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Air transport control has been recognized as critical to the proper functioning of buildings. Airflow is related to all facets of environmental control because it influences transport of heat and moisture and affects indoor environment as well as the durability of the building enclosure. To a lesser degree, we also recognize that contamination of wall cavities in building assemblies by organic materials from inside or outside provides both the nutrients and the inoculation potential for mold growth. Moisture carried by air may also increase the rate of emission of volatile organic compounds from these materials. While keeping rain out of building enclosures is a primary consideration in design, controlling airflow through the building enclosure comes a close second in importance to allow environmental control within buildings. Yet, an increase in the airtightness comes with a cost as well as an increased risk of moisture entrapment in case of any failure, and this, in turn, relates to the type of the building.

Latent heat thermal energy storage (LHTES) using phase change materials (PCM) is one of the most promising ways for thermal energy storage (TES), especially in lightweight buildings. However, accurate control of the phase transition of PCM is not easy to predict. For example, neglecting the hysteresis or the effect of the speed of phase change processes reduces the accuracy of simulations of TES. In this paper, the authors propose a new software module for EnergyPlus™ that aims to simulate the hysteresis of PCMs during the phase change. The new module is tested by comparing simulation results with experimental tests done in a climatic chamber. A strong consistency between experimental and simulation results was obtained, while a discrepancy error of less than 1% was obtained. Moreover, in real conditions, as a result of quick temperature changes, only a partial phase transformation of the material is often observed. The new model also allows the consideration of the case with partial phase changes of the PCM. Finally, the simulation algorithm presented in this article aims to represent a better way to model LHTES with PCM.

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The structure and thermal properties of external walls affect both the thermal conditions inside the building and the energy demand. This applies to the energy requirement for heating as well as cooling. While the relationship between thermal insulation and heating is well-known, the effect of thermal insulation on overheating is not evident. One can find opinions that thick thermal insulation creates a “thermos effect” and significantly deteriorates the comfort conditions during the summer. In order to prove these statements, an office room with south-oriented glazing and a high thermal load from equipment was simulated by means of the Energy Plus program. The reference variant was a two-layer wall made from ceramic blocks and a 10 cm layer of thermal insulation. The duration of overheating in the investigated intensively used office space without window shading was approximately 26 to 29 days per year, depending on the expected comfort acceptance range, while in the case of the not insulated wall, it would be shorter by over 3 days. Increasing the thickness of the thermal insulation layer by up to 30 cm extended the overheating period by 4% to 9%. In relation to the whole simulation period, covering four summer months, this means approximately two extra days of discomfort. The effects of various passive methods of protecting buildings against overheating were also investigated. The use of night ventilation in this facility enables reducing the unfavorable conditions by as much as 31%, or up to 46% of the initial period of overheating. The change of the thermal inertia of a building by replacing the ceramic layer with heavy structural concrete allows a further reduction of the overheating duration by 8% to 9%. When the most effective ways of overheating protection are applied, such as night cooling, even a significant thickening of insulation no longer has any impact on its duration. The results shown above are obviously related to the adopted assumptions. However, on the basis of the conducted analyses, it is possible to reduce concerns relating to excessive insulating the building with respect to overheating. Having an optimal window area with nighttime cooling of buildings, window shading, and the inertial benefits associated with a massive construction are the most important and effective measures of protection against overheating. Efficient thermal insulation of the walls does not conflict with the thermal comfort conditions.

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It is especially difficult to provide optimal microclimatic conditions in sports facilities during summer time. The internal heat gains and an airtight building insulation, combined with high external temperature can easily lead to overheating and upsetting of the body's thermal balance. This article focuses primarily on the effect of natural night ventilation on the thermal comfort in a passive sports hall building. Based on experimental studies of thermal conditions in the hall, a simulation model was made using the Design Builder program. Through simulation analysis, the program considered thermal conditions that arise in various scenarios of natural and mechanical ventilation. Results presented in this article show that the natural ventilation at night in a large volume building is the most effective and the easiest way to reduce overheating in summer.