Heritage Restoration, Inc.

Why old windows are better than new

IMG_1858We are told old windows are drafty, do not function well, and lose energy through the single panes. Window replacements are pitched as giving us better energy efficiency and longevity. But is it true? And with claims replacement windows can save 60-80% on energy costs, why not tear them all out?

As a builder/remodeler/preservationist I have a chance to observe buildings. I have seen the most advanced window products fail in ten years or less. Rot, failing double glazing, broken operating systems, and poor installation are just some of the issues.

As time passed, we wanted more comfort and energy savings, while continuing to provide natural light and ventilation. Historically, a storm window provided additional protection, but air still flowed through. Today, storm windows can reduce airflow significantly, trapping air and creating better energy efficiency. Insulated glass was patented in 1865 but it didn’t see much traction until 1950’s, providing some minor energy improvement but the biggest benefit was sound dampening. Let’s cut to the chase.

Waste

Each year 32 million windows are thrown into the landfill. About 30% of replacement windows are less than 10 years old. Vinyl windows are toxic, with the national vinyl industry consuming over 40% of the chlorine gas produced. And when vinyl is burned, the highly toxic dioxin is emitted hurting both people and the environment. Most double glazed windows cannot be repaired, only replaced. Repairing single paned glazed windows has little waste and the materials are easily sourced. If lead is a concern, the lead can be removed and disposed of responsibly instead of throwing away an entire window unit. A storm window can be fully recycled.

Airflow Reduction

Airflow reduction is the biggest concern. Just replacing windows does guarantee airflow reduction. In fact, most replacement windows are only factory tested and not tested for field performance. Recent studies have determined a storm window can equal the airflow reduction as a replacement unit for a fraction of the cost.

 Insulated glass saves more money.

Glass is a great heat conductor, so glass separation is key. A single pane main window with a good storm window has the equivalent heat transfer of a ½” insulated glass unit. If you really want to be efficient, go with a 4-pane high performance glass unit, but your house must be equally tight for it to be worth it.

Longevity?

Most insulated glass units last 20 years at best, the same as a storm window. Fogging, condensation, and seal failure cause these windows to become less efficient. Old single glazed windows can last hundreds of years.

Payback

Storm window have the quickest payback of about 10-15 years. Replacement windows can take decades to “pay back” and sometimes have to be replaced before the “pay back”.

The Bottom Line

It’s about airflow more than heat transfer. Storm windows can be a quarter of the cost of replacement windows, last as long if not longer, and can be easily replaced. More and more studies recognize that keeping old wood windows with a good storm window is the most responsible, cost saving option. This isn’t just chat rooms, blogs, and field observations, but real scientific data.