Frequently Asked Questions
What is Thermal Bridging?
There a 3 ways heat can transfer through building elements; conduction, convection, and radiation.
A thermal bridge is where heat loss, or gain, takes the path of least resistance through the most conductive material in a building envelope (or exterior wall).
What is a Thermal Break?
A thermal break is when a low thermal conductive material is used to break a highly conductive material.
These thermal break materials are used to assist in reducing the flow of heat loss or gain between conductive materials. This method does not eliminate thermal bridging but reduces the heat loss or gain.
Why does Thermal Bridging Matter?
Thermal bridging can weaken the insulation properties, increase energy consumption, reduce interior comfort, compromise the structural integrity, and can lead to condensation, mold and mildew in the envelope (or exterior wall).
Where does thermal bridging occur in mobile units?
Where there is a continuous conductive material from the outside to inside of the envelope (exterior wall) such as wood or metal studs, metal structural corners, window and door frames, and fasteners penetrating the envelope cavity.
R-Value vs Effective R-Value (U-Value)
R-values measure the effectiveness of a material. R-values are additive. An effective R-value is the overall thermal resistance of an assembly or envelope (exterior wall) in this case. It is a weighted average of all the materials in the envelope. All these materials contribute to the thermal performance of an assembly or envelope.
By eliminating conductive materials and thermal bridging, leads to a more thermal effective assembly or envelope.
How to solve?
Thermal bridging can be eliminated when choosing materials which are non-conductive or utilizing continuous thermally broken construction materials and methods.
What materials transfer the most heat or cold?
Wood and metal. With metal being more conductive than wood.
How Environmentally Friendly is fiberglass?
- The main ingredient is silica (sand). Since silica is an abundant non-depleting ingredient where mining is sustainable.
- The manufacturing is far less energy intensive then many other construction materials.
- Excellent thermal insulation, extremely low thermal conductivity, and expansion. Which translates lower energy consumption, fuel and costs to keep the space warm or cool.
- Fiberglass is highly durable and long lasting. Once cured and installed it does not creep, deform or corrode overtime. This means less waste, maintenance, or repairs. Further it has long lasting natural resistance to outside elements.
- Fiberglass is recyclable and can be repurposed as benches, polls, and tables.
Blowing Agents, Thermal Drifting and LTTR?
Blowing agents are used to create some closed cell foam cores such as XPS, PU and PUR to enhance the R-value. Overtime, the R-value diffuses and is replaced with air. As the blowing agent dissipates, the R-value decreases. This is known as thermal drift.
Even though the blowing agents increase the thermal properties initially and have good flammability ratings, they are made with toxic chemicals (refrigerant gases) such as chlorofluorocarbon (CFC’s), hydrofluorocarbon (HFC’s) or hydrochlorofluorocarbon (HCFC’s).
In the manufacturing of XPS, PU and PUR, a method called Long Term Thermal Resistance (LTTR) was created and is used to estimate the R-value for insulation with captive blowing agents to estimate the thermal resistance after 5 years. The manufacturers of these products are expected to provide information about the expected future R-value.
LTTR does not apply to EPS and rPET, because it is manufactured with air, and there is no loss of R-value and does not degrade overtime.
What is the difference between fiberglass pultrusions and fiberglass extrusions?
Fiberglass pultrusion is where continuous fiberglass strands are pulled through a die along with resin. Fiberglass extrusion is where a chopped fiberglass strand fibers are pushed through a die along with resin. Fiberglass pultrusion’s are stronger than fiberglass extrusion’s.