Journal of Building Physics

The quest for a sustainable built environment brought dramatic changes to architectural design because of the integrated design process. The integrated design process is the modern way to realize “performance architecture,” that is, design with a view to field performance. Integrated design process permits merging of concepts from passive-house designs, solar engineering, and an integration of the building enclosure with mechanical services. In part 1 of this series, the emergence of many new multi-functional materials was discussed. Yet, current innovation is guided by lessons from history. Thermal mass in heavy masonry buildings allowed periodic heating. The authors postulate integration of a hydronic heating system with the walls and the use of smart temperature control of the heating system to modify and optimize the thermal mass contribution. To use the mass of a building, one must accept transient temperature conditions where the indoor temperature varies but is confined by comfort requirements for both summer and winter conditions. On the other side, resiliency requirements dictate that in the absence of electricity the air temperature does not fall below about 12°C over a period of several hours. This requirement implies that summer cooling will likely be separated from the heating systems and that operation of a low-energy building is heavily dependent on the design of smart control systems. Analysis of control systems provided in this article for earth-to-air heat exchangers and cooling of houses with lightweight walls lead us to the requirements of separation between heating and ventilation and needs for different sources of fresh air. Finally, a new concept emerges.

Hydronic floor heating models provide predictions in estimating heat transfer rates and floor surface temperature. Information on the model performance and range of validity of its results are often lacking in literature. Researchers have to know the accuracy and robustness of the model outcomes for performing energy and climate comfort calculations. This article proposes a novel validation methodology based on the uncertainty analysis of input data/parameters of one-dimensional model of hydronic floor heating tested in a thermostatic booth simulator and compared with experimental measurements. The main results are: (1) prediction accuracy between 0.4% and 2.9% for T ¯ f and between 0.7% and 7.8% for q · up when the serpentine has tube spacing (p) of 0.30 m, (2) prediction accuracy between 0.5% and 1.4% for T ¯ f and between 8.7% and 12.9% for q · up with p = 0.15 m and (3) T ¯ fld mostly affects predictions with oscillations between 6.2% and 2.2% for q · up . This model provides robust and reliable predictions exclusively for q · up when p = 0.30 m.

The influence of the massive wall material, thickness and ventilation system on the Trombe wall thermal performance was analysed based on an analytical methodology. Results obtained from experimental work will also be added to this study. During the heating season, for the non-ventilated Trombe wall, the global heat gains decrease is not proportional to the thickness increase, and this ratio depends on the massive wall material heat storage capacity. A ventilation system in the massive wall leads to higher heat gains due to the air convection, but this growth is not in the same proportion for the different materials. If solid brick or earth is used, heat gain values are much higher than those obtained if there is no ventilation system, increasing to the double in the case of earth and 2.5 times more in the case of solid brick. When the massive wall is ventilated and made of granite, an increase in the gains of 44.06% is obtained when compared with the non-ventilated. During the cooling season, closing the ventilation system and the external shutter leads to heat gains considerably lower than those obtained during the heating season. In this case, earth can be a suitable material.

Nowadays, the construction is one of the main European sectors responsible for the high levels of energy consumption and raw material extraction. Increasingly, the energy consumption from renewable sources and industrial waste reuse are the only ways to minimize these environmental and societal problems. Simultaneous incorporation of phase change materials and fly ash in the mortars increases the energy efficiency and decreases the waste materials landfilled. The development of mortars with phase change materials and fly ash incorporation contributes to a significant improvement of the building comfort parameters and the environmental quality. The phase change materials possess the capability to normalize the temperature flux inside the buildings, using the solar energy as resource. The main purposes of this study were the physical, mechanical, and thermal characterization of mortars with phase change materials and fly ash incorporation. It was concluded that the phase change materials and fly ash simultaneous incorporation leads to homogeneous and suitable mortars with increased thermal behavior compared with the phase change material addition alone.