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The Zen Windows Guide To Energy-Efficient Replacement Windows for Pittsburgh & Central Pennsylvania

What You Need To Know About Window Energy Efficiency Before Making A Buying Decision.

If you’re looking for energy-efficient replacement windows in Pittsburgh and Central Pennsylvania (including Harrisburg, York, and Lancaster), you have a lot to consider. Energy efficiency can vary widely from window to window, and there is a surprising amount of technical terms and information to know.

We’ve created this page to educate you about window energy efficiency. By reading this page, you’ll learn what makes a window energy efficient, how much efficient windows can cut your utility costs, how to read a window’s NFRC label, and more.

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Do Energy-Efficient Windows Save Money?
(And How Much Do Energy-Efficient Windows Cost?)

ENERGY STAR®—America’s leading energy efficiency authority—examined how much money homeowners can save on utility costs when they replace their old windows with energy-efficient windows. ENERGY STAR® examined energy savings in every region of the country and determined Pennsylvania homeowners can save $424 per year on energy bills when they replace their old single pane windows with ENERGY STAR®-certified windows.

Here’s the other great news: To get the most energy-efficient windows, you don’t have to spend a fortune. You can get vinyl replacement windows with the highest energy efficiency benefits for around $499 to $699… installed!

The only reason to spend more than this is if you need something like wood windows for a custom home. And if you’re considering replacement windows in the sub-$400 range, be careful. These are “builder-grade” windows, and they’re lucky to hit a 2 or 3 out of 10 in terms of energy efficiency.

One last note on price and savings: In addition to cutting your energy costs with energy-efficient windows, you can also take advantage of financial incentives. Many energy providers offer savings bonuses for purchasing ENERGY STAR®-certified windows. You can also claim federal tax credits for installing energy-efficient windows.

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How To Read A Window’s NFRC Label

Almost everything you need to know about the energy efficiency of windows can be found on the NFRC label. The NFRC label is a black and white sticker attached on all windows that are part of the Energy Star program (see pictures below). The label shows exactly what kind of energy performance you can expect from a window.

If you don’t know anything about energy efficiency measurements of windows, the NFRC label might look like a bunch of random numbers and confusing terms. Below, we break down what every number and term on the NFRC label means. So when you’re shopping for replacement windows, you’ll have the knowledge you need to make the best buying decision.

national fenestration rating council energy performance seal highlighting the U factor of a window


U-Factor measures the rate of heat loss between 0 and 1. The lower the U-Factor number, the better the window keeps heat in your home. Well-insulated windows with a low U-Factor keep your home a comfortable temperature year round and while reduce utility bills. Pennsylvania winters can get very cold, so U-Factor is the most important energy standard to consider.

national fenestration rating council energy performance seal

Solar Heat Gain Coefficient

Solar Heat Gain Coefficient (SHGC) measures the fraction of solar radiation admitted through a window and is expressed in a number between 0 and 1. Lower numbers are more desirable EXCEPT in some instances in Northern climates (including Pennsylvania) because of colder temperatures.

national fenestration rating council energy performance seal highlighting thevisible transmittance factor window

Visible Transmittance

Visible Transmittance shows the amount of visible light transmitted, and includes the impact of the frame that doesn’t transmit any visible light. Ratings are expressed between 0 and 1. Higher numbers mean more daylight gets through.

national fenestration rating council energy performance seal highlighting the air leakage value of a window

Air Leakage

Air Leakage (AL) measures how much air enters a room through a square foot of window. The lower the number, the fewer drafts you’ll experience. 0.1 is considered outstanding; 0.2 is good; 0.3 is average; 0.4 or higher is poor.

national fenestration rating council energy performance seal highlighting the condensation resistance of a window

Condensation Resistance

Condensation Resistance measures a window’s ability to resist the formation of condensation on its interior surfaces. Measurements are expressed between 1 and 100, with higher numbers being better. Anything under 50 is poor; 50 to 60 is good; 60 or more is great.

Components of an Energy-Efficient Window

What makes a window energy-efficient? It’s not one single component, but a number of parts working together as a whole. Below are the parts of a window that work together to create an efficient whole.



Two or three glass panes—with air or gas in between them—are much more energy efficient than single glass panes. Multiple panes not only offer superior efficiency, but also provide better sound insulation and impact resistance.



Low-E is a special coating that is applied to the glass of a window. Low-E reflects infrared light and ultraviolet light without compromising the amount of VISIBLE light that is transmitted. Low-E coating reflects heat from both inside and outside your home, helping to keep your home warm during winter and cooler during summer. Low-E coating also protects your indoor furnishings from fading.



Energy-efficient windows contain gases like argon and krypton in between the panes. These gases are odorless, colorless, non-toxic, and insulate much better than air.


A high-quality frame improves insulation and reduces heat transfer. Windows with fusion-welded corners and high-density insulation within the frame provide the best protection against air leakage and heat loss.



Spacers ensure the proper distance between the glass panes. Non-metallic and metal/non-metal hybrid spacers also insulate pane edges, reducing heat transfer through the window.

Get An Emailed Quote On THE Most Energy-Efficient Windows
In The State

Choosing a high-quality, energy-efficient window can impact your quality of living for decades. Energy-efficient replacement windows can greatly improve the comfort of your home and reduce your utility costs. Selecting the right brand is crucial.

At Zen Windows PA, we sell multiple exclusive lines of award-winning energy-efficient vinyl replacement windows. Here are a few reasons our windows are an excellent choice for Central PA and Pittsburgh area homeowners…

  • Our windows have won the Energy Star award for the past three years. This means they are THE most energy-efficient replacement windows you can buy.
  • Our windows are loaded with components that keep your home a comfortable temperature and your utility rates much more reasonable. This includes special glazed and gas-infused glass, double- and triple-pane options, dense foam insulation within the frame, and more.
  • Even our most modestly priced windows include advanced energy efficiency features like double-insulating Low-E glass system and wool-pile weather stripping. Bottom Line: You get fantastic energy savings, no matter which Zen Windows line you choose.
  • Depending on the line of windows and type of glass you choose, you can get a U-Factor as low as 0.18—the best U-Factors on the market!

woman drinking coffee and enjoying her new replacement window

Get An Easy Quote Online

Visit our Get An Online Quote page for a quick and accurate estimate on our energy-efficient windows for Central PA and Pittsburgh. If you have questions, you can also contact us. We’re happy to provide you with more information.

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