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Ottawa Energy Efficient Windows

Are you aware that a significant portion, up to 25%, of your energy expenses could be attributed to inefficient windows? That’s why many homeowners are turning to LOCKTIGHT™ window replacements. If your current windows are aged or in poor condition, they might be inflating your annual energy bills by as much as 25%. Thankfully, Big City Windows & Doors offers top-tier glass and glazing solutions to address this issue.

At Big City Windows & Doors, we prioritize both aesthetics and performance. Our LOCKTIGHT™ windows are meticulously crafted to surpass industry standards, and are backed by a LIFETIME transferable warranty. Each window is meticulously designed with precision and attention to detail, ensuring not only visual appeal, but also exceptional functionality. Our LOCKTIGHT™ products offer advanced durability, insulation, and superior thermal retention, exceeding ENERGY STAR® requirements for energy-efficient products and making them among the most energy-efficient options available.

Whether you're renovating or constructing a new home, our intricately designed windows are a wise investment. Enhancing your home's curb appeal and integrating the latest technology and finest materials, our windows provide unmatched safety, beauty, and efficiency. Our energy-efficient uPVC windows are crafted from a 100% lead-free uPVC special powder compound, enhancing impact resistance and preventing discolouration.

Our Innovative Windows Technology
See the comparison between generic window and LOCKTIGHT™
PVC Window
Air Tightness
Energy Efficiency
Easy to Maintain

What are Energy Efficient Windows, and How do They Work?

Energy-efficient windows are designed to minimize heat transfer between the interior and exterior of a building, reducing energy consumption for heating and cooling. They feature low-emissivity (Low-e) glass coatings, which reflect infrared light while allowing visible light to pass through, reducing heat gain in hot weather and heat loss in colder seasons. These windows often incorporate multiple panes of glass with insulating gas fills, like argon or krypton, creating a barrier against heat transfer and improving thermal efficiency.

High-quality window frames are made from vinyl to minimize air leakage and provide additional insulation. Overall, energy-efficient windows work by effectively reducing heat transfer, improving insulation, and optimizing the energy performance of buildings. This results in lower energy bills and increased comfort for occupants, making them a valuable investment for homes and buildings seeking to improve energy efficiency and reduce environmental impact.

Our Energy Efficient Windows Benefits

#1 in energy efficiency

Low maintenance, easy to clean

100% eco-friendly, recyclable

Durable, sturdy, reliable

Prevents frame discolouration

Always accessible, always affordable

Exceptional insulation

Wide range of customizable sizes, colours, and shapes

Rot and corrosion-resistant hardware

Scratching and cracking-resistant build

Top-notch personalized security

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Glass Options of Energy Efficient Windows


Clear glass

Clear glass allows light from both outside and inside to pass through without resistance. It also helps to reduce noise compared to a single pane glass frame.

Triple Glass

Three panes of glass compared to a double pane: what's the difference? Big City Windows & Doors triple pane glass provides the best energy efficiency on the market. While our insulating frames work to keep hot air in during winters and out during summers, our Low-E coatings increase the retention of solar gain. This results in the ultimate jack- of-all-trades energy efficient window model.

Low-E Glass

Low-emissive coatings applied to the panes of glass make your windows more energy efficient and can lead to lower energy bills. Low-E glass helps keep the heat in during winters and out during summers for a comfier, more affordable home all year long. We offer different Low-E glass options to provide different levels of heat reflection to better suit your home. Finally, Low-E glass windows minimize harmful ultraviolet light which helps avoid warping, cracking, and discolouration.

Architectural Glass

At Big City Windows & Doors, we rely on one of the leading providers of quality glass products in the world. Heavily invested in research and development while designing and producing the most advanced glass products in the industry, we partner with the latest technology producers in frame and pane science.


LoĒ-I89 Glass

Introducing LoĒ-I89 glass: this enhanced performance glass improves your glass' U-factor to a remarkable 0.20 when coupled with LoĒ2 or LoĒ3 and an argon-filled double-pane unit.

Performance characteristics

Turn your double-pane windows into triple pane performers

LoĒ-i89 reflects heat back into your room and minimizes its U-factors. This double pane unit delivers unparalleled performance (a centre of glass U-factor of just 0.20 compared to 0.35 with clear triple-pane) to bring you the ultimate blend of comfort and affordability. Ask us how including LoĒ-i89 in your window designs can make all the difference.

The advantages are more than clear

In addition to providing maximum energy efficiency in a double-pane unit, LoE-i89 offers several other customer-pleasing benefits by greatly reducing condensation and potential for moisture.

LoĒ-i89 insulating glass units meet the most stringent energy standards – even with double-pane units!

