사물 인터넷을 활용한 주거용 건물에서의 결로 해결 방안

학위논문 (박사) -- 서울대학교 대학원 : 공과대학 건축학과, 2020. 8. 여명석.The building technology have been developed in a way to minimize damage from inadvertent moisture penetration and generation in the living space. Researches and building technologies related with the condensation in building is actively reviewed with applying appropriate combinations of insulation and ventilation. However, condensation still ranks high on the list of defect dispute issues for newly built apartment buildings in Korea. The building industry is trying to solve the issue by increasing the design criteria for condensation prevention. However, this may cause other unintended effects which this study was designed to address: The aim was to provide an Internet of Things (IOT) concept approach solution for preventing condensation in the balconies of Korean apartments, which is reported to be the most problematic space in a residential unit. The research proceeded as follows to solve the condensation in the balcony space. Long-term monitoring was conducted to identifying the cause of condensation to derive a strategy to prevent condensation. The monitoring result revealed not only the construction factors of the balcony but also occupancy activity influences condensation. Condensation prevention effect through control of these factors were reviewed by EnergyPlus simulation (Insulation thickness and ventilation rate) and the control of occupancy activities were reviewed with the use of a field experiment. However, the uncertainty related to the moisture generation rate by the occupants made it difficult to ascertain the buildings physical parameter values. Although restricting the occupancy activity effectively lowered the moisture generation to prevention condensation occurrence. Although a method to control the behavior of occupancy dose not ensure the effectiveness from the engineering point of view, it was confirmed that it is feasible by combining technology with the concept of IoT. Author installed IoT experiment onsite accessed by internet WiFi. Real-time data value collection and analysis algorithms are processed through micro-processor (Raspberry Pi) to operate the balcony door actuator and ventilation fan installed inside the balcony. As a result of the experiment it was confirmed that the condensation prevention control combined with the Internet of Things shorten the condensation occurrence time. In this study, as a method for solving condensation in buildings categorized into fixed parameter and occupancy parameter. Fixed parameters are considered during design phase while occupancy parameters are applicable during use stage. Occupancy parameters are actively respond to changes in the indoor environment by using IoT technology to block the moisture transfer and remove generated moisture while fixed parameters are a way to reflect the possibility of condensation to derive insulation thickness and ventilation rate. Previously, the indoor condition of building was left to the autonomy of the occupants after building have been constructed. Through this study provides a vision of designing to control the architectural feature in use stage of building is possible.건물은 거주 공간의 의도치 않은 수분 침투 및 발생으로 인한 피해를 최소화 하기 위한 방향으로 기술 발전 되어 왔다. 특히 결로와 관련된 연구 및 관련 건축 기술로는 단열 및 환기 등의 적절한 조합을 통해서 적용 될 수 있는 방안들이 활발히 검토되었다. 그럼에도 불구하고 여전히 공동주택 건설현장에서는 결로와 관련된 하자 분쟁 및 민원이 끊이지 않고 있는 실정이다. 이러한 결로 문제를 해결하기 위해서 단열과 환기와 같은 결로 방지 설계 기준을 높이려고 하지만, 다양하고 복합적인 요소들의 구성체인 건물에서 단순히 결로 만을 위한 조건을 상향 시킬 경우 건물 내에서 의도치 않은 다른 환경변화를 야기 할 수 있다. 따라서 본 연구에서는 복합적인 환경변화 요소들을 고려 할 수 있는 사물 인터넷 기술을 활용하여 주거공간에서의 결로 문제를 해결하는 방안을 새롭게 제안하고자 하였다. 주거공간 내 결로 문제 해결 방안 도출은 다음과 같이 진행되었다. 결로 발생 원인 파악을 통한 결로 방지 전략 도출을 위해서 주거 공간 내 결로 피해 문제가 심각한 비확장 발코니 공간을 대상으로 장기 모니터링을 진행 하였다. 