•Transient thermal performance analysis of typical external walls was conducted.•Light and heavy weight walls were compared under typical summer conditions.•Light walls exhibit larger fluctuations ...and mean values of indoor temperatures.•The effect of passive cooling is dependent on the wall type and configuration.•Thermal insulation position is identified as a decisive factor in thermal response.
Quality of indoor environment as well as energy consumption in buildings are a growing concern in the context of overheating of buildings, as the EU legislation is primarily focused on heating season. The statistical data of EU have shown that there is already a large amount of buildings not comfortably cool during summer and the trend is increasing. Therefore, the main goal of this paper is to evaluate the influence of high intensity passive cooling as one of the passive solutions for overheating of buildings on the overall thermal response of building envelope systems. Specifically, a variety of multi-layer external walls during realistic summer time conditions of Central European climate were considered. For this purpose, a finite element method was used to simulate the non-stationary thermal response of several heavy weight and light weight external wall constructions. The results have shown that indoor air change intensity as well as internal heat gains have a significant impact on heat flow through the building envelope. Clear difference in thermal behaviour was detected between light weight and heavy weight envelope systems, as a consequence of different thermal mass and thermal insulation position. While the results of the conducted study represent guidelines to architects, designers, investors and other stakeholders in building industry, the growing popularity of light weight constructions, especially in residential buildings, dictates further research of building envelope configurations and passive cooling system impact on the thermal response of constructions.
Simulation and experimental investigation of the indirect green façade (IGF) impact on thermal behaviour of buildings is presented in the paper. The study was conducted in Punat, Krk, Croatia, in the ...summer of 2018. The IGF reduced the incident solar radiation by up to 505 W/m2 and façade temperatures by up to 13.5 K. Experimental results were used to simulate the indoor thermal comfort of a simple building model. When IGF was positioned across the entire sun-exposed wall, an average decrease of operative temperature was up to 6 K for a new house and up to 5 K for a traditional stone house.
Global warming will seriously affect buildings, and the Montenegrin building stock is no exception. Since the country is one of the most inefficient energy users in Europe, improving the energy ...efficiency of buildings is essential. Therefore, the study implemented a novel multi-aspect approach to energy retrofitting, linking building thermal performance, occupant interaction and climate change. A representative existing multi-apartment building in Podgorica was selected, and a survey among occupants was conducted to identify their satisfaction with indoor thermal comfort and to evaluate the acceptability of the proposed energy retrofit measures. Next, the thermal performance of the building was simulated under current and future climate conditions. Finally, a comprehensive parametric analysis was performed by applying different retrofit scenarios. The selected retrofit measures were evaluated based on their impact on energy efficiency and occupant acceptability. The results showed that the most impactful retrofit measure would be thermally insulating the building envelope, followed by a lower shading set-point and natural ventilation cooling. Applying the best retrofit combinations would reduce the total energy demand by 75% under the current climate and by 66% and 59% at the end of the 21st century under the RCP4.5 or RCP8.5 scenarios, respectively. However, the occupant survey results disclosed that beyond thermally insulating the building, occupants have limited awareness about the potential of energy retrofit actions, while summer thermal discomfort is the dominant issue. Therefore, building energy retrofit and climate adaptability actions should also address occupant views.
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•a multi-aspect retrofit was proposed to address future overheating resistance.•Global warming would markedly increase the energy need of un-retrofitted building.•Shading and natural ventilation are 2nd and 3rd most effective retrofit actions.•Best combinations of passive measures reached up to 75% energy need reduction.•Occupants underutilise the most effective, albeit low cost, passive measures.
•Thermal response of roof/wall was analysed by altering U value and solar properties.•Solar absorptivity has significant effect on total energy use, especially at U > 0.3.•Optimal total energy use in ...Hamburg and Granada was always achieved by cool coating.•Coating’s solar properties affect indoor thermal comfort in summer and winter.
