Mathematics confirm the efficiency of horreos with slots

February 21, 2012
This image shows the air flow patterns in a hórreo dry-store structure (vertical plane). Credit: C. Saá, J.C. Morán, J.L. Míguez et al.

Horreos, a type of Galician dry-store structure, with slotted floors regulate temperature better in sunny weather conditions, which helps preserve the corn stored there. This is something that people from ancient times knew, and has been ignored in recent restorations, that is proven now with a mathematical model developed in the University of Vigo (Spain).

In many restorations of old hórreo dry-store structures in recent years, slots that perforated the floor were removed. This was not a good idea, according to a study that researchers from the University of Vigo have just published in the Energy and Buildings journal.

The slots not only ventilate the inside, where the corn and other food is kept, but they also reduce the temperature when the sun shines. Scientists have confirmed this by placing "thermohygometric" sensors in the hórreo and entering the records into a . Fluid mechanic equations have served as a reference.

"Although on principle one could think that the heat is good for drying the corncobs, if the temperature raises a lot, the corn's hygrometric balance curve changes and it begins to absorb moisture from the environment. This helps the proliferation of bacteria which makes the corn rot" said César Saá, researcher at the University of Vigo and lead author of the study.

This image shows the air flow patterns in a hórreo dry-store structure (longitudinal plane). Credit: C. Saá, J.C. Morán, J.L. Míguez et al.

The researcher highlights that "the main advantage of having a slotted floor in hórreo dry-store structures is that it clearly shows better results in two parameters: the efficiency in ventilation and preventing internal temperatures from rising."

There is scientific evidence supporting the traditional custom of opening the access doors of the dry-store structure (normally there are two, one at the front and one on the side) to improve ventilation when the solar radiation is high during the September to May storage period.

Throughout these nine months the team analysed the hórreo's response to climate, which has been the basis for this first published study. Further studies will be subsequently published. As a model, a "Pontevedra style" structure was used, made of stone and wood, which is different from the "Coruña style" which is just made of stone.

Mathematical simulations and flow patterns

In order to carry out the mathematical operations, a simulation software was used and created a calculation net of eight million elements. Air flow patterns were obtained, which are fundamental to understanding the ventilation of the dry-store structure in different climate action situations.

The graphics of the vertical transversal and longitudinal sections of the dry-store structure show a large upward flow towards the middle of the building through the slots in the floor. The emissions escape en masse through the top row, and to a smaller scale through the first line of the side slots.

The whole study was carried out in a dry-store with no corn. "In this situation, the flow patterns can differ from ones with a stocked hórreo (due to the interference from the corncobs) but we believe the conclusions regarding the efficiency of ventilation and temperature contention do not vary much" Saá highlights.

The food is preserved in these buildings using only the energy provided by the atmosphere. "From this point of view, the hórreo dry-store structures are very efficient, and maintenance of them is virtually unnecessary over the years" the researcher concludes.

Explore further: How sweet is it?

More information: C. Saá, J.L. Míguez, J.C. Morán, J.A. Vilán, M.L. Lago, R. Comesaña, (J. Collazo). "The influence of slotted floors on the bioclimatic traditional Galician agricultural dry-store structure (hórreo)". Energy and Buildings 43 (12): 3491-3496, December 2011. Doi:10.1016/j.enbuild.2011.09.015

Related Stories

How sweet is it?

November 5, 2007

We love it fresh, canned and frozen. It's grown in every state, and according to a recent study published by the American Society of Horticultural Science, adds up to a whopping $807 million per year industry in the U.S. ...

'Dry water' could make a big splash commercially

August 25, 2010

An unusual substance known as "dry water," which resembles powdered sugar, could provide a new way to absorb and store carbon dioxide, the major greenhouse gas that contributes to global warming, scientists reported today ...

Recommended for you

Glider pilots aim for the stratosphere

November 20, 2015

Talk about serendipity. Einar Enevoldson was strolling past a scientist's office in 1991 when he noticed a freshly printed image tacked to the wall. He was thunderstruck; it showed faint particles in the sky that proved something ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.