How Secondary Windows Help Save Energy & Money

The Northwest Energy Efficiency Alliance (NEEA) engaged Evergreen Economics to conduct a characterization study of the market for secondary windows. This blog post will review some of the highlights, but you can read the whole report here.

two coworkers talking in front of a desk with natural light from commercial window attachments

What Are Commercial Window Attachments?

Commercial Window Attachments are called many things – most often storm windows or window inserts. They are a retrofit on the existing window to enhance the performance without replacing the window.

Commercial Window Attachments Help With:

  • Air infiltration
  • Energy loss
  • Solar heat gain
  • Soundproofing

Commercial window attachments have many different styles. The version Indow designed is compression fit, which means it doesn’t require hardware for installation, making it the least invasive option.

Indow is an interior product, which is the majority of the secondary systems in the report. Indow is AERC certified. AERC, the Attachments Energy Rating Council, is an unaffiliated organization that rates window attachment products on energy efficiency by measuring various factors such as Air Leakage (AL) and U-Factor.

The biggest benefits customers listed were energy savings, cost effectiveness relative to replacement, and tenant comfort (noise and thermal).

man installing secondary window attachments for energy savings, cost effectiveness, and comfort

What were the key findings from the report?

The NEEA report was funded to understand the current market of secondary windows, their costs, how they fit with code, and their performance. 

Main takeaways of NEEA report:

  • There is a lack of knowledge this market exists. When it is known, it is often kept to historic preservation projects, but the fact is it really would help all types of spaces increase their efficiency in a more cost-effective manner.
  • More education should be provided to building decision makers about these options— how to install, what code concerns there are.

These key points were collected after interviews with manufacturers of secondary glazing systems, building owners and decision makers of those that purchased secondary glazing systems, and other market actors such as architects, general contractors, and energy services companies who have used secondary glazing on projects.

The study notes that the “knowledge of storm windows for the residential sector and an understanding that similar principles apply to commercial windows. However, residential storm windows sometimes carry the stigma of being an inelegant make-shift solution. There was little awareness of the full breadth of products and manufacturers available to the commercial market.” The benefits of being a cost-effective solution make it a great fit for building owners across the country, yet this information isn’t reaching them.

The study went on to say,“ Architects consistently described replacement of windows as the standard market solution for addressing window performance issues or improving aesthetics of existing buildings.”

Embassy Suites Orlando with secondary window attachments installed in their commercial windows

Case Studies That Proved Benefits

The report took a closer look at 3 specific projects in their report. All 3 were located in Oregon in historic commercial properties. Two of them specifically got the window attachments for noise issues, but the energy savings was a secondary benefit. “The secondary attachments eliminated most of the noise from the nearby venues, and the owners were satisfied with the performance of the attachments.”

All 3 locations said cost was an important factor. The secondary glazing was lower than the cost of replacements.

Two of these locations used Indow window inserts in their project. You can read the full details on page 38 of the report, but here are the highlights:

Olympic Mills

exterior view of Olympic Mills building with commercial secondary windows used for noise reduction

  • Upgraded 60 windows. All of them were the original wooden single-pane windows.
  • Owners of the hotel were doing a $3-4 million renovation project that this fit into. Through the State Historic Preservation Office in Oregon, the owners received a federal tax credit of 20% on their building renovation.

From the report: “The property manager saw the secondary attachments as a viable noise reduction strategy. Tenants facing the train tracks have reported reduced noise. One tenant, in particular, stated that after the attachments were installed, they did not even notice the sound of the train anymore. Other tenants on the west side of the building also said that the sound of the trains no longer bothers them, although they could still feel the train passing by through the vibrations from the building”

Read our full case study on Olympic Mills.

The Society Hotel

society hotel sign and exterior view of commercial secondary window

  • Upgraded 60 windows. All of them were the original wooden single-pane windows.
  • Owners of the hotel were doing a $3-4 million renovation project that this fit into. Through the State Historic Preservation Office in Oregon, the owners received a federal tax credit of 20% on their building renovation.

From the report: “Overall, the owners have been satisfied with the performance of the secondary window attachments. They called out their satisfaction with the improvement of thermal comfort in the rooms. When the hotel opened in 2015, a few of the rooms still did not have secondary attachments installed. One of the owners mentioned that there was a clear difference between rooms with secondary attachments and rooms without secondary attachments. The rooms without attachments were draftier and noisier than rooms with attachments, and the owners quickly installed attachments in the remaining rooms.”

Read our full case study on the Society Hotel.

The main message here is that Commercial Window Attachments are an effective way to retrofit windows. It is unfortunate it is a niche market with little knowledge and acceptance within the commercial building sector. We must educate about the availability and benefits of these sort of options, particularly under our current economic situation.

Give us a call today and we will be happy to give a product demo and presentation on how our commercial window attachments can help your space.