Measurement and Verification of Geothermal Heat Pump ECMs by pptfiles

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									Measurement and Verification of Geothermal Heat Pump ECMs
John A. Shonder Oak Ridge National Laboratory
FEMP M&V Summit New Orleans, LA May 5, 2003
OAK RIDGE NATIONAL LABORATORY
U. S. DEPARTMENT OF ENERGY

Motivation for this work
 Streamline M&V process for geothermal heat pump projects  Build on existing FEMP M&V guidelines  Develop a template that specifies in detail what the M&V should encompass
 Annual measurements  Calculations  Reporting

OAK RIDGE NATIONAL LABORATORY
U. S. DEPARTMENT OF ENERGY

GHP makes up a significant fraction of the $363M investment to date under DOE’s Super ESPC
GHP Tech Specific Super ESPCs 15%
4%

GHP ECMs in Regional Super ESPCs

Other Regional and Tech Specific Super ESPC

OAK RIDGE NATIONAL LABORATORY
U. S. DEPARTMENT OF ENERGY

The Family Of GHP Systems

OAK RIDGE NATIONAL LABORATORY
U. S. DEPARTMENT OF ENERGY

Equipment manufactured in a variety of sizes and configurations

Residential -- Each GHP has its own ground loop

25 Ft.

4 Ft.

200 Ft. One heat pump on its own loop

20 Ft.

Commercial: Multiple GHPs on common loop, central pumping subsystem
Heat Pump Heat Pump Heat Pump Heat Pump Heat Pump

Signal Wire to Drive Purge Valves

Interior Pipe Transducer Headers
DP

Aux. Pump
Pump

Multiple heat pumps on a common loop
Variable Speed Drive

How an M&V plan for a GHP project is developed in practice
 ESCO proposes a plan based on customer’s requirements, company’s experience and interpretation of FEMP M&V guidelines  Site personnel, HQ support agency, and PF review the plan and suggest changes  Iterate as necessary until everyone is satisfied -- which takes time

OAK RIDGE NATIONAL LABORATORY
U. S. DEPARTMENT OF ENERGY

Development of baseline and guaranteed savings estimate
 ESCO must develop guaranteed savings estimates for the installed ECMs to establish payment stream  In all but the simplest projects, savings estimates require modeling with BEA software
 Pre-retrofit (baseline)  Post-retrofit

 Modeling with BEA software is virtually always done in GHP because loads are required for borefield sizing  Since it’s being done anyway, calibrated BEA model can be an integral part of M&V
OAK RIDGE NATIONAL LABORATORY
U. S. DEPARTMENT OF ENERGY

Developing these estimates can be a challenge
 In commercial applications, GHPs often replace systems supplied by a central plant (CHW, HTHW, steam)
     Building level energy use data is extremely rare Central plant fuel use data may or may not exist Pumping power? Heat loss between plant and buildings? Steam/water losses?

 Use as-built plans to develop building models, calibrate to short-term metering data to develop baseline  Update model to incorporate GHPs
OAK RIDGE NATIONAL LABORATORY
U. S. DEPARTMENT OF ENERGY

Similar problems arise in residential projects
 Lack of energy use data
 Meters on individual residences are rare  May be only one meter for the entire base/facility  Some meter housing areas separately  Calibrated?  Read correctly?  All read on same date?  Others use allocation formulas  Usually assigns a constant percentage  Is it meaningful to calibrate to?

OAK RIDGE NATIONAL LABORATORY
U. S. DEPARTMENT OF ENERGY

We see the calibrated simulation model as an integral part of M&V (like Option D)
 Use calibrated simulation to develop baseline annual energy use  Replace pre-retrofit equipment with GHPs in calibrated simulation and re-calculate annual energy use  Guaranteed annual savings = some fraction of post-retrofit prediction minus baseline  Annually, spot check a random sample of the GHPs (and pumping subsystem) to ensure they are performing as modeled in the software
OAK RIDGE NATIONAL LABORATORY
U. S. DEPARTMENT OF ENERGY

What would be done annually
 Select a random subsample of installed units (3 to 5% of total, or 3-5% in each building)  Annually or semi-annually (e.g., during last week of August, on work days between the hours of 2:00 and 4:00 PM):
 At each of the selected heat pumps, measure steadystate EER and capacity to ensure they are within +/-X% of modeled values (catalog performance)  Measure EWT to ensure it is below design value  For systems with central pumping, on each central loop measure pumping power, motor speed and pressure drop, ensure power is +/- X% of modeled power at these conditions

 Prove that the system is performing the way it was modeled in the BEA software
OAK RIDGE NATIONAL LABORATORY
U. S. DEPARTMENT OF ENERGY

GHP components
Air-torefrigerant coil Air filter Fan Expansion valve Water-torefrigerant coil Water loop Heat recovery coil Compressor p/t plug Power Conditioned air (Supply)

Entering air

Reversing valve

OAK RIDGE NATIONAL LABORATORY
U. S. DEPARTMENT OF ENERGY

Performance (capacity and EER) depends on a number of factors

OAK RIDGE NATIONAL LABORATORY
U. S. DEPARTMENT OF ENERGY

Measurements to be taken from each selected heat pump
 Water pressure drop across water-torefrigerant heat exchanger  Temperature of entering and leaving water (steady state)  Electrical power (steady state)  Entering air temperature (and RH if cooling)

