Furnace Retrofit for All-Around Comfort

Furnace Retrofit for All-Around Comfort

Welcome back to the Collins/Ruddy Residence, where our very own Todd Collins and his family have been overhauling their entire tri-level home! Some of us have the opportunity to build our dream home from scratch and give it all the sustainable features we want. But for most, we find ourselves retrofitting an older home that may have other less-sustainable features and designs than we might have chosen if building a new house. That’s exactly where Todd and his family found themselves in the home they love in Golden, Colorado. 

They’ve done a ton to the house already, from improving insulation, installing more efficient windows and doors, and breaking from their reliance on natural gas. Today, we dive into how they’ve retrofitted their furnace and how they heat their home.

The Big Switch!

The Collins/Ruddy Residence replaced the furnace with a Mitsubishi heat pump condenser and whole-house indoor air handler, which allowed them to use their existing ducting for the most part while also going electric. As part of this new setup, they placed the exterior compressor on the south side of the home to increase efficiency in the warmer parts of the day. They also went with an electric heat pump, eliminating their need for natural gas. They went with a 36 kBTU unit which allows for variable speed and it runs as hard as it needs to. As a result of this new setup, the house also required some new ducting in the family room to eliminate(disconnect) sub-slab ineffective ducts. 

The Collins/Ruddy Family worked with Bill Lucas to help them with this new setup and installation. That is partially because Bill is big on recycling as many of the older unit components as possible to prevent them from going into a landfill.

Improved Air Filters

Traditional furnace filters are generally 1” thick MERV 8. Todd and his family went with a MERV 11 filter to improve their indoor air quality (IAQ), which has more of a curtain style shape and is 4” thick. These don’t need to be changed as frequently as the traditional smaller filters and provide greater filtration without impacting air flow as some standard sized (1”) high MERV filters do.

Benefits All Around:

  • Improved Air Quality: With this new heat pump, they can leverage a more efficient air filter, increasing their indoor air quality and efficiency of their unit. 
  • Electric-Only, allowing for more sustainable energy sources and lower energy bills. This will also help the homeowner go Net Zero in the future.
  • Sound! The new internal heat pump is extremely quiet where all you can hear is the air flowing compared to a traditional fan/motor that was noisy whenever it was operating. 
  • Air Conditioning: This new unit includes both air conditioning and heat in one device, meaning that the family could get rid of the older traditional air conditioning unit that had sat near their patio. Now on a summer day, they can enjoy their quiet patio instead of hearing the noisy air conditioning unit. 


  • Time: Due to the variable speed on the unit, it doesn’t go into the highest fan speed often. Instead, it runs at a lower level to heat the house and as a result, it can take a little longer to get the house up to the desired temperature. 
  • Different: You might be thinking this all sounds different from anything you’ve ever seen in a house visit or home inspection. Very few homes pursue this kind of transformation to where you’re ready to ask your gas company to permanently cap the meter. As a result, sometimes you come across scenarios where contractors don’t understand what you’re doing, or even energy companies don’t understand what you’re doing. For example, Xcel Energy still charges a “connection fee” until you officially cap off the connection to the meter. There are small things to ask questions around when you’re working with third parties like energy companies. Since you’re going a little off the beaten path, you have to be an advocate for yourself in the project. 

The switch to this Mitsubishi whole-house heat pump has been a game-changing move for the Collins/Ruddy family. It’s allowed them to achieve their goal of capping their gas connection to the entire house, while also improving air quality. Retrofitting a home is never an easy task, but it can be extremely rewarding when you see the amazing benefits and overall performance that accompany decisions like these! 

Goodbye Gas Line: How the Collins-Ruddy Residence Reduced Their Reliance on Natural Gas

Join us today as we dive into another big update for the Collins-Ruddy residence. Todd Collins and his family have been on a multi-phased journey to retrofit their existing home in Golden, Colorado. They’re on a journey to become as close to net zero as possible, while still maintaining a comfortable environment to live in. Their most recent phase featured literally capping their gas line after replacing their water heater and furnace. Today, we want to take a closer look at the water heater, what drove their decisions, how they approached the update, and how it’s working so far. 

