Thursday 17 November 2011

Critical publication review:Traditional, state-of-the-art and future thermal building insulation materials and solutions – Properties, requirements and possibilities (Bjørn Petter Jelle a,b,∗ )

In this article the Jelle outlines the advantages and disadvantages of thermal building insulation materials. He investigated traditional, state-of-the-art and possible future materials. The table attached compiles all of the various properties, requirements and possibilities analysed. This table is intended as a reference table and a learning tool for insulation materials and will be updated over the course of my studies.

Currently there is no single material that is capable of fulfilling all requirements. The new materials being introduced have their limitations, and Jelle stresses the importance of knowing these.
Jelle notes how recent studies point out that insulation of buildings is more cost-effective than the creation of renewable energies. It makes good fiscal sense to take account of these advances and for investment to be put into thermal products.

Thermal background in brief:
The main key property of thermal building insulation materials are the thermal conductivity (W/(mK)) and a low thermal transmittance U-value (W(m2K)).

Traditional insulation materials:
Traditional thermal insulating materials were robust with respect to perforation vulnerability and flexibility. They generally have a thermal conductivity value of between 30 and 40 mW/(mK). However this increased with an increase in moisture content.

State of the art insulation materials:
The author is most impressed with vacuum insulating panels (VIPs) and Aerogels. VIPs can achieve a thermal conductivity of between 3 and 4 mW/(mK) when in good condition. However, vacuums have a problem with maintaining their thermal conductivity over a long time period (vacuum can be lost with air and moisture penetration due to diffusion). Perforations also create an increase in thermal conductivity to 20mW/(mK).
Aerogels can achieve a thermal conductivity of as low as 4mW/(mK) at a pressure of 50 mbar. Aerogels conductivity does not increase over time, and perforations present no problem. As Aerogels can be manufactured in a translucent state this may mean that their application may be considered for projects where clients may be willing to pay higher costs.

Future Materials:
Currently the Nano insulation materials (NIM) solution seems to be the best high performance, low conductivity thermal material for the foreseeable future.
Dynamic insulation materials (DIM) and NanoCon also show good potential, due to their thermal insulating properties and their good load-bearing properties respectively.


Conclusion:
The author concludes that NanCon, the theoretical insulating material is the most desirable solution. I think that the DIM shows the most potential for global use due to the fact that its thermal properties can be altered in relation to the geographical climatic conditions.
The Passive House Standard is a standard that is global. It has been well discussed that Ireland does not require the very high standards set out by the Passive Institute. There may be an option to build using materials that have the potential to reach the standard when needs arise, but are of a much lower standard than needed in mainland Europe.

If the properties of the DIM (for thermal adaptability), NIM (Nano Insulation Materials: for strength and thermal conductivity), and the Phase Change Materials (PCM: these change from solid to liquid when heated and then when cooled release the energy used as heat back into building thereby keeping internal temperature constant), while also having a material that could adapt to moisture content, we would have the ideal solution. 


Link to the table of Insulating materials


Link to "Traditional, state-of-the-art and future thermal building insulation materials and solutions – Properties, requirements and possibilities"