bluuebunny/crossref_metadata_2025 huggingface dataset:
Using convolutional neural networks for hygrothermal predictions to extrapolate to other external climates
Authors: Tijskens Astrid , Janssen Hans , Roels Staf
Published: June 2020

When simulating the hygrothermal behaviour of a building component, many uncertainties are involved (e.g. exterior and interior climates, material properties, configuration geometry). In contrast to a deterministic assessment, a probabilistic analysis enables including these uncertainties, and thus allows a more reliable assessment of the hygrothermal performance. This easily involves thousands of simulations, which easily becomes computationally inhibitive. To overcome this time-efficiency issue, a convolutional neural network, a type of metamodel mimicking the original model with a strongly reduced calculation time, can replace the hygrothermal model. This was proven in a previous study for a massive masonry wall, where variability of exterior and interior climate, brick material properties and wall geometry was included. However, the question rises whether it is possible to train the network on a limited number of climates, and afterwards use the network to predict accurately for other climates as well. This paper thus focuses on this aspect, and results show that, as long as the range of the new climate data falls within the range of the climate data the network was trained on, the network is able to predict accurately for new climates as well.
Modelling the moisture redistribution in concrete floors with screed and flooring material with varying properties
Authors: Nilsson Lars-Olof , Olsson Nilla , Mundt-Petersen S.Olof , Lindmark Sture , Lindskog Mathias , Kumlin Anders , Oxfall Mikael , Tannfors Johan
Published: June 2020

Flooring materials and adhesives can be degraded by high pH moisture from e.g. concrete. One way to avoid this degradation, is to dry the concrete and the screed to a sufficient moisture state prior to application of the flooring material. One way to evaluate the moisture state in the materials sensitive to high pH moisture is to calculate the redistribution of moisture in the flooring system from application and onwards. The calculations require substantial knowledge in both moisture related material properties and mass transport calculations in porous materials. The availability of more user-friendly calculations tools stresses the need for a common methodology for both performance and documentation of the calculations. Several input parameters are needed for the calculation, such as boundary conditions, initial moisture distribution and material properties. The most important material properties are the water vapor sorption isotherms (desorption, absorption and scanning) and moisture transport coefficients. This study is investigating the sensitivity of the moisture redistribution calculations to different input parameters, and assumptions needed for the calculation. It is also clarifying what relative humidity intervals that are relevant for different materials in the system and identifying a required accuracy in the different material properties. A first part of round-robin studies with selected cases has been performed to evaluate difference between calculations tools and users.
Use of radon barriers to reach an acceptable radon level
Authors: Valdbjørn Rasmussen Torben , Cornelius Thomas
Published: June 2020

A method is presented for theoretically estimating the necessary airtightness of a radon barrier. Radon barriers are used to balance the indoor radon concentration. To balance radon at an acceptable level, for a given ventilation rate for indoor air, a barrier must fulfil the requirements for airtightness and the indoor-air radon penetration from the soil, which is determined by the radon concentration in the soil gas. The method identifies the optimal radon barrier for a building. Ten different radon barriers are evaluated. Barriers include system solutions based on materials such as bitumen-based radon blockers, wet-room membranes, reinforced fix mortar pastes, and polyethylene membranes. The barriers are tested using a modified version of the test method NBI 167/02 radon membrane: test of airtightness. The radon barriers are evaluated for a typical building construction for a single-family house with radon exposure from the ground. An acceptable radon concentration of 100 Bq/m3in indoor air is used in combination with a number of higher radon levels. The different radon barriers are evaluated in accordance with their ability to prevent air penetration from the ground. Furthermore, how mounting a barrier can affect the durability of a building is discussed, as the measures may create a far more vulnerable building.
The Impact of Infiltration on Heating Systems Dimensioning in Estonian Climate
Authors: Simson Raimo , Rebane Taaniel , Kiil Martin , Thalfeldt Martin , Kurnitski Jarek
Published: June 2020

