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What does the Energy Star Mean?

The bottom line for the energy-conscious consumer is a window’s Energy Rating, or ER number. A window’s ER rating is a measure of its overall performance based on three factors:

1) solar heat gains;
2) heat loss through frames, spacer, and glass; and
3) air leakage heat loss.

A number is established in watts per square metre, which is either positive or negative, depending on heat gain or loss during the heating season. The ER system is based on a formula which calculates a single ER number for a specified window size in each of seven window categories (e.g., a 24 inch by 48 inch casement selected as representative of that window type). Because all window Energy Ratings (ER) are evaluated in the same way, this makes it easy to do comparison shopping between different manufacturers-although a consumer should be aware that the rating given will be for windows inn the standard size, and not a particular window.

However, there are still several things to keep in mind when comparing ER numbers of different windows. Most fixed windows tend to have better (higher) ER numbers than operable ones. There are two reasons for this. First, the standard size for a fixed window is nearly twice as large as most of the operable windows and thus has more glass area relative to frame area. Frames are also thinner because they do not need separate moveable sashes. This translates into more solar gains and less frame losses-hence a higher ER number. Second, fixed windows tend to have less air leakage compared to operable ones. There is always going to be less air leakage with a window you can’t open than with one you can. This translates into less heat loss and a higher ER number for fixed windows.

It stands to reason from this discussion that, when you shop, make sure you’re comparing apples to apples. Compare ER numbers within each window category-fixed, casement, sliders, etc.-because the ER numbers vary considerably for each type.

Although intended only for comparison purposes, the ER number may be a good indicator of the effect windows will have on the annual heating costs in the home. A positive ER number means the windows actually add more heat to the nome than they lose during the heating season, decreasing the home’s heating costs. An ER number of zero should be considered a minimum performance level for a fixed window. A window with an ER of zero loses as much heat as it gains over the heating season. Consequently, it will have no impact on the house’s annual fuel consumption.

A negative ER means a window loses more energy than it gains, making the heating system work harder. The lower the number, the more heat is lost and the harder the heating system has to work in colder weather. For example, an ER of -38 is worse than an ER of -20. An ER number of -11 is a good minimum performance level for an operable, standard high performance window.

The ER system is a major step in giving consumers the information they need to make informed decisions about the energy performance of windows. Ir is a rating solely of a window’s performance-regardless of how, or with what materials it was built.

Energy performance is only one of many considerations in the purchase of a window. Appearance, price and durability are also important considerations. A high-performance window that meets CSA standards and has a good ER number will also tend to be better designed and manufactured, and will offer better resistance to condensation.

What is North Star's Self-Cleaning Glass?

North Star is the first window manufacturer in North America to offer Pilkington Activ? Self-Cleaning Glass is an available premium option for every window we sell. The time-consuming chore of cleaning windows is made much easier with this award-winning product which uses the power of sun and rain to gently clean away dirt.

The manufacturer’s specialized process enables natural sunlight to continuously and gradually break down, loosen, and dissolve dirt, soil, tree sap, and other organic residue. Rainwater then sheets off the glass so windows dry, minimizing streaks or spots. The durable treatment won’t peel, discolour, separate, or disintegrate over time because it is a permanent part of the glass surface.

How do I care for my North Star Self-Cleaning Windows?

Self-cleaning glass is built to last. However, special care is needed to prevent exposure to harsh chemicals such as silicone and to sharp or abrasive materials that may damage the treated surface. Also, it takes up to seven days for the unique properties of self-cleaning glass to begin working after installation.
Here are some helpful tips for caring for your North Star Self-Cleaning Windows…


During dry weather conditions a light spray of water will quickly resotre clean windows. Hard water will need to be softened using a spray attachment with a small amount of liquid dish soap.


Grease, paint, or heavy dirt should be soaked and then leaned using soapy water and a clean soft cloth or sponge. Special attention is needed when removing mortar or cement products. It is not advisable to try to scrape them away.


Tough paint splatters require a soft cloth and a solvent such as denatured alcohol or acetone. Be careful to protect vinyl and painted surfaces form the solvent.


If silicone comes in contact with treated glass, wash only the affected area with acetone or a silicone solvent, then clean with soapy water and rinse throughly.

How does North Star Self-Cleaning Glass Compare to other products?

