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Energy Trust of Oregon Small Commercial HVAC Pilot Program. Stellar Processes December 15, 2009. Small Commercial HVAC Pilot Program . Goal: test feasibility of specifying a standard repair treatment that can be applied by contractors in a production mode in order to reduce deployment costs.

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Energy trust of oregon small commercial hvac pilot program

Energy Trust of OregonSmall Commercial HVAC Pilot Program

Stellar Processes

December 15, 2009

Small commercial hvac pilot program
Small Commercial HVAC Pilot Program

Goal: test feasibility of specifying a standard repair treatment that can be applied by contractors in a production mode in order to reduce deployment costs.

  • Install a new programmable thermostat. Set up proper scheduling and night setback.

  • Install drop-in economizers where appropriate. Ensure that economizers are connected with two-stage control wiring. Install the new sensors that permit better economizer operation. Properly set economizer changeover point.

  • Repair noticeable air leaks around roof curbs.

  • Clean coils.

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Production mode for rooftop units
Production Mode for Rooftop Units

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Energy signature analysis example
Energy Signature Analysis Example

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Short term monitoring
Short-term Monitoring

Minimal metering. Short term measurements of

(1) energy consumption by the HVAC unit and

(2) temperature of the delivered air.

Does not allow an explicit measurement of economizing or isolation of specific measures.

Slope and intercept parameters from Energy Signature plot used to extrapolate savings. Are data sufficient?

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Site details
Site Details

Strip mall site containing a representative mix of small business types.

Included are two sit-down restaurants, a fast food outlet, a retail store, an office and professional services (dentist, veterinarian, hair salon).

Standard repair protocol on a row of essentially the same HVAC unit.

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Field treatment
Field Treatment

  • Three of the HVAC units already had economizers. Only one was functional. The other two units did not have two-stage controls.

  • With one exception, outside ventilation was disabled on all the units.

  • None of the businesses had proper scheduling of HVAC operations.

  • All the units received a pressure wash of the coils.

  • Repair noticeable air leaks around roof curbs.

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Implementation challenges
Implementation Challenges

  • Metering was still a challenging task.

  • True power to avoid any power factor issues.

  • Equipment problems on two HVAC units. However, both of these units had an identical twin serving the same space.

  • Data collected at one-minute intervals to bin consumption into heating or cooling events. This requires a database operation to merge all the data streams and align by time of day.

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Analysis challenges
Analysis Challenges

Sometimes the model fit is not clear and the regression must be forced through a zero point. In such cases, some judgment is necessary to estimate a fit to the observed data points.

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Test of extrapolation method
Test of Extrapolation Method

“Before” and “after” weather conditions lead to savings estimates that are similar but not exactly the same. Difference due to relative amount of change expected for compressor cooling (slope) versus the ventilation savings (flat part).

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Test of annual extrapolation method
Test of Annual Extrapolation Method

Average estimated savings on an annual basis agree closely with the average of short term results.

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Local microclimate versus long term weather data
Local Microclimate versus Long-Term Weather Data

Are the short term results representative of the 365-day weather data used for the annual extrapolation? This question is not resolved by the current study.

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Summary of electric savings
Summary of Electric Savings

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Computed space heat savings
Computed Space Heat Savings

Observed instances of the warm-up length and balance temperature for seven cases. Assumed fixed percent outside air and airflow rate. Average for all units, 2.5 annual therms or 0.6% of space heat.

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Program cost effectiveness
Program Cost Effectiveness

Cases Average KWh Average Therm

studied Savings Savings

13 Directly monitored 2,145 38% 2.4 0.6%

15 Including all units 2,074 37% 2.5 0.6%

Unit cost $1,685

PV of electricity, per kWh $0.980 $0.702

PV of Gas, per therm $7.872 $6.078

PV of Benefits $2,052 $1,471

BCR 1.22 0.87

Discount Rate 5.2% 5.2%

Lifetime 15 10

Levelized Cost, per kWh $0.078 $0.105

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  • In general, the energy signature methodology appears successful. A question remains regarding the use of long-term (TMY) data for extrapolation.

  • Savings averaged 2,074 annual kWh or 37% of VAC consumption. Estimates should still be validated with long-term billing simulation.

  • Energy Signature method provided reasonable extrapolations to annual savings.

  • Savings were due to a variety of treatment measures. Most important were proper scheduling and programming of night setback and the addition or repair of economizers. The verification methodology does not allow savings to be isolated to specific treatments.

  • For about one third of the cases, the tune-up repairs did not result in savings. This is a small amount of “dry holes” and it is probably not necessary to attempt to screen out such cases.

  • Before the repairs, most of the systems exhibited problems.

  • Computed small gas warm-up savings averaging 2.4 annual therms. The savings are due to lockout of outside air during morning warm-up and are accomplished by the new programmable controls.

  • Unit cost averaged $1,685 for labor and materials. The estimated Benefit Cost Ratio is 1.22 for 15-year life or 0.87 for 10-year life.

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