Why Cut the Gas to Your House?

One of their family’s goals was to get to net zero, so they knew cutting out natural gas was eventually in the cards. They have a desire to reduce greenhouse gas emissions and fossil fuel consumption as part of their core values. That meant eliminating all combustion appliances, including their water heater. Eliminating gas reliance makes for a healthier, safer environment, while also removing the variable of fluctuating natural gas prices on their monthly bills. Electric appliances don’t carry risks of carbon monoxide poisoning nor health risks of VOC’s from burning natural gas.  Without gas entering the house, there is now no need for even carbon monoxide detectors.

Also, natural gas prices increased significantly during the last two winters, and now the Collins-Ruddy residence is not at the mercy of global demand for natural gas. Instead, they are more reliant on their own solar production of electricity as well as the more local costs for on-grid electricity. All in all, there was a compelling argument to kick that water heater to the curb! 

Timing These Heat Pump Upgrades

Their water heater was already approaching its end of life, so part of the timing here was strategic. They wanted to be prepared, rather than be dealing with an emergency situation. The old water heater was manufactured in 2005, making it roughly 18 years old. They knew it could peter out at any point leaving them stranded without hot water, which is no fun, and especially problematic in the winter months in Colorado. Better to replace in advance of a failure!

Strategically Shifting the Water Heater Location for Better Performance

One thing most people think about is replacing the appliance itself, but not many consider relocating the hot water heater to a more strategic location in the home to eliminate heat loss. In the Collins-Ruddy home, they relocated the tank directly below the kitchen and baths, reducing the length of pipes by about 20-25 feet. As a result, there is significantly less heat loss as the hot water travels from the tank to the faucets. In addition, rather than waiting 30-35 seconds for hot water at the kitchen sink, they now wait about 6 seconds with the new placement.

What Now? 

After ditching the 40 gallon gas-powered water heater, they switched to a 66 gallon A.O. Smith 66-gallon all-electric Heat Pump Water Heater. While it is larger, it is incredibly well insulated. Should the power go out, it only loses 1.5 degrees per day. As a whole, they’ve been extremely happy with the solution. However, Todd shared how the new water heater takes heat from the ambient air around the unit and puts that heat into the water. As a result, the area around the water heater is noticeably colder while it is running. While running, the air temperature can drop between three and five degrees fahrenheit. They’ve learned the goal is to run it low and slow and note that the recovery time depends on what mode you have it on. So far, their family with two teenagers and two adults has been able to operate well on the heat pump only mode and with this amount of hot water. (Of course, keep in mind they’ve already done some things to improve water efficiency in their home including low-flow faucets.) 

The update to the water heater was phase III of this multi-step approach to retrofitting their home in Colorado. The Collins-Ruddy residence still has a ways to go to get to net zero, but with each small step, they are improving the energy efficiency of their home while improving their own quality of life and well-being. We love the idea of building a passive house design from scratch, but that’s just not a reality for most homeowners. Most find themselves in a similar situation to Todd and his family, retrofitting an existing home to be more comfortable, more sustainable, and more efficient all around. 

Are you remodeling and want to geek out over how to make your own project more sustainable? Call up our team for a chat. We love sharing what’s working in our own homes, as well as those of our customers.
Did you catch the retrofit phase I and phase II? Read the full story!

Going Extinct: Saying Goodbye to Fossil Fuels and Hello to Net-Zero-Energy

Just like the dinosaurs, fossil fuels are going extinct in some communities! We’ve heard it mentioned for years, but many communities are starting to put policies in place to actually reduce the reliance on fossil fuels. Fossil fuel bans are showing up more and more in municipalities and communities around the United States and creating quite the buzz! 

