How to Get Energy-Efficient Walls with Insulated Concrete Forms

How to Get Energy Efficient Walls Header

Fox Blocks create energy-efficient walls with continuous insulation and vapor control.

An energy-efficient wall system, like Fox Blocks, contributes towards a tight energy-envelope and continuous interior and exterior insulation for the whole building. Other parts of the envelope include the foundation, roof, and openings (windows, doors, skylights, ventilators). All parts of a high-performing building envelope must serve as barriers that control the intrusion of rain, vapor, air and the transfer of thermal radiation (heat). A high-quality energy-efficient wall minimizes air inflation and blocks the flow of heat. An energy-efficient wall also controls water and vapor intrusion and protect against thermal radiation.

Continuous Insulation Controls Heat and Air Transfer Through a Wall


Use of continuous insulation across all structural members of a building’s envelope is essential to minimizing air inflation and preventing the flow of heat by conduction, convection, and radiation. Continuous insulation also prevents thermal bridging, which is a common issue with conventional construction like wood and metal framing. Importantly, the ASHRAE 90.1 and the 2018 IECC require continuous insulation in both commercial and residential structures.

The ASHRAE Standard 90.1-2013 defines continuous insulation as insulation that is uncompressed and continuous across all structural members without thermal bridges other than fasteners and service openings. These standards define the amount of insulation required, based on the building’s climate zone, to minimize air infiltration, stop thermal bridging and increase the effective R-value in a wall system. The most useful method of minimizing air infiltration is by installing continuous insulation, along with an air and moisture barrier, in accordance with ASHRAE 90.1 and 2018 IECC codes and standards to any part of the building envelope that does not admit light.

Water and Vapor Control of an Energy-Efficient Wall System


Construction of an energy-efficient wall must control intrusion of rain, groundwater, and vapor. The design of an energy-efficient wall also stops thermal convection and air- and moisture-infiltration through a variety of methods.

1. Install Overhangs to Limit Water Intrusion

The first line of protection against moisture intrusion are overhangs, which keep the water away from the walls. The cladding also limits water intrusion to the interior of the wall system. However, some cladding systems can absorb significant amounts of moisture; therefore, the design of wall assemblies must also manage the inward flow of moisture from groundwater and rain.

2. A Tightly-Sealed Building Envelope Limits Thermal Convection

Thermal convection occurs when heat moves by the flow of liquid or air molecules from the hotter to the cooler side of a wall. Uncontrolled thermal convection causes drafty homes and buildings and is often the greatest source of energy loss in a structure. In wood-frame construction, convection happens through the framing connections, floor, wall, roof, and fenestration intersections. A tightly sealed building envelope with a high-quality air and moisture barriers can prevent thermal convection and create a comfortable, draft-free, environment for the occupants.

3. Control Air and Moisture Infiltration with a WRB

A vapor-permeable, weather-resistant barrier (WRB) is an essential element of an energy-efficient wall assembly for air and moisture control in humid and warm climates. A WRB shields a structure from air and water infiltration. A WRB also lets water escape from the wall assembly, which protects a structure from deterioration and damage. High-quality WRBs are both moisture- and air-resistant and permeable to vapor. A WRB ensures a structure is energy-efficient, healthy and comfortable.

Low Emissivity and High Reflectivity of an Energy-Efficient Wall

Thermal radiation moves heat from warm areas to cooler spaces by electromagnetic waves, which for buildings is primarily the sun’s rays. Thermal radiation will occur between two surfaces in view of each other; they do not require a substance, like air and water, to move through space. All materials reflect, absorb, and emit radiant energy. A material's ability to radiate absorbed energy, or emit energy as thermal radiation, is called emissivity. A high emissivity material has low reflectivity and will quickly absorb energy that strikes it.

The cladding of an energy-efficient wall should include materials with low emissivity and high reflectivity so to limit the absorption of radiant heat. Two examples of energy-efficient cladding systems in the market are exterior insulation and finish systems (EIFS) and insulated metal wall panels.

How Fox Blocks Create Energy-Efficient Walls


Fox Blocks are two foam panels filled with concrete and reinforced with steel rebar that build energy-efficient walls with continuous insulation and vapor control.

  • Fox Blocks insulated concrete forms exceed ASHRAE/ANSI 90.1 energy code requirements, and create sustainable buildings with superb moisture resistance and energy performance.
  • Fox Blocks provides a solid continuous monolithic concrete wall with a perm rating of less than 1.0, which controls moisture intrusion and prohibits the growth of mold, mildew, and rot.
  • Fox Blocks also provide continuous insulation with an R-value of 23, which create an airtight building envelope with better performance than wood- or steel-frame construction.

Fox Block Series is also fast and easy to install because it is a one wall assembly. Please contact Fox Blocks for more information on building energy-efficient walls.