20 Best Window Companies in Princeton Meadows, NJ (2024 Reviews)

Looking to replace your home's windows? We’ve got all the information you need in this guide to the best window installation companies.

We analyzed all the top-rated window companies in Princeton Meadows and selected the best 20 based on:

  • Customer reviews
  • Window installation expertise
  • Popularity with home-owners like you
EcoWatch Local Advisors

By EcoWatch Local Advisors

Updated February 01, 2024

Why you can trust EcoWatch

Our panel of energy experts work tirelessly to create unbiased reviews and informative content to help homeowners make educated decisions. No other windows site has covered energy efficiency and sustainability as long as EcoWatch, which means we're going to help you find windows replacements that will save on your energy bill and put more money back in your wallet.

Although environmentally friendly energy sources like wind and solar are important when it comes to lowering your carbon footprint, improving your house’s energy efficiency can also have a large impact on home energy conservation. If you have traditional, outdated windows, your HVAC system could be working extra hard to heat or cool your home. This means higher electricity bills.

Installing energy-efficient windows on your property can help you save money each month on your energy bills — and you can help the environment, too.

Efficient windows are especially important in Princeton Meadows, where the temperature varies throughout the year. According to Energy Star, making the switch to energy-efficient windows can save the average homeowner up to $306 each year.

Best Availability

Renewal by Andersen

★★★★★
4.5
  • Great industry reputation
  • Member of US Green Building Council
  • Manufactures products in-house
Buy One Window, Get One 40% OFF
Get Estimate

Best Energy-Efficient Features

Champion

★★★★★
4.5
  • Many years of experience
  • Low prices relative to competitors
  • Limetime warranty
Buy 2 Windows, Get 2 Free
Get Estimate

Power Home

★★★★★
4.5
  • Uses eco-friendly materials
  • Well-trained, certified installers
  • Lifetime or lengthy warranty
Next-Day Appointments Available
Get Estimate

Best Window Installation & Replacement Companies in Princeton Meadows

The EcoWatch Reviews team researched dozens of installers across the country to find the best window replacement companies for our readers. The providers in this article scored best in our review categories, which include energy-efficient offerings, customer service, price, local expertise, availability and more.

Window World logo
FAST QUOTE
as little as 30 seconds
Best Affordability

Window World

★★★★★
BBB Rating: A+
Locations: Nationwide
Founded: 1995
Pros:
  • Pros icon EnergyStar Partner
  • Pros icon Large serice area
  • Pros icon Low prices relative to competitors
  • Pros icon Great industry reputation
  • Pros icon Lifetime warranty
Cons:
  • Pros icon Quality of service will depend on your area

Window World provides windows expertise in Princeton Meadows. It's the largest window replacement company in the country, known for its vinyl windows and affordability. Window World has around 27 years of experience in the window replacement sector. Its reputation is backed by several positive reviews on customer review websites.

You may want to consider choosing Window World if you're looking for a company that is certified by the Environmental Protection Agency (EPA) and Energy Star and supports charities like St. Jude Children’s Research Hospital.

Energy Efficiency of Window World Windows

Its high-performance Low-E (low-emissivity) coatings and argon gas insulation offer exceptional efficiency and performance for any home. Not all of Window World’s windows are Energy Star certified, so be sure to mention that you want Energy Star windows when inquiring.

How much does Window World cost in Princeton Meadows?

Prices are not available on Window World’s website because the cost of window replacement differs based on how many and what type(s) of windows you need. However, it's known for offering some of the most affordable window installations around. Getting a free quote on its website is the best way to get more accurate information.

Renewal by Andersen logo
FAST QUOTE
as little as 30 seconds
Best Overall

Renewal by Andersen

★★★★★
BBB Rating: A
Locations: Nationwide
Founded: 1995
Pros:
  • Pros icon Great industry reputation
  • Pros icon Award-winning company
  • Pros icon Member of US Green Building Council
  • Pros icon Manufactures products in-house
Cons:
  • Pros icon No lifetime warranty
  • Pros icon More expensive than competition

Renewal by Andersen provides the best availability in Princeton Meadows. It's a subsidiary of the Andersen Corporation, a major manufacturer of windows and doors. Andersen has around 27 years of experience in the window replacement sector. Its reputation is backed by several positive reviews on customer review websites.