The Fossil Fuel Ban Trend

Cities like Boston and Berkeley, have been more prominent in the news with new building codes to reduce natural gas infrastructure and the associated greenhouse gas emissions that come with fossil fuels. The city of Golden, Colorado is also actively building out new code regulations to reduce the reliance on fossil fuels to operate buildings. 

We’re also seeing sustainable communities on the rise where homeowners actively seek out a net-zero lifestyle. One example of this is the Geos Neighborhood in Arvada where the houses are built with net-zero energy. They are built to take advantage of solar energy, geothermal energy, and even goat energy (weed control!). They’ve shown that it can be done and done in a way that doesn’t hike up construction costs. 

The Challenge

Any change like this is set to ruffle a few feathers from those who are used to doing things the fossil fuel way. The shift toward sustainable industries has always received a fair amount of pushback from those in the fossil fuel industry, as well as those who simply don’t want a change. 

But there are some very real concerns with changing the game for building codes. First, in any of these towns and cities, you are faced with a transition and not a clean switch. You have decades of buildings running off of fossil fuels, so you have to account for the transition where you have both fossil fuels operating as well as cleaner energy, like electric, operating in the same neighborhood – a situation found nearly everywhere. Secondly, many land-locked towns that are largely developed already, like Golden, struggle with solar access. Many towns the size of Golden also struggle with the costs of making a change like this on a large scale. 

Then, you encounter scenarios where fossil fuels still are a dominant need.  Noting that Todd Collins is not a spokesperson for the City of Golden or the City’s Sustainability Board, Todd shares about Golden’s Sustainability Board’s assessment: “We also knew there were industrial, or process energy, situations that posed difficulties. So, we focused our attention on the buildings’ energy consumption- where energy is being used to operate the buildings (including lighting, plug loads, water heating, heating and cooling, etc.).” As a result, Golden is considering a more focused, prescriptive approach while getting immense buy-in from the community and industry experts. Making these types of policy changes is a fairly significant process. 

It’s not a cut-and-dry answer to switching away from fossil fuels. 

The Opportunity:

It’s clear there is an interest by a large portion of homeowners, and there is also a shift in local policy to transition to electrification and away from fossil fuels. It’s also clear that the way to get there is not always simple and easy. 

What’s fun is to see that it IS possible! Seeing communities like Geos Neighborhood pop up and new code requirements arise means we’ll see these norms change. Sustainable solutions will become the standard instead of the exception. It’s an exciting time to be part of change!

As electrification becomes more dominant, high performance becomes a must! We no longer can settle for the inferior construction approaches we’ve put up with for years. Instead, we know that high-performance design, workmanship, materials, and products actually save us in the long run. All of these new code trends have increased the demand on high-performance construction products, especially with windows, doors, and insulation. These and a solid attention to details make a big difference! 

Three Simple Things You Can Do:

You may not live in a community where fossil fuel bans are in place, but you can still do your part as a homeowner to reduce your load on fossil fuels. 

  1. Purchase energy-efficient appliances. Make a sustainable choice at your next appliance purchase, or consider upgrading sooner. 
  2. Go solar. We live in a sunny state making solar panels an easy way to move toward electrification. 
  3. Efficient windows. Make a smart choice when you purchase your windows and doors. Energy-efficiency matters here and can go a long way to reduce your heating and cooling costs, which as a result, reduces your fossil fuel consumption. Your energy bills each month will also thank you! 

Not sure where to start? Our team can help point you in the right direction. Whether you’re building from scratch or retrofitting your home, you can easily reduce your own fossil fuel load with a few simple choices for your home!

Energy-Minded Design: The Balance Between Form & Function

There are some pretty snazzy design ideas out there in the world. If you look at design contests, architectural school projects, or even just down your own street, you’ll probably see some very beautiful designs that simply don’t make a lot of practical sense. It comes back to the age-old question of form vs. function. Designers have been walking that delicate balance for thousands upon thousands of years, and in today’s world, it’s no different. Simply put: certain design attributes cause complexity with energy efficiency and force project owners to make hard decisions. 