Dual action (photocatalytic and hydrophilic)
TiO2 (titanium dioxide) coating applied “on line” during the molten state
Chemical mix applied just below “ignition” temperature
Activiation within hours on sunny days, and within 1-2 days when cloudy (with no human interference)
Hydrophilic surface attracts water and gets under dirt to lift it off the surface
Tints will be available in the future
Silicone is a “barrier” that hinders activation, but does not harm or remove the Activ? coating

Dual action (photocatalytic and hydrophilic)
Similar coating and action as Pilkington product

Single hydrophilic
Passive coating (doesn’t loosen organic particles)
2-stage application (“off line” production)
SiO2 (silica metal oxide) coating applied on glass
ZnO (zinc oxide) applied over silica coating and needs to be removed by vinegar to activate the hydrophilic properties
Needs to be “rejuvinated” occasionally

Single hydrophilic
Called “low maintenance” glass by manufacturer
Needs activation with one time “auto oxidation”
very durable, hard surface
Chemically inert coating applied “off line”
Note…all information for these four companies as presented by them in November, 2002 at Win Door Show.

What is condensation?

Condensation on windows interior surface is the passing of a substance form a lighter to a denser physical state. In this instance, water passes from a gaseous (vapour) state to the denser liquid one. Because it is caused by too much humidity, condensation is also the symptom of a more serious problem-excessive moisture at work in your home’s atmosphere.

In seeking cooler, drier outside air, water vapour exerts pressure and forces its way through most building materials. Wood, brick, and drywall are too porous to stop moisture from migrating to the outside. But because window glass is denser and its surface colder than the surrounding walls, vapour is stopped by glass and condenses on it. While glass-the coldest, least porous (and most visible) material in a building-may show condensation first, it may also be noticed on exposed nail heads and other metal surfaces.

Why does condensation occur?

Problems arise because air can hold only a limited amount of water vapour, varying with the temperature. Condensation is related to two conditions always present in the atmosphere inside your home. It is likely to form whenever there is an improper balance between:

Relative Humidity
A ratio between the water vapour in the air compared to the maximum amount that air can hold at a given temperature. For example, 50% means the air is carrying 1/2 of the total water vapour it is capable of holding at that temperature.

A particular temperature where the relative humidity becomes 100% is called the “dew point”. At the dew point, the air is saturated with moisture and begins to lose it in the form of condensation.

Where does condensation occur?

In practice, condensation will occur first over the lower part of the window because glass surface temperatures are not uniform, being lower at the bottom than at the top. Windows with a metal sash usually have more severe problems at the base and sides. Occasionally, it may occur on cold spots, such as nail heads and in corners of outside walls and closets where insulation value is reduced.

What are the usual sources of moisture?

The humidity level in a house during the winter will depend on both the moisture added to the air through family living habits (see chart) and the rate at which this moisture is removed by ventilation or condensation.


What is insulated glass?

Insulated glass also know as a sealed unit is two pieces of window glass parallel with each other and spaced apart usually 1/2″ by a product called a spacer. After these are assembled together there is then a sealant that goes around the entire perimeter of the unit to seal the dry air inside and not allowing outside air to enter. The air sealed inside is “dead” not being allowed to escape or move around and thus is a good insulator between two poor insulators [ie glass]. Glass in and of itself is a very poor insulator.

Why is argon gas put into sealed units?

Although dead air is a good insulator, the key is that the air does not circulate at all. In order to assure this does not happen the air is replaced, while in production, with argon which is a heavier than air gas and thus harder to make circulate. Argon also is a better insulator than plain air. Argon is colourless, odourless, non flammable and non toxic and therefore very safe.

What is Low-E glass?

Low-E stands for low-emissivity and is a transparent coating on the glass which acts as a thermal mirror reflecting heat [infrared] and fading [ultraviolet] rays back to its source. Because it is clear it allows almost all of the visible light into your home while blocking out the undesirable parts of the spectrum. This process works year around and will depend upon which side of the window the heat is from.[ie in the winter time the heat is generated by your furnace and therefore reflected back into your home]. North Stars standard low-E is Advantage, meaning it allows for natural solar gain [free heat] in the winter and still blocking out a significant amount of harmful rays in the summer. This is of course desirable in out heating dominated climate. North Star also offers Solar low-E for certain situations [ie southern facing sunrooms] but it is not recommended for the whole house since a certain amount of free heat would be forfeited. Low-E≤ is also of a similar characteristic and thus recommended for climates much further south than us with more cooling days than heating in our homes.

Why should I consider changing my windows?

Although there are several reasons for upgrading your windows here are 3 main reasons:

a) Energy efficiency. New technology has produced much warmer glass [80-90% of your window is glass]. As well weatherstripping may not even be a part of your old windows or it may have deteriorated over the course of time, thus allowing air to pass by the sashes.

b) Maintenance free exteriors. Painting is not most peoples favourite job. As well as time consuming, windows are also very tedious to paint. New maintenance free exteriors and resealing also prevent further unseen structural damage or prevent any damage from starting.

c) Easy to live with. This is sometimes the number 1 reason for changing windows. Old windows that are hard to operate and awkward to clean can be a pain as well as dangerous in some cases. Interior tilt in sashes as well as Activ self cleaning glass exterior glazings make cleaning your windows a breeze!

