Grand Trunk Leisure and Fitness Center
Review of Equipment Trial
Blackhawk Power Conditioner
City of Edmonton
Grand Trunk Leisure and Fitness Centre
A trial of the Blackhawk power conditioner was conducted at the Grand Trunk Leisure
and Fitness Centre, with the cooperation of the City of Edmonton, during the month of
The unit was found to reduce energy consumption by an average of 350 kW.h per day
resulting in an estimated reduction of 127,750 kW.h consumed per year. Associated
CO2 emissions reductions are 115 tonnes annually. The Blackhawk installation has an
estimated simple payback of 1.6 years and a ten year 61% return on investment.
Benefits associated with equipment longevity are noted as being significant, but are not
included in the economic analysis.
Analysis of the results also suggests that the unit installed may be undersized for the
kVAR inductance of the facility. As a special note, some City facilities may be on rate
DAS-MC, which charges based on peak kilo Volt Ampere (kVA) demand. The
economics of the Blackhawk power conditioner would be further improved when used
on these facilities.
Gray Energy Economics Inc. has been retained to review the results of a trial of a
Blackhawk power conditioner installed at Grand Trunk Leisure and Fitness Centre,
13025 112 St, Edmonton, AB. The facility combines a swimming pool, water slides, hot
tub and other aquatic features with a large fitness facility, gymnasiums, offices and
The trial consisted of installation of a 35 kVAR Blackhawk power conditioner and
comparison of energy consumption with the unit on and off. The Blackhawk power
conditioner, among other things, provides capacitance to the building electric system,
balancing inductance and improving the building power factor.
Data and Methodology
Data analysis was conducted on hourly kW.h (hourly energy), kW (peak kilowatt
demand) and kVA (peak kilo volt ampere demand) for the period July 1, 2013 to July 31,
2013 from meter data provided by the City and read by EPCOR. The Blackhawk power
conditioning unit was on during the period July 1 to hour 12 of July 22.
Two methods were used to evaluate the data provided, for the purpose of determining
the effect of operation of the Blackhawk power conditioner on energy consumption,
power factor and kVA demand:
1 Load duration comparison: The largest determinant of energy consumption is the
pattern of usage of the electrical equipment in the facility. In order to isolate the
effect of the Blackhawk power conditioner on energy consumption, two large
sub-samples of data were selected with matching days of the week, one
sub-sample with the Blackhawk on and one with it off. The sample data was
re-ranked from highest energy consumption hour to lowest energy consumption
hour to derive the load duration curve for each sub-sample.
2. Regression analysis: In order to normalize the sample data for weather and to
isolate the effect of the Blackhawk power conditioner, a multivariate regression
analysis was performed using three formulations of temperature data and a
dummy variable for Blackhawk operation.
Load Duration Comparison
The two largest data-subsets with matching days of the week were Tuesday, July 2 to
Wednesday July 10, 2013 and Tuesday July 23, 2013 to Wednesday July 31, 2013.
Statutory holiday, July 1, 2013, was excluded from all analysis.
With Blackhawk Without Blackhawk Difference Percentage
Total Energy Consumption 49042 51156 2114 4.13%
Average Hourly 227 237 10 4.13%
Min 136 125 -11 -8.73%
Max 296 289 -7 -2.52%
Without adjusting for temperature, the reduction in consumption attributable to the
Blackhawk power conditioner is estimated by this method at 235 kW.h per day.
Regression Analysis for Weather Normalization
In order to correctly separate the effects of ambient temperature on building cooling
requirements and the operation of the Blackhawk power conditioner, the hourly energy
consumption at the facility was used as the dependent variable in all linear regression
models, with daily cooling degree days and a dummy variable for operation of the
Blackhawk unit as independent variables. For July 22, 2013, the dummy variable value was set to 0.5 for 1/2 day of operation.
Three formulations were evaluated:
1 Daily energy consumption vs. same day cooling degree days and Blackhawk
2 Daily energy consumption vs. prior day cooling degree days and Blackhawk dummy variable
3 Daily energy consumption vs. average of same and prior day cooling degree
days and Blackhawk dummy variable
Model 3, using a moving average of the current and prior cooling degree days was the
best fit model, with the following results:
Daily Energy Consumption Constant Cooling Degree Days Blackhawk
Estimate 5550.4 150.6 -350.4
Variance 107.7 60.0 183.5
Statistically Significant Yes Yes Yes
This method indicates that the effect of the Blackhawk power conditioner is a reduction
of 350.4 kW.h per day, temperature normalized. This is a reduction of 6.2% in energy
consumption for the facility.
Using the temperature adjustment factor of 150.6 kW.h/day consumption per cooling
degree day (2 day average), one can also adjust the previous estimate for savings
derived from the sub-samples.
Comparing the two sub-sample periods, cooling degree days totaled 22.5 during the
period when the Blackhawk was operating, and 5.5 when it was not operating. The
difference of 17 degree days between the sample periods would add another 2560.2
kW.h or 284.6 kW.h per day to the savings attributable to the Blackhawk over the nine
day sample periods. Adding this to the estimate of 235 kW.h per day savings from the
sub-sample analysis totals 519 kW.h savings per day.
As the regression analysis explicitly accounts for temperature difference and is
statistically the best, linear, unbiased estimate of the underlying parameters, the
estimate of 350.4 kW.h per day savings is used for subsequent economic analysis. The
higher value determined by adjusting the sub-sample analysis corroborates and
validates this estimate as conservative and reasonable.
After adjusting for differences in cooling degree days over the sample periods, the
Blackhawk power conditioner is estimated to have saved 350.4 kW.h per day of
operation. Extending these savings for one year, annual energy savings are estimated
to be 127,750 kW.h. At 900 kg of CO2 produced per 1,000 kW.h (1 MW.h) of Alberta electricity generation, greenhouse gas reductions associated with this installation are estimated to be 115 tonnes per year.
The facility is served by EPCOR Distribution on rate DAS-TOU applicable to commercial
or industrial facilities using between 150 and 5,000 kVA. This rate uses peak kW to
determine demand charges and an on-peak charge per kW.h of $0.00854.
The rate paid for electric energy has not been provided, but is estimated at $0.075 per
kW.h. Estimating that 60% of energy consumed is on-peak, the effective rate per kW.h
Annual savings from use of the Blackhawk power conditioner at the facility are
estimated to be $10,378. The installed cost of the unit was $16,805. Simple payback on
the device is 1.6 years. The 10 year rate of return on investment is estimated to be
No estimate of improvements to equipment life have been included in this estimate. In
the author’s experience, extended equipment life is a significant factor in power factor
David Gray BA,MBA,MM
President, Gray Energy Economics Inc.
August 27, 2013