OAK RIDGE NATIONAL LABORATORY
U. S. DEPARTMENT OF ENERGY

M&V measurements on heat pump unit

Entering air dry bulb temperature, relative humidity (in cooling)

Fan DP

LWT EWT Compressor Electrical power

OAK RIDGE NATIONAL LABORATORY
U. S. DEPARTMENT OF ENERGY

Required calculations
 Water pressure drop determines flow rate  Flow rate and temperature difference determine heat of rejection (absorption)  Power and heat of rejection determine capacity  Power and capacity determine EER  Entering air dry bulb and RH determine wet bulb temperature (accuracy is a concern)  Water flow rate, EWT, EA DB/WB specify performance

OAK RIDGE NATIONAL LABORATORY
U. S. DEPARTMENT OF ENERGY

Finding catalog performance for the given operating conditions

May require interpolation

Other mfrs publish data for 80/67 only, plus “correction factors” for other conditions

OAK RIDGE NATIONAL LABORATORY
U. S. DEPARTMENT OF ENERGY

Annual deliverable for M&V
 Spreadsheet containing all data and calculations  Written report presenting
 Average steady state efficiency and capacity of each measured heat pump  Percent by which this efficiency is above or below catalog performance  Average pumping power, compared to modeled pumping power  Peak EWT measured at each heat pump  Any problems the tests highlighted, and corrective actions taken

 Bottom line -- statement that savings is being achieved
OAK RIDGE NATIONAL LABORATORY
U. S. DEPARTMENT OF ENERGY

The annual M&V can be considered as small-scale retro-cx
 Check hose connections, filter, drain pan, reversing valve, etc.  Low capacity may indicate charge problems  High EWT may indicate flow problems, or underdesigned borefield  Check of pumping subsystem may indicate control problems
OAK RIDGE NATIONAL LABORATORY
U. S. DEPARTMENT OF ENERGY

Plan must allow flexibility
 Some buildings have large water-to-water heat pumps for OA pre-treatment
 Measure performance of OA pre-treatment heat pumps plus random subset of zone heat pumps in each building

 Some heat pumps have desuperheater loops to produce hot water
 Must ensure that these do not run during the measurements  Ensure that they function

 And other special conditions which must be examined on a case-by-case basis
OAK RIDGE NATIONAL LABORATORY
U. S. DEPARTMENT OF ENERGY

Standing column well: Two large projects going in under Super ESPC
A A

soil

sleeve

discharge
formation

submersible pump

perforated intake

Common Loop Conditioned by Surface Water
A

Lake

A

HDPE Coils with UV Protection in Loose Bundles

OAK RIDGE NATIONAL LABORATORY
U. S. DEPARTMENT OF ENERGY

The same plan can serve for residential systems as well
 Preventive maintenance requires periodic visits to residences  M&V measurements can be performed as part of a normal service call  In some projects ESCO has on-site service organization that could perform the measurements

OAK RIDGE NATIONAL LABORATORY
U. S. DEPARTMENT OF ENERGY

Implications of this proposal
 It’s imperative that we have confidence in the baseline
 Army ESPC audit specifically mentioned baseline development as a problem area

 We must also have confidence in the BEA software
 FEMP guideline specifies accuracy of calibrated simulation model

 More rigorous temporary metering may be required during project development  Installed equipment must include provisions for annual measurements
OAK RIDGE NATIONAL LABORATORY
U. S. DEPARTMENT OF ENERGY

Benefits of the M&V template
 Streamline project development process by reducing time required for negotiation  Provide confidence that ECM is delivering guaranteed savings  Annual retro Cx of the subsample and the pumping system ensures correct performance  Will highlight any operating problems sooner rather than later
OAK RIDGE NATIONAL LABORATORY
U. S. DEPARTMENT OF ENERGY

Other issues being addressed
 Not all hourly simulation programs represent vertical/horizontal bore GHPs accurately
 We have compared six commonly available programs  We will recommend acceptable software

 For other system types (standing column well) there are no proven system representations in common BEA software
 GHP core team will intervene  Motivating research to develop practical tools for other GHP system types as needed  PFs must take great care in assessing ESCO savings estimates
OAK RIDGE NATIONAL LABORATORY
U. S. DEPARTMENT OF ENERGY

We are working with a major heat pump manufacturer to determine
 Is the measurement plan viable?  Can the required measurements be performed accurately in the field?  Is the manufacturer confident that heat pumps will perform “as advertised”?  Particular concern is determining wet bulb temperature  Measurements are being taken in the manufacturer’s laboratory to verify proposed techniques
OAK RIDGE NATIONAL LABORATORY
U. S. DEPARTMENT OF ENERGY

Current activities
 In the short term, GHP Core Team assisting ESCOs and PFs in development of M&V plans  Maintaining a central database of GHP M&V plans and annual M&V reports  Developing “Guide to Measurement and Verification for GHP Systems”  Specify required measurements and instrumentation  Model M&V plan for three different systems  Include case studies from real projects

OAK RIDGE NATIONAL LABORATORY
U. S. DEPARTMENT OF ENERGY

Where we stand now
 We have the beginning of a plan  Work is at an early stage of development  We are seeking the assistance of others to develop consensus
      ESCOs Federal agencies FEMP M&V experts GHP manufacturers ASHRAE IGSHPA

OAK RIDGE NATIONAL LABORATORY
U. S. DEPARTMENT OF ENERGY


								
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