In this study we analysed the climatic conditions for infiltration estimation, different calculation methods and infiltration impact on heat load for heating systems dimensioning. To determine the wind conditions at low air temperatures of the coastal- and inland climatic zones in Estonia, 42 years of climatic data for Tallinn and Tartu were investigated. Calculation models with detailed air leakages were constructed of a single and two-storey detached house using dynamic simulation software IDA ICE. Simulations were carried out with the constructed calculation models, simulating various wind and sheltering conditions to determine the heating load of the buildings under measured wind conditions at the design external air temperatures. The simulation results were compared with results calculated with European Standard EN 12831:2017, methodology given in the Estonian regulation for calculating energy performance of buildings and with simulations using the default settings in IDA ICE based on the ASHRAE design day conditions. The percentage of heat losses caused by infiltration was found as 13-16% of all heat losses for the studied buildings. Simulations with historical climate periods showed that even in windy weather conditions the heating system dimensioned by the methods analysed may not be able to provide the required indoor air temperature. Analysis using the coldest and windiest periods showed that when systems are dimensioned by the studied methods, the highest decline in indoor air temperature occurs on the windiest day and not on the coldest day. The impact of high wind speeds and low sheltering conditions resulted up to 50% of all heat losses.
Influence of airtightness of steel sandwich panel joints on heat losses
Authors: Kuhnhenne Markus , Reger Vitali , Pyschny Dominik , Döring Bernd
Published: June 2020

Energy saving ordinances requires that buildings must be designed in such a way that the heat transfer surface including the joints is permanently air impermeable. The prefabricated roof and wall panels in lightweight steel constructions are airtight in the area of the steel covering layers. The sealing of the panel joints contributes to fulfil the comprehensive requirements for an airtight building envelope. To improve the airtightness of steel sandwich panels, additional sealing tapes can be installed in the panel joint. The influence of these sealing tapes was evaluated by measurements carried out by the RWTH Aachen University - Sustainable Metal Building Envelopes. Different installation situations were evaluated by carrying out airtightness tests for different joint distances. In addition, the influence on the heat transfer coefficient was also evaluated using the Finite Element Method (FEM). The combination of obtained air volume flow and transmission losses enables to create an "effective heat transfer coefficient" due to transmission and infiltration. This summarizes both effects in one value and is particularly helpful for approximate calculations on energy efficiency.
Development of air tightness prediction method of masonry walls
Authors: Geležiūnas Valdemaras , Banionis Karolis , Paukštys Valdas , Kumžienė Jurga
Published: June 2020

Recently, the construction of external walls of various blocks, which are externally insulated with mineral wool thermal insulation layer, with ventilated air gap and external finishing (ventilated wall structures) is becoming popular for public and office buildings. These blocks are used without internal rendering because they have a good interior surface, stable dimensions, and various filling of masonry joints provide an attractive architectural appearance. This reduces the cost and duration of construction work, however, problems with airtightness of such walls often occur. The air can penetrate through blocks or their joints, and the thermal insulation and wind protection layer does not usually provide the required air tightness of the wall. Currently, there are no standard methods to predict the air tightness of such wall, in practice, samples of particular walls are produced and their air permeability is measured at the laboratories. This is a costly job, which is only suitable for a combination of particular building materials. For the broader use of results of laboratory air permeability measurements, a methodology has been developed to predict the air permeability of block masonry walls using experimentally determined air flow resistances of the individual layers. The masonry from blocks, made of ceramic, expanded clay and aerated concrete with various joints, were used for the research; mineral wool boards of various air permeability were used for thermal insulation and wind protection layer. After measuring the air resistance of masonry units, thermal insulation and wind protection boards, the air flow resistances of the walls of different construction were calculated. The comparison of calculated and measured air permeability of wall samples showed that in cases where the nature of air movement (laminar to turbulent) through a single material remains similar with the nature of air movement through the product incorporated in the structure, the calculation and measurement data differ no more than 12-15%. In structures with building products with very different air permeability properties, especially at high thicknesses of air permeable thermal insulation products, air movement parameters change occurs and calculated and measured results have larger differences.
Cold windows induced airflow effects on the thermal environment for a large single-zone building
Authors: Zhang Ying , Olofsson Thomas , Nair Gireesh , Zhao Chenbo , Yang Bin , Li Angui
Published: June 2020

With access to modern building technologies and HVAC-systems, it is possible to obtain low energy use and good thermal comfort for complex design, such as large building volumes. However, the situation is different for large single zone buildings with large volumes. They often have insufficient thermal comfort. The problem could be partially attributed to the unwanted airflows due to the cold surfaces, especially the windows. With increased knowledge of the airflow, it is possible to identify suitable renovation strategies in such buildings. In this work, we study a church building with mechanical air change system and floor heating. CFD-simulations with dynamic airflow was conducted based on building geometries and technical data. The validation was based on data from the ventilation control and the space-heating system. The results show how the window-to-wall ratios and the positions of windows affect the thermal comfort. It contributes with knowledge of advantages and disadvantages of different envelope design in the existing environment with floor heating.
Field measurements and CFD simulation of a room in an elderly care center in Lithuania to evaluate air quality and thermal comfort
Authors: Dobravalskis Mantas , Šeduikytė Lina , Didžiariekytė Ugnė
Published: June 2020

Aging is one of the biggest challenges that our society will face in the next decades to come. Multiple sources predict that the number of elderly people will rapidly increase in a lot of regions around the world. In Europe alone it is estimated that the number of elderly people will increase by up to 5 times in the next 30 years. With a growing number of elderly people, the importance of taking care of them also grows. Therefore, we need to make sure that the conditions they live in are suitable for their specific needs: both comfort vise and health vise.