You may want to consider choosing Andersen if you're looking for a company that uses in-home estimates and advanced digital tools to help you plan and visualize your project before getting started.

Energy Efficiency of Renewal by Andersen Windows

A handful of windows manufactured by the Andersen corporation were awarded Energy Star’s “Most Efficient” in 2021, and Andersen was named Energy Star’s Partner of the Year in 2019. Not all of Andersen’s windows are Energy Star certified, so be sure to mention that you want Energy Star windows when inquiring.

How much does Renewal by Andersen cost in Princeton Meadows?

Prices are not available on Andersen’s website because the cost of window replacement differs based on how many and what type(s) of windows you need. However, based on customer feedback, you can expect to pay anywhere between $750 to $1,250 per window for an installation with Andersen. Getting a free quote on its website is the best way to get more accurate information.

Aeroseal Windows logo
FAST QUOTE
as little as 30 seconds
Best for Businesses

Aeroseal Windows

★★★★★
BBB Rating: A+
Locations: Regional
Founded: 1999
Pros:
  • Pros icon Many years of experience
  • Pros icon Great industry reputation
  • Pros icon Low number of customer complaints
  • Pros icon Manufactures products in-house
  • Pros icon Custom Designs
Cons:
  • Pros icon No lifetime warranty
  • Pros icon Not ideal for residential installations

Aeroseal Windows provides the best window installation for businesses in Princeton Meadows. It's an installer that mainly serves commercial and multifamily properties, and also specializes in railings. If you’re looking for residential window installations, you should probably refer to one of the other companies on this list. Aeroseal has around 23 years of experience in the window replacement sector. Its reputation is backed by several positive reviews on customer review websites.

You may want to consider choosing Aeroseal if you're looking for a company that installs windows and doors at businesses across the Eastern U.S.

Energy Efficiency of Aeroseal Windows Windows

The company claims it helps businesses save on energy expenses and reduce their carbon footprints with energy-efficient windows, as well as practices like Low-E glass coating, weatherstripping and more. Not all of Aeroseal’s windows are Energy Star certified, so be sure to mention that you want Energy Star windows when inquiring.

How much does Aeroseal Windows cost in Princeton Meadows?

Prices are not available on Aeroseal’s website because the cost of window replacement differs based on how many and what type(s) of windows you need. However, it provides high-quality windows at a competitive price point. Getting a free quote on its website is the best way to get more accurate information.

Universal Windows Direct logo
FAST QUOTE
as little as 30 seconds
Best Warranty

Universal Windows Direct

★★★★★
BBB Rating: A
Locations: Nationwide
Founded: 2002
Pros:
  • Pros icon Makes charitable contributions
  • Pros icon Manufactures products in-house
  • Pros icon Wide variety of products and services
  • Pros icon Lifetime warranty
Cons:
  • Pros icon Limited service area
  • Pros icon Some installations carried out by third-party contractors
  • Pros icon Quality of service will depend on your area

Universal Windows Direct provides the best warranty in Princeton Meadows. It's a company that has grown immensely since its inception in 2002, and now has several franchise dealers nationwide. Universal has around 20 years of experience in the window replacement sector. Its reputation is backed by several positive reviews on customer review websites.

You may want to consider choosing Universal if you're looking for a company that has an industry-leading warranty covering products, parts and workmanship for life.

Energy Efficiency of Universal Windows Direct Windows

The company offers energy-efficient UniShield brand windows. According to its website, UniShield window packages have higher gas fill rates and longer gas retention than most other brands on the market, and they are Energy Star products. Not all of Universal’s windows are Energy Star certified, so be sure to mention that you want Energy Star windows when inquiring.

How much does Universal Windows Direct cost in Princeton Meadows?

Prices are not available on Universal’s website because the cost of window replacement differs based on how many and what type(s) of windows you need. However, installations typically range from $225 to $425 per window based on customer feedback. That makes Universal Windows Direct more of a budget-friendly option for window repair and replacements. Getting a free quote on its website is the best way to get more accurate information.

One thing to note is that the companies in this section are national, meaning the quality of the service may depend on your local crew. We have tried to be unbiased and transparent by mentioning pros and cons for every company.

