Figure 1 Front window of the Tailwaggers Thrift Shop (Photo by J. Osborne).

Tailwaggers Thrift Shop, as seen in Figure 1, is a small retail thrift store located in Eureka, California. The store sells used merchandise such as books, jewelry, men and women clothing, silverware and dishware, arts and crafts, music, furniture, antiques and collectibles. The local thrift store is run by a staff of friendly volunteers who give their time for the benefit of the Sequoia Humane Society. Tailwaggers Thrift Shop is owned by the Sequoia Humane Society and "100% of Tailwaggers' profits go to support the adoption, spay/neuter and education programs of the Sequoia Humane Society."[1] The Sequoia Humane Society is a nonprofit organization that promotes not only animal welfare, but also our own individual responsibility to protect and care for animals.

Energy Audit[edit | edit source]

On September 24, 2007, Redwood Coast Energy Authority (RCEA) completed an energy audit project that involved installing 22 new linear fluorescent light tubes into existing light fixtures at Tailwaggers Thrift Shop. The new linear fluorescent light tubes consume about 3/4th the energy as compared to the outdated fluorescent light columns.[2]

RCEA Energy Retrofit[edit | edit source]

Store Layout[edit | edit source]

RCEA visited Tailwaggers Thrift Shop in early 2007 with plans to fit the store with new energy efficient fluorescent lights. Tailwaggers is being lit by 9 pairs of fluorescent light fixtures and 4 single fluorescent light fixtures, shown in Figure 2. All 22 T12 fluorescent lights drew 34-watts and used magnetic ballasts. The RCEA retrofit replaced the T12 fluorescent lights to T8 32-watt fluorescent lights. The new lights were fit with NEMA Premium electronic ballasts, lowering their energy consumption. Switching to T8 fluorescent lights lowered total power consumption from 748 watts (22 x 34), to 704 watts (22 x 32).

Figure 2 Store layout with approximate locations of all lights changed during the retrofit.
Table 1 Floor Plan Legend
aa Two column light
aa Single column light
aa Four-blade ceiling fan

Energy Saving Opportunity[edit | edit source]

In 2006, Tailwaggers Thrift Shop was unaware of the energy saving opportunity that was available by switching from their current fluorescent light bulbs to energy efficient fluorescent light bulbs. During the winter months (2006-2007), there was a lot of energy being consumed for light because December, January, and February are the darkest and coldest months of the year. After the new lights were put in, energy consumption in the winter months of the following years decreased by roughly 450kWh. For example, during the months of February and March of 2007 and 2008, the energy consumption was reduced by 32% seen by the trend lines in Figure 3.

Figure 3 Tailwaggers Thrift Shop's monthly energy consumption from 2007 - 2008.

Predicted Results vs. Actual Results[edit | edit source]

The Tailwaggers Thrift Shop saved money and energy by participating in RCEA's lighting retrofit. A year after the retrofit (9/07 - 8/08), they saved $212, about $68 less than RCEA's prediction. Tailwaggers Thrift Shop's yearly savings paid back the $412 installment cost after two years. This time period is known as simple payback, and is 0.5 years later than RCEA's predicted payback time. Furthermore, the shop is now saving roughly 1,500 kWh per year (data shown in Table 2).

A light bulb's energy consumption emits a green house gas known as CO2. CO2 is a major green house gas because of its high concentrations as well as its strong absorption of energy (heat).[3] By taking part in RCEA's energy watch program, Tailwaggers Thrift Shop reduced their annual CO2 emission by 790 lbs of CO2, 175 lbs less than RCEA's estimated annual CO2 emission reduction.

Table 2: RCEA's estimated results versus the actual results(1)(2)
Type of
RCEA Report

(Predicted results)

1st year after light retrofit

(Actual results)

2nd year after light retrofit

(Actual results)

Yearly Savings $278.10 $211.90 $194.90
Monthly Savings $23.20 $17.70 $16.20
Yearly Energy Savings 1,664.0 KWH 1,506.0 KWH 1,509.0 KWH
CO2 Emission Reduction 865.0 lbs/year 789.1 lbs/year 790.7 lbs/year
Payback Time 1.5 years 2.0 years

(1) RCEA Calculations based on average cost of $0.16716 per kWh and 06Com-90 rebate.[4]

(2) CO2 emission Calculations based on PG&E's power mix average - 0.524 LBS/kWh.[5]

Customer Behavior[edit | edit source]

Figure 4 Three lights that get turned off during bright and sunny days (Photo by J. Osborne).

The behavior of the Tailwaggers Thrift shop volunteers went unchanged after the the new lights were implemented. The lights continued to remain on only during business hours (Monday-Friday 10am – 5pm, and Saturday 11am – 3pm). The executive director of the Sequoia Humane Society, Cyntha MacMillan, agreed to install the new light fixtures because she knew they would save the non-profit organization some money as well as eventually pay for the initial installment cost. MacMillan would not have completed a lighting upgrade if it were not for the RCEA's assistance. Furthermore, MacMillan is not looking for any new retrofits at this time. Nevertheless, MacMillan is pleased with the lighting retrofit, but it did not change the attitude of any of the volunteers.[6]

After hours the lights were always turned off. The managers would often turn off the lights in the front (Figure 4) because the bay window let in enough sunlight. However, during the winter months, there would be a higher energy consumption because December and January are the darkest thus most energy-demanding months of the year. The owners and long-term volunteers are pleased about the switch, but the change in lights had no change in their behavior. Manager Elly Burger only wishes she had known about the retrofit opportunity sooner.

References[edit | edit source]

  1. Sequoia Humane Society. (2009). Tailwaggers thrift shop. Retrieved October 16, 2009, from
  2. Redwood Coast Energy Authority. (2009). RCEA: redwood coast energy watch. Retrieved November 22, 2009, from
  3. Davis, Mackenzie, and Masten, Susan. (2009). Principles of environmental engineering and sciences: second edition. New York, NY: McGraw-Hill
  4. Dickinson, B. (2009). RCEA customer report: tailwaggers thrift shop audit summary data. Retrieved October 1, 2009.
  5. Grafman, L. (2009). Appropedia category: RCEA energy audit reviews. Retrieved October 16, 2009, from
  6. Interview with Tailwaggers Thrift Store volunteers, held on October 26, 2009
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