To evaluate the current situation and issues in elderly care centers field measurements were taken in ECC in Kaunas, Lithuania. During these measurements, data were collected about temperature and relative humidity at multiple rooms in the care center. Gathered data was analyzed and major issues were noticed. The second stage of this study included CFD simulations of one of the rooms that ECC residents live in. Currently, this building only has natural ventilation in all of its rooms. Mechanical ventilation was simulated to see how it would impact air quality and thermal comfort in such rooms. Two main types of ventilation were simulated: mixing ventilation and displacement ventilation. Both methods were compared to natural ventilation and each one was evaluated as a potential solution for solving current issues in elderly care centers. It is also important to make sure that the solution chosen is sustainable and can be widely implemented.
Influence of the lateral source/building separation on vapour intrusion: A numerical study
Authors: Rios Mora Juan Sebastian , Collignan Bernard , Diallo Thierno , Abadie Marc , Limam Karim
Published: June 2020

Various vapour intrusion (VI) models have been proposed in order to predict indoor concentration of Volatile Organic Compounds (VOCs) in buildings. However, these models tend to be conservative, and overestimate or underestimate vapour flux emissions due to several assumptions. Particularly, most of these VI models only consider an infinite uniform contaminated groundwater as the principal source of VOCs in the soil, and lateral pollution source in the vadose zone are disregarded. It has been shown that ignoring the lateral source position may lead to uncertainties on the estimations. In this paper, a numerical model is developed in order to better understand the relationship between the lateral source position in the soil, including both a source in the vadose zone and a source located at the groundwater level, and the resulting indoor air concentration. Results show that source position plays a significant role on vapour intrusion attenuation. In fact, indoor concentration of VOCs decreases with increasing lateral separation. Finally, it is shown that considering the source position can significantly improve the quality of VI predictions.
Compact wooden roofs with smart vapour barrier – Pilot project experiences
Authors: Schjøth Bunkholt Nora , Gullbrekken Lars , Geving Stig , Kvande Tore
Published: June 2020

Compact roofs are normally built without organic materials between the vapour barrier and the roof membrane due to moisture safety risks. However, laboratory measurements indicate that organic materials could be used provided that a smart vapour barrier (SVB) is applied at the warm face of the roof construction. The aim of this study is to investigate the moisture and temperature conditions in three full-scale flat compact wooden roofs with SVB. The roofs are part of two pilot projects located in Longyearbyen, Svalbard and Malvik, Norway. The paper presents the two projects including the premises for construction of the roofs and provides preliminary measurement results. The roofs are instrumented to measure moisture content and temperature in the wooden roof beams. The initial results from Longyearbyen show that the moisture content in the wooden beams is low and indicate that compact wooden roofs with SVB may be a solution with acceptable moisture risk in the arctic climate. The initial results from Malvik show that there might be a risk of mould growth in the roof as the built-in moisture in the wooden beams was up to 24 weight-%. In both projects, the moisture content in the beams in general was higher close to the roof underlay than close to the SVB.
Comparison of hygrothermal 2D- and 3D-simulation results with measurements from a test house
Authors: Ruisinger Ulrich , Kautsch Peter
Published: June 2020

This article examines whether transient two-dimensional simulations are sufficient or three-dimensional simulations are necessary for the hygrothermal analysis of the three-dimensional detail of a beam support. Detailed measurement series from a test house with various interior insulation systems available for the investigation allow the results of two- and three-dimensional simulations to be verified with the measured data. In both the cases, a very good agreement between measurement and simulations was found. With the thermal simulations, agreement with the measured data is similar in both two- and three-dimensional calculations. However, the hygric measurements agreed slightly better with the three-dimensional calculations. For planning real tasks, two-dimensional simulations should be sufficient, provided that the simulation settings are selected within the secure margins. The actual comparison is initiated by the validation of the software DELPHIN 6 by means of a three-dimensional, stationary test case from EN 10211.
PCSP’s Diagonal Tie Connectors Thermal Bridges Impact on Energy Performance and Operational Cost: Case Study of a High-Rise Residential Building in Estonia
Authors: Kiil Martin , Käärid Martin-Sven , Klõšeiko Paul , Võsa Karl-Villem , Simson Raimo , Sarevet Henri , Thalfeldt Martin , Kurnitski Jarek
Published: June 2020

