windows Archives - AE Building Systems

The Yeti is in the Details: Window Spacers

You may have heard the devil is in the details, but when it comes to ice buildup on a cold window, we know it’s probably more fitting for the abominable snowman. Have you ever wondered why ice forms around the edges of your windows on a cold day first? You may look at a window and not even realize the spacer inside of the window is playing such a large role. The spacer is the thermal bridge in the insulated glazing unit (IGU) and overall window, and therefore, the material choice for this often overlooked part is extremely important.

What Role Does a Window Spacer Play?

A spacer is the piece within the IGU that holds the panes of glass apart from each other. A double-pane window will have just one spacer between the two panes of glass, while a triple-pane window has two spacers. There are even quad-pane windows that will have three spacers with four panes of glass. The window spacer should be analyzed in order to prevent condensation (or ice) from forming on the edge of the glass, as well as decrease in performance of the window or door.

The Weak Link: Window Spacer

Window spacers are the thermal bridge between the glazing and the rest of the window. While it may seem like a small, insignificant part, it can be a weak link in the overall window design. In the past, lower-cost windows have used aluminum or galvanized steel spacers as these are relatively inexpensive, but if you think about how metal feels in the cold temperatures, you can easily see how these materials aren’t helping with insulation! Surprisingly, these materials are still very prevalent in low-cost window brands today. So, while you may get a better deal upfront, you end up paying more in the long run with higher energy bills.

A Stronger Option: Warm Edge Spacer

A smarter window choice will utilize a better insulating material for window spacers. Thermally-broken spacers are often referred to as “warm edge spacers.” Our friends at Alpen use a product referred to as a “super spacer,” which is a composite material with enhanced condensation resistance compared to the more traditional metal spacer. These include edge-seal durability, superior argon gas retention, and low conductivity. They use high-quality silicone and a highly breathable flexible foam matrix to improve performance. We’ve done a quick demo showing the difference between a metal spacer and these composite options that explains the difference in a simple manner.

If you’re looking for an energy-efficient window choice, you can be as educated as possible on the various spots where thermal bridging can occur within your window. It pays to get some broad information about the products you are considering so you can compare what one brand says compared to others. Pay attention to what brands aren’t talking about too! The best way to know what they’re not telling you about is to talk to a few different competitors, or talk to energy nerds like us at AE Building Systems who can break down all the various things to be watching out for if your goal is to get an energy-efficient window option.

When it comes to energy-efficiency, sometimes the smallest part of a design can have a BIG impact. That’s the case when it comes to window spacers and why we’re so passionate about the tiny details in the products we carry at AE Building Systems. We’re all about providing products that have the same passion for quality and energy-efficiency. It’s core to who we are and how we do business!

Options for Large Windows in High Wind Load Areas

“It is the great north wind that made the Vikings.” – Scandinavian Proverb

If the great north wind helped make the epic, strong Vikings, it’s no wonder that the wind impacts some of the recent innovations to create better, stronger construction practices! We’re seeing it happen day in and day out with new approaches for fenestration – windows and doors.

The Challenge

Homeowners increasingly want larger and larger expanses of glass in their homes. At the same time, municipalities, including Boulder, CO, have realized that due to climate change, wind speeds have increased. As a result, Building Departments have increased the required Design Pressure (DP) ratings for windows and doors. The DP rating represents a building component’s ability to withstand a given amount of wind load.

And the challenge is not simple because the wind loads vary based on numerous things including: is the component closer to the edge of a wall or higher up on the building – e.g. multi-story buildings. In short, wind loads are a bit of a moving target across the building facade.

Additional Challenges

With large glazing assemblies, often windows are mulled together creating hinge points which are weak points in the window assembly. Also, as the size of the assembly increases, the DP rating generally suffers – decreases. There are ways to increase the strength and DP rating of window assemblies which include adding structural mullions, thicker glass, and/or frame reinforcements. However, these methods help only so much and eventually additional approaches must be considered – especially since homeowners are increasingly requesting entire window walls. The question becomes … How do we create a window wall with high performance and well insulated assemblies without having to use generally lower performance, more costly, commercial focused, structural storefront, curtain wall and ribbon window technologies?