Complex Design Attributes: There are a handful of common design attributes that simply add complexity to the energy efficiency of a house. For someone designing a Passivhaus building, or just wants to be energy-aware, the question usually comes up and you have to decide between bump-outs that make the energy model more challenging and something that will help prevent energy loss.
Design Features: Bump-outs, cantilevered floors, dormers, knee walls, and more are some of the common culprits. Often, these are poorly insulated and add extra exterior wall surface area and seams in a wall or roof construction. All of these factors lead to energy losses due to air infiltration and thermal bridges.

Conditioned Breezeways: Breezeways that are conditioned, heated, and cooled, are another common culprit for energy loss. While these are great for connecting parts of a home, they often have multiple exterior facades, increasing the potential for thermal inefficiency. The surface area to volume ratio is much higher in a breezeway than typically is found in the primary parts of a home. 

Poor Orientation: Orientation of a home is often the last consideration, but especially in sunny climates like Colorado, the way a home faces the sun can make a big difference. Whether you’re dealing with a room overheating or a spot in the home being too cold from lack of direct light (and heat) from the sun, it can make a difference. 

How to Design Well, But Efficiently
Simple is Better: Every time you add a turn, an opening, or additional surface area to the exterior, you increase the potential for energy losses while increasing the complexity of how you will maintain thermal integrity at that juncture. Simplicity allows for higher performance than highly complex building envelopes!

Orient Well: Take note of the orientation from the start. You’ll want to consider your views as well, but keep in mind which side of the home will get the most sunlight and daytime heat. Also, think through where the windows will be positioned in relation to this orientation. It makes a big difference in states like Colorado where the sunlight can cause huge temperature swings for some spaces. 

Materials Matter: If your overall exterior facades are fairly simple, you can still add some elements of great design and interest with the placement of unique finish materials and colors. Breaking up a facade with a few materials and complementary color schemes can add interest without causing extra energy losses. In fact, you can even incorporate these design material choices in a way that supports extra insulation (e.g. continuous insulation). Finish and insulation material selections can help protect a home even more from the harsh sun, wind, or outside temperatures. 
Purposeful Corners: If you are adding complexity to your design with additional corners and bump-outs, make sure you are designing those weak points with intention. Proper design and use of materials to seal off and improve the thermal performance of these junctures is vital!

Exterior Living Spaces: Consider how exterior living spaces like porches, pergolas, and covered patios can allow depth and great design, while strategically protecting the home from energy losses. 

Are we saying your house needs to look boring to be energy-efficient? Absolutely not! Some of the most efficient, sustainable homes we’ve encountered are true works of art. However, an energy-efficient home doesn’t happen by accident. It must be a continual conversation between you, your architect, and your contractor to ensure any and all goals on the project are met. 

As you consider these energy-efficient options for your home, make sure to keep our team involved in the process. We often help our clients find the balance between form and function so that your home is truly the energy-efficient work of art you’ve always dreamed of!

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. 

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.

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 2Ă—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.

Collins Residence Part II

Last month, we took you on a behind-the-scenes peek at the Collins-Ruddy project. This tri-level home was a retrofit from a 1970’s where energy-efficiency was clearly not in the original blueprint of the home. Todd and his family began a journey to improve the energy loss in their home, and incorporate Passive Haus techniques wherever possible. 

We use the word “journey” because that’s truly what it has been. They started this project in 2012 and are still to this day finding ways to improve. If you’re just catching this journey here in this article, take a look back at the first half of the journey we shared last month.

