Tower at 1301 Gervais, a Case Study: 18.5% Reduction in Annual Electrical Usage & Just 44 Months to 100% ROI

When trying to reduce your monthly utility bills, it’s common to try replacing inefficient HVAC equipment or to increase insulation. Yes, these are routes to lower energy consumption – but you may find that the return on investment is measured in decades or that your building simply doesn’t have space for additional insulation.

But you don’t have to resign yourself to perennially high bills or sacrificing comfort during the dog days of summer! High performance window films help to slash your energy bills and offer incredibly rapid ROI. This case study will look at over 8 years of data from Tower at 1301 Gervais and examine the dramatic benefits they received from window films.

The Tower, in Brief

Tower at 1301 Gervais, as the building is known, finished construction in 1973. At the time of its construction, the 20-story building was the tallest building in Columbia until the Palmetto Building surpassed it in 1983.

Quick Facts

  • Built: 1973
  • Rentable Square Feet: 298,926
  • # of Windows: ~1620
  • # of South Facing Windows: 524
  • # of Windows with Sun Exposure: ~1100

Built just prior to the energy crises of the 1970s, the structure lacks many of the modern insulating features that would become more common in the following decades. Tower has single-paned windows and was only lightly insulated. Not only was insulation sparse to begin with, adding insulation to the structure has been deemed non-viable due to space constraints. These factors resulted in Tower at 1301 Gervais spending over $703,000, or a monthly average of $58,500, on electricity in 2015. The following two years enjoyed slightly more moderate weather and saw a slight dip in overall energy expenditures, bringing the monthly average electricity bill to just over $57,000 for the 2015 to 2017 time period.

The Solution: Vista VE35 Window Film from LLumar

With over a thousand windows that receive direct sunlight, applying a window film was a logical choice for reducing Tower at 1301 Gervais’ energy consumption.

At Sun Shades and Graphics we have decades of experience applying window films and have seen first hand the amazing results provided by LLumar’s products, and recommended the Vista VE35 Window Film. This particular film is a ‘Low-E’ film, or low-emissivity, and is specially designed for its insulating properties.

Why Low-E?

The largest benefits of Low-E films are their capacity to reflect infrared light, or radiant heat. All objects when they are warmed by the sun reflect that heat back into their environment as infrared light – this is why infrared cameras are able to ‘see’ hot objects and why your stove’s broiler is able to rapidly char foods.

By applying a Low-E film to windows, we are able to prevent the radiant heat that is emitted from the ground, cars, and neighboring buildings from entering into the building. For this reason, we opted to apply the window film to all four sides of 1301 Gervais – including its north facing windows – because even without direct solar exposure, radiant heat was still a major contributing factor in summertime energy expenditure. The benefits of Low-E film aren’t limited to summer heat, as these films are able to help prevent radiant heat from escaping during the cold winter months. This works using the exact same principles as during the summer – with radiant heat (this time from inside the building) being reflected back inside instead of being permitted to escape.

A quick note on thermodynamics: In the simplest terms, heat always seeks to move from areas of high heat to low heat. This means that while we are running the AC in the summer, external heat is trying to migrate indoors. When we’ve got the furnace on in the winter, heat will be trying to escape outdoors.
The LLumar Vista VE35 has a 67% summer solar heat gain reduction and a 32% winter heat loss reduction. This means that 67% less heat is permitted to enter through treated windows during the summer and 32% less heat is permitted to leave during the winter. These numbers don’t just sound impressive, as this high-performance film delivers equally impressive results.

Graph showing average energy use before and after window tint.

The Results: 18.5% Reduction in Total Energy Consumption

From October to December 2018 we installed Vista VE35 on over 1600 windows, and the results speak for themselves.

  • Average monthly energy use BEFORE film*: 463,823 kW-h
  • Average monthly energy use AFTER film*: 378,333 kW-h

*A note on these figures: October 2018 to December 2018 have been excluded from these calculations.

This represents an 18.5% reduction in energy consumption and translated into over $100,000 in annual savings each and every year since. Keep in mind that this is not an 18.5% reduction in HVAC energy consumption, but in total energy consumption for the entire property!

In just 44 months the films had completely paid for themselves and 1301 Gervais is now banking those savings.

The Future

The LLumar Vista VE35 film has a 10-year warranty, but in our experience should provide 15-20 years of reliable service. This means that even if energy costs remain unchanged, the building owners will save well over a million dollars in direct costs. Secondarily, the building’s HVAC system will last longer as less demand is being placed on it – boosting ultimate savings even further. However, there is a big assumption contained in the previous paragraph: “if energy costs remain unchanged.”

Since 2002 the average retail electricity price per kilowatt hour in South Carolina has nearly doubled. As the price of electricity increases, the financial benefits of window film installation are drawn in even starker relief. Another trend that we’re seeing is the transition to electricity being billed using Time-of-Use Rates. This means that during ‘Peak Hours’ (generally 6am to 9am in the winter and 4pm to 7pm in the summer) consumers can expect to pay double or even triple the standard rate. This means that finding ways to reduce demand during these hours is critical.

Low-E window films are a great way to reduce peak demand by rejecting external heat during the hottest hours of summer afternoons and by helping to trap heat during the coldest winter mornings.

Roller shade installation services

The Benefits are Clear to See

In a landscape filled with dozens of energy efficiency boosting solutions, window films are proven to deliver incredibly rapid return on investment and provide decades of benefits. Even if the current trends of increasing energy prices and a switch to peak-rate pricing doesn’t manifest, businesses and homeowners alike will still see a meaningful reduction in monthly energy costs.

For Tower at 1301 Gervais the results were dramatic: an 18.5% decrease in energy consumption and a fully realized return on investment in less than 4 years. If you’re ready to see your energy bills fall, Sun Shades and Graphics is Columbia’s local window film experts. Send us a message or give us a call and see the benefits for yourself!

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