To thermally upgrade exterior masonry walls, interior insulation is often the only possible retrofitting technique, especially when dealing with historic buildings. Unfortunately, it is also the riskiest post-insulation technique, as frost damage, interstitial condensation, and other damage patterns might be induced. To diminish those risks, nowadays so-called capillary active interior insulation systems are often promoted. These systems aim a minimal reduction of the inward drying potential, while interstitial condensation is buffered.
Currently, several capillary active systems are on sale. These different types have, however, widely varying properties. In this article, a closer look at the hygrothermal properties and the working principle of a number of “capillary active” interior insulation systems is made. The spread in capillary absorption coefficients and the vapor diffusion resistances of the different systems is discussed and their influence is illustrated. Based on all this, a more nuanced view on capillary active insulation systems is pursued.
An analysis of energy use by Neanderthals in Northern Europe during the mild Eem interglacial period is carried out with consideration of the metabolic energy production required for compensating energy losses during sleep, at daily settlement activities and during hunting expeditions, including transport of food from slain animals back to the settlement. Additional energy sources for heat, security and cooking are derived from fireplaces in the open or within shelters such as caves or huts. The analysis leads to insights not available from archaeological findings that are mostly limited to durable items such as those made of stone: Even during the benign Eem period, Neanderthals faced a considerable heat-loss problem. Wearing tailored clothes or some similar measure was necessary for survival. An animal skin across the shoulder would not have sufficed to survive even average cold winter temperatures and body cooling by convection caused by wind. Clothes and particularly footwear had to be sewn together tightly in order to prevent intrusion of water or snow. The analysis of hunting activity evolvement in real time further shows that during summer warmth, transport of meat back to the base settlement would not be possible without some technique to avoid that the meat rots. The only likely technique is meat drying at the killing site, which indicates further skills in Neanderthal societies that have not been identified by other routes of investigation. 相似文献
The remains of a ditched field system dating from the late Iron Age to the early post-Roman period, and two associated corn drying ovens (dating to the 5th–6th centuries AD) were revealed during archaeological excavations at Goldthorpe, South Yorkshire. The site was excavated during 2012 and 2013, during which bulk environmental samples were taken in order to retrieve any surviving botanical remains from deposits associated with the corn drying ovens, and other features across the excavated area. Early post-Roman occupation is under-represented in the archaeological record, especially in northern England, as such human activity and subsistence during this period are currently not well understood. This paper combines evidence for the field system, the physical remains of the corn drying ovens and their associated botanical remains to further understand early post-Roman change and continuity in landscape use and crop production and processing practices. 相似文献
Salt crystallization is a major cause of degradation in old buildings. One of the issues that stills need clarification is regarding the influence of the salts on the capillary absorption and subsequent drying of porous building materials. This article presents an experimental study that included capillary absorption and evaporative drying tests on two types of material (lime mortar and ceramic brick) using pure water or saturated solutions of six salts (sodium chloride, sodium sulfate, sodium nitrate, sodium carbonate, potassium nitrate, or potassium carbonate). The results of capillary absorption agree only roughly with the linear relationship, predicted by theory, between sorptivity and the square root of the ratio between viscosity η and surface tension σ of the solution (σ/η)1/2. This poor agreement is probably due to material heterogeneity. The drying dynamics was regular and showed little dispersion between specimens, but only for the uncontaminated materials. Indeed, the drying dynamics of the salt contaminated materials was often irregular or diverged among similar specimens, and the same happened with their salt decay patterns. The main conclusion is that soluble salts can amplify the effects on drying of the small structural heterogeneities that porous building materials normally depict. 相似文献
Very large late Holocene shell middens (‘megamiddens’, some over 10 000 m3 in extent) along a 20 km section of the west coast of South Africa provide a particular interpretative challenge in determining whether they result from residential visits or from logistical processing of shellfish for transport and consumption elsewhere. The latter interpretation is preferred here and is consistent with stable carbon isotopic readings on coastal human burials and site contents that illustrate that groups visited specific localities, collected and dried black mussels and then transported and consumed the dried product inland. The sizes and contents of these large middens contrasts sharply with those of unquestionably residential residues from earlier and later time periods. This approach is supported with reference to the ethnographically described processing and consumption of mongongo nuts by 20th century San of the Kalahari. 相似文献