This study analyses the effect of air circulation around diagonal tie connectors in precast sandwich panels on heating energy demand, energy performance value and heating costs of a sample residential building. Dynamic simulations were performed using 4 different climatic boundary conditions: Estonian test reference year, Estonian 48-year weather dataset as well as data from Eastern Germany and Northern Finland. The results show that the effect of the thermal bridge is most noticeable in total room heating energy demand (increase of 10.3%), while the influence on energy performance value was 1.1%. The relative increase of total room heating energy demand was similar (7.0-10.3%) in all studied climatic regions.
Evaluation of Thermal Bridges Using Online Simulation Software
Authors: Moga Ligia , Moga Ioan
Published: June 2020

In order to reach nearly Zero Energy Buildings, a thorough design must be given in designing proper junctions, which will overall reduce the impact of the thermal bridges on the thermal performance of the building envelope. It is well-known that a thermal bridge is a weak thermal area of the building envelope through which increased heat losses occur. For the thermal bridges' evaluation, several numerical simulation software exist on the market, but their usage implies knowledge regarding the numerical modelling and simulation using various numerical methods (i.e. finite element method, finite difference methods, and others). Due to time constraint, designers use thermal bridges atlases that provide values for the linear heat transfer coefficient for several types of thermal bridges. Nevertheless, the multitude of existing thermal bridges requires more and more atlases which are not feasible in elaborating, due to time constraints. In order to respond to this demand, the authors developed a software for the modelling and simulation of thermal bridges that can be easily accessed by practitioners. The paper presents the software its components and the way that the user can interact with it.
Moisture safety in CLT construction without weather protection – Case studies, literature review and interviews
Authors: Olsson Lars
Published: June 2020

This project aims to expand understanding of how cross-laminated timber (CLT) constructions, including joints, connections and attachment points, are impacted by precipitation during construction. The project’s case studies have been based on measurements of moisture contents and material sampling as well as microbiological analysis during the construction stage of the structure. The study does not include control of remediation. A literature review and interviews with seven individuals also were conducted. The results are based on two case studies with a total of four buildings. The field measurements show microbiological growth in all buildings and essentially on all investigated floor structures. Of a total of 200 analysed measuring points, half had some growth and about a third had moderate or extensive growth. Based on the outcome, it seems difficult or impossible to avoid the appearance of microbial growth during construction with CLT without weather protection. The literature review shows that microbiological analysis of CLT is extremely rare in both laboratory and field studies, which indicates that there are obvious shortcomings in the scientific work in practical studies. However, there seems to be good awareness in the literature that theoretical studies often conduct mould growth risk evaluations. In the survey, half of those interviewed believed that remediation was needed only in the case of growth visible to the naked eye. There appear to be no moisture safety assembly methods or solutions for CLT construction without weather protection or declaration of the critical moisture conditions for CLT products. As a result, it is recommended that weather protection is used, preferably complete weather protection.
Wetting and drying performance of cross-laminated timber related to on-site moisture protections: Field measurements and hygrothermal simulations
Authors: Wang Lin , Wang Jieying , Ge Hua
Published: June 2020

Cross-laminated timber (CLT) panels are increasingly used in mid-rise buildings or even taller structures in North America. However, prolonged exposure to moisture during construction and in service is a durability concern for most wood products including CLT. To investigate practical solutions for reducing on-site wetting of mass timber construction, CLT specimens with a range of moisture protection measures, in six groups were tested in the backyard of FPInnovations’ Vancouver laboratory from Oct. 2017 to Jan. 2018. This study investigates the wetting and drying behaviours of the tested CLT specimens through 2-D hygrothermal simulations. The simulations are performed for base specimens (no protection measures) of group 1 (without joint or plywood spline) and group 2 (with a butt joint and plywood spline). For group 1, three data sources of material properties are used to create the models, and the data that led to the best agreement between simulations and measurement are used for creating the models of group 2. For group 2, two types of hygrothermal models are created with or without considering the differences in water absorption between the transverse and the longitudinal grain orientations. In addition, rain penetration is taken into account for the joint area. It is found that the model with considering the differences between transverse and longitudinal grain orientations shows a better agreement than that without considering such differences.
Relying on reference cases when evaluating new technical solutions? Evaluation of technical documentation in a case study
Authors: Svensson Tengberg Charlotte , Hagentoft Carl-Eric
Published: June 2020

