Many historic buildings cannot and should not be torn apart to have their original parts replaced by new, higher performing materials. Yet the need for energy efficiency is still necessary. Denver is a leading city when it comes to green initiatives, such as the Denver Green Roof Initiative. But the city’s love for historic preservation is not at odds with its concerns around the environment. They’re blended. This makes energy efficiency upgrades, such as interior storm windows, perfect for both residential and business buildings.

Denver Landmark Preservation “helps preserve the well-loved character of the city and its neighborhoods”. This can feel counter-intuitive: updating historic buildings to make them more energy efficient and therefore desirable to new occupants. How do building managers keep current tenants happy? How do property owners manage cost? How does resale value factor in?


Why Green Initiatives Should Target Windows for Energy Efficiency Updates

40% of a building’s energy is consumed by heating and cooling, so checking air sealing and insulation is the first step for energy efficiency. Regulating temperature when you have historic windows is challenging. Many property owners assume window replacement is the best option, but this isn’t always the case. 

Old windows come with old-growth wood frames. Because old-growth wood grew slowly, instead of the rapid growth wood that is cultivated for construction today, its rings are closer together creating a denser wood. When cared for, or restored properly, old-growth wood frames can last for generations.

Interior storm window insert in an underperforming historic window to improve energy efficiency.

Why Choose Storm Windows & Are Interior Or Exterior Better?

Storm windows add insulation to help regulate temperature without requiring window replacement or construction. They keep the original windows where they belong, adding to the building’s value. But when it comes to options, there are some significant differences between exterior and interior storm windows. 

Exterior storm windows detract from the aesthetic and curb appeal of a building. Exterior storm windows attach to the window frame using a wood or aluminum casing via screws and caulk. This not only harms the aesthetic of the building, but it can cause physical damage to the building as well.

Interior storm windows can provide all the same energy savings as exterior storm windows without causing any physical damage or hurting the curb appeal. Interior storm windows, sometimes called window inserts, are custom made for the window and pressed into the inside window frame. They increase resale value because the upgrade, and energy savings, stay with the building.

Energy Efficiency in an Historic NYC Building

Project manager Joseph Casillo wanted to keep intact what made his landmark building beautiful: moldings, fixtures, wavy glass & old-growth wood frames. But modern efficiencies save money and bring convenience to tenants. Joseph’s solution was to incorporate interior window inserts in his New York landmark building. New York has stricter landmark laws in place than Denver, but he faced many of the same concerns.

Front of historic NYC building fitted with Indow window inserts for energy efficiency.

The windows in this landmark building were over 100 years old and let drafts and grime in. They also let NYC city noise in. Joseph wanted to provide comfort to his tenants without having to rip out, restore, and reinstall each one of the windows in his multi-family building. He used Indow window inserts, which required no construction, adhering to all of New York’s Landmark Preservation Commission regulations. 

They can’t be seen from the outside and are barely visible from the inside. Joseph says the tenants have noticed a difference in drafts and noise and he expects the “green” addition will help facilitate sales.

Learn more about Indow window inserts and how they can help make your historic building more energy efficient by downloading our Commercial Resource Packet.