모니터링 결과 발코니의 시공 요소로 인한 원인과 재실 행위에 의해서 결로가 발생하는 것으로 분석되었고 이러한 요소들의 제어를 통한 결로 방지 효과를 EnergyPlus 시뮬레이션 모델(단열, 환기 방안)과 현장 실험(재실 행동 제어 방안)을 통해서 검토하였다. 시뮬레이션 모델과 현장 실측 검토 결과 기존의 결로 방지 방안인 단열 및 환기 전략 보다는 재실 행동 제어 방안을 통해서 즉각적이고 효과적으로 결로 발생을 방지 하는 것으로 나타났다. 재실 행동을 제어하는 방안을 결로 방지 해법으로 제시하기에 공학적 측면에서 그 효과를 담보 할 수 없지만 사물 인터넷 개념과의 기술 결합을 통해서 실현 가능한 것을 확인하였다. 실시간 데이터 값 처리 및 분석 알고리즘을 통해 발코니 문 자동 구동체와 발코니 내부에 추가 설치한 환기 팬을 결로 발생 조건에 따라 작동되도록 마이크로 프로세서(Raspberry Pi)와 연결하였고 해당 기기는 와이파이로 접근 가능하도록 실제 현장에 구현하였다. 실험 결과 사물 인터넷과 결합한 결로 방지 제어를 통해서 결로 발생 시간이 적용 전과 비교하여 단축되는 효과를 확인하였다. 본 연구에서는 건물에서의 결로를 해결하기 위한 방안으로 설계단계에서의 대응과 재실 단계에서의 대응으로 구분하였다. 설계단계에서는 건물에서의 결로 발생 가능성 등을 종합적으로 고려하여 단열 조건 및 환기량이 설계에 반영되는 방안으로 현존하는 건물 설계 방법이었다면, 건물 사용단계에서 재실 활동에 따라 수증기 이동 차단 및 발생된 수증기를 배출하는 방안을 사물 인터넷 기술을 활용하여 실내 환경 변화에 따라서 능동적으로 대응 할 수 있도록 새롭게 제안하였다. 기존에는 건물 완공까지의 상황만을 고려하고 이후의 재실 및 사용에 따른 건물 내의 환경 변화에 대응하는 설계는 고려 대상이 아니었다. 건물 사용에 대해서는 재실자의 자율성에 맡겨두었다면 본 연구를 통해서 건물 완공 이후 건물이 사용되는 상황을 제어하는 설계의 가능성을 엿볼 수 있게 되었다.CHAPTER 1. INTRODUCTION 1 1.1. BACKGROUND AND PURPOSE 1 1.2. SCOPE AND METHOD 7 CHAPTER 2. EXISTING STRATEGIES FOR CONDENSATION CONTROL 11 2.1. CONVENTIONAL KOREAN BALCONIES 11 2.2. DESIGN CRITERIA FOR CONDENSATION CONTROL 14 2.2.1. Temperature Difference Ratio 14 2.2.2. Moisture control design 15 2.3. PRELIMINARY STUDY OF CONDENSATION PREVENTION 16 2.3.1. Preliminary studies on unheated space condensation 16 2.3.2. The solution application by Korean industry 17 2.4. SUMMARY 19 CHAPTER 3. INVESTIGATION OF THE INFLUENCE OF CONDENSATION BY OCCUPANCY PATTERNS 21 3.1. MEASUREMENT SETUP 22 3.1.1. Monitoring target space 22 3.1.2. Data collection points and sensor information 25 3.1.3. Data collection status 27 3.2 CAUSES OF CONDENSATION IN THE BALCONY SPACE 30 3.2.1. Seasonal influence of condensation 30 3.2.2. The influence of the daily schedule on condensation 36 3.2.3 The influence of activity on condensation 40 3.3. CONTROL PARAMETERS DERIVED FROM DIAGNOSIS 48 3.3.1. Fixed parameters 49 3.3.2. Occupancy parameters 50 3.4. SUMMARY 51 CHAPTER 4. EVALUATION OF CONTROL PARAMETERS 53 4.1. EVALUATION OF FIXED PARAMETERS 54 4.1.1. Simulation model setup and validation 54 4.1.2. Insulation thickness evaluation 60 4.1.3. Ventilation rate evaluation 62 4.2. EVALUATION OF OCCUPANCY PARAMETERS 64 4.2.1. Onsite experiment setup 64 4.2.2. Moisture transfer control evaluation 67 4.2.3. Moisture removal evaluation 70 4.3. LIMITATIONS OF CONTROL PARAMETERS AND OCCUPANCY PARAMETERS 71 4.4. SUMMARY 73 CHAPTER 5. APPLICATION OF THE INTERNET OF THINGS FOR CONDENSATION CONTROL 77 5.1. INTERNET OF THINGS (IOT) APPLICATION 77 5.1.1. The concept of the Internet of Things 77 5.1.2. Application cases involving the Internet of Things 80 5.2. THE INTERNET OF THINGS EXPERIMENT SETUP 81 5.2.1. Microprocessor device setup with wireless communication 81 5.2.2. Sensor and actuator connection with the physical element 84 5.2.3. Condensation determination 89 5.3. THE ALGORITHM BASED ON THE OCCUPANCY PARAMETERS 91 5.3.1. Activity detection-based control 92 5.3.2. Sensor value-interpreted control 97 5.4. SUMMARY 102 CHAPTER 6. FEASIBILITY OF IOT APPLICATION AT HOME 105 6.1. RESULT OF THE ONSITE IOT EXPERIMENT 105 6.1.1. Door control for preventing moisture transfer by condensation detection inside balcony 105 6.1.2. Intermittent fan operation by condensation detection inside balcony 108 6.1.3. Control algorithm by combining and applying different parameters 111 6.2. LEVELS OF APPLICATION WITH FEASIBILITY 115 6.2.1. The IoT application level for condensation control 115 6.2.2. The effectiveness of condensation reduction among the different levels 118 6.4 SUMMARY 121 CHAPTER 7. CONCLUSION 123 REFERENCES 127 국 문 초 록 130 APPENDIX 133Docto

