Modelling the hygrothermal behaviour of crop-based insulation products is essential to assess their impact on the energy performance of the building, predict indoor climate conditions, and prevent any risk of unexpected degradation. Traditionally, transient numerical models that predict internal conditions of construction materials consider that the variation of moisture storage with temperature is negligible although the sorption behaviour is known to be temperature dependent. This paper investigates this particular effect for crop-based materials and uses a refinement of standard mathematical representations. For this purpose, the effects of a thermal shock on the evolution of hygrothermal conditions inside a straw-bale wall are studied with several versions of a flexible research model. The latter is capable of incorporating the temperature dependency of the sorption curve with both a physically-based and an empirical description. A large climate chamber is used to gather experimental data and is able to host a full-size straw bale prefabricated panel. Internal conditions of straw bales are obtained with proper sensors bars. Results show that when large temperature gradients occur in a crop-based material, a model that considers temperature effect on moisture storage enhances greatly the prediction of internal conditions.

Measurements obtained from two non-air-conditioned outdoor full-scale test cells during a year in Torreón, Coahuila, Mexico, are used to compare the thermal performance of two envelope constructive systems for walls and roofs of monolithic concrete buildings. The two constructive systems have the same thickness, one is mono-layered and other is two-layered. The two-layered constructive system has a better thermal performance due to its larger thermal resistances and thermal capacity, and the more-layers effect. The experimental data were compared with numerical simulation results obtained with EnergyPlus using the time-dependent heat transfer model. The numerical results are, in general, in good agreement with the experiments. The surface lag time is the variable with the largest differences.

Water penetration in porous materials is ubiquitous to building envelopes subjected to environmental conditions. Such liquid uptake can occur at different temperatures. The effect of temperature on liquid uptake is investigated in the range of 5°C–55°C in this work. Experiments are performed in controlled conditions, and the rising water front is monitored through electrical conductivity measurements along the height of the samples. The effect of temperature on the uptake process is further studied by numerical simulations, validated with the experiments. In modeling, although directly taking into account the temperature dependence of liquid viscosity is preferable, simply taking into account the temperature dependence of saturation vapor pressure seems to be sufficient.

In the last years in European countries, important measures were taken in order to reduce the energy need of buildings. Nevertheless, the energy need for cooling of buildings is rising. In most cases, to assure the required operative temperature, air conditioning systems are installed. Consequently, in summer period, the power networks of different European countries are overloaded. In order to determine the effects of glazed area orientation, air change rate, and thermal mass on the indoor air temperature, at the University of Debrecen, the Passol Laboratory was built. Measurements were performed from 2009 to 2013. Using the methodology given by EN ISO 13790:2008, the variation of indoor temperature was calculated and the theoretical values were compared with values obtained from measurements. The indoor temperature variation and the energy need for cooling were analyzed for different building structures, different orientations of the glazed area, and air change rates. The calculations have proven that the energy need for cooling can be reduced even to 25% of the thermal mass and the air change rate is chosen properly.

The temperature effect on water vapor transport properties of calcium silicate is studied, together with the influence of sample thickness. For material characterization purposes, the bulk density, matrix density, and total open porosity are measured at first. Sorption and desorption isotherms are measured using dynamic vapor sorption device in order to characterize the water vapor storage in researched material. The sorption process is analyzed for original material samples as well as for finely ground samples in order to evaluate the effect of inner porous space on water vapor storage. The steady state cup method is used for determination of water vapor transport properties, whereas the measurements are performed at several temperatures and for three different sample thicknesses. The obtained data show an important effect of temperature on water vapor transport and storage in studied material. The results also indicate a substantial influence of sample thickness on the calculated water vapor transmission properties.

Interior thermal insulation is frequently one of the only possible solutions for thermal upgrade of the building envelope where the external appearance cannot be changed. In this study, four insulation materials were used in a case study in a historical school building in in situ test walls. The indoor climate in the test room was controlled to simulate the typical dwelling with high moisture load. The temperatures, relative humidity, and heat flows were monitored over 9 months to analyze the hygrothermal performance of four different insulation materials. The hygrothermal performance of insulation materials during drying and wetting periods are presented. Moisture test reference year was used in working out possible energy-renovation solutions. The results show that timing of the renovation works is a matter of consideration to avoid the hygrothermal risks inside the renovated wall assemblies. The results show that in all the cases, thermal comfort can be improved by increasing the inner surface temperature and decreasing thermal conductivity. However, in some cases, the risks of mold growth and interstitial condensation were present inside the retrofitted wall assemblies. Computer simulations of the wall assemblies with moisture reference years under different humidity loads concluded that all solutions are suitable for future analysis.

