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This paper discusses experimental and simulated data regarding the thermal bridging effect in a reinforced concrete corner pillar, which belongs to a building dating back to the 1980s and located in Southern Italy. The thermal field determined by the concrete pillar corner has been evaluated, introducing an experimental procedure based on both direct measurements and indirect observations of the inner superficial temperature by means of thermal imaging techniques and surface temperature probes. Moreover, indoor and outdoor air temperature and relative humidity were measured to provide suitable boundary conditions in the numerical simulations, performed with a commercial software tool widely used in Italy based on 2D finite element techniques. The experimental measurements show that, at more than 50 cm from the corner, the surface temperatures become almost constant, meaning that the thermal bridging effect becomes less evident. However, the surface temperature in the corner is around 1.5 °C lower than in the undisturbed flanking walls. In terms of local heat flux, the discrepancy between simulations and measurements is below 3%. Finally, this paper verifies the effectiveness of External Thermal Insulation Composite System (ETICS) renovation in reducing the thermal bridging effect of the corner pillar. The results also include the calculation of the linear thermal transmittance with a series of relations available in well-known atlases for thermal bridges and show that these relations are more reliable in the case of uninsulated pillar than for the insulated one. [ABSTRACT FROM AUTHOR]

This paper advances the current knowledge on the use of prefabricated timber-based panels in building renovation by analyzing in detail the thermal performance achieved by two different renovation solutions developed in the framework of the ongoing e-SAFE H2020 project. In particular, these solutions apply to the external walls of a pilot building located in Catania (Italy) as a double-skin façade that increases also the seismic performance of the building. The dynamic energy simulations reveal that the proposed solutions allow reducing the energy need for space heating and space cooling by 66% and 25%, respectively. One further finding is that, although the proposed timber-based renovation solutions are not affected by mould growth and surface condensation risk, the impact of thermal bridges cannot be neglected after renovation. Indeed, despite the strong reduction in the magnitude of heat losses due to thermal bridges (from 667 W·K−1 down to 213.1 W·K−1), they still account for about 21% of total heat losses after the renovation. This suggests that more complex and expensive technological solutions should be introduced to further reduce heat losses in some thermal bridges, but a cost-benefit analysis should justify their adoption. Finally, overlooking these thermal bridges in dynamic energy simulations can lead to an average underestimation of the heating and cooling energy demand after the renovation, by about 16% and 5% respectively. In this regard, the paper proposes a simplified yet reliable approach to include heat transfer through thermal bridges in the post-processing stage of dynamic energy simulations under thermostatic control. • Two different timber-based panels are investigated in the e-SAFE H2020 project. • The paper reports technological details and discusses challenges and solutions. • The energy needs for space heating and space cooling decrease by 66% and 25%. • Thermal bridges are described and quantified in a detailed way through 2D modeling. • After renovation, they still account for about 21% of total heat losses. [ABSTRACT FROM AUTHOR]

In the thermal design of low sloped roofing assemblies, two parameters are overlooked, one is the surface temperature of the roof assemblies which provides the required temperature gradient for heat flow, and the other is the mean operating temperature of the roof assembly, which has direct implications on the thermal performance of the insulation. An in situ field study was conducted in collaboration with Alberta Roofing Contractors Association (ARCA) on their headquarters building located in Calgary, to generate data on the mean operating temperature of the roof assemblies and to determine whether the thermal design of roofing assemblies using conventional methods is an accurate portrayal of in-service thermal performance. For the present study, two roof assemblies insulated with polyisocyanurate insulation, one with a white reflective roof membrane and the other with the black membrane were selected and instrumented. During the monitoring period, the mean operating temperature (MOT) of the roof assembly whether it is calculated as the average of interior and exterior ambient (MOTAIR,) or the average of surface temperatures (MOTSurface), was found to be below 24 °C (75 °F), which opposes the current roof thermal designs that are being designed using label R-value (thermal resistance) of the insulation reported at the mean temperature of 24 °C (75 °F) rather than temperature-dependent thermal resistance. The comparison of two energy transfer theoretical models, QConvention and QMOT, with the measured data indicated that the conventional approach of roof thermal design underestimates the energy performance of the roof assembly on average by 30%. The use of roof surface temperatures and the corresponding temperature-dependent thermal resistance of the insulation as in QMOT has been demonstrated to improve predictions of the energy performance. In addition the loss in thermal resistance due to blowing agent diffusion in polyisocyanurate was evaluated after two years of in situ installation. [ABSTRACT FROM AUTHOR]

Building Energy Simulation (BES) tools usually make use of single Typical Weather Years (TWYs) but the increased calculation capacity now allows for multi-year simulations based on Actual Weather Years (AWYs). This research analyzes how the use of a TWY affects the prediction of the energy demand and the peak load in a residential and an office building located in Catania (Italy), if compared to a multi-year approach. Different TWYs are considered, either developed by the authors according to standard international procedures and based on recent measurements from a local weather station, or already available on the internet. Results show that the adoption of a TWY is useful to assess the mean long-term energy demand, with a preference for the IWEC procedure (mean bias error below 2%). However, TWYs would underestimate the peak heating load by 12.5% and the peak cooling load by around 18% in the residential building, while in the office building the underestimation can be even higher. In the absence of specific design weather files when the aim of the simulations consists in sizing the mechanical systems, the peak values of the AWYs distribution based on the last 10–15 years of measurement should be preferred to TWYs. • Different weather datasets can be used in Building Energy Simulations (BES). • Typical Weather Years (TWYs) and Actual Weather Years (AWYs) are contrasted. • TWYs are found reliable enough to assess the mean long-term energy demand (MBE<2%). • AWYs are preferrable for sizing mechanical equipments. [ABSTRACT FROM AUTHOR]