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The buildings we inhabit and the infrastructure we use must have certain thermal qualities; whether that means being able to maintain structural integrity or being able to provide insulation against extreme temperatures.
Buildings and structures must be able to tolerate a wide range of temperatures. There is very rarely a significant period in the life of a building with a continuously maintained temperature state. For instance, in winter, even though the temperature range between night and day is steady in many regions, a building will be subjected to many daily temperature changes, due to alterations in occupancy and the radiant solar energy.
Robust thermal analysis of building materials and structures is therefore essential to the building and construction industry.
Analysis of Building Materials
The amount of building materials in construction increases significantly with the areas of application, and this supports the need to make informed decisions concerning the qualities of various materials. The assessment of building materials does not just ensure compliance with all relevant laws; it also reduces the liability of those on a construction project.
Simultaneous Thermal Analysis (STA) is ideal for the analysis and characterization of materials like concrete and stone. Glass transitions and decomposition qualities can be examined, in addition to temperature-related expansion and shrinkage.
Rather than an evaluation using two separate methods, the STA has the benefit of gauging weight change and the caloric reaction concurrently. The same test conditions, like atmospheric pressure or heating rate, pertain to thermogravimetry (TGA) and differential scanning calorimetry (DSC). STA also allows for more precise outcomes and greater overall insight.
The temperature-dependent shrinkage and expansion of building materials, both during production and use, is also commonly established with a technique called dilatometry. A dilatometer heats a sample, and the degree of shrinkage or expansion is determined by placing a pushrod against the sample, which may be displaced by a sample shrinking or expanding due to temperature change.
Thermal conductivity and diffusivity are the most significant parameters to consider for the description of the heat transport in a building material. For accurate measurements of thermophysical qualities, the Laser Flash technique (LFA) is a quick, adaptable and exacting method.
Another unique thermophysical property, the thermal conductivity of a material, can be established using a heat flow meter (HFM).
Building Envelope Thermography
Regardless of building or structure type, infrared thermography offers an insightful, non-destructive means of analyzing thermal performance and gaining information.
Structural breakdowns, in addition to their causes and ultimate results, often cannot be seen until after the damage has occurred. When damage occurs, the only option may be comprehensive and costly reconstruction. Infrared thermography allows for the ability to see invisible thermal signatures associated with various building issues. When correctly used, thermography allows owners, architects, builders, and inspectors to identify complications, check building performance, and confirm the success of solutions.
In infrared thermography, infrared cameras can document thermal information as either digital images or video. Various radiant temperatures are typically indicated as different colors or degrees of grey. While it may seem beneficial to know exact temperature values; this knowledge is generally not necessary. Rather, the differences are of the most interest. Given the proper conditions, most buildings have tell-tale thermal patterns that can be translated by a qualified inspector.
Infrared thermography systems are quite user-friendly; yet interpreting imagery, knowing a root cause to an issue and developing a solution are all more difficult tasks. Because of this complexity, thermographers often work in concert with a team of experts and stakeholders.
Common applications of Infrared thermography include checking insulation and Exterior Insulation and Finish Systems (EIFS), as well as searching for air leakage or moisture intrusion.
Sources and Further Reading