More Window Companies in Princeton Meadows

Renewal by Andersen of NJ/NY Metro

Cranford, NJ
4.8
★★★★★
  • Pros icon Price Transparency
  • Pros icon Educational Website
  • Pros icon Good Customer Service
  • Pros icon Free assessment

Services Offered

  • Service icon Window Replacement/Installation
  • Service icon Skylights
  • Service icon Bay Windows
  • Service icon Double-Hung
  • Service icon Glass Doors

Website: https://www.renewalbyandersen.com/window-company/535-nj-ny-metro/retailer
Address: 70 Jackson Dr Suite A, Cranford, NJ 07016
Phone: (908) 497-1020

Champion Replacement Windows of Philadelphia

Moorestown, NJ
4.5
★★★★★
  • Pros icon Free assessment
  • Pros icon Price Transparency
  • Pros icon Good Customer Service

Services Offered

  • Service icon Glass Doors
  • Service icon Bay Windows
  • Service icon Double-Hung
  • Service icon Window Replacement/Installation

Website: https://www.championwindow.com/Philadelphia/
Address: 1256 N Church St Unit 1, Moorestown, NJ 08057
Phone: (267) 297-4669

Window World of Jersey Coast

Edison, NJ
4.9
★★★★★
  • Pros icon Price Transparency
  • Pros icon Free assessment
  • Pros icon Timely Service
  • Pros icon Educational Website
  • Pros icon Good Customer Service

Services Offered

  • Service icon Bay Windows
  • Service icon Glass Doors
  • Service icon Window Replacement/Installation
  • Service icon Custom Window Designs
  • Service icon Energy-Efficient Options
  • Service icon Double-Hung

Website: https://www.jerseycoastwindows.com/
Address: 27 Northfield Ave, Edison, NJ 08837
Phone: (732) 417-5700

Window Nation

Pennsauken Township, NJ
4.6
★★★★★
  • Pros icon Price Transparency
  • Pros icon Educational Website
  • Pros icon Good Customer Service
  • Pros icon Free assessment

Services Offered

  • Service icon Double-Hung
  • Service icon Bay Windows
  • Service icon Custom Window Designs
  • Service icon Glass Doors
  • Service icon Energy-Efficient Options
  • Service icon Window Replacement/Installation

Website: https://www.windownation.com/cherry-hill-showroom/
Address: 9256 Commerce Hwy, Pennsauken Township, NJ 08110
Phone: (856) 566-7200

Jammer Doors

Trenton, NJ
4.9
★★★★★
  • Pros icon Free assessment
  • Pros icon Good Customer Service
  • Pros icon Price Transparency

Services Offered

  • Service icon Window Replacement/Installation
  • Service icon Glass Doors

Website: http://www.jammerdoors.com/
Address: 2850 US-1, Trenton, NJ 08648
Phone: (609) 883-0900

J&D Building and Windows

East Brunswick, NJ
4.9
★★★★★
  • Pros icon Good Customer Service
  • Pros icon Timely Service
  • Pros icon Price Transparency
  • Pros icon Free assessment

Services Offered

  • Service icon Window Replacement/Installation
  • Service icon Glass Doors

Website: https://buildingandwindows.com/
Address: 614 Cranbury Rd Unit 6206, East Brunswick, NJ 08816
Phone: (732) 213-8110

Mr. Handyman of Princeton and Robbinsville

Princeton, NJ
4.8
★★★★★
  • Pros icon Timely Service
  • Pros icon Free assessment
  • Pros icon Price Transparency
  • Pros icon Educational Website
  • Pros icon Good Customer Service

Services Offered

  • Service icon Window Replacement/Installation

Website: https://www.mrhandyman.com/princeton-robbinsville/
Address: 707 Alexander Rd Ste 208, Princeton, NJ 08540
Phone: (609) 372-5867

Norman's Glass & Auto Services

Trenton, NJ
4.6
★★★★★
  • Pros icon Good Customer Service
  • Pros icon Educational Website
  • Pros icon Free assessment
  • Pros icon Price Transparency

Services Offered

  • Service icon Custom Glass
  • Service icon Window Repair
  • Service icon Mirrors
  • Service icon Window Replacement/Installation
  • Service icon Glass Doors
  • Service icon Glass Showers

Website: http://www.normansglass.com/
Address: 390 Whitehead Rd, Trenton, NJ 08619
Phone: (800) 821-2496

Cooks Glass & Mirror

Trenton, NJ
4.6
★★★★★
  • Pros icon Good Customer Service
  • Pros icon Free assessment
  • Pros icon Price Transparency

