Make your building systems last longer — with window film.
By Steve DeBusk
Investigating and implementing energy-efficiency improvements is essential for keeping down operating costs in a retail building, but it’s just one of many responsibilities for facilities professionals. Managing upgrades to major building systems takes research, time, money, and staff resources. The good news is that you can positively impact the energy use of several building systems at once with one green investment, helping to reduce utility and operating costs.
The right window film not only reduces energy use year-round and improves shopper and employee comfort, but also helps you make the best of your existing building systems and prevents unnecessary equipment upgrades or replacements.
Increase R-Value of Existing Windows
According to the U.S. Department of Energy, inefficient windows are to blame for 25% to 35% of wasted energy in commercial buildings. When retail facility owners hear this, it’s not long before the topic of window replacement comes up. But replacing windows requires time and upfront capital; it also requires careful planning so customers and employees aren’t inconvenienced.
Return on investment for new windows can take up to 30 years — and that’s for glass replacement only. Based on RSMeans data, replacing dual-pane windows with low-e glass costs between $40 and $55 per square foot. If window frames need to be replaced, costs will increase and paybacks will take even longer. That can be a tough sell when most facilities professionals are searching for upgrades and retrofits that offer a full payback in 5 years or less.
Window film is known for its ability to control glare and reduce solar heat gain in warm months. But today’s high-performance, low-e window films improve window insulating power (R-value) year-round in all climates. The insulating power of newer low-e window film gives single-pane windows the same insulating performance as double-pane windows; it provides double-pane windows with the same insulating performance as triple-pane windows. Whether your retail facility is located in Los Angeles or Philadelphia, it’s possible to reduce energy costs every month when the right kind of window film is installed.
If new windows are being considered as an energy-efficiency project for your retail facility, it’s likely that window film installation will provide the same result with considerably less upfront expense and a faster return on investment.
Cut Down on Electric Lighting
E-Source, a firm that provides the industry with objective energy-efficiency research, says that 60% of a retail facility’s energy usage goes toward lighting. That doesn’t come as a big surprise, considering the special product and grocery displays, lighting for freezer and cooler doors, overhead lights, and parking lot lighting that most retail facilities need.
When solar heat gain and glare aren’t controlled, blinds and shades are often used to protect merchandise, reduce fading, keep shoppers and staff members comfortable, and stop glare from affecting screens and displays. Blinds and shades do address these issues, but they may also limit views, cause a need for more interior artificial lighting, and prevent natural daylight from entering the space.
Over the years, numerous studies have shown a strong association between natural daylight and increased sales. Reports like the one from Heschong Mahone Group show that the average effect of daylighting on sales can range from 1% to 6%. These studies have also indicated that daylight has as much explanatory power in predicting sales as other measures of retail potential, such as available parking, number of local competitors, and neighborhood demographics.
Despite the myth that window film makes indoor spaces darker and increases lighting usage, installing window film can actually help decrease lighting costs. A research team from the University of Padua in Italy recently studied the use of window film and its effect on lighting. MG Tower — a modern building with up-to-date HVAC systems and new windows — was struggling with occupants who were uncomfortable due to solar heat gain and glare from sunlight entering the building. The team discovered that window film installation addressed both the glare and occupant comfort problems. It also offered the building a considerable increase in the amount of useful daylight because blinds were used much less to control glare and heat.
When controlled daylight is allowed into a retail space, artificial lighting can often remain off or dimmed, which also reduces HVAC loads. According to ENERGY STAR’s Building Upgrade Manual, 5% of U.S. electricity is used to offset waste heat generated by artificial lighting. This number can shrink if artificial lighting isn’t used as often.
Extend HVAC Lifecycle
All building equipment has a lifespan and eventually needs to be replaced, but reducing loads can extend the life of an aging HVAC system. Maintaining HVAC equipment at peak operating efficiency not only helps lengthen equipment life, but also ensures a comfortable environment for shoppers and employees.
Before investing in HVAC upgrades or retrofits to achieve energy savings, many energy consultants recommend reducing heating and cooling loads first. Take a close look at your retail facility’s HVAC loads; think about ways to reduce runtime and extend the life of the existing HVAC system. By doing this, you not only lower operating costs but also decrease the amount of stress placed on the system.
The California Energy Commission estimates that 40% of a commercial building’s cooling requirements are due to solar heat gain through windows. Improving your window’s R-value and reducing solar heat gain through windows can keep your retail facility’s heating and cooling systems from running as long or as often.
Installing window film in any kind of building — from schools and hotels to offices and stores — can lower HVAC runtime and costs. In retail settings, different environmental zones — stock rooms, dressing rooms, offices, refrigerated sections, etc. — have different temperature needs. Spots that are too hot or too cold can negatively impact the shopping experience for customers; employee productivity can also suffer.
One recent experiment shows just how much of a difference window film can make in reducing HVAC energy use. The Hyatt Regency Houston installed low-e window film in 48 of its guestrooms and used an extensive metering system to measure heating and cooling usage; the data was then compared to heating and cooling use in 48 rooms without window film.
The results, which were compiled by an energy management consultant and verified by the local utility for a rebate, found that heating energy use decreased by 25% and cooling energy use decreased by 23% in rooms with low-e window film. HVAC runtime also significantly decreased, and prevented replacement of the HVAC system (which had been struggling to keep up). Although the facility isn’t a retail space, these results could be mirrored in almost any commercial building.
Reduce Plug Load
Plug loads in retail facilities present a unique challenge. In most situations, the plug load is tied to revenue (vending machines) or merchandise displays (TVs, computers, smartphones, etc.). In these situations, window film can’t help with plug load levels. However, in offices, lounge areas, break rooms and restrooms, window film can help reduce plug load when fans, space heaters and task lights are being used to regulate temperatures, compensate for an underperforming HVAC system, or add light to spaces where blinds and shades are closed due to glare and solar heat gain.
With this one green upgrade, it’s possible to improve the shopper’s experience, prolong HVAC and lighting equipment lifecycles, upgrade the insulating performance of existing windows, cut plug load, and decrease monthly utility costs in a retail facility.
— Steve DeBusk is global energy solutions manager for the window film division at Eastman Chemical Company. DeBusk has 30 years of experience in energy efficiency. He is a Certified Energy Manager, a Certified Measurement and Verification Professional, and a Certified Sustainable Development Professional. You can visit his blog at blog.vista-films.com or follow him on Twitter @greenbldgs.