Serial failures have occurred when introducing new technical solutions in the Swedish construction industry. In an earlier interview study exploring introduction of new technical solutions, documentation and reference cases provided by the supplier are given as the main sources for evaluation. This paper aims at addressing the questions: 1. What kind of documentation concerning building physics are provided by suppliers? 2. How well does the suppliers’ documentation meet the need for verification? In order to address these questions, the case of hygrothermal performance of cross laminated timber structures in multifamily dwellings was chosen. An inquiry of data was sent out to four suppliers at the Swedish market, asking for documentation and reference cases provided. Based on the documentation given, an assessment was made of to which extend the documentation can support verification of appliance to the relevant requirements of the Swedish building regulations. The case study shows reference cases are scarce and existing documentation is not comprehensive, thus indicating the building industry might have a disproportional high confidence in reference cases. The results will be used to suggest requirements for reference cases to be used for verification.
Moisture handling mechanisms in ice rinks
Authors: Pomerancevs Juris , Rogstam Jörgen , Līckrastiņa Agnese
Published: June 2020

The paper addresses the moisture handling function in ice rinks. Dehumidification has an important role in ice rinks to avoid structural damages and maintain a sustainable indoor environment. Field measurement analysis in a number of ice rinks in Sweden is performed, showing the indoor climate dependency on the ambient conditions. Indoor temperatures vary between +5°C to +10°C and humidity ratio between 2.5 to 6.0 gH2O/kg of air. [1] Moisture source evaluation shows that the most critical load is imposed by air leakages, while internal loads such as people can generate peaks but have a short-term nature. Control strategy of the dehumidification equipment has a significant impact on the appropriate humidity level and moreover poor controls can easily lead to a 30% energy penalty. [2] [3] In ice rinks it is concluded that the acceptable setpoint is in the range of 0°C to 2°C dewpoint temperature.
Models for residential indoor pollution loads due to material emissions under dynamic temperature and humidity conditions
Authors: Rode Carsten , Grunewald John , Liu Zhenlei , Qin Menghao , Zhang Jianshun
Published: June 2020

The IEA EBC Annex 68 project on “Indoor Air Quality Design and Control in Low Energy Residential Buildings” has been recently completed. The project considered indoor air pollution loads in dwellings, particularly how such pollutants are emitted in dependency of the hygrothermal conditions: temperature, moisture and air flows. Thus, a proper understanding of the mutual interactions between hygrothermal conditions and pollutants was needed to obtain optimal paradigms for demand-controlled ventilation. The project adopted a similarity approach for modelling the transports of moisture and volatile organic compounds (VOCs) in materials, and thereby it was possible to provide a comprehensive set of data and tools whereby the indoor atmospheric conditions of buildings can be optimized, e.g. with respect to the need for ventilation. The paper explains the experimental and modelling approach and presents a summary of the results.
Residential buildings with heat pumps peak power reduction with high performance insulation
Authors: Sarevet Henri , Fadejev Jevgeni , Thalfeldt Martin , Kurnitski Jarek
Published: June 2020

Revised EPBD directive has set ambitious targets for nearly zero energy buildings. In residential buildings, energy performance can be improved mainly by applying better insulation of building fabric and by efficient energy sources, i.e. heat pumps. Electricity use and peak powers will increase when heat pumps, both air to water and ground source heat pumps, are used for heat source in new residential buildings compared to heating solutions that do not use electricity. The purpose of this study was to determine how much the high performance thermal insulation can compensate the increase of electricity use and peak power caused by extensive application of heat pumps in Finland residential buildings. The present study used five residential buildings that describe residential newbuild market. Finnish regulation defines minimum insulation level and high performance insulation level which were applied to single family houses, terraced house and apartment buildings to simulate electric power values all year round. Hourly electrical power values were simulated with dynamic simulation software IDA ICE. Results show that electricity use and peak powers are rising significantly when heat pumps are used, but better insulation level significantly decreases or even fully compensates the amount of additional electric power. The results can be used for the assesment of implications of extensive use of heat pumps to power grid.
Hygrothermal performance of paper plaster: influence of different types of paper and production methods on moisture buffering
Authors: Soolepp Mihkel , Ruus Aime , Nutt Nele , Raamets Jane , Kubjas Ardo
Published: June 2020