Consider Steel Tube, LVL or Lumber posts between the windows and doors

While we are not structural engineers here at AE Building Systems, we have been able to help our customers manage the new DP rating requirements necessary for code by suggesting solutions like leveraging steel tube, LVL, or lumber posts at the breaks in the window assemblies. You might think that it’s going to greatly reduce the performance due to thermal bridging and you’re right. Insulating those posts is critical.

Overview of the Steel Tube/LVL/Lumber Assembly:

Insulate Strategically

Good design that withstands higher wind loads is possible with this steel tube/LVL/Lumber window surround or vertical posts. In the assembly diagrammed below, double LVL’s are used and then insulated with a block of insulation. The insulation is then wrapped in break metal. While a double 2x could also be used, LVLs and steel tube are stronger and more dimensionally stable than say a double 2×4. The use of steel tube and LVL helps minimize the bulkiness/width of sight lines, and these are done on the vertical as vertical posts. Keep in mind that windows at the edge of walls or near corners typically have higher DP or wind-load requirements than those in the center of the wall. Also keep in mind that the width of the steel tube or LVL is an important consideration as ideally the window screw flange (often referred to as nail fin) doesn’t overlap.

Especially if you use the steel tube option, you will have significant thermal bridging, so it’s vital to insulate strategically. The image above shows a fairly small thermal break proud (to the bottom) of the LVLs. We would suggest a deeper block of insulation and then the brake metal wrap should be designed accordingly. Some builders have used fairly thick blocks of insulation outboard of the LVLs or steel tube – e.g. 3” of foam. As mentioned above, you generally do not want to overlap the screw flanges (nail fins). One option might include increasing the RO just enough to accommodate the flanges without overlapping them.

Benefits:

Large assemblies or even “window walls” using this vertical post approach are possible and meet the wind-load requirements.
Steel Tubes and LVLs can help reduce the bulkiness of vertical posts.
Vertical posts can help reduce the required header size generally required for large expanses of glass.
Allows for more design freedom to build creative elements into the design of the home, while still sticking within code parameters.
Allows for smaller glazing assemblies which can more readily be transported without heavy equipment, reducing cost.

Cons:

Requires insulation as the use of the steel tube or heavy lumber can be a significant source of energy loss. It is critical that the design includes an insulation component, and more is better.
This assembly can be more costly and require more labor to build.

If you find yourself working on a project with tight constraints around wind-load parameters, consider an approach like this. Our team is more than happy to talk through how this works in real life and what considerations you may want to have as you design out this assembly!

Disclaimer: Please consult your structural engineer when using these concepts.

Hottest High-Performance Topics from 2022

A quick reflection on high-performance principles discussed in 2022

As we wind down the year, the data nerds in us wanted to see which AE blog post topics resonated most in 2022. After reviewing our performance stats, here’s what we discovered and are now labeling “hottest high-performance topics from 2022.”

Here’s what this tells us, there is an appetite for understanding the building envelope and airtightness, energy-efficient windows are important to the overall project, and there is an increased awareness for Passive House Practices.

1. Debunking the Myth that Insulation is ALWAYS Better Than Glazing for Thermal Performance

The immediate place our minds go when it comes to improving the performance of a wall is to insulate. That seems to be the easiest and simplest approach to improving performance and energy efficiency. But, what if we told you the glazing is where you really get the bigger bang for your buck? Would you be surprised?

Most people are, and note we are assuming more standard residential construction, and assumptions include 2X framing and batt insulation. Construction with steel studs, concrete, continuous insulation, thermal bridging, etc., alter the results in different ways.

A window is essentially a thermal “hole in the dike,” and insulation in walls above certain R-Values becomes less and less helpful when looking at the overall performance of the wall – window included.

Okay, so we can all get behind the idea that insulation in the walls is a good thing, and surely it’s effective for energy-efficiency. Is it not a pretty bold statement to say that glazing is MORE effective?

While it feels counterintuitive, going for the high-performing windows actually moves the needle further than beefing up insulation in the wall itself. Read more about how we debunk the myth and prove the math.

Plus, watch this video by Todd, going into more detail on frame types, triple vs. quad panes, spacer options, and gas types.

2. Anatomy of a Window: Basics for High-Performance Windows

It’s time to get up close and personal with windows! We usually just focus on the scene we can see through the window, but what looks so simple can actually be very complex.