Also tightly sealed windows and Super Spaced glass will make your house quieter from outside noises.

Will I get a return on my investment should I sell my house?

This question is a valid one and asked quite frequently. All upgrades to our homes cost us money but in the case of windows and doors being replaced there is a energy savings in actual dollars. Depending on how inefficient your old windows were and how long you plan on staying in your home, the investment may pay for it self in lower energy bills, keeping in mind that an air conditioned house stands to save as much in summertime energy savings as well as winter heating bills. Why through your money out the windows!?

But aside from energy savings there is also an appreciation to the value of the home. For the reasons considered in question 11 most consumers see great value in a home with new upgraded energy efficient, maintenance free easy to live with windows. Exactly how much could you expect to recoup on your investment will depend on how bad the old windows are and somewhat as to the styles and quality of the new windows. Style meaning do they look good and fit the type and style of house? And quality meaning is it a recognisable brand with all the latest and best features as well do the windows come with a transferable warranty? According to the above facts and other studies relating to the above question it is estimated you could recoup up to 80% of investment costs.

Who will install my windows if I order new windows from Stephenson Windows?

All of Stephenson’s products bought installed are installed by our own employees and nothing is passed on to a subcontractor. We have seasoned well experienced installers known for their quality workmanship and quality installations. So there is never any danger of getting into a “pass the buck” type situation if a problem should arise. We back up all our installations with a lifetime warranty for peace of mind. A premium window also depends on a premium installation.

How do I maintain Vinyl Window and Door Frames?

The true beauty of vinyl windows and doors is that they come closer to being maintenance-free than most exterior building products.

Although rain usually does a satisfactory job removing dirt from vinyl window and door frames, follow these simple instructions if necessary to keep them clean and looking as good as new.

Normal Maintenance Tips

  • Use a soft cloth or long-handled soft-bristle brush to wash frames.
  • If necessary, use a mild abrasive cleaner such as SoftScrub®, Ajax®, BonAmi®, etc. (Note: the use of any abrasive material could have a detrimental effect on the surface of glass and window or door frames.)
  • Do not use cleaners containing aggressive organic solvents (such as chlorine bleach; liquid grease remover; strong soaps and detergents containing organic solvents) because they could damage the surface appearance of the vinyl.
  • Use the readily available household cleaners listed below for tough dirt and stains such as top soil, caulking, rust or mold and mildew. Please refer to the manufacturer’s instructions on use of cleaners.
  • Avoid washing windows with high pressure spray.

Cleaners to Remove Stains from Vinyl and Wood Door Frames*

Bubble gum Fantastik®; Murphy Oil Soap®; Solution of 30% vinegar and 70% water; Windex®
Crayon Lestoil®
DAP (oil-based caulk) Fantastik®
Felt-tip Pen Fantastik®; water-based cleaners
Grass Fantastik®; Lysol®; Murphy Oil Soap®; Windex®
Lipstick Fantastik®; Murphy Oil Soap®
Lithium Grease Fantastik®; Lestoil®; Murphy Oil Soap®; Windex®
Mold and Mildew Fantastik®; Solution of 30% vinegar and 70% water; Windex®
Motor Oil Fantastik®; Lysol®; Murphy Oil Soap®; Windex®
Oil SoftScrub®
Paint Brillo® Pad; SoftScrub®
Pencil SoftScrub®
Rust Fantastik®; Murphy Oil Soap®; Windex®
Tar SoftScrub®
Top Soil Fantastik®; Lestoil®; Murphy Oil Soap®


  1. North Star does not endorse proprietary products or processes and makes no warranties for the products referenced herein. Reference to proprietary names is for illustrative purposes only and is not intended to imply that there are not equally effective alternatives.
  2. These tips are based on a study conducted by the Vinyl Window and Door Institute on the efficiency of cleaning agents and their effects on the appearance of vinyl window frames after two years of outdoor exposure.

Maintaining Self-Cleaning Glass

North Star windows and patio doors are available with optional Pilkington Activ™ Self-Cleaning Glass, which features a thin, clear, permanent, coating on one of its surfaces. The coating makes raindrops spread out, or sheet, across the surface to wash away dirt particles. It also acts as a catalyst, when activated by sunlight, to break down organic dirt into water vapor and CO2 gas.

Because self-cleaning glass needs a slightly different cleaning procedure, please refer to Pilkington Activ™ Self-cleaning Glass cleaning instructions

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    Strathroy, Ontario N7G 1L2
  • 519-245-0256
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    Saturday: by appointment
    Sunday: CLOSED

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