Paper as a material needs a lot of input energy. Many measures have been suggested to recycle paper, but still a huge amount of it ends in landfills. Hereby, one possibility for recycling paper - making paper plaster and putting it into service in indoor environment - is introduced. The study focuses on the moisture buffering properties of paper plaster. Two questions are under consideration in this article. Firstly, how paper type and production method influence the properties (dry density, drying shrinkage) of paper plaster, and secondly, what the material moisture buffering properties of paper plaster are. The plasters for testing were made from four types of paper (printer paper, glossy paper, newsprint and book paper). The production methods used were rumpling, grinding with a shredder or special crusher (prepared for the study) and soaking the paper after that. The dry density of groups varied from approx. 240 kg/m3 to 400 kg/m3. The shrinkage properties were from 3% to 10% in diameter. To evaluate the moisture buffering ability of paper plaster, the methodology introduced in the Nordtest protocol was used. Paper plaster is an outstanding water vapour buffering material [MBV=2.23-3.91 g/(m2·%RH)] belonging to the moisture buffering class "excellent" defined by Rode [15]. From the production methods rumpling gave the best value while printer paper showed the best values from the chosen materials. The tests with glossy paper resulted in modest values. To conclude, all the paper materials and preparation methods introduced in this study can be used to make paper plaster
Dynamic Hygrothermal Models for Monumental, Historic Buildings with HVAC Systems: Complexity shown through a case study
Authors: Posani Magda , Veiga Maria Do Rosario , Peixoto de Freitas Vasco , Kompatscher Karin , Schellen Henk
Published: June 2020

Our global climate is changing and the problem got so serious that the European Commission is calling for a climate-neutral Europe by 2050. To reach such an ambitious and urgent goal, an energy efficient renovation of the existing building stock is needed. Nonetheless, some buildings must be treated with special attention because of their historical value. Thus, it is advisable to evaluate their retrofit with the aid of calibrated hygrothermal simulation models, whose calibration can be complex and time demanding.

This work shows the strategy adopted for obtaining a calibrated model for a XVI-century construction located northern Italy, by means of indoor air temperature and relative humidity monitoring, plus CO2 measurements and in situ inspection. This study accounts for the first 9 months of measurements performed on the case study and it adopts HAMBase as a simulation tool because of its ability to combine heat and moisture calculations in monumental buildings with HVAC systems.

This paper aims at showing the main problems found in developing and calibrating the simulation model while defining a procedure to overcome them. The major outcome of the study is that the stratification of temperature detected in the main monumental room could be successfully modelled via dividing this space into different zones, vertically, by introducing fictitious interzonal surfaces made of a material with high thermal conductivity and vapour permeability. All in all, the strategy adopted in this work can be used by other researchers and professionals to overcome problems that can be commonly met when modelling similar historic constructions.
Attic Conversion – Hygrothermal Assessment of Historical Roof Truss
Authors: Sojkova Katerina , Stanek Kamil
Published: June 2020

In the City of Prague centre, an investor had the intention to convert the unused attic space of a historical palace into office and exhibition floor. It was necessary to design such a solution that would not worsen the humidity conditions and would not jeopardize the original Renaissance roof truss. The requirements of the heritage protection agency and the architect predetermined the use of very efficient thermal insulation above the rafters. The paper introduces and assesses several design solutions for: (1) new roofing layers and (2) the critical detail near the eaves, including variants with active heating elements. The assessment was based on results of 2D steady-state hygrothermal modelling using two criteria: (1) the interior surface temperature under winter design boundary conditions and (2) the relative humidity in the area of the timber elements under average January boundary conditions. The results showed hygrothermal implications of different design measures and helped to identify acceptable solutions for further project phases.
Survey on thermal environments in bathrooms and elderly behavior while bathing in old residential buildings in Nanjing, China
Authors: Shi Pengcheng , Li Yonghui , Ying Yuan , Hokoi Shuichi
Published: June 2020

Bathing is a typical daily behavior among Chinese elderly people, which causes large thermal environmental fluctuations especially in winter. Rapid fluctuations of the thermal environment can lead to a drastic change in human blood pressure and may cause accidents while bathing. The most common style of Chinese bathing is showers. Information on the thermal environment during bathing is limited, making analysis difficult. This study aims to understand the current situation of bathing in old residences in Nanjing, China. To examine elderly bathing behaviors and thermal environments in bathrooms during bathing, we monitored the thermal environment in three elderly families and administered a questionnaire survey from which 49 responses were obtained. Results were categorized into environmental and personal factors that affect blood pressure during bathing. In winter, the temperature in a bathroom is often below 10℃. A heating device is installed close to the head (87%); thus, the thermal environment is vertically non-uniform (air temperature difference often exceeds 10℃). Most elderly individuals bathe for less than 30 minutes and the rise in air temperature often exceeds 10℃. This information will be used as the boundary conditions for thermo-physiological models that can quantitatively assess the impact of the environment on the elderly, and for the renovation of bathrooms.
Prediction of Ventilation Effects on Reducing Moisture Damage in Tishun Tang in the Palace Museum in Beijing, China
Authors: Ma Yan , Li Yonghui , Hokoi Shuichi , Zhang Xiaogu
Published: June 2020

