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Energy Efficiency

The energy-efficient properties in our windows and doors can reduce your energy bills and keep your home comfortable year-round. Learn how you can start saving immediately!

More Comfort. More Savings.
Go Energy-Efficient Today.

The Technology

Science Behind The Savings


Low-E Glass

Low-E glass was created to minimize the amount of UV rays and unwanted temperatures into your home in all climates.

Warm-Edge Spacer

Intercept’s™ warm-edge spacer insulates the exterior edges of a sealed unit and can tack on 5% savings on monthly energy costs.

Vinyl Framing

Vinyl window frames are constructed with a complex array of compartments internally to help trap and repel unwanted weather.

Advanced Weatherstripping

Airtight weatherstripping seals the sides, top and bottom frames of your door to prevent air infiltration.

Insulated Core

Insulated polyurethane core provides an additional thermal barrier.

Durable Frames

Composite frames resist rotting, rusting and warping to withstand constant exposure to the elements.

Energy-Saving Door Lites

Decorative and ENERGY STAR-compliant door lites that allow light in but keep the elements out.

Climate Requirements

What It Means To Be ENERGY STAR® Certified

ENERGY STAR is a government-sanctioned symbol for energy efficiency, signaling credibility, sustainability and cost-savings to consumers. Browse below to explore what’s required to become ENERGY STAR-certified and how those requirements change based on climate.

Your Climate

U-Factor Requirements

U-Factor measures the rate at which heat flows through an object. The lower your U-value, the less heat your windows allow through them.

  • Northern: ≤ .27
  • North-Central: ≤ .30
  • South-Central: ≤ .30
  • Southern: ≤ .40

R-Value Requirements

R-Value determines how well the insulating layer inside your window is performing. The higher your R-value, the better insulated your window is.

  • Northern: 13 – 21
  • North-Central: 13 – 21
  • South-Central: 13 – 21
  • Southern: 13 – 21

In Colorado: You Need A High-Performing Insulated Product

Window World of Denver is located in ENERGY STAR’s Northern Climate category. To maintain certification in this area, windows and doors must register a U-Value of ≤ .27 and an R-Factor from 13 to 21.

Glossary Of Terms

Industry Terms You Need To Know

Low-E Glass

Low-E glass is a type of glass that has been treated with a microscopic, undetectable metallic coating designed to filter certain types of light into your home. The glass blocks heat gain from the sun’s reflected rays in warmer months and allows warmth from the sun’s shorter rays to flow into your home during cooler seasons.

Warm-Edge Spacer System

Our Intercept™ warm-edge spacer system is a new-age technology used to extend the shelf-life of window glass by reducing condensation build-up and edge-to-glass temperatures. Designed to seal in escaping heat, this spacer system is the most effective of its kind.

Argon Gas

Argon is the third-most prevalent gas in our atmosphere. It is a colorless, odorless and nonreactive insulating property with extremely high density and extremely low thermal conductivity, making it a an ideal agent for year-round comfort.

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