Residential Window Film

Solar heat gain through south and west facing windows is a serious problem for convenience stores even in winter. Heat is already being generated by equipment, lighting, staff and customers. Large expanses of glass raise temperatures and air conditioning bills.

For several RaceTrac convenience stores in the southeast solar heat led to the following problems:

• Thousands of dollars of heat damaged merchandise from melted candy to faded labels on boxes and cans;
• Unproductive staff and uncomfortable customers;
• Inability to use space near windows;
• Frequent use of heating and air conditioning (HVAC) equipment;
• Unacceptable energy costs.

"We definitely needed to do something to solve our overheating problems," explained Joe Chastine, national account manager for maintenance at RaceTrac, a 349 store chain headquartered in Smyrna, Georgia. "But until recently we couldn't find a solution."

Overheating was also a serious problem at Prime Time convenience stores in Kansas, Missouri and Arkansas. Faded labels on shelved beer and food cartons caused management to spend time relocating slow moving items away from direct sun. "Worse yet, we had to move our ice cream machines from their window location because of the heat," said Steve Wood who owns 25 Prime Time stores. "Even running full time they couldn't keep the ice cream frozen."

Quik Trip, a 333 convenience store chain operating across the south from Arizona to Florida is concerned about overheating in newly constructed stores. "Our architects were telling us that new stores in Arizona would require larger sized air conditioners than we had been using elsewhere," explained Danny Ward, parts and materials buyer for the Tulsa-based chain. "We wanted to avoid that expense and find another solution."

For many convenience store operators the quick fix involved keeping a watchful eye on shelved merchandize and putting up unsightly blinds on store windows in the hope of blocking the heat. Clearly in an age of pay at the pump high tech convenience for customers, store management needed a convenient and affordable solution to overheating.

Traditional solutions to overheating

A window should let in desirable energy (daylight) and block unwanted solar energy (near infrared heat) which causes overheating and ultra violet (UV) which is a cause of fading damage.

Heat gain can be mitigated by replacing existing glass with expensive solar control glass. Solar control glass may be cost effective for some new construction but is generally not feasible in existing structures. At far less cost, solar control films can be applied to existing windows. Tinted or mirrored window films block unwanted heat but reduce visible light and darken interiors.

Stores with dark films on their windows may have to increase lighting to compensate for the decrease in visible light. The additional use of electricity for lighting (which increases energy costs) may actually increase temperatures requiring more air-conditioning. Increased utility costs defeat the major benefit of the film - cost savings.

In retail environments, dark films on windows may prevent customers outside from seeing inside and staff inside from seeing out.

"For us, putting dark film on our store windows was no solution," explained RaceTracâs Joe Chastine. "Customer need to see in at night and our people need a clear view of the gas pumps outside."

"Visually clear at night is a big deal for customer and employee safety," said Danny Ward of Quik Trip.

The best solution to overheating - spectrally-selective clear film

Transparent, almost colorless spectrally-selective applied window film offers the best ratio of visible light transmission to heat and UV rejection. Clear and almost colorless films do not change the aesthetics of existing glass be it clear or tinted, nor do they change the color of the light entering the facility. These films are constructed with a scratch resistant coating on one side and an adhesive coating on the other, allowing for retrofit application to existing glass.

Meeting the challenge

RaceTrac, which intends to expand to 500 stores by 2001, used V-Kool spectrally selective applied film as a test at a store in Suwannee, Georgia.

"V-Kool performed exactly as predicted, blocking heat while maintaining the clear look of our original glass," explained Joe Chastine. "Our candy vendors were happy, our store staff was happy and our customers were happy too."

Since then RaceTrac has installed approximately 600 sq. feet of V-Kool at stores in Orlando, Ft. Lauderdale and Georgetown, Texas.

The stores, ranging in size from 3,200 to 3,800 sq. feet, report no heat or UV damaged merchandise and reductions in air conditioning costs of 10%.

Steve Wood of Prime Time believes his company will also see significant savings in air conditioning bills now that V-Kool has been installed at stores in Newton, Kansas; Harrison, Arkansas; and Branson, Missouri. "We will see savings If only we can get the staff to stop changing the thermostat," he admitted.

For six Quik Trip stores in Arizona and Texas, larger air conditioning units were not necessary with the installation of V-Kool film. "We didn't have to buy larger units but were able to reduce the load on our standard size units by using V-Kool," explained Danny Ward.

While Quik Trip admits they haven't yet worked out the numbers, the company believes all indications regarding V-Kool's performance are favorable. "In our stores with V-Kool we've had no heat damaged merchandise and no complaints about high temperatures," reports Ward.

Marty Watts is president and CEO of V-KOOL, Inc., Houston, TX., a sales and marketing distribution company of V-KOOL heat reflective applied films for architectural, automotive and specialized vehicular applications. V-Kool, participates in Energy Star® a voluntary partnership among the U.S. Department of Energy, the U.S. Environmental Protection Agency, product manufacturers, local utilities and retailers. Energy Star partners promote energy efficient products using the Energy Star logo and by educating consumers about the benefits of energy efficiency.

V-Kool's solar control films are manufactured by Southwall Technologies, Palo Alto, CA, whose window film technology was recognized by Popular Science as one of the 100 greatest inventions of the past millennium.