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Kristo Kalbe

Other affiliations: Tallinn University
Bio: Kristo Kalbe is an academic researcher from Tallinn University of Technology. The author has contributed to research in topics: Moisture & Thermal transmittance. The author has an hindex of 2, co-authored 7 publications receiving 11 citations. Previous affiliations of Kristo Kalbe include Tallinn University.

Papers
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Journal ArticleDOI
TL;DR: In this paper, the authors focused on data collected from existing zero-energy buildings (nZEB) day-care centers, in order to be able to assess possible differences between predicted and actual energy and indoorenvironmental performance.
Abstract: The European energy policy pushes the member states to transform building stock into nearly Zero-Energy Buildings (nZEB). This paper is focused on data collected from existing nZEB day-care centres,in order to be able to assess possible differences between predicted and actual energy and indoorenvironmental performance. Building structures, service systems and the indoor climate and energyperformance of five day-care centres were investigated in Estonia, Finland and Norway.Indoor climate condition measurements showed that in general, the thermal environment and indoor airquality corresponded to the highest indoor climate categories I and II (EN 15251). Building heating andventilation systems in studied buildings are working without major problems. Good indoor climate conditions were also reflected in the occupant satisfaction questionnaires. For most of the studied buildings, over 80%of the people marked all indoor environment condition parameters (thermal comfort, indoor air quality,acoustics, odour and illuminance) acceptable. The thermal environment in the cooling season was reportedproblematic because it was lower than the minimum temperature for indoor climate category II.Energy consumption analysis showed that measured real energy use was higher, or even significantlyhigher, than the energy use calculated during the design phase. Potential causes of the higher actualenergy consumption are caused by differences of measured and designed solutions, methodology of theenergy calculations, and the differences in user behaviour.Lessons learnt from previously constructed day-care centres can be utilised in the planning and designof new nZEBs.

6 citations

Journal ArticleDOI
01 Sep 2020
TL;DR: In this paper, the authors observed the construction works and monitored the timber moisture content (MC) of a cross-laminated timber (CLT) building and proposed a set of activities and designed connection details that could help to avoid moisture ingress during the installation of CLT panels.
Abstract: Wetting of timber structures during erection can have a harmful effect on their durability and could lead to adverse health effects. The probability of dampness related problems is very high when timber is exposed to free water. However, it is not always possible to implement full weather protection and thus there is a need for cost optimal solutions to increase the moisture safety of precipitation-exposed timber construction. In this study we observed the construction works and monitored the timber moisture content (MC) of a cross-laminated timber (CLT) building and proposed a set of activities and designed connection details that could help to avoid moisture ingress during the installation of CLT panels. Our findings showed that the most sensitive area to wetting is the end-grain on the CLT panel and the MC remained within critical limits in structures where drying was prohibited. Therefore, the most vulnerable section of the CLT structure is the foundation connection. We suggest using liquid-applied membrane coating on the cut edges of CLT panels to protect the end grain and to cover the horizontal CLT panels with self-adhesive membranes and vertical CLT panels with temporary clear weather protection foils.

4 citations

Journal ArticleDOI
TL;DR: In this article, the influence of window frame thermal transmittance, window frame width and window installation depth on the energy consumption of a single-family prefabricated timber nZEBlocated in Estonia was examined.
Abstract: One of the largest sources of heat loss in buildings are the windows. However, windows are alsoimportant to increase solar heat gain and provide daylight. It is necessary to understand how windowdetails influence the energy performance of very energy efficient houses. This is valuable informationfor the design decision making process and may lead to further research or product development. Thispaper examines the influence of window frame thermal transmittance, window frame width and windowinstallation depth on the energy demand of the building. A single-family prefabricated timber nZEBlocated in Estonia was used as a reference building for this study. The results show that decreasing thethermal transmittance and width of the window frame have a remarkable effect on the energy demandof the nZEB (a variation of 42% and 25% respectively). The effect of optimising window installation depthis insignificant (ca 3% variation of heat demand on most of the window placement range and up to 10%of increase in heat demand when comparing the optimal placement to the least effective one). However,it can further improve the energy performance.

