High-Efficiency Replacement Windows
Our windows are built to resist the heat and cold, offering four-season comfort. This not only keeps you comfortable, but also saves you money through energy savings. Need proof? We meet or exceed the current standards for ENERGY STAR® Version 6.0 requirements in all 50 states and can exceed requirements for the Northern Zone, by up to 48% with select window packages. Below are four common ratings that are provided for windows certified by the National Fenestration Rating Council (NFRC).
- U-Factor – A measure of the rate of heat flow through a window. A lower U-Factor indicates a higher performing window that can help reduce heating and cooling costs.
- Solar Heat Gain Coefficient (SHGC) – The amount of solar radiation allowed to pass through a window. The lower the number, the less solar heat gain and UV rays the window permits to enter.
- Visible Light Transmittance (VT) – Ranging from 0 – 1, visible transmittance is a measure of how much light passes through the window. The higher the number the more light can pass through.
- Condensation Rating (CR) – CR measures how well a window resists the formation of condensation on the inside surface. CR is expressed as a number between 1 – 100.The higher the number, the better a product is able to resist condensation.


Energy Efficient Window Ratings
NFRC Ratings | U-Factor | SHGC | VT | CR |
Energy Miser 2-IS | .22 | .24 | .38 | 53 |
Energy Miser 2 | .25 | .24 | .40 | 64 |
Energy Miser IS | .26 | .26 | .50 | 41 |
Energy Miser | .30 | .27 | .51 | 52 |
Clear (No LowE) | .49 | .59 | .61 | 38 |
*Air Infiltration ratings are ≤ 0.3 US (≤ 1.5 Metric) or better for all Window Source Windows.
Energy Miser window options keep you warmer in the winter and cooler in the summer.

All Energy Miser Options Are UV Resistant
Harmful UV rays can do more damage to your home than you might think. For example, if you don’t use the proper precautions on your windows, these rays can fade valuable items you have inside your home. Our UV resistant windows can act as a sunscreen for your house, blocking damaging ultraviolet rays without noticeably reducing the light coming inside. The Low-E coating options on our windows increase window performance and help to significantly reduce fading and sun damage to your furnishings, carpets and floor, so they stay colorful and beautiful. All of these energy saving features will save you money!


Will installing high-efficiency replacement windows in Colorado Springs save on energy costs?
Yes! in all cases, installing energy-efficient replacement windows does reduce energy costs.
If you have old, drafty, inefficient windows and doors in your home, you are guaranteed to see your heating and cooling costs decrease by 25% immediately.
If you currently have builder-grade windows and doors in your home, installing our high-performance windows will have immediate benefits. When properly selected and installed, energy-efficient windows will pay for themselves through lower heating and cooling bills. Your furnace and air conditioner will work less to maintain the temperature in your home—this more efficient operation also extends the lifespan of both units.
What makes a window energy-efficient?
You will achieve energy-efficiency through a combination of standard features and extra-cost enhancements to our high-quality vinyl windows.
Our product features:
- Foam filled frames
- Low/E coatings
- Argon gas
- Warm edge technology
- Custom manufacturing of your windows to your openings
- Multi-chambered premium vinyl frames
- Fusion-welded vinyl sash and main frames
- Double insulated pane
We design our High-Performance Package option for excellent performance in the Colorado Springs climate.
Call us for more specifics on our High-Performance Package option.
What is the Energy Star Certification?
Energy Star is an international standard for energy-efficient consumer products. This same standard applies to many products such as kitchen appliances, building products, computers, etc.
The Energy Star window certification program in the United States is designed to help you select energy-efficient windows optimized for your climate.
Energy Star replacement windows must meet minimum performance criteria to qualify for Energy Star certification. The NFRC criteria are based on whole window performance ratings and are different for each of the four United States climate zones as follows:
- Northern Zone: U-Factor of .27 or less, SHGC any
- North Central Zone: U-Factor of .30 or less, SHGC of .40 or less
- South Central Zone: U-Factor of .30 or less, SHGC of .25 or less
- Southern Zone: U-Factor of .40 or less, SHGC of .25 or less
Colorado Springs is in the northern zone.
All of The Window Source replacement windows and doors we sell are available with our Energy Star replacement windows upgrade.
What does Low-E mean for my windows?
The term Low-E means low emissivity. Low-E is a coating treatment applied to the window pane.
When a window is treated with Low-E, the surface emits lower levels of radiant heat. All surfaces reflect, absorb, and transmit heat. A Low-E coating reduces the amount of heat transfer through the window.
Hence, the Low-E coating reflects heat, so your home stays cooler in the summer and warmer in the winter.
The Low-E coating is applied to the inside of the pane, so it won’t scratch off.
In addition, Low-E protects against UV fading of any furniture that receives direct sunlight.
We guarantee the certification of our Energy Star replacement windows, so you will receive the best Low-E that is optimized for the Pikes Peak region.
What are the advantages of Argon Gas?
Window efficiency is further improved by using Argon gas to fill the space between the panes.
Argon gas is denser than air and therefore provides more thermal efficiency than having air between the panes. The Argon gas acts as an insulator, working in both summer and winter to protect your home from outside temperatures.
Argon gas also helps prevent frost from forming at the bottom of a window and improves the sound barrier capability of a window, thus lowering the noise in your home from outside sources.
Argon gas is odorless and non-toxic and should last the lifetime of a double-glazed window.
How much do high-efficiency replacement windows in Colorado Springs cost?
Our High-Performance Package energy efficiency option is an add-on cost to our replacement windows and doors. The cost of this treatment varies depending on window style and size.
You can expect this treatment to add to the cost of each window, but keep in mind the price will vary depending on the size and style of a particular window.
Click for more information about replacement window costs.
We can help you save money on purchasing energy-efficient windows in Colorado Springs. The Window Source of the Rockies can offer very affordable prices on energy-efficient premium vinyl replacement windows because of our large national buying power.
Will I get a return on investment by installing energy-efficient replacement windows?
The return on investment from lower utility bills depends on the type of windows you are replacing, and the style of window you are installing.
Did you know a gap in your window frames as small as 1/16 of an inch lets in as much cold air as leaving the window open three inches?
If you have old, leaky, single-pane windows with wood or aluminum frames, then you are going to enjoy a significant reduction in utility bills. We often see savings of 25% or more.
Window style is also a factor in improving the energy efficiency of your home.
Picture windows, casement windows, and hopper windows are the most energy-efficient styles of windows. This is due to the air-tight nature of the design of these windows. Therefore, you need to factor window style, window size, and the condition of your existing windows into your energy savings calculations.
You should also consider the increased value of your Colorado Springs home that will result when you install new high-efficiency replacement windows. Your home will be worth more and will gain curb appeal after you upgrade your windows.
Tax credits and utility company rebates
In addition to saving money on heating and cooling, installing high-performance windows can save you money on your tax return and put cash rebates in your pocket.
The federal government offers tax credit to selective years. Please see the link below to learn more. Homeowners may receive a tax credit equal to 10% of the product cost (does NOT include installation costs), up to $250 for eligible windows, and up to $500 for eligible doors. Click to learn more about ENERGY STAR.