Services Offered

  • Service icon Glass Doors
  • Service icon Screen Repair
  • Service icon Glass Repair
  • Service icon Custom Glass
  • Service icon Window Replacement/Installation
  • Service icon Mirrors
  • Service icon Tempered Glass
  • Service icon Glass Showers
  • Service icon Storm/Impact Windows

Website: http://www.cooksglassandmirrors.com/
Address: 289 Whitehead Rd, Trenton, NJ 08619
Phone: (609) 584-0727

Kepo Siding & Windows

Hillsborough Township, NJ
4.9
★★★★★
  • Pros icon Good Customer Service
  • Pros icon Timely Service
  • Pros icon Free assessment

Services Offered

  • Service icon Glass Doors
  • Service icon Window Replacement/Installation
  • Service icon Energy-Efficient Options

Website: https://www.keposidingwindows.com/
Address: 15 Ilene Ct building 12 unit 15, Hillsborough Township, NJ 08844
Phone: (908) 553-5850

Glass Castle

Lawrence Township, NJ
4.6
★★★★★
  • Pros icon Good Customer Service
  • Pros icon Free assessment
  • Pros icon Timely Service
  • Pros icon Price Transparency
  • Pros icon Educational Website

Services Offered

  • Service icon Mirrors
  • Service icon Glass Repair
  • Service icon Glass Showers
  • Service icon Glass Doors
  • Service icon Window Replacement/Installation

Website: http://www.glasscastle.com/
Address: 1811 Princeton Ave, Lawrence Township, NJ 08648
Phone: (609) 530-1115

Creative Custom Construction, Inc.

Allentown, NJ
3.5
★★★★★
  • Pros icon Free assessment
  • Pros icon Timely Service
  • Pros icon Price Transparency
  • Pros icon Good Customer Service

Services Offered

  • Service icon Window Replacement/Installation

Website: http://www.cccinc2013.com/
Address: Old York Rd, Allentown, NJ 08501
Phone: (609) 851-4346

Window & Door Outlet Inc

Edison, NJ
4.7
★★★★★
  • Pros icon Free assessment
  • Pros icon Price Transparency
  • Pros icon Educational Website

Services Offered

  • Service icon Energy-Efficient Options
  • Service icon Glass Doors
  • Service icon Window Replacement/Installation
  • Service icon Wood Frames
  • Service icon Vinyl Frames

Website: http://windowdooroutlet.com/
Address: 2171 Woodbridge Ave, Edison, NJ 08817
Phone: (732) 393-1008

Home Genius Exteriors

Somerset, NJ
4.7
★★★★★
  • Pros icon Good Customer Service
  • Pros icon Free assessment
  • Pros icon Educational Website
  • Pros icon Timely Service
  • Pros icon Price Transparency

Services Offered

  • Service icon Glass Doors
  • Service icon Energy-Efficient Options
  • Service icon Window Replacement/Installation

Website: https://homegeniusexteriors.com/new-jersey/
Address: 399 Campus Dr Ste 311, Somerset, NJ 08873
Phone: (732) 624-6442

Gliner Construction LLC

Hamilton Township, NJ
3.3
★★★★★
  • Pros icon Good Customer Service
  • Pros icon Price Transparency
  • Pros icon Educational Website
  • Pros icon Free assessment

Services Offered

  • Service icon Energy-Efficient Options
  • Service icon Window Replacement/Installation
  • Service icon Glass Doors
  • Service icon Bay Windows
  • Service icon Double-Hung

Website: http://glinerwindows.com/
Address: 53 4th Ave, Hamilton Township, NJ 08619
Phone: (609) 558-0661

S & L Glass Works

Fairless Hills, PA
4.9
★★★★★
  • Pros icon Good Customer Service

Services Offered

  • Service icon Window Repair
  • Service icon Storm/Impact Windows
  • Service icon Vinyl Frames
  • Service icon Energy-Efficient Options
  • Service icon Glass Showers
  • Service icon Window Replacement/Installation
  • Service icon Glass Doors
  • Service icon Tempered Glass
  • Service icon Mirrors
  • Service icon Screen Repair
  • Service icon Glass Repair

Website: http://www.slglassworks.com/
Address: 662 Lincoln Hwy, Fairless Hills, PA 19030
Phone: (215) 428-4010