There are 3 main sections to the overall anatomy of a window:

Frames
Spacers
Glass

While we often focus on the stunning view through the glass—understanding ALL parts of the window is vital for overall performance and ultimately providing better thermal performance for any house. Continue over to the full blog post for more on the anatomy and the most common options for residential window glass.

3. Collins-Ruddy Residence Part I (retrofit)

We explored how our very own Todd Collins retrofitted his home.

The Collins-Ruddy Residence is probably much like your own home: it wasn’t built from scratch with Passive Haus/energy-efficiency in mind. So many homeowners buy a home that meets other needs but often doesn’t tick the box of efficiency. And so, we enter a retrofit situation!

The Collins-Ruddy Residence is a 1971 tri-level home with a basement (four levels in total) with 2×4 construction, and fiberglass batt insulation. The home had the original single-pane aluminum frame windows replaced, but they were still lower-performance windows. The house has forced air heat with a gas furnace, and a gas hot water heater as well. The house also came with a programmable thermostat, a reasonably new range with a convection oven, an electric resistance cooktop, and an old Montgomery Ward Fridge.

The Collins-Ruddy family keeps the thermostat roughly at 68 degrees F in evenings and mornings, and 60 degrees F at night and when not occupied. Read the full post to see what went into phase one of Todd’s energy retrofit.

Get a tour of Todd’s house and progress in this video.

The team at AE Building Systems sends out a monthly newsletter with Passive House and high-performance building insights—have you subscribed? We wish all our clients, colleagues and industry friends a wonderful New Year; see you in 2023.

Anatomy of a Window: Basics for High-Performance Windows

It’s time to get up close and personal with windows! We usually just focus on the scene we can see through the window, but what looks so simple can actually be very complex.

There are three main sections to the overall anatomy of a window: frames, spacers, and glass. While we often focus on the shiny, pristine look of the clear glass, we understand that ALL parts of the window are vital for overall performance and ultimately providing better thermal performance for any house.

Window Frames:

We often focus on the glass performance, but the frames are quite literally what holds so much integrity for the window performance. Not only do they offer structural support, but they are huge opportunities to preserve energy efficiency. Most companies don’t insulate the frames, but high-performance manufacturers will use various types of insulation. These can vary from EPS, wood fiber, and Polyurethane.

At AE Building Systems, we’re big fans of:

Tyrol, Tyrol PH+ Windows, with either EPS or Graphite for insulating support
Zenith Windows (with Polyurethane), which offers higher insulation value per inch
Smartwin by Advantage offers wood fiber and XPS insulation options
Advantage Mira, not insulated much, as it’s made of mainly wood (R-1 per inch)

Window Spacers:

Spacers are a vital part of every window’s anatomy and help provide structural integrity of the glazing unit while promoting a thermal and moisture seal. Spacers are usually made with either aluminum, steel, stainless steel, warm-edge, or composite. When a high-quality spacer is used along with gas filling and low-e-coated glass, the overall energy-efficiency of the window is improved.

Window Glass:

Simplicity is the ultimate sophistication. – Leonardo Da Vinci

While it may look like just a simple, clear pane you look through, what’s going on is actually pretty sophisticated. There are so many factors to think of when it comes to insulated glass. Insulated glass is insulated with gas, such as Argon or Krypton, and the cost for these gasses varies based on the current market price. Elevation also plays a factor in expansion levels for gas, and with our team based in Colorado, we are highly aware of ensuring that windows are manufactured appropriately based on the elevation they will be used at. To quote our friend Leonardo, insulated glass is highly sophisticated, but can appear so simple to the untrained eye!

Below are some of the most common options for residential window glass:

Double-Pane Windows:

A double-pane window has two panes of glass set into each window frame. The two glass panes have a small space between them, which creates an air pocket to provide a small level of insulation. If you’ve ever felt a single-pane window on an antique window or in an older home, you know that there’s minimal insulation and the glass is going to be very cold or very hot depending on the season. However, many homes historically have leaned toward double-pane windows, which will still be warm or cool to the touch, but not as drastic. While more cost-effective upfront, double-pane windows can cost you more in the long run as they aren’t nearly as efficient for insulation and energy transfer as other options available today.

Euro Triple-Pane Windows:

European windows are well known for their high energy efficiency. Their design allows less heat to pass through from your house when it is cold outside. Triple-pane windows are better thermally because of the added pocket depth for argon gas between the window panes. They ultimately have the potential to reduce energy costs, reduce noise, increase comfort, and even reduce the size and wear on HVAC equipment.

