Learn about the benefits of secondary glazing for commercial applications.

Interior low-e panels were installed at 400 Market Street, a 12-story office building in Philadelphia, Pennsylvania. 400 Market Street experienced significant energy savings as a result of the secondary glazing system retrofit, including 25% whole building heating and cooling energy savings, as well as improved comfort and decreased street noise.

This field study of a single historic home in Seattle, WA documents the performance of Indow Window's interior storm window inserts. Using the defined analysis approach, it was determined that the interior storm windows produced a 22% reduction in heating, ventilation, and air-conditioning energy use and reduced building envelope leakage by 8.6%

This field evaluation compared the performance of low-e storm windows with clear storm windows and no storm windows in six Chicago homes with single pane windows. Overall heating load reduction due to the storm windows was 13% with the clear glass and 21% with the low-e windows. Simple paybacks for the addition of the storm windows were 10 years for the clear glass and 4.5 years for the low-e storm windows.

Browse ENERGY STAR certified storm windows and retailers. Products that earn the ENERGY STAR label meet strict energy-efficiency specifications set by the U.S. EPA.

This study presents energy-modeling results for a large number of window combinations with window attachments in typical residential buildings and in varied climates throughout the United States.

In 2011, Pennsylvania became the first state weatherization program to explicitly integrate low-e storm windows into its list of priority weatherization measures. This study evaluated 37 homes in Pennsylvania using NEAT, estimating a savings-to-investment ratio of 1.4 to 2.2.

A field evaluation comparing the performance of low emittance (low-e) storm windows with both standard clear storm windows and no storm windows was performed in a cold climate. Six homes with single pane windows were monitored over the period of one heating season. Overall heating load reduction due to the storm windows was 13% with the clear glass and 21% with the low-e windows. Simple paybacks for the addition of the storm windows were 10 years for the clear glass and 4.5 years for the low-e storm windows.

This study from the Pacific Northwest National Laboratory (PNNL) examines the energy performance of low-e storm windows and interior cellular shades through a field evaluation using an identical pair of all-electric, factory-built Lab Homes.

This Summit was held on March 9th, 2023 and served as a venue for utilities, program implementers, weatherization organizations, and manufacturers to share best practices and lessons learned when including storm windows and insulating panels into their programs. The Summit also included a number of manufacturers who featured case studies highlighting successful applications of their products.

Initial analyses by the U.S. Department of Energy and the window covering industry suggested that window coverings—blinds, shades, curtains, and awnings— could save significant energy at low cost. This report characterizes the installed base of windows, the installed base of window coverings, and how users operate window coverings in order to enable precise quantification of energy savings.

This report describes the experimental design and results of testing the energy performance of Hunter Douglas double-cell cellular shades under various control schemes in the Pacific Northwest National Laboratory’s (PNNL) Lab Homes. The results of both heating and cooling season experiments are presented, where testing is designed to assess the heating, ventilation, and air conditioning (HVAC) savings resulting from the thermal insulating properties as well as the automated and dynamic control strategies of shading devices. 

PNNL, in collaboration with Lawrence Berkeley National Laboratory (LBNL), evaluated exterior shades at the PNNL Lab Homes and three occupied field sites in Richland, Washington. At the Lab Homes, the energy performance of exterior shades was evaluated in a controlled side-byside environment. At the occupied field sites, exterior shades were characterized by measuring shade usage, documenting installation practices, and surveying customer perspectives.

In this study, the team analyzed the energy savings potential of cellular shades in residential homes via experimental testing for two heating seasons and energy simulations. Five shading devices—three single-cell and two double cellular/cell-in-cell shades—were used to compare the performance with generic horizontal venetian blinds using two nearly identical side-by-side rooms in a residential home. The experimental testing showed daily heating energy savings in the range of 17%–36% compared with the case without shades.

To examine the energy performance of cellular shade window coverings, a field evaluation was undertaken in a matched pair of all-electric, factory-built “Lab Homes” located on the Pacific Northwest National Laboratory (PNNL) campus in Richland, Washington. The baseline home included two scenarios: one with no window coverings and the other with standard typical white vinyl horizontal blinds. Different operational schedules were tested to help understand this effect on HVAC energy use.

Insulating cellular shade interior window attachments have the ability to improve window thermal resistance to heat transferring to the outdoors during the winter heating season as well as resistance to heat transferring in through the window during the summer cooling season. During the winter when the window is fully covered, however, the added insulation reduces the amount of warm indoor air that reaches the window surface, thereby lowering the temperature of the window glass and frame and increasing the potential for condensation to collect on the interior surface of the window.

Learn more about various window attachment technologies and their energy savings potential.

In this paper, we explore affordable window retrofit strategies, such as low-emissivity (low-e) storm windows, solar screens, cellular shades, and window inserts, which promise substantial improvements, lower costs, and less tenant disruption. We share results of the Twin Cities (Minnesota) Multi-Family Storm Windows Replacement Pilot along with other window attachment lab and field studies.

Review this presentation to discover a non-invasive low-cost easy-to-install retrofit, learn about the benefits of modern storm windows, and understand the research, ratings, and resources available.

Center for Energy and Environment (CEE) partnered with Xcel Energy and Pacific Northwest National Laboratory (PNNL) to evaluate interior storm windows as an energy savings measure. Funding for this field testing was provided in part by the U.S. Department of Energy’s Storm Window and Insulating Panel (SWIP) Campaign to develop cost-effective energy saving technologies. The home was selected through an energy audit as a candidate that could benefit from storm window improvement.

The AERC Certified Product Search allows you to browse through the current window attachment products that have received the AERC certification and narrow your search using the various filters in order to find products based on your specific needs and preferences.

The energy savings and cost-effectiveness of installing low-emissivity (low-E) storm windows and panels over existing windows in residential homes were evaluated across a broad range of US climate zones. This work updates a similar previous analysis of low-E storm windows and panels, using new fuel costs and examining the separate contributions of reduced air leakage and reduced U-factors and solar heat gain coefficients to the total energy savings.

This study examined the energy and air-leakage performance of interior low-e storm windows at the PNNL Lab Homes. The measured energy savings averaged 8.1% for the heating season and 4.2% for the cooling season for identical occupancy conditions.

To examine the energy, air-leakage, and thermal-comfort performance of low-e storm windows, a field evaluation was undertaken in a matched pair of all-electric, factory-built Lab Homes located on the Pacific Northwest National Laboratory (PNNL) campus in Richland, Washington. This study found an annual energy savings of 10.1% and a simple payback period between 5 and 7 years.

This report examines the market for low-e storm windows based on market data, case, studies, and recent experience with weatherization deployment programs. This study estimates that market adoption of low-e storm windows could reasonably achieve savings of 140 trillion Btus of primary energy annually by 2025.

In this case study, clear glass storm windows were replaced with low-e storm windows and evaluated on two large three-story residential multifamily apartment buildings in Philadelphia. This retrofit resulted in 18-22% reduction in heating use, 9% reduction in cooling use, and a 10% overall reduction in apartment air leakage.

This consumer marketing flyer provides homeowners with an overview of storm window and low-emissivity technology as well as a product identification guide.

This decision tree was created to help auditors and contractors identify the appropriate window improvement for a home.

This fact sheet provides an overview of the SWIP Campaign.

This playbook outlines the technology of modern storm windows and insulating panels and provides guidance for utilities interested in implementing programs to get these products in the hands of consumers, resulting in significant energy savings.