Today, we want to share more details about this project:

Biggest Lessons Learned:

  • Solar: Todd wishes he had installed more solar panels than he needed originally to account for these future needs. While they maxed out the federal incentive, as it stands, they will need to upgrade their solar system to get them to Net Zero with vehicles, equipment they have, and what they plan to have in the next several years. 
  • Entry Doors & Floors: The doors were installed prior to considering a wood floor upgrade. Because the doors were installed lower, standard wood floors were no longer possible or the door would not be able to open. Instead, Todd installed engineered flooring which is not as thick. 
  • Attic Insulation: Todd says if he had to do it over, he would have started from scratch.  Clear out the old insulation, then start with a thick layer of foam at the attic perimeter and wall connections, foam the j-boxes and any other penetrations… and then finish with a huge layer of blown cellulose. It’s more costly to do it this way, but it’s also more effective for a couple of reasons:  higher r-value at the perimeter and is more airtight. 
  • Win the Lottery: While a pipe dream, Todd jokes that he would have won the lottery before approaching this project. It sure would have made the process easier! The process can get pricey with the more costly upgrades like windows and solar panels.  

What’s Still to Come?

Remember we mentioned that this is a journey? That said, between budgets, finding quality labor/contractors, sourcing supplies, and just mere time, retrofitting a house to be more energy-efficient usually doesn’t happen overnight. 

Here are a few projects they plan to tackle in the future: 

  • Remove the siding, add an air barrier and then 3” of mineral wool continuous insulation, and finish the exterior with new siding.
  • We might consider re-insulating our walls at some point as there is only poorly installed batt insulation. The re-insulation process entails cutting holes and filling the walls with cellulose.  
  • Purchase a new heat-pump water heater.
  • Replace the furnace with a whole house heat pump when it approaches end of life.
  • Increase solar panels to get to Net Zero.  
  • Go all electric and cut the gas. 
  • Go all electric for our cars as well … and utilize our solar energy production to charge them. While we have started this process with a RAV4 prime – plug-in hybrid, future vehicles will eventually be all electric.  

Here’s the new video >>

Why Do All This? 

Sometimes they get quizzical looks from neighbors and friends as they share about their journey and projects. Why would you invest so much effort into improving so many things that you will never see? Sure, there are fun things like a kitchen remodel that you see and experience day in and day out that make a difference.  Initially, it was about their children sleeping through the night and it’s pretty easy to forget the fact that you don’t have to cover your feet on freezing floors or the fact that you can live without space heaters in the dead of winter.  Finally, Todd has the peace of mind that energy price increases won’t be that impactful on his bill. 

Their family knows the power of energy-efficiency and how it can not only save a lot of money in the long run, but it reduces the need to rely on creating more heating or cooling. They’re proud supporters of sustainability efforts that reduce their carbon footprint and energy load on the earth. If we can build a better space that asks less from our energy resources on earth, why shouldn’t we? That’s their approach. 

At AE Building Systems, we want you to know that you don’t have to be breaking ground on a brand new custom build to employ energy-efficiency into your home. Odds are, most of us reading this have purchased a home where we inherited energy-efficiency issues, thermal bridging, and other concerns in a pre-owned home. Most of us will be where Todd and his family were: faced with retrofitting and solving problems as best we can with the house we’re in. 

We want you to know you CAN make a difference in your own home. Small steps can make a BIG difference when it comes to energy-efficiency, energy savings, cost savings, and sustainability efforts. You can be part of it, and we want to help you on your own journey. 

Got questions for Todd or want to know where to start? Feel free to reach out! 

Todd Collins 720.287.4290

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 Walls and SIPs

When building an energy efficient home, High Performance wall assemblies are critical components, and can be grouped into a couple of categories: 1. Built on-site advanced wall assemblies and 2. Prefabricated walls, to include SIPs.

Note that this blog post is largely dedicated to Polyurethane SIPs.  

ICFs, Insulated Concrete Forms, are a good option and are manufactured by several companies. Faswall and Nexcem have an interesting woodchip product. There are pros and cons for ICFs, and it is important to understand both.