Quad-Pane Windows:

Quadruple Pane Windows, or Quad Glazed Windows, include four high-performance layers of glass with three gas-filled sealed air spaces in between. With an added pane of glass, they are a solid solution in terms of insulation, heat transfer, and other aspects as well. Think of all the benefits of double-pane and triple-pane windows but with an additional pane. Of course, any time you add material, you add weight, cost, and complexity. For many residential situations, triple-pane ends up being the nice winner for an all-around solution that supports energy-efficiency, more common construction practices, and construction budgets.

Thin Glass vs. Thin Film Windows

Thin Glass and Thin Film are like cousins, who are similar, but just not completely the same product. They also are very similar to triple-pane windows in a high-level concept. Thin Film has been Alpen’s go-to for many, many years, and will still be available for many of their lines, such as Zenith and Tyrol. However, Alpen recently released Thin Glass, which acts like a triple-pane window at a double-pane’s weight. Of course, it’s much more complex than that. You can read up on more of the details to these innovative options here, where we break down how they’re similar and how they differ.

Innie vs. Outie Window Construction

In construction, this great debate has been going on for some years and it can be confusing to know what the right solution is for your project. Each style has been used in various ways over the years, but if you’re like us and are concerned about thermal performance and energy savings, you will want to read our detailed blog.

Windows are one of the most important features in a home, especially if you love where you live (like we do here in Colorado)! You want to let the local scenery and the sunshine in, but you also don’t want to sacrifice thermal efficiency. That’s why it’s so important to get the window purchase right when you’re building or upgrading a home. Some window options will be better for you than others and that’s where our team is here to help! Let us help you find the best high-performance window to meet your needs. We’re here to answer any and all questions; email info@aebuildingsystems.com.

High-Performance Windows & Air Infiltration

Generally speaking, windows are the weakest link in our building envelopes. When evaluating windows, often the insulative specifications (R-value / U-factor) are the primary focus. Just as important are the air infiltration rates. Code-built homes often lose 20 to 40% of the heat in the home through air infiltration. Windows and doors are a significant source of this heat loss.

For windows and doors, air infiltration is defined as a volume of air (cubic feet per minute) divided by the window area (in square feet) when subjected to a 25mph wind (blowing perpendicular to the window) – Cubic feet per minute per square foot at 25mph windspeed. As of 2017, window manufacturers were only required to report air infiltration numbers if the windows were to be labeled Energy Star.

An Energy Star Compliant window allows air infiltration to be as high as 0.30 cfm/sq ft

Now some quick math for a 10sqft window:

0.30cfm/sqft x 10sqft = 3.0cfm total air infiltration allowed.

To think about this another way: A basketball has a volume of 0.26 cubic feet.

3.0cfm / .26 cubic feet = 11.5 basketballs per minute or 690 basketballs per hour from a single window. Imagine how much air this equals for a typical home of many windows.

Now let’s compare an Advantage or Alpen High-Performance windows to an Energy Star compliant unit:

While we can’t prevent a basketball from being thrown through a window, let’s talk about how Advantage and Alpen prevent these air infiltration “basketballs”.

Gaskets & Seals – While fixed units have the best infiltration rates, operable units must also be considered. Any sliding window uses a friction type gasket material to seal the window for air and weather. Over time this material can break down and will not perform as well as a compression seal. Consider awnings, casements, and tilt-turns which use compression seals rather than hung or sliders that use a friction type gasket. We always recommend against sliders and hungs and for fixed, casements, awnings, and tilt-turns.
Hardware – Consider the window hardware used to seal the windows. With a friction fit, there isn’t a practical way to better seal a window other than applying slight pressure or replacing the weatherstripping. With a compression style, minor hardware adjustments can be made to place more or less pressure on the seals, and while weatherstripping can be replaced, typically minor adjustments are all that is required to achieve an excellent air seal.

High-Performance windows help create comfortable, quiet, high-performing homes conserving energy for future generations. We are burning through our fossil fuel resources rapidly and bad windows and doors are a primary source of wasted energy use. If you have any questions about air infiltration or other aspects of high-performance windows, please call us at 720.287.4290 or send us an email. info@aebuildingsystems.com

Thermal Bridging and Issues with Windows

As a homeowner, heat loss is or should be a big concern. Energy escaping through the building envelope (walls, roof, floor) means more energy is required to maintain a consistent temperature or better said – comfort -within your home. It also means higher utility bills whether you’re building a new home or looking to refurbish an existing home. One of the most significant considerations should be how to make your home more comfortable but also more energy-efficient – less costly to operate. Which leads us to the topic of Thermal Bridging!

