The Ultimate Insulation Guide [How to Keep the Heat In or Out]

www.thermawood.co.nz Whether you are dealing with cold drafts, the sun’s overheating or both, your are where the most heat transfer takes place, making them your home’s major thermal vulnerability.

Instead of letting the heat seep out in the • A comfortable environment; cold weather or allowing it to turn your • Energy bills that are a fraction of what home into an oven in warm weather, they once were; and installing the right double glazing will effectively keep the warmth in when you • The satisfaction that you are getting want it and out when you don’t. the best from your windows, rather than losing money and comfort Today, builders are constructing buildings because they aren’t equipped to fulfil with double glazed windows and property 21st century expectations. owners are upgrading to double glazing because more people understand just How does double glazing work to how profound the energy efficiency manage both warm and cold climates? advantages are, as well as the benefits of enjoying a living or working space that What options do property owners offers superior, almost effortless comfort. have for insulating their windows?

The historical practice of installing Are there any DIY alternative solutions windows with a single glass pane no that will help to insulate a home? longer makes sense. It wastes energy and turns the cost of heating and cooling into When it comes to , an unnecessary burden, whilst increasing there are many approaches. But only the your carbon footprint. It also leaves you most advanced technology will give you susceptible to other problems like chronic the results you are looking for. Efficient noise pollution and makes keeping the and consumer-driven, the best method interior environment the pleasant space it for insulating your windows isn’t always should be, a never ending challenge. the most expensive. But it is the one that makes the most sense. Modern double glazing technology has completely transformed what our windows Find out the facts on window insulation can do for us. When you have double – why double glazing is so effective, glazed windows tailored for your property’s the science behind low-e glass and a unique needs, they insulate from the cold comprehensive look at your options for and the heat, leaving you to enjoy: getting the best value out of your windows. CONTENTS:

• DIY Window Insulation Considerations 3

• Why Double Glazing Makes a Major Difference 5

• Why the Best Solution Isn’t the Most Expensive 6

• The Science Behind Low-E Glass 7

• Where Is the Low-E Coating in an Insulated Glass Unit? 8

• Why Doesn’t Low-E Glass Impact Visible Light? 8

• Does the Low-E Coating Impact the Colour of the Glass? 9

• How Much Does Low-E Glass Cost? 11

• Gas for Even Better Results 12

• What You Need to Know about Draft Seals 13

• Insulating Windows for Heritage Buildings 14 DIY WINDOW INSULATION CONSIDERATIONS

There are different ways to insulate your windows. With each option, you’ll get a varying degree of thermal insulation from both heat and cold.

One of the easiest do-it-yourself methods is to put up window dressings that offer greater insulation than standard curtains and blinds, such as thermal drapes or cellular shades. Cellular shades, also known as honeycomb shades, contain cell pockets that trap in the air around your windows. You can opt for double or triple cell shades for added insulation. Another tactic is to use layered window dressings, for example combining thermal curtains with cellular shades.

Of course, window dressings can’t do anything about drafts, which means you’ll still get a lot of the chilled air permeating your home, along with heat loss.

In warmer climates, the shading effect of window dressings helps, but there won’t be a significant benefit. You’ll also risk trapping in too much heat, making your overheating problems worse if you aren’t careful. And, you’ll have to keep your curtains, blinds or shades closed to get even the minor insulation they provide, which means you’ll sacrifice that beautiful natural lighting that makes having windows worthwhile.

Another method is to seal your windows with caulking around the window casings and weather stripping around the sash. This helps to close off air leaks, preventing heat loss.

Page 3 A third DIY method is to apply an insulating window film. In this case, you attach a film directly to the inside of your window. It does create an air gap, which helps to reduce heat transfer.

Low-emissivity, or low-e film can be used, essentially turning your existing window into a sort of single glaze, low-e product. This will reflect heat back into the interior, reducing heat loss. However, as with thermal window dressings, the impact will never come close to double glazing. First, you’ll still have draft issues, which can almost negate the effect of the air gap and reduce heat transfer. Second, an insulating film won’t change the quality of your single glaze. When your window glass gets too hot or cold, it still has to radiate the energy, meaning you will still get unwanted warmth or chill entering your property.

