Timber buildings and thermal inertia: Open scientific problems for summer behavior in Mediterranean climate

•Thermal inertia for a new real estate market of timber buildings.•Thermal mass as a thermal stabilizer for indoor climatic conditions, in particular in Mediterranean climate.•The energy efficiency challenge is more complex in the Mediterranean climate than in northern climates.•As mass humid sand has been infelt in a wall cavity, to give performances with a low costs.•Test in climate chamber are not enough for demonstrating the behavior of loose sand in the wall stratigraphy.

In a climate that features warm winters and hot summers, the houses that perform better are heavy houses. Heavy stone or masonry walls work as thermal masses that guarantee winter comfort and absorb thermal loads in summer. The real estate market is now putting pressure and emphasis on quality of buildings and building components performance control. The best way to achieve them is through industrial products and prefabrication. Wood technology in construction is well received by the market. It is very precise, thanks to CNC machining and offers good performance at seismic forces. The only issue with wood construction is its lightness: it is useful for transportation and assembling, but it has mass values far from traditional masonry. The Team MED in Italy for Solar Decathlon 2012 tested in the prototype for Madrid a new wall stratigraphy where, aside from insulation panels, heavy materials put in a layer once the house was assembled. This solution gave a mass value that is nearly double the value of a normal framed wall, and therefore very close to a traditional masonry wall. At the same time, this also increases the acoustic performance, by solving a problem that is typical of lightweight construction.