gallagher (CARB); Kara Bush (CA grocers); Samuel Yana Motta, Chris LaPietra, Ron Vogl (Honeywell); Jamy Bacchus (NRDC); Sean Gouw (SCE); Mike Straub (Heatcraft); Haider Khan, Cliff Timko, Pamela Mathis (ICF); Cavell Hollis, Travis Lumpkin (Kysor/Warren); Buzz Schaeffer, Dan Manole, Jeff Berge, Clay Rohrer (Hussman IR); Jon McHugh (McHugh Energy); Ron Gorman (Sempra); Ron Vallort (ASHRAE); Lance Durr (Stater Bros); Viktor Anderson; Roger Ansted (Altech); Glenn Barrett (danfoss); Dan Bertocchini, Kevin Brown, Kevin Galbraith, Richard Heath, Bob Krahn, Martin Luckcuck, Charles Mensah, Tim Peters, George Ronn (Supervalu); Rolf Blom (parker); Mary Boucher (ES); Bruce Campbell (URI); Sam Cantrell (Raley’s); Patti Conlan (Arkema); Andrew Cook; Frank Davis, Jerry Stutler (Sprouts); Peter Gibson, Armin Hauer, Louis Moffa (ebmpapst); Barry Greive, Larry Meeker (Target); Tim Gwyn, Tom Wolgamot (DC Engineering); Steve Hagen (Fresh and Easy); Geo Harris (SW Refrigeration); Bruce Hierlmeier (zero-zone); Tom Hutchison (enreps); Jeremy Litow, Scott Moore, Paul Schertz (PECI); David Menninger (Kroger); Rajan Rajendran (Emerson); Maryline Rassi (AHRI); Sarah Widder

Meeting Notes

Slide 16

Q. What are the size limitations for small stores? What is the smallest size store that will be covered?

A. There is no specific size cut off yet, but the intent is not to include the very small convenience stores because they have different equipment than what is being studied. We will probably use a square footage value.

Slide 19

Q. How did you determine the impact of floating head pressure on charge size?

A. When aggressively floating head pressure with evaporative condensers , unintended ambient sub-cooling may cause increased charge size.

Slide 21

Q. What did you use and/or how did you come up with sizing numbers used to create building prototypes?

A. Savings by Design (SBD) average values were used. SBD numbers are from actual stores and provide values for case line-ups and walk-in sizes, etc.

Slide 22

Comment: Concerned that the kWh numbers for the pie chart are too low - would expect to see 1.1 to 1.2 million kWh for annual refrigeration.

Floating Head Pressure (FHP)

Makes assumptions on realistic control.

Comment: I would think that there should be two calculations for this measure, one for Air Cooled Condensers (ACC) and one for evaporative coolers (Evaps). The reasoning is that floating head pressure has different impact on system performance between ACC’s and Evaps. Need to compare compressors and condensers.

Comment: There may be inefficiencies mandating a certain TD set point for different system designs. Depending on the compressor and condenser sizing, a different TD may be needed to minimize the load of the compressor and the condenser.

Response: Fixed set point vs. variable set point: Control using ambient is a minimum not a requirement. If a better strategy can be defined, it could be used instead, such as load following. We have to determine how to do this in the code language.

Comment: There may be problems with retrofits because size constraints will limit equipment selection and may cause certain control measures to be ineffective.

Comment: Fans should be cycling near or at floating set-point which would reduce kWh load.

Remote Condenser Specific Efficiency

This measure is compared relative to FHP with variable speed so these are incremental savings. With the adjustments, savings might be a little too conservative.

Q. How do you account for the life expectancy of the equipment?

A. TDV accounts for equipment replacement cost over the expected life of the measure.

Q. What is the time frame evaluated for cost effectiveness?

A. 15 year lifetime of the equipment

Comment: We know that EC motors save money over the year compared to non-variable speed fans. Yet, your specific efficiency graphs indicate that EC motor condensers are inefficient. That doesn’t seem to make sense. The flexibility of EC motors is what saves money. Looking at annual consumption of the motors, would show that they are much more efficient [than full speed efficiency implies, since] motors aren’t running at full speed at most times.

Response: Capacity and power at full speed was used as the basis for the specific efficiency calculation. The savings analysis is based on annual operation, and assumes variable speed and floating head pressure as the “baseline” reference, and takes into account operation at variable speed. The standard would still have to define a certain rating point for specific efficiency.

Comment: If you pick 70 Btuh/W, you are eliminating EC motors.

Response: Not for all manufacturers, and since EC maximum speed can be set, EC efficiency can be readily “dialed in” to match a desired specific efficiency.

Q. How do we prevent inherently variable speed EC motors from running over their “rated speed?”

A. The electronics in the EC motor can be programmed for the maximum fan speed.

Q. How much modeling data will be made available?

A. Data will be made available upon request by interested parties.

Q. Where do the equipment costs come from? Do you account for changes in material costs (changes in the price of copper, etc.)?

A. List price from the manufacturer is used. We assumed escalation for all materials. Potential future changes/variation in material costs is not included.

