# Presentation: 949862

## 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

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

- GHP Tech Specific Super ESPCs

- GHP ECMs in Regional Super ESPCs

- Other Regional and Tech Specific 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

- One heat pump on its own loop

## Commercial: Multiple GHPs on common loop, central pumping subsystem

- 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**

**Fan**

**Air 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 measurementson 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

## 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**