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.

Fresh Air Ventilation & Monitoring

Fresh air is a commodity that everyone needs and wants. Who doesn’t like to breathe fresh air? Generally, the best source of fresh air is the outdoors. But since most of us don’t live outside, we can still supply fresh air to our homes by opening windows and doors. However, we all know it’s neither cost-efficient nor wise to leave our windows and doors open during the cold winter or hot summer.

Many older homes are leaky enough that fresh air enters through all tiny cracks and holes in the walls and around the windows and doors. With high-performance homes, the foundation is to build it air-tight and add ventilation. The catch phrase is, “build it tight and ventilate right.” But how exactly do we “ventilate right” in an airtight home when our objective is to keep cold air out in the winter and cool air in in the summer?

We must mechanically bring in fresh air. The Build Equinox CERV system does just that. The CERV recirculates air, brings fresh air in and removes stale air while offering both heat recovery and air filtration. Put simply, the CERV makes sure you have fresh, filtered air and keeps heat where it belongs, in or out based on the setting on the unit.

Designed with sensors to detect VOCs (Volatile Organic Compounds) and CO2, the CERV will “smell” the air and put itself into circulation or ventilation mode appropriately based on the sensor readings. The VOC and CO2 levels drive the demand of the unit based on the thresholds the owner programs on the unit.

A CERV returns air from rooms such as the baths, the kitchen and possibly other rooms that might have more “smells” or humidity such as workout rooms, laundry rooms, etc. It brings that air back to the unit to either simply filter/recirculate it or to replace it with fresh air from outdoors while exchanging the heat that is in the air.  In the winter, it keeps heat in and in the summer it reverses the process and keep heat out of the building.

One of the more unique features of the CERV is that it uses a heat-pump to move heat to the incoming or exiting air stream.  While it is not meant as a primary source of heating or cooling, the CERV actually provides a small amount of heating or cooling capacity.

Components of the CERV System:

Heat-Pump Module (A)
Module A of the unit heats, cools, dehumidifies and exchanges energy between incoming incoming(fresh) and exiting(stale) air streams, with no low temperature operation restriction.  Most H/ERV’s require some kind of anti-freeze function or capability.  This is not necessary with the CERV.

Fresh Air Control Module (B)
Module B of the CERV houses the electronics, integrated pollutant sensors (CO2, VOC, temperature and humidity) and damper, and this is where the CERV intelligently monitors air quality and activates fresh air ventilation. When fresh air is not needed, recirculation adds heating/cooling to unify comfort and indoor air quality. Also, the Fresh Air Control Module is fully insulated with no thermal bridges. It has a very user-friendly color touch screen controller with large print, easy to navigate control and status screens. The controller can also be placed anywhere in the house. In addition, it has an option to connect to the Internet, through the CERV-ICE Online Gateway, making it possible to control the system directly from a smart phone, tablet or computer.

Inline ECM Supply & Exhaust Fans

These are variable-speed ECM fans which balance air flow efficiently, supplying fresh air to the occupants and exhausting polluted air from house.

Inline Filter Boxes
These boxes remove air contaminants from incoming air to the home and are placed where fresh air enters. The CERV uses common filter sizes which can be purchased from several sources.

An important fact to consider in fresh air ventilation is the natural atmosphere CO2 (carbon dioxide) level of outdoor fresh air is 400 ppm (parts per million CO2). At more than 900ppm, a person’s mental performance, sleep quality, and productivity decreases. Currently, the indoor air quality ASHRAE standard for newly constructed homes is 1100ppm! If that is the standard, then we can clearly see why our air quality is a problem (source: https://ehp.niehs.nih.gov/1104789/). The good news is the current average indoor air quality level for homes in the CERV community is 686ppm.

Also note that some homes integrate various accessories that accomplish various objectives.  For example, booster switches can be added to bathrooms and kitchens to help evacuate humidity and pollutants from those spaces.  In addition, there are accessories that either help to pre-condition the air as it comes into the CERV from outside or to heat the air after it leaves the CERV.  Please contact us for more information on these accessories.

In summary, as part of the high-performance home or any home for that matter, the Build Equinox CERV system makes good sense:

  1. Fresh, clean air for the family
  2. Recovers heat/doesn’t lose it
  3. Provides health benefits of reduced CO2 levels (improved brain function, sleep quality and productivity), lowered pollutant/contaminant levels of things we bring into our home (i.e. off-gassing of new items we purchase, paint fumes, as well as pollutants created within the home, such as cooking odors, bathroom and laundry room odors or pet odors).

If fresher, cleaner air in our homes is the goal, then a Build Equinox CERV home makes next-to-outdoor fresh air in a home quite achievable.

For more information about the Build Equinox CERV, call us at 720.287.4290 or visit our website https://aebuildingsystems.com/product/build-equinox-cerv/.

Source: buildequinox.com