ImproveRite Home Remodeling

Yardley, PA
4.5
★★★★★
  • Pros icon Good Customer Service
  • Pros icon Price Transparency
  • Pros icon Timely Service
  • Pros icon Educational Website
  • Pros icon Free assessment

Services Offered

  • Service icon Window Replacement/Installation

Website: https://2improverite.com/home-renovation-contractors/
Address: 166 S Main St, Yardley, PA 19067
Phone: (267) 393-4555

Luk Remodeling

Lawrence Township, NJ
3.3
★★★★★
  • Pros icon Good Customer Service
  • Pros icon Educational Website
  • Pros icon Price Transparency

Services Offered

  • Service icon Glass Doors
  • Service icon Custom Window Designs
  • Service icon Window Replacement/Installation

Website: https://www.lukremodeling.com/
Address: 1177 Brunswick Ave, Lawrence Township, NJ 08648
Phone: (609) 672-3317

Windows and Doors By The Men With Tools

South Amboy, NJ
4.9
★★★★★
  • Pros icon Free assessment
  • Pros icon Timely Service
  • Pros icon Price Transparency
  • Pros icon Good Customer Service
  • Pros icon Educational Website

Services Offered

  • Service icon Window Replacement/Installation
  • Service icon Custom Window Designs
  • Service icon Bay Windows
  • Service icon Vinyl Frames
  • Service icon Energy-Efficient Options
  • Service icon Double-Hung
  • Service icon Glass Doors

Website: http://www.themenwithtools.com/
Address: 399 Oak St Suite B, South Amboy, NJ 08879
Phone: (908) 795-1836

Acre Windows & Doors

Metuchen, NJ
4.6
★★★★★
  • Pros icon Good Customer Service
  • Pros icon Educational Website
  • Pros icon Free assessment
  • Pros icon Price Transparency

Services Offered

  • Service icon Glass Doors
  • Service icon Window Replacement/Installation
  • Service icon Energy-Efficient Options

Website: https://acrewindows.com/
Address: 335 High St b3, Metuchen, NJ 08840
Phone: (908) 975-1881
Princeton Meadows Window Cost Calculator

Calculate how much you can expect to pay for window installation and replacement in Princeton Meadows, NJ using our customized window cost calculator.

Estimated Window Cost:
161 homeowners have requested a free estimate in the last 3 days.

Estimates will vary based on window dimensions and other unique factors to your home. Getting in touch with a local window installer is the best way to get an accurate cost estimate for your home.

How Installing Energy-Efficient Windows in Princeton Meadows Saves You Money

There are quite a few benefits of upgrading to energy-efficient windows. A few reasons you may want to consider making the change include the following:

  • Save money on energy bills: Once you install energy-efficient windows, you can expect a reduction in your bills by about 12% since you’ll need less energy to heat or cool your home.
  • Reduce your carbon footprint: You can reduce your carbon footprint by about 12% once you install Energy Star certified windows. In Princeton Meadows, that’s about 206 pounds per year on average.
  • Protect your investment: When your home is on the older side, your windows could also be outdated or leaky. Upgrading and repairing your windows is an important part of maintaining your property and its value.
  • Protect your valuables: Many energy-efficient windows have low-emissivity coatings, which not only insulate your home better, but also filter out harmful UV rays, preventing your furniture, carpet and other valuables from fading.

Estimated Cost of Window Replacement in Princeton Meadows

Windows come in different shapes and sizes, so costs and services will vary considerably. Here are the average costs and the primary services that you can find from the average window installation company.

How Much Do New Windows Cost?

Typically, homeowners in Princeton Meadows can expect that most replacement window installations will range from $250 to $1,200, with the average cost at about $600. But prices vary remarkably depending on the size of your home, complexity of the installation, your location and the quality of the company you choose. Many window companies also provide door replacements, which have a higher price tag.

With windows, efficiency is one of the most important factors for many homeowners. High efficiency windows may cost more off the bat, but by increasing the efficiency of your home — especially during the summer and winter — they can provide decades of energy savings. According to Energy Star, purchasing certified energy-efficient windows can save Princeton Meadows homeowners $306+ each year after replacing single-pane windows.

The cost of your window installation will also vary based on the type of window material you choose for the frames. Wood windows are usually the most expensive, although it depends on whether they are completely wood or clad with aluminum or vinyl. Fiberglass windows also tend to be somewhat more expensive than vinyl, but they are shown to be more efficient.