Q. Why do you care about fin spacing (FPI) on condensers?

A. Changing the FPI is a way to circumvent the measure and too many fins lead to rapid fouling. Most chains limit FPI in their specifications anyway.

Q. What about row limitations?

A. This should not be a problem since choice of rows (and other design choices by manufacturer) is all inherently addressed in specific efficiency, without dictating design.

Floating Suction Pressure

Q. Is it better to control by valve closure? Measure case temperature and close the valve when the temperature is met. This reduces load to zero. How does that help me if I set at highest possible temp for worst case? It seems completely redundant.

A. Other controls (liquid solenoids, suction valves) have to be secondary to floating suction, so the control system has to have enough intelligence to do this. The overall case load doesn’t change by cycling the solenoid for control. The purpose of floating suction is to operate the compressors at the highest suction that meets the load and reduce lift and save energy. Rather than cycling the solenoid, the liquid solenoid (or suction stop) stays open and the coil operates at a closer TD and the suction pressure can be no lower than necessary.

Comment: Does not make sense, it won’t save energy.

Mechanical Subcooling

The minimum design requirement may have no cost, if the savings in low temp compressor HP is considered. The requirement (only LT subcooling with a MT system) would be the minimum requirement; subcooling LT and MT with a higher temperature system would provide more savings and go beyond the minimum requirements.

Q. You say that it’s relatively no cost. What about the additional insulation cost?

A. Common practice is already to have insulation on liquid lines.

Q. What about reducing line sizes and refrigerant charge through sub-cooling?

A. Yes, the line size and charge can be reduced, often one line size reduction due to lower mass flow and higher allowable pressure drop, but it would be difficult for the standard to mandate line sizing for mechanical sub-cooling. There is the potential for a negative performance impact if done improperly.

Comment: If sub-cooling fails, flashing results and risks product integrity while waiting for repairs.

Comment: HFC does not belong in an energy code, advantage to mechanical sub-cooling.

Evaporator Coil Specific Efficiency

It looked like a good opportunity initially, but when we dug more deeply, it was more complicated. Airflow and airside TD gives a nice product line, but a lot of variation in efficiency and the amount of air circulated per unit of capacity. Info available to do this measure is inadequate, until there is a standard test. Showed a lot of potential, but needs to go into the next code cycle, it needs standards and certification before we draw the line.

Comment: Don’t drive an efficiency standard at the expense of product quality. I am concerned about how this will affect air flow rates in cases.

Response: Evaporator coil specific efficiency is only for walk-ins

Q. Do you need to include an electronic expansion valve?

A. We need to include the cost, but don’t mandate it

Evaporator Coil Variable Speed

Comment: Concerned about air circulation problems in the case with variable speed and how this will impact product quality. Even now with constant speed fans you sometimes end up with warm spots.

Q. Are we potentially going about this the wrong way by requiring a large amount of additional equipment (variable speed drives) just to achieve a small amount of energy savings. What about sustainability?

A. Underlying assumption is EC motors with inherent variable speed capability, not addition of a VFD. We need to think about what can be done by Jan. 1, 2013, when code takes effect.

Comment: Concerned that this measure is too advanced of a technology for now. This may be a measure that is not common practice, can’t make judgment on this if we don’t have any point of reference and we don’t have costs.

Response: Agree it is not currently in use for supermarkets. Conceptually very simple, and (as noted for specific efficiency) there is often excess air circulation, and variable speed is in wide use in refrigerated warehouses. It may make more sense on medium profile coils in larger boxes.

Comment: Concerned that the maintenance cost for this measure is too low given the number of coils involved, especially relative to other maintenance costs that have been shown for other measures. Commenter did not have any other cost estimates.

Liquid Suction Heat Exchangers

Get more cooling out of each lb of refrigerant. Higher suction, more superheat. Was common prior to R-22, then went away due to R-22 superheat sensitivity, but for HFC refrigerants this is pretty attractive. Placement is important, if you aren’t doing mechanical sub-cooling, it helps the expansion valve work better. Only applies to DX systems, and doesn’t pencil out on HT SST.

Q. Are these products readily available?

A. Yes (response from the audience)

Comment: These heat exchangers provide a large source of refrigerant leakage due to line breakage, usually at the liquid elbows, due to expansion. We remove them regularly.

Response: We want to define a good solution that would be reliable, and evaluate using the cost of a good solution.

Q. Do we have to mandate the use of a heat exchanger? What about other methods such as welding the lines inside the case together.

Q. What if we have mechanical sub-cooling as well? Does this have a benefit if you are mech. subcooling? And what temp are you seeing?

A: Low temperature analysis assumes 55 F mechanical subcooling (at entry) and 17 F of subcooling by LSHX.

Q. Would it be easier or more cost-effective to subcool to a lower temp than to put in this equipment?

A. The benefit is sub-cooling gained from suction superheat that would otherwise be non-productive superheat, not only from more subcooling. Gave example of leaving gas temperature and return gas temperatures at compressors.

Q. Are you going to have to insulate the liquid line in the medium temperature cases? Does it cause service (maintenance) issues?

A. No. No difference from what already exists if for example a MT system is subcooled (and lines in the case are not insulated).