The Palace Museum in Beijing is World Cultural Heritage and representative of Chinese traditional brick buildings, but has been suffering deterioration for centuries. Environment monitoring showed that the special construction of foundation resulted in the humid micro-environment and moisture damage near wall bottom and floor in buildings. In order to make clear the effects of ventilation on reducing moisture damage, we took Tishun Tang as example and built a two-dimensional hygrothermal simulation model. There are two ventilation plans. One is direct ventilation, letting the outdoor air go into indoor space directly through the flue under floor. The other is to add air temperature and humidity control during that produce, called controlled ventilation. In those two plans, ventilation rate is raised to 1 time per hour from 0.4 times (current state). The results show that compared with direct ventilation, controlled ventilation is more efficient for reducing moisture damage. In controlled ventilation plan, heating outdoor air before the air exchange in winter benefits to raising indoor surface temperature by one degree and reducing area of freezing-thawing damage. Dehumidifying the outdoor air during ventilation in summer is the most important point of decreasing the high mould risk from 22 ~ 25 days to 7 ~ 10 days.
Green Buildings in the Arctic region: a literature review
Authors: Ravasio Lucrezia , Riise Raymond , Sveen Svein Erik
Published: June 2020

Green Buildings are defined as environmental-friendly buildings aimed at minimizing the impact on the natural environment through a sustainable and efficient use of resources over their life-cycle. This is, perhaps, a recently-introduced building concept that is increasingly gaining attention due to the policies and strategies intended to reduce the carbon footprint of conventional buildings, which nowadays represent a large portion of the global energy consumption and C02 emissions. This study provides a systematic literature review of the existing body of knowledge of research related to Green Buildings in the arctic region. Despite numerous studies and projects developed during the last decades, a study describing the current research for this specific region is still missing. Starting from the definition of Green Building and Arctic Region, an examination is made of research approaches developed to achieve the required green building standards, for which rating tools currently in use for their evaluation are also identified. The result is a critical analysis highlighting benefits and critical issues of Green Buildings located in the Arctic in comparison with conventional buildings, focusing on the environmental, economic and social dimensions. Finally, future research opportunities are presented and discussed.
Energy performance assessment and optimization of extensive green roofs in different climate zones of China
Authors: Ran Jiandong , Yang Zhenjing , Feng Ya , Xiong Ke , Tang Mingfang
Published: June 2020

There are many research and engineering projects on extensive green roofs, however, there is still no design guide for green roofs` climate energy efficiency, which limits the further promotion and usage of it, especially in China containing five climate zones. Taking different climate zones of China as examples, the verified building model is used in the DesignBuilder software, and 2-4 typical cities in each climate zone are selected, then combined the genetic algorithm (GA-Ⅱ) to optimize the energy efficiency of the building under green roofs. The results show that in all the cities studied in the five climatic zones, extensive green roofs are more energy efficient than ordinary thermal insulation roofs, and the energy saving rate is between 1-26.4%; except for the Nenjiang, which the energy is mainly used for heating, the cooling energy consumption is reduced and the heating energy consumption is increased after the optimized green roof is adopted in other cities; it is also found that the energy saving rate of the green roof with optimization has a high correlation with the total annual solar radiation value of the city. In addition, the energy efficiency optimization of green roofs in all cities shows that a larger leaf area index is more conducive to energy conservation; however, in southern China, it is not recommended to use a thermal insulation layer in the roof structural layer below the soil.
A study of solar panel efficiency in Latvian climate conditions
Authors: Telicko Jevgenijs , Heincis Daniels , Jakovics Andris
Published: June 2020

With solar panels increasingly used in nearly zero energy building solutions it is important to clarify if the panels can achieve the efficiency indicators specified by their producers in real operation conditions. To determine the efficiency of poly- and monocrystalline panels depending on their spatial orientation and the seasons a set of test panels was installed in 2018 in Riga, Latvia for long-term monitoring of the amount of generated power and produced energy. Here we summarize the results of the first year of monitoring. Data indicate that orientation has high significance, very small amounts of energy are generated in autumn/winter and that there is a good correspondence of the actual efficiency to the standardized estimated values. The energy production is significantly reduced by the cloudiness that is characteristic for Latvia’s climate from October till January. To make a generalization of the results possible it is planned to continue the monitoring for several years.
Water vapor sorption dynamics in different compressions of eelgrass insulation
Authors: Frandsen Kirstine Meyer , Antonov Yovko Ivanov , Møldrup Per , Jensen Rasmus Lund
Published: June 2020