In recent decades, high level of urbanization, air pollution and climate change have caused a frequent occurrence of urban heat islands, resulting in thermal discomfort and increased energy use of buildings. As a response, a lot of attention has been paid to building envelope characteristics, with an increasing number of studies investigating building envelope solar properties as one of the important factors affecting thermal performance. However, different climate characteristics are the reason why solar properties may have different efficiency at various locations, also because in cold or temperate climates building envelope has to be more thermally insulated, namely having lower thermal transmittance. Therefore, within this study, building energy use and indoor thermal conditions were analysed for an office cell using different types of solar absorptivity (e.g. white, dark grey, collector or cool coating) and thermal transmittance, on either external wall or roof. The analysis was conducted for hot-arid and temperate climate locations. The results showed that solar absorptivity can have a significant effect on total energy use, especially in cases with higher envelope thermal transmittance. It also showed that the application of cool coatings is more reasonable if the external building envelope is not intensively thermally insulated (e.g. in hot-arid climate). In general, the optimal total energy use in both analysed climates was always achieved by implementing cool coatings. Furthermore, the results showed that white and cool coatings have comparable external (20–30 K above Tair in summer) and internal surface temperature responses, while dark grey coatings cause the surface to heat up significantly (external surface 60 K above Tair in summer).
Climate zoning is fundamental to improving building energy efficiency through bioclimatic design principles and passive design strategies. In Sri Lanka, buildings consume approximately 37 % of ...primary energy and about 33 % of total generated electricity. This study aims to carry out bioclimatic zoning and estimate the passive design potential for each bioclimatic zone. Utilising dimensionality reduction through Principal Component Analysis (PCA) and Hierarchical Clustering on 31 years of weather information, Sri Lanka is classified into three distinct bioclimatic zones, namely Z1 (Hot and humid), Z2 (Cool and humid) and Z3 (Warm and humid). An hourly method was used for each zone to determine HDD and CDD. Accordingly, regression models were constructed (R2 > 0.77) to estimate the CDD for each zone for cooling load. Bioclimatic potential analysis is carried out to link climate parameters with building performance. The results demonstrate that natural ventilation is the most effective passive design method with potential 64 ± 13%, 63 ± 10, and 83 ± 4% in a year for hot and humid, cool and humid, and warm and humid zones, respectively. The results emphasise the importance of using bioclimatic classification to design energy-efficient buildings to achieve national energy efficiency goals in low-income countries like Sri Lanka.
•A hierarchical agglomerative clustering method was employed in the study.•Sri Lanka is classified into three bioclimatic zones.•Three bioclimatic zones are Warm and humid, Hot and humid and Cool and humid.•Regression models were proposed to estimate cooling degree days for each zone.•Natural ventilation has the highest potential for passive adaptation of buildings.
The study aimed to develop a holistic, evidence-based calibration strategy and define a hybrid step-by-step methodology for building thermal simulations during the warm season. The methodology was ...demonstrated using the thermal performance of a naturally ventilated single-family log house in a temperate climate. The calibration process was supported by on-site measurements of indoor thermal conditions and occupant behavioural reports between April and July. Hybrid calibration methodology combines statistical indicators, such as NMBE, CV(RMSE), and R
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, and a graphical evaluation of the deviation between the simulated and measured values. After 28 proposed calibration steps, a final calibrated model predicted the actual thermal response of the log house with an accuracy of ±1°C at 71.6% or ±2°C at 98.4% of the considered time. The results showed that occupant-related information, material properties and infiltration rates are crucial to improving the reliability of building thermal models. Moreover, in the calibration process of log houses, appropriate determination of building envelope materials' thermal conductivity, wood's solar absorptivity, and airtightness showed high importance. The study highlights the importance of calibration for reliable building thermal models, specifically in overheating prevention simulations.
U radu je prikazana simulacija i eksperimentalno istraživanje utjecaja indirektne zelene fasade (IZF) na toplinsko ponašanje zgrade. Istraživanje je provedeno na lokaciji Punat na otoku Krku u ...Hrvatskoj tijekom ljeta 2018. godine. Primjenom IZF-a utjecaj sunčevog zračenja smanjen je do 505 W/m2, a temperature na vanjskoj površini fasade smanjene su do 13,5 K. Eksperimentalni su rezultati korišteni za simuliranje toplinske ugodnosti u unutrašnjosti zgrade primjenom jednostavnog modela. Kada je IZF postavljen preko čitavog zida izloženog suncu, prosječno smanjenje operativne temperature iznosilo je do 6 K za novu zgradu, tj. do 5 K za tradicionalnu kamenu kuću.
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