4 citations

Journal ArticleDOI
01 Sep 2020
TL;DR: In this paper, the authors analyzed moisture dry-out from a steel faced insulated sandwich panel in a laboratory under different climatic conditions and to obtain data for simulation model calibration using the Delphin simulation tool.
Abstract: This study analyses moisture dry-out from a steel faced insulated sandwich panel Three test walls, with lower parts close to the free water level, were studied in a laboratory under different climatic conditions to measure their dry-out capacity and to obtain data for simulation model calibration The hygrothermal simulations were done with the simulation tool Delphin in stable climatic conditions to determine the magnitude of the moisture dry-out capacity Comparison of the measured and simulated relative humidity showed sufficiently good agreement The results indicate that panels of this type have some dry-out capacity under summer and spring climatic conditions (about 2–3 g/day at best) but during autumn and winter their dry-out capacity is limited In case of a water leakage (eg due to rain during the installation of the panels), the moisture dry-out is negligible To minimise the wetting of insulation, weather protection during construction and during storage is necessary

2 citations

Journal ArticleDOI
01 Sep 2020
TL;DR: In this article, the authors present results from laboratory measurements of mineral wool insulated steel sandwich panels and study how the structure behaves in water leakage situation, which implies that the limiting factor for moisture source was the evaporation rate from the water leakage and that the vapour pressure throughout the insulation layer is determined strongly by the possible condensation layer.
Abstract: This study presents results from laboratory measurements of mineral wool insulated steel sandwich panels. The purpose of the work was to have a better understanding on the heat and moisture conditions inside sandwich panels and to study how the structure behaves in water leakage situation. The tests were done by sealing the structure from all sides and regulating the temperature on one side of the test structure while measuring the temperature and relative humidity conditions inside the structure. Water leakages were created by injecting liquid water onto the insulation layer. According to the results, water vapour pressure differences stayed relatively small both in stationary and dynamic conditions. This implies that the limiting factor for moisture source was the evaporation rate from the water leakage and that the vapour pressure throughout the insulation layer is determined strongly by the vapour pressure at the possible condensation layer. The paper discusses also the determination of sensor accuracy and impacts of a thermal bridge from the probe itself. Also, measurement results from a new radio wave monitoring method are presented.

2 citations


Cited by
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Journal ArticleDOI
TL;DR: In this paper, a broad range of building performance monitoring, sampling, and evaluation was conducted periodically after construction and spanning more than a year, for an occupied office building constructed using mass timber elements such as cross-laminated timber (CLT) floor and roof panels, as well as glue-lammed timber (GLT) beams and columns.
Abstract: A broad range of building performance monitoring, sampling, and evaluation was conducted periodically after construction and spanning more than a year, for an occupied office building constructed using mass timber elements such as cross-laminated timber (CLT) floor and roof panels, as well as glue-laminated timber (GLT) beams and columns. This case study contributes research on monitoring indoor environmental quality in buildings, describing one of the few studies of an occupied mass timber building, and analyzing data in three areas that impact occupant experience: indoor air quality, bacterial community composition, and floor vibration. As a whole, the building was found to perform well. Volatile organic compounds (VOCs), including formaldehyde, were analyzed using multiple methods. Formaldehyde was found to be present in the building, though levels were below most recommended exposure limits. The source of formaldehyde was not able to be identified in this study. The richness of the bacterial community was affected by the height of sampling with respect to the floor, and richness and composition was affected by the location within the building. Floor vibration was observed to be below recognized human comfort thresholds.

11 citations

Journal ArticleDOI
TL;DR: In this article, the authors analyzed the air leakage of joints filled with polyurethane foam and its influencing factors and found that planed, sawn and plastic-coated cavities and two cavity thicknesses contributed to very variable airtightness.
Abstract: Air leakage through the building envelope joints is usually one of the main reasons why airtightness targets are not achieved. The objective of this study was to analyse the air leakage of joints filled with polyurethane foam and its influencing factors. Wooden test specimens (54 in total) with planed, sawn and plastic-coated cavities and two cavity thicknesses were filled with three different polyurethane foams and tested according to standard EN 12114. The surface type and thickness of the joint had a significant effect on the air leakage of joints filled with polyurethane foam. In laboratory conditions, a consistent and very low air leakage rate was obtained with planed timber surfaces. Joints with plastic-coated and sawn timber surfaces performed worse, on average, by a factor of two or more and contributed to very variable airtightness, with up to 28% and 50% of the test specimens failing the airtightness testing. On the basis of the high ‘failure rate’, polyurethane foam may classify as a not completely trustworthy solution in guaranteeing the airtightness of construction joints. A comparison of estimated and previously measured overall airtightness of an entire building envelope showed dependency on ‘failure rate’ rather than on average measured leakage rate.

