The U.S. Department of Energy and a recent study published by CONSOL Energy show 3M Window Films can reduce energy usage up to 19 kwh per sq ft of windows. That adds up to a lot of savings on a building's energy bill. With typical ROI's of less than three years, building owners and managers all over North America have discovered the cost savings associated with 3M Window Films. In fact, with utility rebates, authorized 3M Window Film dealers have completed projects yielding payback in as little as one year.
What's more, many cities and states have turned up the heat on commercial building owners and managers. Recent law changes require many buildings to reduce their energy consumption and audited, non-compliant buildings could be forced to pay fines. Finding cost-effective energy saving technologies, like 3M Window Films, is now imperative to maintaining buildings bottom line. 3M Window Films can help increase your ENERGY STAR® Portfolio Manager™ score, assist your building in obtaining ENERGY STAR certification, and help save you money in the process.
3M Window Film can help you:
Security, solar and decorative window films can change your view of what window films can do. Solar and tinted window films save valuable energy and increase worker comfort. Security and safety window films provide shatter-resistant protection in severe weather and bomb blasts. Decorative window films add privacy and style within your building. Now you can provide sun control, UV protection, window tinting and privacy while increasing energy savings. 3M™ Window Films help improve tenant comfort, reduce hot spots and increase window safety in buildings.
Window film is designed to save energy in much the same manner as a window. In fact, window films are certified by the NFRC (National Fenestration Rating Council), the same organization that certifies the performance values of a window. Windows and window films have 3 key specifications that correlate to the amount of energy that a building uses, Visible Light Transmission (VLT), Solar Heat Gain Coefficient (SHGC) and U value. 3M™ Window Films are designed to upgrade existing windows at a fraction of the cost of replacing the windows, by helping to reduce the SHGC & U value.
The SHGC measures the amount of solar radiation that passes through the window. An SHGC of 1.0 would suggest 100% of the solar radiation comes into the building, and an SHGC of 0.25 would suggest that 25% of the solar radiation comes into the building.
Nearly half of all the energy that comes from the sun is visible light, so while lower SHGC’s may reduce the amount of solar energy entering the building, there is a trade-off between the darkness of the window and the SHGC. It is important to note that Low E windows are often thought of as high performance, but by definition, a Low E window is intended to reduce the U value. If you have a Low E window, this does not necessarily mean you have a low SHGC window.
The U value is the measure of the rate of heat transfer through a window due to conduction or convection. Reducing the U value is often completed by going from a single pane to a double pane window or by adding a Low E coating. The U value helps save energy when there is a temperature difference between the inside and the outside of the building. In general, reducing the U value is more beneficial in cold climates.
VLT is the amount of visible light that transmits through a window, so the lower the number the darker the window. In many commercial buildings today, lights are turned on at the beginning of the work day, and off at the end of the work day, regardless of how much natural light penetrates the window. Therefore, VLT is not often considered when determining energy savings potential of a window or window film.
For larger more sophisticated projects it is recommended to leverage hourly analysis energy simulation software. This is the typical methodology recommended for any building envelope upgrade, as the modifications to the building envelope affect many building systems. In addition, simple Excel based calculations typically do not take into account how the window performance changes as the angle of the sun changes. To do these calculations, you have two options. 3M will work with you to provide an hourly analysis model free of charge, or 3M can help enter the performance of our films into your preferred energy simulation system.
About 3M’s calculations:
3M utilizes the US DOE recommended EnergyPlus™ algorithm to calculate potential energy savings. The output report is generated using a Graphical User Interface (GUI) to EnergyPlus called EFilm, but all calculations are completed by the EnergyPlus Algorithm. We recommend EnergyPlus as it can be audited by 3rd parties, including utility companies and rebate auditing firms.
Using eQuest® or TRACE™ 700:
It is important to note that if you are modeling window films in an alternative software, you should NEVER model the performance of the film by entering in a single SHGC value. In fact, EnergyPlus will not allow users to enter a single value for the performance of a window as research has shown this significantly changes the performance of the building.
The SHGC of a window changes with the angle of the sun, and 3M can help you enter in the performance of our films at all angles. Contact 3M™ Technical Service for support.
eQuest is a commonly used hourly analysis building energy simulation tool. eQuest leverages the DOE-II algorithm. Though eQuest is still commonly used with-in the market, the DOE-II algorithm is no longer supported and has been replaced by the US DOE recommended EnergyPlus algorithm. TRACE 700 is a tool also used to calculate potential energy savings and is offered for purchase through Trane. Both tools will accept the angular performance data of 3M™ Window Films.
Utility companies have been incentivizing 3M Window Films for years, either through prescriptive or performance based incentives. In some cases, utilities have paid as much as 40% of the project costs. 3M has a team in place that will help complete an energy audit for your building, and we will also help navigate the rebate process and work directly with your utility company on your behalf to ensure you receive the highest possible incentives available.
Read the case study “1501 Clinton” to see how one building had 40% of their project cost paid for!
Contact 3M and schedule an audit for your building today.
Commercial building benchmarking is becoming more common in the United States. A number of cities and states have adopted differing policies on benchmarking requirements. Many of these policies revolve around utilizing the ENERGY STAR® Portfolio Manager™. The Energy Star Portfolio Manager compares your historical energy use to other buildings of similar size in your area and rates your building on a scale of 1-100. A score of 75 or greater makes your building eligible to receive an Energy Star Rating and suggests that your building is more efficient than 75% of all similar buildings in your area.
3M Window Films can help you meet or exceed your benchmarking goals. View Energy Star Portfolio Manager Example (PDF, 44 KB) to see how 3M Window Films helped one building reach their benchmarking goals.