Can lower the U-Factor to just 0.20

Can meet the performance requirements of a triple pane window

Enhanced winter performance glass


LoĒ-180 Glass

The combination of high solar gain and excellent insulating value allows LoĒ-180 glass to achieve one of the highest ER values for a double-pane glass in the Canadian window rating program. Big City Windows & Doors double-pane windows can achieve even the most stringent of Canadian ENERGY STAR® compliance in the far north.

Performance characteristics

LoĒ-180 makes it cozy inside

During cold weather, the insulating effect of your windows can have an impact of night and day on your room. The superior insulating capability of argon-filled LoĒ-180 is a key factor in the construction of comfortable windows for cold climates. Enjoy year round comfort with LoĒ-1B0's ability to control and maintain your home's humidity to prevent condensation on your windows.

Visible light Transmittance

We employ a state-of-the-art sputter coating process that is unmatched by any other glass manufacturer. The glass is coated with a microscopically thin, optically transparent layer of silver sandwiched between layers of anti-reflective metal oxide coatings. This protective coating is applied to ensure maximum durability and longevity for all Big City Windows & Doors windows.

Quality-Ensured Glass: with patented inspection systems, our glass is thoroughly examined from start to finish

Superior energy savings

Passive solar control glass

Better humidity control

Outperforms tinted windows

Blocks 75% of harmful UV rays


LoĒ-272 Glass

Get superior thermal performance year-round with LoĒ-272 glass, the clearest choice for total comfort. No matter the conditions outside, you can count on LoĒ-272 glass to comfort you and your loved ones on the inside all year long.

Performance characteristics

Solar control with the coolest windows under the sun

When it's hot outside, the raging sun can often render your house uncomfortable. This high solar heat gain can in turn contribute to air-conditioning costs. LoĒ-272 blocks enough solar heat that cooling loads can be lowered much more than ordinary Low-Ē and clear glass. Controlling solar gain not only saves energy during the air conditioning season, but also makes sunny rooms far less of a pain during brutal summers.

Hot or cold outside, comfort inside

Say goodbye to thermal discomfort. Whether it is 20 below or 40 in the shade, you can bring year-round comfort to your home with LoĒ-272 glass

Superior insulation: higher ranking performance improvement in winter nighttime insulation

Great glass for all climates

Blocks the harmful ultraviolet rays

LoĒ-272 reflects heat back into the room in winter

LoĒ-272 rejects the sun's summer heat and damaging solar rays

Increased insulation value of your ordinary insulating glass unit with LoĒ-272


LoĒ-366 Glass

LoĒ-366 glass is the ultimate performance glass. Get the ideal balance of solar control and high visibility alongside the highest levels of year-round comfort and energy savings available. With an unprecedented triple layer of silver coatings, make LoĒ-366 the perfect glass no matter where you live.

Performance characteristics

New shield of protection

The average Canadian household spends vast amounts of money on energy costs. However, you might be surprised to learn that you can reduce your monthly energy bills by simply using low-emissivity glass. Not only does it make financial sense, but you will also help protect the environment – by using products that reduce energy consumption, you also decrease the size of your carbon footprint.

Energy savings all year long

The full-year benefits of LoĒ-366 are clear as day: when temperatures soar in the summer, ordinary window glass just can't beat the heat while tinted glass spoils the view. Meanwhile, LoĒ-366 is formulated to reject solar heat while maintaining attractive visibility. This keeps the heat out while letting light in.

Unprecedented third layer of silver coatings

Blocks up to 95% of damaging UV rays

Blocks even more solar gain than other Low-E performance glass

Most advanced all climate glass

Retains the room's side of heating or cooling

Highest R value for better insulating performance

What are Energy Efficient Windows, and How do They Work?

The potential savings for a property owner through the installation of energy-efficient windows can vary depending on factors such as the size of the property, local climate conditions, energy costs, and the efficiency of the windows installed. However, studies suggest that replacing old, inefficient windows with energy-efficient ones can lead to significant cost savings over time.


On average, homeowners can expect to save anywhere from up to 25% on their heating and cooling costs by upgrading to energy-efficient windows.

For example, a homeowner with high energy bills due to inefficient windows might see a reduction of hundreds of dollars annually after installing energy-efficient replacements.

These savings accrue due to several factors. Energy-efficient windows help to better insulate the home, reducing the need for heating in winter and cooling in summer. They minimize heat transfer through low-emissivity coatings, multiple panes, and insulating gas fills, maintaining a more consistent indoor temperature year-round. Additionally, improved sealing and insulation provided by quality window frames prevent air leakage, further enhancing energy efficiency.

Over time, these reduced energy costs can offset the initial investment in energy-efficient windows. Moreover, many governments and utility companies offer incentives, rebates, or tax credits for energy-efficient home upgrades, further reducing the upfront costs and increasing the long-term savings potential.

Ultimately, installing energy-efficient windows not only contributes to lower energy bills, but also enhances comfort, reduces environmental impact, and increases the overall value of the property.



