I bring you today an interesting project, carried out by Michael Shernick, which focuses on the viability of building with the material earth in Front Range (USA). This study was developed as part of the requirements for a MA in Architecture in 2009.
Shernick states that in order to see earth architecture flourish along Front Range, it needs to grow based on the local building culture, rather than on imported designs from, for example, Santa Fe. It is therefore important to develop context-specific solutions which can respond to expectations from local markets and people, and above all, respond to local climate.
Regarding the latter, the author suggests combining the use of earth with other materials, given the high insulation needs in the Front Range. Using standard construction with a high insulation value on the north walls and rammed earth on east and west walls, which would limit unwanted heat gain, is a potential solution. Additionally, Shernick recommends that a vast area of glazing is used on the south walls.
This study mentions what many of us, looking at the characteristics of the building material earth, have been saying for a long time: steady-state calculations for determining U-values for walls do not seem to take into account the insulation effect of the thermal mass on the earth walls. However, apparently, this can be overcome through the application of a correction factor -‘M Factor’ - to the calculations. “The M factor is a simple means of quantifying the effect of thermal inertia on heat-loss calculations without the aid of a computer. It permits a more accurate prediction of dynamic thermal performance than steady-state methods, and is deliberately conservative.” (Beall, 2003, p. 211)
This is actually quite an interesting concept, and could probably solve many of the problems that the material earth is facing today with meeting increasingly demanding building regulations and standards.
Below there is a short quote of Michael Shernick’s work where he discusses the M Factor. It is also worth having a look at the full document HERE.
‘For example, if a wall is calculated to have a steady-state U value of 0.14 and the locale of the wall has 2000 heating days per year and the wall weighs 20 pounds per square foot, the M factor corrects the U value to 0.12
This is not a huge effect on the U value, but it may be enough to prove the efficacy of using massive masonry walls for their thermal inertia/insulating capabilities to individuals in the local building culture who are sceptical. If sceptics state that no insulating credit is to be given to massive masonry, the M factor can disprove their concerns. The M factor has been integrated into energy calculations, as seen in the 2006 IRC table, but it is worth knowing that the insulating effect of mass can be separated out for examination if necessary.’ (Shernick, 2009, p.11)
Beall, C. (2003). Masonry design and detailing: for architects, engineers, and builders. New York, McGraw-Hill.
Shernick, M. (2009). Front Range Earth Architecture: Why and Why Not?. University of Colorado Denver