What is thermal bridging?

In a heating climate and similar to air infiltration, thermal bridging results in heat loss and occurs when heat escapes from the inside of the building to the outside, via conduction and through the building envelope. If you’ve ever been in a house that has a “drafty” spot or just constantly feels cold, that’s likely the result of thermal bridging as much as or even more than air infiltration. Even airtight homes can have a heat-losses of 20 to 50 percent due to thermal bridges.

Types of Thermal Bridges

There are several types of thermal bridges that designers, builders, and homeowners should be aware of and the following are three common types:

Repeating or Systematic thermal bridges: A common cause of heat loss are repeating thermal bridges which are predictably found inconsistent breaks in the thermal envelope allowing heat to pass through easily. It’s important to keep these in mind during a building’s design. Common Examples include wood and steel studs, steel wall ties, ceiling joists, and insulated suspended floor joists.
Non-repeating thermal bridges: This method of heat loss doesn’t follow a pattern in the way that repeating thermal bridges do. A non-repeating thermal bridge tends to pop up in specific areas impacted by an interruption or break in the construction. Common culprits include things that penetrate the thermal envelope to include windows and doors, structural beams, pipes and cables, and cantilevers.
Geometrical Thermal bridges: Generally found where the building envelope changes directions and where the materials meet, Geometric thermal bridge examples include wall corners, wall to roof and floor junctions. The more complex a building design is, the more geometric thermal bridging will be prevalent.

Regardless of the source, avoiding thermal bridges wherever possible is essential – and knowing where your home is losing heat can help you take the proper measures needed to reduce the problem.

Thermal Bridging and Windows

Often, it is windows that are a major culprit when it comes to heat loss and thermal bridging in the home. Standard or code minimum windows often represent a compromise. “We” accept their lower thermal performance because we enjoy the view, natural light, and ventilation they provide. However, when adding high-performance windows with higher R-values (lower U-values), windows become less of a concern for thermal bridging, especially when properly installed.

In an existing home, an expert can determine the state of a home’s windows by doing an inspection. They know what to look for in terms of damage, deterioration, and condition. Knowing a window’s age is a big help as well. Most older windows did not have high-performance glazing nor did manufacturers generally consider thermal bridging in the frames and spacers.

With new construction or existing homes, to reach your energy and comfort goals, it is important to consider high-performance windows. The thermal image below shows the thermal bridging – shown in blue/purple. This is likely why you have seen condensation on windows.

This image below shows the thermal bridging – shown in blue/purple. — The magic of thermal imaging!

Note also high-performance windows help with other variables to include sound attenuation. They reduce the sound coming from the busy street in front of your house for example.

Thermal Bridging Results in Condensation – and Mold

Four variables come into play with condensation: outdoor temperature, indoor temperature, your home’s humidity level, and the indoor surface temperature of an exterior building envelope component. Since outdoor temperatures are not something we have control over, we focus on what is in our control. Windows that have well-insulated frames, multi-panes of gas-filled glass and have higher performance spacers will help increase the interior surface temperature of the windows. Higher interior surface temperatures help to effectively prevent the condensation of moisture on your windows preventing mold from growing. This subsequently improves your air quality. We would be remiss if we didn’t also mention the importance of ventilation systems which improves indoor air quality.

Check out this SIGA Fentrim F for preventing condensation

How To Prevent Window Thermal Bridging

Glass: Pursue options that included triple or even quad glazing.
Gas: Gas filled glazing is no joke. Argon gas is cost effective and provides a good boost in performance over air-filled units. Krypton gas, while more costly, provides an excellent increase to performance.
Frames: Select frames made of low conductive materials. Aluminum frames without thermal breaks are a complete no-no for energy efficiency and comfort. Aluminum is a tremendous conductor of heat. Better options are wood, fiberglass, and PVC with insulating air chambers. These frames are even better if they are insulated. Note, thermally broken aluminum is a good option depending on how good the thermal break is.
Spacers: Selecting windows with better spacers can help prevent thermal bridging in the windows as well. These spacers separate the panes of glass and appear where there are divided lights. Avoiding spacers made of aluminum and steel, and selecting stainless steel and various composite materials are much better options. Warm Edge, Super Spacer, and Swiss Spacer are some of the composite spacers that are available.
Installation: Proper window installation including air sealing and insulation around the windows will significantly reduce the amount of energy loss. To reduce thermal bridging around windows, Thermal Buck is a great product for the installation.