What Services do Window Installers Offer?

In regard to window replacements, there are generally two kinds that your installer will have: full-frame and pocket installations.

Full-frame installations are necessary when you want to change the style of your windows or your window has significant deterioration. With this service, your installers will replace the full window, including the frame, sill and trim. Pocket installations are on the simpler end and won’t cost as much because they entail simply replacing the window within its existing frame. But if the frame has any damage or deterioration, you may have to get a full-frame installation instead.

Your window installation company should be able to help you understand what’s best for your needs. In Princeton Meadows, the decision will mostly depend on how old your home is and if there’s any damage. Wood can decay if not properly maintained over the years, so it’s good to have a professional check on your frames and window sills.

Best Availability

Renewal by Andersen

★★★★★
4.5
  • Great industry reputation
  • Member of US Green Building Council
  • Manufactures products in-house
Buy One Window, Get One 40% OFF
Get Estimate

Best Energy-Efficient Features

Champion

★★★★★
4.5
  • Many years of experience
  • Low prices relative to competitors
  • Limetime warranty
Buy 2 Windows, Get 2 Free
Get Estimate

Power Home

★★★★★
4.5
  • Uses eco-friendly materials
  • Well-trained, certified installers
  • Lifetime or lengthy warranty
Next-Day Appointments Available
Get Estimate

How We Choose the Best Window Installers in Princeton Meadows

EcoWatch reviews are different from most reviews, as we assess these companies through a sustainability lens. We have reviewed the top window replacement companies in Princeton Meadows mostly based on their energy efficient offerings, as it’s what’s best for the environment and for you as a homeowner. Energy-efficient windows can lower power bills by hundreds of dollars. Along with energy efficiency, our rating methodology takes the following factors into consideration:

Service Area

Because this is a guide for Princeton Meadows, we gave more points to companies that provide services to the city. There are other reputable providers that didn’t make the cut because of the low odds that they would serve the average homeowner in Princeton Meadows.

Work Quality

When selecting new windows, the quality and variety of services can often play just as important of a role in overall efficiency and performance as the brand you opt for. We do give window installers more points if they offer high-quality products, but we also consider workmanship as reflected in customer feedback.

Customer Reviews

We analyzed patterns in recent online reviews to find the companies with the most customer satisfaction, weighted by sample size. Customer satisfaction might be the most important factor, as it reflects the quality of services across most other categories, including quality of installation, professionalism, warranty, cost, quality of parts and more.

Cost

This one is a give-and-take: similar to other services, cheap window installation companies are not going to provide the highest quality service. On the other hand, we want to ensure we’re highlighting companies that offer a variety of price and financing options so they’re accessible to most homeowners.

Warranty

As discussed, windows are a substantial investment, so you’ll want to make sure that investment is protected. Window installation companies with lengthy warranties for products, parts and labor rank higher with EcoWatch.

Years of Experience

Because of Princeton Meadows’s climate, homeowners will want to mitigate rot, low efficiency and water damage. We factored in local experience to reflect the ability of Princeton Meadows window companies to prepare homes for the climate. If a company has less than 10 years of experience, it loses points in this category.

Princeton Meadows, NJ Window Replacement FAQs

How much should window installation cost?

The average cost of replacing a single window ranges between $450 and $650. There are many factors that affect how much it costs, which include your property’s location, the number of windows, how energy-efficient the windows are, styles and sizes of windows, local labor costs and the materials used in designing the windows.

What are the most common types of replacement windows?

The most common kinds of windows for homes are bay windows, awning windows, slider windows, casement windows, picture windows, double-hung and single-hung windows and transom windows.

What services do window installation companies do?

Window installation professionals visit your house to remove your old windows and replace them with new ones. Some providers install products sold by other companies, whereas others are both manufacturers and installation companies combined. The installer will also clean up after the installation is done.

What time of year is the best time to replace my windows?

Although you can install windows any time of year, warmer weather is often better for installing replacement windows. Additionally, it shouldn’t be raining, as rain can make the installation more difficult.

Should I replace my windows all at the same time?

If your windows are greater than 20 years old, you most likely need to replace all of them. At that point, they are typically less efficient, draftier and/or more damaged than new windows. Replacing your windows all at the same time will involve less paperwork and less time.