Advanced Wall Assemblies

The goal is to improve the wall construction of conventional, stick built homes with advanced wall assemblies to include double stud, stagger stud or continuous insulation walls.

Double stud walls consist of two stud-framed walls set up next to each other to form an extra thick thermally broken wall cavity that can be filled with insulation. Because the interior and exterior framing are separated by insulation, thermal bridging is reduced or, ideally, eliminated.

Stagger stud walls use top and bottom plates that are normally 2×6 (5.5”) – 2×12 (11.25″).  Vertical 2 x 4 studs are then staggered alternately on each side of the plates. This is a good option for extra insulation, reduced thermal bridging and sound-proofing of spaces as well.

Another option is standard construction with a Continuous Insulation (CI) layer. In CI, builders add a continuous layer of insulation across the exterior of all structural members to reduce or eliminate thermal bridges, except for fasteners and service openings. Insulation is installed generally on the exterior of the building and is an integral part of the building envelope. Comfortboard 80 is an excellent vapor open product that can be used for a CI approach. Mineral Wool is generally favored, as foam tends to have low perm ratings and generally the desire is for our walls to dry to the outside.  Often folks using a CI approach do not use enough insulation to move the dew point outside of the wall assembly.  It is critical to have a vapor open approach if the dew point falls within the stud cavity.

Prefabricated Walls

Prefabricated walls are built in a factory, transported to the building site and craned into place. Manufacturers of these types of walls include:

Phoenix Haus, which designs and produces open sourced housing templates for walls that save energy, provide better insulation and allow homes to be more efficient with or without solar energy.

Build SMART simplifies the process of building a high-performance, energy-efficient structure with factory-manufactured modular components. Continuously insulated panels come with pre-installed, energy-efficient windows and doors and are delivered to the building site.

SIPs – Structural Insulated Panels. There are several types of SIPs out there. Generally, the difference between SIPs is the insulation.  Most are made with OSB (oriented strand board) skins, but some SIPs have different skins to include metal or MgO (Magnesium Oxide) skins. Most often, the insulation is EPS or Polyurethane.  However, there are some that are made with mineral wool, PolyIso (Polyisocyanurate) or XPS (extruded polystyrene).

Some SIPs are not considered structural (e.g. most metal SIPs), and they might be referred to as Sandwich Insulated Panels.

SIP panels made of EPS, XPS or PolyIso are glued together generally with Polyurethane adhesive. SIPs made with Polyurethane foam are adhered together with the foam itself creating a tremendous bond and a very strong wall panel solution.

Thermocore SIPS are made with polyurethane insulation core with interior and exterior skins of OSB. Panels are precisely and custom manufactured to the architectural drawings. Included in the SIPs are door and window bucks, headers, sub facia and electrical conduit boxes. Also, beam pockets and additional structure like 2x, LVL or steel posts can be built into the panels.

Construction with Thermocore SIPs is quicker than framed homes. The time from foundation to dried-in is significantly reduced. Labor costs are lower, which is ideal in places where available labor is scarce, costly, unreliable or poor quality. Thermocore SIPs are stronger than framed walls, with lower thermal bridging.

Thermocore SIPS often have higher material cost, the electrical requires pre-planning and can be considered less environmentally friendly due to foam, which is a petrochemical product.

The thermal performance values of SIPs and lower labor costs often make up for the initial cost and planning. SIPs help to achieve a more air tight building as well. In the Passive House and Zero Energy industry, where energy efficiency, comfort and clean air are the goals, Thermocore SIPs are an optional building solution.

For more information on SIPS, call us at 720-287-4290.

Sources: U.S. Department of Energy, Greenbuildingadvisor.com, Thermocore.com

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):

  1. 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.
  2. Seals – High performance windows generally have multiple seals, which promote not only weather tight but also air tight seals.
  3. 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.
  4. 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.
  5. 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.