Final Thoughts

Bringing awareness of thermal bridging to all of your construction partners will aid in your goal. An architect can design to minimize thermal bridges. By not paying attention to the details on the construction site or if there is a lack of training, reaching your goals will be difficult.

If you’re looking for ways to minimize thermal bridges and select high-performance windows for your project, contact us today.

What Are Construction Thermal Bridges in Buildings?

Do you have a random “cold spot” in your dining room or perhaps in an area where a sweater is always needed, no matter how high the thermostat is set? Thermal bridges may be at play.

If you don’t work in or around construction, you may have never heard the term “thermal bridging”–but you’ve likely felt its effects. In a nutshell, it’s the movement of heat across an object that is more conductive than the materials around it.

Thermal bridging not only causes a loss of heat within the space, it can also cause the warm air inside to cool down. As we approach the coldest season of the year, this means higher utility costs and potentially uncomfortable shifts in temperature inside your home or building.

Keep reading to find out exactly how thermal bridging works and what you can do to stop it:

What is thermal bridging?

When heat attempts to escape a room, it follows the path of least resistance. Likewise, the same process occurs during the summer, only in reverse, allowing heat to enter your otherwise cool building.

Thermal bridging happens when a more conductive material allows an easy pathway for heat flow–usually where there is a break in (or penetration of) the insulation. Some common locations include:

The junctions between the wall and the floor, roof, or doors and windows.
The junction between the building and the deck or patio
Penetrations in the building envelope to include pipes or cables
Wood, steel, or concrete envelope components such as foundations, studs, and joists
Recessed lighting
Window and door frames
Areas with gaps in insulation

Impacts and risks assumed due to thermal bridging

What does all of this mean for you? In addition to poor climate control, there are several other lesser-known (but still serious) effects caused by thermal bridging.

Thermal bridges can increase the risk of condensation on internal surfaces, and also cause condensation within the walls. Both can lead to mold growth, which in turn can cause unpleasant odors, poor air quality, and most importantly long-term health problems. Additionally, unchecked condensation may eventually cause rot and structural damage.

Thermal Bridging in windows

Thermal bridging can have a significant effect on the energy efficiency of windows. The frames and spacers are the primary culprits. Spacers are the, typically metal, “strip” that goes between and separates the glass on double and triple pane windows. Different materials have different conductivity and impact the performance of the windows differently. Condensation on a double pane window is generally due to the spacers.

With retrofit situations, knowing exactly how old a window is, as well as the component materials, can provide you with a general idea of its efficacy. Unfortunately, if your windows are rather dated or just poorly made, it is nearly impossible to add thermal breaks into an existing framing system.

Issues with roofs and foundations

By their very nature, roofs and foundations present a large number of challenges in terms of maintaining a thermal boundary. Drains, vents, and holes for pipes and wires (amongst other things) create unavoidable penetrations in the building envelope and insulation. Heat transfers from the building into the ground or from the building into the air are often inevitable, though they can be minimized.

Strategies and methods to reduce thermal bridges in buildings

Bottom line? In new construction, design it right which a whole topic in itself. With existing homes, if you suspect there is thermal bridging occurring in your space, you need to eliminate or reduce the effects as much as possible.

Proper planning, design, and construction can help remedy thermal bridges in new structures. However, if you live in an older home, there are still steps you could take. These strategies include:

Performing an energy audit to identify thermal bridges in your home
Installing double or triple pane windows with argon or krypton gas, better spacers and insulated frames
Updating and/or adding insulation to your home – ideally adding a continuous insulation layer.
Installing storm doors (especially if you have metal doors)
The ultimate remedy is to complete a deep energy retrofit that addresses everything and more than mentioned in this blog

Studies show that in an otherwise airtight and insulated home, thermal bridges can account for a heat loss of up to 30%. Whether you’re building a new home or retrofitting an existing structure, care should be taken to avoid unnecessary breaks or penetrations so that the possibility of thermal bridging decreases.