Are there government incentives or rebates available for installing energy-efficient windows?

Government and utility companies generally offer incentives, rebates, or tax credits for installing energy-efficient windows. These incentives aim to encourage homeowners to make environmentally friendly upgrades that reduce energy consumption and lower greenhouse gas emissions.

Do energy-efficient windows provide any sound insulation benefits?

Yes, energy-efficient windows can provide some degree of sound insulation, especially when compared to older, single-pane windows. The multiple panes of glass and insulated frames help reduce outside noise infiltration, creating a quieter and more comfortable indoor environment.

Do energy-efficient windows offer UV protection for my furnishings and interior?

Many energy-efficient windows are designed to block a significant portion of ultraviolet (UV) rays from entering the home. This helps protect furnishings, flooring, and interior décor from fading and damage caused by prolonged exposure to sunlight, prolonging their lifespan and reducing the need for replacement or refurbishment.

What is the typical payback period for energy-efficient windows in terms of energy savings?

The typical payback period for energy-efficient windows varies depending on factors such as the cost of installation, local energy prices, and climate conditions. However, homeowners can generally expect to recoup their investment within 5 to 10 years through reduced energy bills.

What is the expected lifespan of energy-efficient windows, and do they require special maintenance?

Energy-efficient windows typically have a lifespan of 20 to 30 years or more, depending on the quality of materials and installation. While they may require occasional cleaning and maintenance, such as lubricating hinges and seals, they generally do not require special maintenance beyond what is recommended for standard windows.

Energy Efficient Windows Gallery

Our Reputation is built on Trust and Quality


Very happy I was shown different windows styles. We went with the larger pane and smaller opening window. It's like looking through a clear opening. We have a big bushy backyard, so nice to see it so well. I actually had a couple deer come peek all I could see were these big ears in the dark. Our windows are lower. Also went with vinyl them. There easy to wash and remove when painting around them.
The installers were also fantastic, they even re-adjusted our front door from last march 2023 without my asking.
Thank you very much.


The company salesman was great rep. He provided all necessary information and facilitated us applying for the government-sponsored interest free loan.
Fourteen windows where quickly changed by competent, knowledgeable and courteous workers. They answered all of our questions and looked after any worries we might have had. The complicated metal sheet flashing of all the windows in our mansard-type roof was done very well. Everything looks great and the house already starting to feel warmer. No cold is felt on the hands when in contact with the vinyl of the windows and very little when on the triple pan glass. Thank you so much to all of the Big City Windows & Doors staff for a job well done.


Weve had nothing but the absolute best service from Big City Windows. They redid all the windows and doors in our heritage house, and we werent easy clients! My dad was in the business for many years, so we had a detailed list of what we wanted and high expectations for how it was to be done Big City installed everything a month ago, and my dad is still singing their praises! Everyone who comes to the house, even strangers, remarks on how gorgeous our new front door is!


Did an awesome Job installing the windows. No major issues. The windows were Installed and ain a timely fashion..they cleaned up after themselves. This is the second time we have used this company.


We recently purchased a older home, Big City Windows helped us with redesigning the whole thing! They really go above and beyond for their clients we could not be happier with the results.

Our doors are showstoppers and the windows keep the house soo warm in the winter. We were hesitant about having them installed during the winter winter months but it was totally worth it- We were feeling the difference instantly!

We highly recommend Big City Windows for your next window project!


We are very satisfied with the work and expertise of the staff who handled our contract. From the sales agent, to the person who took the measurements and to the two installers, everyone was professional and respectful. The installers were perfectionists, their work was excellent. We will share your company.


I had Big City Windows replace a patio door and a large living room window, through a recommendation from our neighbour. Well from the start of the process, to the finish. I couldnt be happier. The quality of work was next to none, the quality of the materials used were amazing The 2 employees were great!! They arrived first thing in yhe morning and worked their butts off till the job was done. My wife and I are completely satisfied!! They left a clean work place when they were done.


It was a seamless experience getting my windows, and patio door replaced with Big City Windows. Timelines were met. The window installation team was professional, and I was very impressed with the work they did.


Employees were helpful at all stages: from check measure, purchase, delivery and installation. Received the patio doors in the time indicated. Installation was professional and clean up was amazing! Their pricing was great! I would recommend Big City Windows and Doors for anyone that is looking for this service. You will not be disappointed.


Big City Windows and Doors is by far one of the best companies with which we have dealt. They took the time to look over our project and come up with recommendations that met our needs.
We had a new side door and door from the house to the garage replaced. We really like the new self closing hinges on the door to the garage.
The installation team was amazing. They took even the smallest detail into account when finishing up the install. You would have never known they were there.
We're already saving towards replacing our front door to make a matching set.
They will be getting our business for the foreseeable future for sure.

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