Another negative of film is that it is extremely vulnerable to scratching. Something as simple as marking the film with your jewellery when you are cleaning your windows will yield some unsightly marks, in addition to the loss of clarity you’ll get when you stick on the film in the first place.

Whilst everything you do helps, keep in mind that you’re not going to get a big difference with do-it-yourself methods, even if you combine every one of them. You’re likely better off investing the time and money spent in DIY methods intoa professional job so you can address your window’s thermal vulnerabilities once and for all.

Page 4 WHY DOUBLE GLAZING MAKES A MAJOR DIFFERENCE

For thermal insulation benefits, you can feel the difference – and see it on your energy bills – when you use double glazed windows. There are several reasons why double glazing is so powerful.

• Double glazing creates a customisable air gap, which reduces thermal transfer. • The added insulation of two panes of glass helps to block out cold air, hot temperatures, as well as noise, whilst keeping warm air in during the winter. • With double glazing, a professional installs an insulated glass unit (IGU) in place of your single pane. This means you are not trying to amend an already poor insulating piece of glass, but rather can use a better glass, such as thermal glass, that has the correct properties for managing your interior temperature.

An IGU is two panes of glass plus an air gap. Each glaze, as well as the air gap, can be tailored to suit your specific insulation needs – for each window in your home.

This means you can opt for thermal glass for those overheated north and west-facing windows that get drenched in sun, a tailored IGU for your south-facing side, which usually is the coldest side of the house in the winter, and have any other issues addressed that are specific to your property. It is this ability to not just throw up more material or create a makeshift air gap, but to create a dynamic thermal insulating system, that makes double glazing so powerful.

But – your options don’t stop at double glazing. The way in which an IGU is installed impacts its performance, and its price. Double glazed windows can be new or retrofitted. Whilst you can get the same customised IGU with either solution, you can get vastly different results.

Page 5 WHY THE BEST SOLUTION ISN’T THE MOST EXPENSIVE

With new double glazed windows, your current window – pane of glass, frame and all – is removed. Then a new frame and the new IGU are installed.

With the Thermawood patented retrofit double glazing system, the existing window is retrofitted rather than replaced.

As long as your current windows have timber frames, you can have your windows retrofitted. The existing wooden window remains in place and is converted. Then the single pane is replaced with an IGU. This more streamlined process costs a third of the price of new double glazed windows. That can translate to thousands of dollars in savings, depending on how large your project is.

Thermawood franchisees use a unique patented dry retrofit double glazing system, which is designed to allow for the greatest possible amount of evaporation. This prevents rot in your windows by reducing condensation from forming on the glass – an essential for your windows’ longevity. If condensation has the chance to form, the moisture can build up on and around the bottom of the window, leading to problems with mould growth and rot.

Whether you use new double glazed windows or retrofit double glazing to insulate your windows, you can get even more out of them by using a special thermal glass called low-e glass. Low-e is useful for both holding heat in when you want to keep your interior warm, and for stopping excess warmth from coming in when you want to keep your interior cool when it’s hot outside.

Page 6 THE SCIENCE BEHIND LOW-E GLASS

Low-e refers to the low emissivity of the glass. Emissivity has to do with how well a material’s surface radiates energy. When you are trying to achieve greater insulation, you want less emissivity.

All materials radiate heat energy to some degree. The more reflective a material’s surface is, the more it will reflect heat and the less it will radiate heat. Radiant heat is one of the primary ways that heat is transferred through windows.

When a glass is more reflective, it has lower emissivity, which means less radiant heat, and less thermal transfer. In the case of low-e glass in a double glazing unit, the thermal energy is being bounced back to where it came from instead of transferring through the glass.

With low-e glass, a micro-thin coating is manufactured onto the glass surface.

This coating is made from layers of silver, as well as other low-e materials. You can’t see the coating; it is thinner than a human hair. Just like a mirror reflects visible light, a low-e coating reflects infrared light. When it comes to insulating your home, it is reflecting the short wave infrared light.