To improve the construction methods of Chinese solar greenhouse wall to enhance the heat storage, we proposed a three-layer wall with phase-change materials, namely, an inner wall layer built with the phase-change materials, an outer insulating layer and a load-bearing wall layer built with heavyweight materials between the two. Based on the field experiment and the proposed valuation indexes of the three-layer wall, the dynamic heat storage characteristics of the wall have been analysed and discussed. The experiment and simulation results showed that the three-layer wall can enhance the heat storage and thermal insulation properties of greenhouse wall, increase the utilisation rate of solar energy, improve indoor thermal environment and increase crop yield and quality. Therefore, these results validated the suitability and correctness of the construction methods of the three-layer wall.

A method of determining the retro-reflectance of retro-reflective materials used for building coatings is proposed in this article. In addition, the durability of retro-reflective materials over long-term outdoor exposure is also estimated. Retro-reflective materials are currently limited to use in specific purposes, such as road traffic signs in Japan. To consider their application as a building coating, it is also necessary to examine the thermal performance and durability of retro-reflective materials. We proposed a method of determining the retro-reflectance of retro-reflective materials (capsule retro-reflective material and prism retro-reflective material were used in this experiment) by experiment. To explore the durability of retro-reflective materials over long-term outdoor exposure, we measured the changes in solar reflectance and retro-reflectance of retro-reflective materials exposed to the outdoors over about 25 months. The solar reflectance of capsule retro-reflective material decreased from 0.69 to 0.51 and that of prism retro-reflective material decreased from 0.83 to 0.81. The retro-reflectance of capsule retro-reflective material decreased from 0.18 to near 0 (0.0072) and that of prism retro-reflective material decreased from 0.44 to 0.42. At the end of the test period, we cleaned the surface of the retro-reflective materials. Both of the retro-reflective materials recovered about 50% of the lost solar reflectance by cleaning. The retro-reflectance of capsule retro-reflective material increased by about 0.08 (46% recovered) by cleaning and that of prism retro-reflective material increased by only 0.01 (with 50% recovered) by cleaning. We concluded that the durability of prism retro-reflective material is better than that of capsule retro-reflective material for use on building coatings.

In residential buildings, a typical rainscreen exterior wall system often incorporates an exterior membrane mechanically fastened to an exterior sheathing. This thin and flexible membrane is an important component of the wall system and performs multiple functions. Under a negative air pressure differential, that is, wind suction, the exterior membrane can deform or balloon. The membrane ballooning has important implications on many performance issues in the rainscreen exterior wall system. That the membrane ballooning changes the air cavity volume and therefore affects rainscreen pressure equalization is one important implication. Since the 1980s, many theoretical pressure equalization models have been proposed. This article takes a unique viewpoint and focuses on reviewing how the theoretical screen pressure equalization models consider the effect of membrane ballooning. It is believed that such a review is essential for future study on how to incorporate the membrane ballooning into the pressure equalization model.

The 2009 ASHRAE Handbook of Fundamentals (Chapter 26) provides a table that contains the thermal resistances (R-values) of enclosed airspaces for different values of airspace thickness, effective emittance, mean airspace temperature, and temperature differences across the airspace. This table is extensively used by modelers, architects, and building designers in the design for thermal resistance of building enclosures. The effect of the airspace aspect ratio (length/thickness) on the R-value is not accounted for in the ASHRAE (American Society of Heating, Refrigerating and Air-Conditioning Engineers) table. However, in previous studies, it was shown that the aspect ratio of the airspace can affect its R-value. In this article, the previous studies by the author who focused on determining the R-value for vertical enclosed airspaces and horizontal enclosed airspace under upward heat flow condition are extended to investigate the effect of the aspect ratio on the R-value of horizontal enclosed airspaces under a downward heat flow condition for different airspace thicknesses and having a wide range of values for effective emittance, mean temperature, and temperature differences across the airspaces. The R-values predicted from numerical simulation are compared with those provided in the ASHRAE table. Considerations were also given to investigate the potential increase in the R-values of enclosed airspaces when a thin sheet is placed horizontally in the middle of the airspace and whose surfaces have different values of emissivity. Thereafter, practical correlation was developed for determining the R-values of horizontal enclosed airspaces for future use by modelers, architects, and building designers. The simplicity of this correlation derived for horizontal airspaces under downward heat flow condition together with those that were previously developed for vertical airspaces and horizontal airspaces under upward heat flow condition suggests that these correlations could be included in the ASHRAE Handbook of Fundamentals.