If you’re looking for ways to minimize thermal bridges in your next project or existing home, contact us today.

Dive into our other blogs on thermal bridging:

» Thermal Bridging and Issues with Windows

» Thermal Bridging in Roofs and Framing

» Thermal Bridging in Foundations and Footers

» Thermal Bridging and Decks, Cantilevers, and Balconies

High-Performance Windows

If eyes are the windows of the soul, then windows are the eyes of the energy-efficient home.

Generally, windows are the weak link in the walls of a home. “I love putting plastic on my windows to keep cold air out and warm air in,” said no one ever. That is why considering the brand and style of the windows in a home is just as important as deciding insulation and exterior materials.

The goal is comfort and operational cost saving, and the goal for builders and architects is providing both.

High performance windows are necessary in keeping with Passive Haus standards of efficiency: design, minimal thermal bridging, air tight, super insulated, optimized glazing, energy recovery ventilation and passive gains.

So we have learned that code built homes often lose 20 to 40% of the heat in the home through air infiltration, and windows and doors are a significant source of this heat loss.

To better grasp just how significant, imagine the volume of a basketball as our measure of air infiltration. According to the National Fenestration Ratings Council (NFRC), the maximum allowable air infiltration in a window, with the outside wind at 25 mph, is 0.3 CFM (cubic feet of air)/sq. ft. Air infiltration for a 10 sq. ft. standard window at the allowable maximum is 3.0 CFM or 11.4 basketballs per minute. At sixty minutes, one window allows in 684 basketballs per hour.

If you have (30) 10 sq. ft. windows, that equals 342 basketballs per minute or 20,520 basketballs per hour. That is a substantial amount of heat loss.

How do we reduce the basketballs?

Consider installing Alpen or Advantage Woodwork High-Performance windows. With a high-performance window, air infiltration at a 25 mph wind is <= 0.01 – 0.05 CFM (cubic feet of air). A 10 sq. ft. high performance window is at 0.10 CFM or .38 basketballs per minute or 22.8 basketballs per hour.

Therefore, (30) 10 sq. ft. windows equals 11.4 basketballs per minute or 684 basketballs per hour. We just went from 20,520 to 684 basketballs per hour. To summarize, that’s approximately a 97% reduction of air infiltration from what the NFRC says is acceptable.

The bad news is loss of air through a structure’s windows is like opening the windows and tossing our hard-earned money out of them. The good news is high performance windows fixes that problem.

The overall quality and performance of windows like Alpen or Advantage High-Performance windows is also superior. What makes these windows even more unique are their individual components, designed to combat heat losses (winter) and gains (summer):

Frames – High performance windows have durable, low conductivity frames which generally include insulation. These frames offer better thermal performance. The R-value of most standard frames is r-2 to r-3.5. High performance window frames are r-4 and up to r-7, 8, and 9.
Seals – High performance windows generally have multiple seals, which promote not only weather tight but also air tight seals.
Glazing – IGUs (insulating glass units). Glazing can have double, triple and even quad glass. High performance IGUs have special coatings that high performance window manufacturers leverage to optimize heat gain from the sun in colder months and reduce heat gain and over-heating in the warmer months.
Spacers – Depending on the material used, the spacers in between the IGUs can help increase the interior surface temperature of a window up to 15 degrees. For example, a galvanized steel spacer in a fixed high profile Alpen 525 window is rated R-5.9, whereas a stainless-steel spacer in a fixed high profile Alpen 625 window is R-6.7. Also, high performance window spacers reduce condensation on the edge of the glass (which reduces opportunity for mold and rot) and increases the inside glass surface temperatures, therefore improving comfort.
Gas – There is “gas between the glass,” as it is denser than air and a reliable barrier to heat loss. Argon or Krypton gases are often used. Argon is much less costly, but Krypton increases performance and is often used in Passive House projects.

While ROI (return on investment) is important, comfort and unnecessary energy use are the primary reasons people pursue high performance windows.

High-Performance Windows help create high performance homes which conserve energy for future generations. We are “burning” through our energy resources (coal and oil) rapidly. Why not own a comfortable, energy efficient home that is also super quiet and will likely last much longer than your neighbor’s home? And … let’s conserve our resources for future generations.

Please do not hesitate to call us at 720.287.4290 to learn more.