O AK R IDGE N ATIONAL L ABORATORY U. S. D EPARTMENT OF E NERGY Measurement and Verification of Geothermal Heat Pump ECMs John A. Shonder Oak Ridge National.

OAK RIDGE NATIONAL LABORATORYU. S. DEPARTMENT OF ENERGY

Measurement and Verification of Geothermal Heat Pump ECMs

John A. Shonder

Oak Ridge National Laboratory

FEMP M&V SummitNew Orleans, LA

May 5, 2003


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


GHP Tech Specific Super ESPCs

GHP ECMs in Regional Super ESPCs

Other Regional and Tech Specific Super ESPC

GHP makes up a significant fraction of the $363M investment to date under DOE’s Super ESPC

15%

4%


The Family Of GHP Systems

Equipment manufactured in a variety of sizes and configurations

Residential -- Each GHP has its own ground loop

200 Ft.

20 Ft.

25 Ft.

4 Ft.

One heat pump on its own loop

Commercial: Multiple GHPs on common loop, central pumping

subsystem

HeatPump

HeatPump

HeatPump

HeatPump

DPSignal Wire to Drive

Transducer

Variable Speed DrivePump

PurgeValves

Aux.Pump

Interior PipeHeaders

A

A

HeatPump

Multiple heat pumps on a common loop


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


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


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


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?


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


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 steady-state

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


GHP components

Compressor

Water-to-refrigerant coil

Air-to-refrigerant coil

Expansion valve

FanAir filter

Entering air

Conditioned air (Supply)

Heat recovery coil

Reversing valve

Water loop

p/t plug

Power


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


Measurements to be taken from each selected heat pump

Water pressure drop across water-to-refrigerant heat exchanger

Temperature of entering and leaving water (steady state)

Electrical power (steady state) Entering air temperature (and RH if

cooling)


M&V measurementson heat pump unit

Compressor

Fan

Electrical power

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

LWT

EWT

P


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


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


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


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


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

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

submersible pump

perforated intake

discharge

sleeve

formation

soil

A A


Lake

HDPE Coils withUV Protection inLoose Bundles

A

A

Common Loop Conditioned by Surface Water


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


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


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


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


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


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


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

O AK R IDGE N ATIONAL L ABORATORY U. S. D EPARTMENT OF E NERGY Measurement and Verification of Geothermal Heat Pump ECMs John A. Shonder Oak Ridge National.

Documents

mv slide

o ak r idge n ational

ghps slide

time slide

configurations slide

common loop slide

mv plan

mv process