This is why low-e glass will keep the same space warmer in the winter and cooler in the summer. It reflects heat back inside, which would otherwise escape in the cold weather. In hot weather, it reflects the sun’s infrared energy back outside, thus preventing overheating. It is always reflecting short wave heat back to where it came from.

As a result, low-e glass boosts the energy efficiency of a building by as much as 40% in both hot and cold climates!

Page 7 WHERE IS THE LOW-E COATING IN AN INSULATED GLASS UNIT?

When using double glazing to insulate your windows, you only need one piece of thermal glass in an IGU. The other glaze can be standard glass or it can be a special acoustic glass if you want to use your windows for acoustic and thermal performance.

The low-e coating is always on one of the two inner surfaces of an IGU – the inside- facing surface of the exterior pane or the outward facing surface of the inner pane.

COLD CLIMATES HOT CLIMATES or CLIMATES THAT CAN BE BOTH HOT & COLD

Page 8 WHY DOESN’T LOW-E GLASS IMPACT VISIBLE LIGHT?

One concern people have with low-e glass is visibility. It’s easy to assume that if the sun’s energy waves are reflected that you are not going to get the same clarity as you would with uncoated windows. This isn’t the case. Low-e technology is designed to block out infrared and UV rays. The visible light spectrum is allowed to pass through. That’s why there is no difference in the visible light transmission when you use low-e coated glass.

DOES THE LOW-E COATING IMPACT THE COLOUR OF THE GLASS?

Today, low-e glass is just as crystal clear as standard glass. However, older low-e technology did come with a minor aesthetic drawback. Glass companies used to use what is known as hard coat low-e to reflect infrared energy. When sunlight hits this type of low-e glass, it creates a murky, somewhat discoloured look. Because of advancements in low-e technology, hard coat low-e glass is rarely used now.

Some consumers assume that tinted glass is a good option for thermal insulation, particularly for shading out the sun’s rays in warm temperatures. When you look at the properties of glass, you can see that tinted glass, like hard coat low-e glass, isn’t ideal for double glazed windows, or even practical. When tinting, also known as hard shading, was used, what happens when the glass is sitting in your window is this: part of the glass will stay cool, whilst the other half can heat up. Glass doesn’t like being both hot and cold in different places. This ‘temperature confusion’ can stress the glass and may cause the glass to break. This is known as Thermal Stress.

Page 9 EXACTLY WHAT IS THE DIFFERENCE BETWEEN HARD AND SOFT COAT LOW-E GLASS?

Hard coat low-e glass is manufactured through the pyrolytic process. When the glass is still being produced, the reflective silver layers are applied to the glass ribbon. This happens when the glass is still hot, fusing the low-e coating with the glass and creating a hard coating.

Hard coat low-e glass isn’t used as widely today, not only because of the dusty look that you get when it is exposed to the sun, but also because it isn’t as effective at blocking infrared energy. Hard coat glass has a lower solar heat gain coefficient (SHGC). Especially when you are trying to insulate windows for warmer weather, sunny windows such as your north and west-facing ones, or even insulation for a temperate climate, this lower SHGC is undesirable because it means you’re still getting some unwanted solar heat gain.

The only climate where a hard coat low-e glass may be useful is where it is frigid most of the year and cool the rest. In this situation, the lower SHGC, would allow some of the sun’s heat energy to come in, rather than reflecting it back.

Soft coat low-emissivity glass is made differently and performs better. This low-e coating is applied at a separate facility after the glass has been manufactured and cut. It’s a softer coating because it isn’t fused to the glass before it has a chance to cool. The result is a lower emissivity and the best possible thermal insulation for both hot and moderate climates. Most of the low-e glass used today is soft coat low-e glass.

Hard Coat Low-E Glass Soft Coat Low-E Glass

Page 10 HOW MUCH DOES LOW-E GLASS COST?

When you get double glazed windows, ultimately the price of your windows depends on the type of glass used in order to achieve the desired performance.