Q. How will this be enforced?

A. Several ways:

Building inspectors would look for any necessary equipment. Some sort of commissioning is needed for controls based measures

Control measures will need acceptance testing

Acceptance tests require certification. Licenses are required for design (engineer) and construction (contractor)

Mechanical (HVAC) compliance forms are filled out by an engineer. Mechanical (HVAC) acceptance forms are filled out by a contractor. We would expect a similar requirement for refrigeration systems.

Q. For measure costs is commissioning included?

A. Yes.

LED Case Lights

Q. What about pre-emption problems? AHRI will challenge this, because it is federally regulated equipment.

A. We are aware of pre-emption issues and working through them with the CEC.

Display Case Lighting Control

Comment: You should allow for the use of motion sensing controls as well.

Open Upright Freezers

Q. (To the Audience) Is there a good reason to allow open upright freezers?

A. Need to ask merchandiser.

A. They are still around but not commonly used. Most stores are taking them out, but they are still being sold.

Q. How would we do this in a remodeling, is it a marketing issue?

A. Offer it as an incentive.

Hot Gas Defrost

Comment: We use it as common practice with no problems.

Comment: We always have trouble with it. Constant problem with leaks. Maintenance is an issue.

Comment: The measure is complicated because you have to balance the tradeoff between case performance and system performance

Comment: CA hasn’t been a big market for hot gas defrost because it hasn’t been done correctly. Would be a good discussion to have with others.

Comment: PNNL has baseline data, comes from manufacturers data, estimated based on what was available. Uncomfortable making it available for this, since it was intended for a different (unrelated) purpose.

Q. Isn’t this measure energy neutral (electric heater vs. hot gas)? Have you looked at whole system impact?

A: The analysis is more complicated than just the electric heater energy because the case needs to make up for time spent in defrost, which is different for electric defrost. The main problems related to extra piping and additional leaks caused by hot gas defrost.

Comment: If you mandate electric defrost, it could limit an alternative defrost.

Response: Doesn’t mandate electric, but prohibits gas defrost

Heat Reclaim For Space Heating

Q. Do we have to mandate that the heat reclaim be used for space heating? What about other uses such as hot water or snow melt?

A. Intent is flexibility to allow lots of ways to use heat reclaim. It needs to be specific to building energy use (not snow melt), but others

Q. Can this work with floating head pressure?

A. Yes

Comment: Almost a contradiction, mandating floating head, which then means you can’t get heat reclaim.

Response: There are ways to accomplish heat reclaim with floating head pressure. For a direct system, the practice by contractors in CA uses a reclaim holdback valve, allowing condensing in HR coil at required SCT and regular floating head pressure at condenser.

Comment: What about HVAC limitations for retrofits? You should only trigger this measure if both the compressor and HVAC system are being replaced.

Comment: For retrofits this will greatly increase charge size, especially if the HVAC and refrigeration systems are not located close together

Comment: There are also problems with condensing in the heat reclaim coils.

Comment: This measure (and all reach codes discussed) is not necessarily feasible.

No Open Upright Cooler cases

Q. (To the Audience) What factors should be considered if we prohibit open cases?

A. Answers from the Audience:

HVAC loading impact

Potential problem with produce in a case is misting

Merchandizing is the largest problem. Sales fall with closed cases and offset the energy savings.

May be a disincentive to remodel. May be unintended consequences.

It would be easier to argue for beverage and dairy in cases and not produce and meat

In general the attendees were in favor of the no open case measure from an energy savings standpoint

End of Presentation Discussion

Comment: There seems to be a tenuous connection between GHG emissions and energy efficiency. Concerned that CARB is using T24 as a failsafe in case AB32 is voted down. Concerned that CARB mandated refrigerant types may not allow us to meet the Title 24 requirements for energy efficiency. Labeling the requirements as an energy measure to make sure it gets through. Don’t see how looking at direct emissions has anything to do with energy code.

Response: Need to look at the whole bldg. as the way to get a better solution.

Comment: Don’t tell us the technology, but have a whole bldg. level. Some agreed that we need to make sure that refrigeration requirements don’t negatively impact energy efficiency. We all want to reduce energy, requiring a specific method impedes any innovative ideas.

Comment: Concerned that there is going to be too many bodies governing the handling and use of refrigerants: EPA, CARB, Title 24, etc.

Comment: Concerned about problems with interpretation of all of these regulations by different inspectors and governing bodies.

Q. What policies exist for when regulations overlap?

A. Overlap should not happen. AB32 only has leak inspection and maintenance measures for existing systems. Title 24 addresses new construction and design issues.

Comment: Mandated measures stifle innovation. We should set a goal without specifying what pieces are needed to meet the goal.

Response: The performance approach is not ready yet but that is the ideal method. Presently we are just trying to eliminate the worst offenders.

Comment: I think the leak reduction in refrigerant system is similar to refrigerant leak reduction HVAC or duct leak reduction in buildings. This is to ensure the system is capable of efficient operation and can be maintained at that level. When it is not regulated a high duct leak rate is high energy use now and forever.

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