9 citations

Journal ArticleDOI
TL;DR: In this paper , the authors carried out a week-long monitoring of CO 2 , temperature and relative humidity (RH) in five low-income residential kitchens of 12 global cities (Dhaka, Chennai, Nanjing, Medellín, São Paulo, Cairo, Sulaymaniyah, Addis Ababa, Nairobi, Blantyre, Akure and Dar-es-Salaam).
Abstract: In-kitchen air pollution is a leading environmental issue, attributable to extensive cooking, poor ventilation and the use of polluting fuels. We carried out a week-long monitoring of CO 2 , temperature and relative humidity (RH) in five low-income residential kitchens of 12 global cities (Dhaka, Chennai, Nanjing, Medellín, São Paulo, Cairo, Sulaymaniyah, Addis Ababa, Nairobi, Blantyre, Akure and Dar-es-Salaam). During cooking, the average in-kitchen CO 2 concentrations were 22.2% higher than the daily indoor average. Also, the highest CO 2 was observed for NV d (natural ventilation-door only; 711 ± 302 ppm), followed by NV dw (natural ventilation-door + window; 690 ± 319 ppm) and DV mn (dual ventilation-mechanical + natural; 677 ± 219 ppm). Using LPG and electric appliances during cooking exhibited 32.2% less CO 2 than kerosene. Larger kitchens ( 46–120 m 3 ) evinced 28% and 20% less CO 2 than medium (16–45 m 3 ) and small (4–15 m 3 ) ones, respectively. In-kitchen CO 2 with >2 occupants during cooking was 7% higher than that with one occupant. 87% of total kitchens exceeded the ASHRAE standard (RH >40%, temperature >23 °C) for thermal comfort. Considering the ventilation type, both the ACH (air change rate per hour) and ventilation rate followed the order: NV dw > NV d > DV mn , while the trend for weekly average CO 2 concentration was NV d > DV mn > NV dw . Larger kitchens presented 22% and 28% less ACH, and 82% and 190% higher ventilation rate than medium- and small-volume ones, respectively. Forty-three percent kitchens had ACH <3h −1 and ventilation rate <4L/s/person, hence violated the conditions for ideal ventilation. Moreover, 10% of the Hazard Ratio values for 25% kitchens exceeded the CO 2 reference value (1000 ppm). Consequently, our findings prompted several recommendations towards improving in-kitchen ventilation and environmental conditions of low-income homes. • In-kitchen CO 2 exposure in 60 low-income homes across twelve major cities was measured. • Larger volume kitchens exhibited 28% less CO 2 concentrations than the medium-sized ones. • Dual (mechanical + natural) ventilation resulted in improved thermal comfort during cooking. • Large-volume (>45 m 3 ) kitchens using natural gas/natural ventilation met daily proper ventilation. • Hazard ratio was above the standard limit in 25% of the investigated kitchens.

7 citations

Journal ArticleDOI
TL;DR: In this paper, the authors investigated the effects of various solutions applied for energy supply to nursery buildings in reference to their energy performance indicators in the cold climate of Central Europe by analyzing various heat source and PV installation setups.
Abstract: Nowadays, high energy efficiency and low environmental impact of buildings are required, regardless of external climate conditions. This demand is essential in the case of nursery buildings, due to strict requirements concerning indoor temperature. The following study investigates the effects of various solutions applied for energy supply to nursery buildings in reference to their energy performance indicators in the cold climate of Central Europe by analyzing various heat source and PV installation setups. A gas boiler and two heat pumps types were tested as the heat source, together with varying PV installation configurations. Nursery building computation model was diversified in terms of ventilation. Both natural ventilation and mechanical ventilation system with heat recovery were tested. A total of 24 variants were suggested and analysed by computation of monthly and annual energy demands. The study was intended to determine the importance of PV installation in nursery buildings for Central European conditions. The analysis of the results indicated that for buildings where power is mostly supplied by electricity, application of PV installations exerts most significant impact on their energy performance indicators. The contribution of clean renewable energy was greatest for the building model with cascade of air-source heat pumps and 60 kWp PV installation. Apart from no PV installation variants, the lowest impact of PV installation was observed in the naturally ventilated building model with gas condensing boiler as the heat source and with 10 kWp PV installation. The present research is applicable for designing energy supply solutions for early education buildings.

6 citations

Journal ArticleDOI
TL;DR: In this paper , the authors evaluated the impact of vapour permeable and low permeable highly insulated external wall assemblies, façade orientation, and initial moisture content on the hygrothermal performance of cross-laminated timber (CLT) external walls.

6 citations