Eelgrass shows potential in meeting the rising demands towards new, sustainable materials. It hosts a range of characteristics that benefits its application as a building material, such as thermal and acoustic insulating properties that can compete with conventional mineral wool insulation. However, as a porous bio-based building material, the moisture performance of eelgrass must be assessed to ensure its practical application. In this study, experimental investigations are conducted by a new automated vapor sorption analyzer (VSA) to measure adsorption and desorption of water vapor on different compressions of eelgrass insulation, ranging from loose strands to densely compacted insulation batts. Overall, higher sorption dynamics are observed in eelgrass insulation compared to conventional mineral wool insulation. Loose strands of eelgrass depict higher dynamics (including hysteresis) for the full range of relative humidity in comparison to insulation batts, potentially due to additional binder. Increasing the compression of eelgrass insulation batts results in lower sorption dynamics in the >70% relative humidity range. A Guggenheim-Anderson-deBoer model is applied that shows good fit with the experimental data and may be applied in moisture transfer calculations. This study furthers the potential of compressing eelgrass for application in passive design strategies through its moisture buffering capabilities.
Moisture dry-out from steel faced insulated sandwich panels
Authors: Kalbe Kristo , Piikov Hubert , Kesti Jyrki , Honkakoski Erkki , Kurnitski Jarek , Kalamees Targo
Published: June 2020

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 (e.g. 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.
Solutions for retrofitting existing, wooden houses in cold climates
Authors: Hrynyszyn Bozena Dorota , Tian Zhiyong
Published: June 2020

Upgrading existing one-family houses to higher energy standards can be a challenge for owners, among others, due to the unclear status of technical regulations in the case of retrofitting at the national level. Retrofitting projects face technical obstacles that can be difficult to exclude with sensible measures. As a result, retrofitting projects are more difficult to complete. How can we effectively increase the rate of retrofitting projects for private owned residential buildings? Challenges associated with a complete renovation were listed, analysed and illustrated based on one of the smallest Norwegian typical wooden houses from the 1960s. Optimal packages of solutions for the retrofitting, based on energy simulation models, were proposed. The analysis showed that existing buildings are vulnerable meeting today’s, much stronger, energy requirements equal for all buildings. More attention should be given to the development of separate regulations at the national level as well as to the development of retrofitting solutions, if the goal of increasing the number of renovations is to be achieved. The efficient use of solar energy becomes an important measure, especially in the context of expected climate change, and a key to achieve sustainable energy management and a better indoor climate. To avoid unnecessary cooling loads and ensure optimal thermal comfort for residents, overheating criteria should be included in energy requirements even in cold climates in the near future.
Comparison and development of daylight simulation software – A case study
Authors: Solvang Helene , Kristiansen Tobias , Bottheim Ruth Marie , Kampel Wolfgang
Published: June 2020

Working with daylight simulations on a regular basis, the authors discovered that it is increasingly challenging to achieve daylight criteria in new building projects. In addition to complex building designs, a new European Standard was published in 2018 named EN 17037:2018 Daylight in Buildings, which includes climate-based daylight simulations. These new criteria require a different type of simulation and presentation of results, compared to the simplified method of calculating average daylight factor, which is mostly used today. The authors have created, tested and validated scripts for performing climate-based daylighting simulations, using Rhinoceros and Grasshopper. The script designed for climate-based daylight simulations, showed too extensive differences between supposedly equivalent criteria for daylight factor and daylight autonomy, meaning it can’t be applied in construction projects as the only documentation of daylight availability. Further testing and investigation of the climate-based daylight script has to be done, in order to perform correct evaluations of realistic daylighting conditions.
Microbial growth behind tiles in bathrooms
Authors: Bok Gunilla , Johansson Pernilla
Published: June 2020

Studies investigating microbial diversity in buildings have been performed mainly through the study of dust collected from e. g. floors and door frames and on moisture damaged building materials. A great diversity of mould fungi has been found and the fungus flora is dominated by the genera Aspergillus and Penicillium. The building materials targeted in this specific study were sampled on the back of ceramic tiles from bathroom walls and floors. Furthermore, two different analyses were used to investigate to which degree this specific environment was supportive of microbial growth. Microbial findings were detected in 48 % of the specimens from the spots exposed to liquid water in the bathrooms. To our knowledge, the microbial occurrence in this type of environment has not previously been investigated..