Energy-Efficient Windows in Denver

WINDOWS MADE FOR DENVER

What A Mile-High Climate Asks of Your Windows

A window that performs well on the East Coast isn’t automatically the right window for your home in Denver. Our mountain climate requires your window glass and frames to:

• Hold heat through cold nights. Denver winters mean chilly nights, and a sufficient U-factor rating keeps heat inside your home.
• Use the sun’s warmth without overheating. Sunny winter days can warm south-facing rooms for free, while west-facing glass can overheat by late afternoon in summer. SHGC controls that balance, so the right glass can differ from window to window.
• Stand up to intense sun. At 5,280 feet, sunlight is stronger. Low-E coatings work like sunscreen and cut the UV and infrared light that overheat your home and fade floors, furniture and window treatments.
• Stay sealed at altitude. Insulated glass built at lower elevations has to handle the pressure change of a mile-high install. How are our windows built for your elevation?
• Remain clear in winter. Condensation or frost on the inside of cold glass points to high indoor humidity. Fog between the panes means the seal has failed.

The Technology

Science Behind The Savings

• Windows
• Doors

Windows

Low-E Glass

Low-E glass is a microscopic coating that reflects radiant heat back to the source. It keeps heat inside in winter and reflects the sun’s heat outside in summer, blocking most harmful UV rays. 

Warm-Edge Spacers

Intercept™ warm-edge spacers seal the edge of the insulated glass unit with a low-conductivity channel. This keeps the glass edge warmer, reducing condensation along the frame.

Multi-Chamber Vinyl Framing

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

Doors

Innovative Weatherstripping

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

Insulated Core

An insulated polyurethane core provides an additional thermal barrier.

Sturdy 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

ENERGY STAR® and Colorado’s Window Standards

ENERGY STAR is a government-sanctioned symbol for energy efficiency, credibility, sustainability and cost-savings for the consumer. Browse below to explore what’s required to become ENERGY STAR-certified and what it looks like in Colorado.

Why You Need A High-Performing Insulated Product

Colorado sets a minimum standard for every window sold in the state. Under HB23-1161 and Colorado Department of Public Health and Environment rule (5 CCR 1004-2), residential windows sold after January 1, 2026, must have a U-factor of 0.30 or lower. The same limit applies to doors that are more than half glass. Skylight U-factors must be 0.50 or lower.

ENERGY STAR sets a higher bar. Denver sits in ENERGY STAR’s Northern climate zone, where certified windows need a U-factor of 0.22 or lower. If your window lets in more of the sun’s heat because of its placement, an equivalent-performance path allows for a slightly higher U-factor.

U-Factor Requirements

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

Standard or Zone	Max U-factor	SHGC
Colorado state minimum (from Jan 1, 2026)	≤ 0.30	No requirement
ENERGY STAR v7.0 — Northern (Denver)	≤ 0.22	≥ 0.17 (tradeoff path allows higher U with higher SHGC)
ENERGY STAR v7.0 — North-Central	≤ 0.25	≤ 0.40
ENERGY STAR v7.0 — South-Central	≤ 0.28	≤ 0.23
ENERGY STAR v7.0 — Southern	≤ 0.32	≤ 0.23

How to Read NFRC Labels

Every certified window carries an NFRC label with up to five ratings. Here’s what each one means for a Denver home.

Rating	What It Measures	Better is…
U-Factor	Rate of heat loss (typically 0.20–1.20)	Lower
Solar Heat Gain Coefficient	Share of the sun’s heat let through (0–1)	Lower on west/summer exposure; higher helps passive winter heat
Visible Transmittance	Share of visible light let through (0–1)	Higher = more daylight
Air Leakage	Air passing through the unit (cfm/ft²)	Lower
Condensation Resistance	Ability to resist interior condensation (1–100)	Higher

AFFORDABLE PRICING FOR COLORADANS

What Determines the Cost of Energy-Efficient Windows?

Every Window World of Denver project receives a custom quote based on your specific home and needs, so there’s no single sticker price. The number isn’t a mystery, though. Five factors affect it, and we walk through each one at your free in-home estimate.

1. Number and size of openings: More and larger windows mean more materials and more labor.
2. Window style: Non-fixed, operational styles like casements and double-hung windows cost more than fixed picture windows.
3. Glass package: Upgraded Low-E coatings, gas fill and triple-pane glass add cost and pay off in better performance.
4. Installation method: An insert fits the existing frame. A full-frame replacement removes it down to the rough opening.
5. Site conditions: Rot, existing structural damage, trim work, second-story access and older construction can all change the scope of installation.

Frequently Asked Questions