For example

You may use thicker glass or acoustic glass to reduce noise, or a special security glass if you wanted to make it one step closer to impossible for anyone, or anything, to break the glass.

Whilst standard double glazed windows offer better insulation than a single glaze because of the air space as well as the insulation from two panes of glass, using one piece of low-e glass within an IGU enhances the window’s insulating impact by 40%.

To upgrade with low-e glass and get a dramatic increase in insulation and energy efficiency, it will cost, on average, from 8% to 12% more over the whole retrofitjob. Because you get a huge jump in benefits for a small increase in price, most consumers choose to use low-e glass when they have their windows double glazed.

Page 11 ARGON GAS FOR EVEN BETTER RESULTS

Are retrofit double glazed windows with low-e glass the best you can do for thermal insulation?

Depending on how much of a difference you are looking for, you can enhance your IGU even further. You can have argon gas added to the air space and achieve even better insulation.

Argon gas is an inert gas. The reason it boosts the insulation of your double glazing is that it is harder for heat to transfer through argon gas than through the dehydrated air. Argon’s is about one-third lower than air.

This small change will boost the insulating power of your standard double glazed windows by approximately another 9%. So, with low-e and argon gas, you get close to a 50% improvement in the insulating power of your double glazed windows. Imagine what that will do to your heating and cooling costs.

Heat Loss Reduction or Heat Gain Reduction

Page 12 WHAT YOU NEED TO KNOW ABOUT DRAFT SEALS

Even with a professional double glazing job, a low-e coating and an air gap filled with heavier-than-air argon gas, you could still have cool air coming in, or moving out. If you’re still getting a draft because your windows weren’t properly sealed, a lot of the effort and money you put into upgrading is going out the window.

Draft seals are essential for stopping any cold air from getting in and warm air from leaking out. The problem is, some double glazing installers don’t automatically install seals. If they do, they may just attach them to the window, which isn’t that effective.

The Thermawood process always includes draft seals. They aren’t simply slapped on, however. They are machined right into the window before the retrofitting, and function seamlessly as part of the window. Even with older windows and different types of windows, such as double hung, casement and awning windows, our experienced installers use a specific process for each type to make sure the seals are machined in.

When your Thermawood window installer comes to your property for your consultation, they will assess other issues for your property, such as acoustic performance. If noise is an issue in addition to thermal insulation, Thermawood will machine in special seals for both drafts and acoustic performance.

This tailored, highly detailed approach is what creates fantastic results. A comfortable home, warm when it’s cold outside and cool in the summer and in tropical climates, all without forcing you to ever have to blast your heating or cooling systems. In fact, you’ll be pleasantly surprised by how many days you don’t have to use your heat and air conditioning system at all.

Page 13 INSULATING WINDOWS FOR HERITAGE BUILDINGS

With Thermawood retrofit double glazing, you can get these results with heritage listed buildings.

Remember with retrofitting you keep your existing timber windows. There’s no ripping out part of the building’s structure and fitting in a new PVC or aluminium window. This means, you get to retain the original aesthetic of your window as well as the functionality of your original heritage windows.

For classic period homes and any older building, let alone a new property constructed with attractive wooden windows, this is a huge advantage as you don’t have to sacrifice charm and character in order to bring your windows up to speed with 21st century performance. But, you enhance the value of your property.

Because our entire system is revolved around sustainability and longevity, Thermawood retrofit double glazing is ideal for heritage buildings and homes. From ensuring our beads are on the same angle and sit in the same place as the existing heritage window, to working to retain every nuance of the original character. Thermawood is working with Heritage architects and councils to educate heritage property owners that what we do can be done.

Page 14 EXPERIENCING THE DIFFERENCE

When you add up the energy savings, the property value increase and the personal benefits, never suffering through another sweltering summer or chilly winter again never sounded so practical and achievable!

Beautiful windows plus optimised thermal insulation at a fraction of the cost of having your existing windows double glazed by Thermawood. Thousands of home owners across New Zealand and Australia are getting their windows retrofitted and enjoying the experience of modern, efficient comfort.

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