Thermal Bridging
From Swikipedia
Introduction
A thermal bridge is a component, or assembly of components, in a building envelope through which heat is transferred at a substantially higher rate than through the surrounding envelope area. It is the unwanted heat loss or gain due to conduction through a material.
An example of thermal bridging is heat loss that occurs with structural steel framing that is insufficiently insulated between conditioned and unconditioned space.
Brief Description
Construction Materials and Thermal Bridging:
• Concrete balconies that extend the floor slab through the building envelope are a common example of thermal bridging.
• Steel is extremely good at conducting heat and cold, causing enormous thermal bridging problems to steel-framed buildings.
• Wood panel sheathing is a cause of thermal bridging, and may even cause moisture to move into the wall cavities.
Classification of Thermal Bridges:
In construction, thermal bridges are classified as:
• Repeating thermal bridges - where bridges occur following a regular pattern, such that made by wall ties penetrating a cavity wall.
• Non-repeating thermal bridges - such as the bridging of a cavity wall by a single lintel
• Geometrical thermal bridges - at the junction of two planes, such as at the corner of a wall.
Solution to Thermal Bridging:
The solution to thermal bridging and creating a comfortable indoor environment, besides saving on energy bills, is insulated sheathing. It is a layer of boards or other materials applied to the outer studs, joists, and rafters to strengthen the wall structure, to insulate the walls and to serve as a base for the home’s exterior siding.
References:
http://www.cityofseattle.net/dpd/GreenBuilding/
http://en.wikipedia.org/wiki/Thermal_bridge
http://www.e-metal-buildings.com/thermal-bridging.php
