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Why Building Envelopes are Essential for Your Energy Efficient Home

The boundary between a building’s exterior and interior, building envelope is an extremely important component of the overall building design. The envelope is directly linked to the protection and maintenance of the structure. Moreover, the energy performance of the building envelope components such as roofs, ceilings, floors, walls, doors, and windows are closely related to the requirement of energy for cooling and heating. This, therefore, is an integral part of building an energy efficient home.

From a global perspective, buildings are responsible for over 30% of overall energy consumption. Out of this, more than one-third is spent on cooling and heating of living spaces. In cold climates, this can very easily cross 50% of the building’s overall consumption.

With an energy efficient building envelope, the owners are able to reduce their energy consumption drastically. This not only saves them money, but also reduces the building’s carbon footprint. Therefore, whether you are planning a new building or looking to retrofit your existing home, a well designed building envelope is key to your project.

Design Strategies:

Energy usage and occupant comfort within a building is impacted significantly by temperature changes across seasons. This is why thermal control is one of the most important aspects of designing thermally efficient buildings. This demands a thorough understanding of heat transfer and how the same can be prevented by using certain materials.

The natural tendency of heat is to flow from high temperature to lower temperature areas. The rate of this flow depends on the temperature difference between the building’s exterior and interior and the nature of materials in the walls. Materials such as concrete, metals, and glass can transfer heat very well, and are known as conductors. Materials such as foam sheathing and fibre glass are resistant to heat flow, and are referred to as insulators.  Conduction, convection, and radiation are the three modes in which the transfer of heat takes place in and out of a building.

The energy efficiency of a building can only be improved by impeding all three modes of heat transfer. Though it is not possible to stop heat transfer completely, the rate of transfer can be slowed down significantly by placing insulators in the path of transfer. This process is known as the breaking of thermal bridging.

Breaking Thermal Bridging:

Thermal bridging is referred to as the path through which heat transfer takes place in poorly insulated buildings. The best way to break this path is to place insulating materials between the conductors. Cavity insulation is done using mineral wool, fibreglass, open- and closed-cell foam plastics, and cellulose, and occupies the spaces within wall cavity. On the other hand, insulating sheathing is done over the exterior walls using extruded polystyrene, expanded polystyrene, or fibreglass board.  Thermal properties of the insulating materials must be checked before selecting them.

Insulation Assembly Types:   

Selection of insulation assemblies is done in accordance with the materials used while constructing the building’s external walls.

Concrete Block and Tilt-up Walls: It is possible to install insulating sheathings on either the exterior or interior of the walls. Foam plastic insulation board is the most commonly used insulating material.

Exterior Insulation and Finishing Systems (EIFS): Installation of EIFS must be carried out as per the manufacturer’s instructions. This will ensure that there is no moisture trapped behind the EIFS.

Steel Stud Cavity Walls: This is the most common type of wall assembly that comprises of a masonry facade. The thermal performance of this assembly can be improved by

  • Incorporation of exterior air barriers capable of reducing air leakage
  • Use of interior air barriers for increasing drying capacity and reducing convective loops.
  • Use of exterior insulating sheathings to increase the temperature of cavity surfaces.

Metal Buildings:

  • Loose Fill Insulation
  • Batt and blanket insulation
  • Rigid board insulation
  • Spray foam insulation
  • Fibreglass insulation
  • Reflective Foil Bubble Insulation

At CGS Façade Group, we have a wealth of experience in creating high-performance building envelopes. Please feel free to contact our experts if you have any questions related to building an energy efficient home.