Indoor air quality and early detection of mould growth in residential buildings: a case study

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DURABILITY OF MASS TIMBER STRUCTURES: A REVIEW OF THE BIOLOGICAL RISKS

Mass timber structures have the potential to change wooden construction on a global scale. Numerous mass timber high-rise buildings are in planning, under development or already built and their performance will alter how architects and engineers view wood as a material. To date, the discussion of material durability and biodegradation in these structures has been limited. While all materials can be degraded by wetting, the potential for biodegradation of wood in a mass timber building requires special consideration. Identifying and eliminating the conditions that might lead to this degradation will be critical for ensuring proper performance of wood in these structures. This article reviews and contrasts potential sources of biodegradation that exist for traditional wood construction with those in mass timber construction and identifies methods for limiting the degradation risk. Finally, future research needs are outlined

LDA-Based Model for Defect Management in Residential Buildings

This study systematically analyzes various defect patterns that occur during the warranty period of residential buildings using the loss distribution approach (LDA). This paper examines 16,108 defects from 133 residential buildings where defect disputes occurred between 2008 and 2018 in South Korea. The analysis results showed that the defect losses were relatively high in reinforcement concrete (RC) work (3/5/10 years), waterproof work (5 years), and finish work (2 years). It is shown that RC work has a high frequency of defects, such as cracks in concrete in public spaces affected by external factors. In addition, it was analyzed that the type of defect needed high repair cost because the area where the defect—such as incorrect installation and missing task—occurred, needed construction again. According to the level of frequency and severity, losses were divided within four zones to provide detailed strategies (by period). This will effectively contribute to minimizing unnecessary losses from defects as quantifying the losses of defects.This research was supported by a grant (19CTAP-C152020-01) from Technology Advancement Research Program (TARP) funded by Ministry of Land, Infrastructure and Transport of Korean government

Stachybotrys: Is Nevada at risk?

Stachybotrys chartarum (atra) is a toxigenic fungus that is known to adversely impact the health of animals. Until recently, there have only been a few documented clinical reports linking Stachybotrys chartarum to human health effects. Scientists are increasingly convinced that Stachybotrys and its metabolites are responsible for several adverse health effects experienced by people all over the world, although conclusive proof has yet to be established. All the physical requirements needed for indoor Stachybotrys sporulation and growth is provided through water leaks (plumbing, roof or ceiling), flood events, nutrient sources (cellulose and nitrogen), pH, and temperature(23° - 28°C). Stachybotrys has been found in several climates around the world that are similar to those found in Nevada. Conditions that support Stachybotrys growth and confirmed contamination site locations were also similar to those found in Nevada. Also, Nevada residents who reside/work in water damaged buildings that have confirmed Stachybotrys contamination have reported similar symptoms to those mentioned in the reviewed literature. Unfortunately, scientists have not identified human toxicity levels or the dose/response relationship for humans exposed to Stachybotrys chartarum due to the lack of test subjects who were exposed and their willingness to undergo testing. Scientists are also trying to determine whether not reported Stachybotrys-related illnesses are the result of exposure to Stachybotrys alone or if there are synergistic effects with other bioaerosols and molds. What is known is that Stachybotrys spores often contain toxigenic properties, such as, macrocyclic trichothecenes which can be absorbed into the body through ingestion, skin contact, or inhalation. Nevadans who work or reside in Stachybotrys-contaminated buildings may be at risk. Health effects are numerous and may be life threatening depending on the person’s age, exposure (duration and route), and toxicity level. Medical professionals and consultants should consider microbial contaminants in their assessment of their patients because there is a potential risk that Nevadans may have been exposed to Stachybotrys and its metabolites. Industrial hygienists should use a multi-method approach when collecting and analyzing microbial samples because it has a higher fungal detection rate than single method sampling

FROSTING IN MEMBRANE ENERGY EXCHANGERS

Frost formation in heat/energy exchangers is undesirable because it may reduce air flow through the exchanger, increase the power consumption of fans, decrease the effectiveness of the exchanger, and in extreme cases, cause physical damage to the exchanger. Frosting is more critical in regions with arctic weather conditions, such as Canada and Northern Europe. Membrane-based energy exchangers are believed to be an important step towards frost free exchangers; however, at the beginning of this PhD study, there was no data available in the open literature documenting frosting in membrane energy exchangers. Therefore, the main goal of this PhD work is to determine if membrane energy exchangers are less susceptible to frosting than conventional heat exchangers. In this thesis, an in-depth study between conventional cross-flow air-to-air heat exchangers and membrane energy exchangers is conducted to (1) quantify the frosting limit; the operating conditions at which frost first begins in an exchanger, (2) develop a theoretical model to predict the frosting limit, and (3) quantify the energy impact of frosting and defrosting cycles on energy recovery. To meet these objectives, a test facility to test exchangers under frosting and defrosting cycles is developed and different strategies to detect frosting inside the exchangers are investigated. For the first time in the literature, it is shown that the temperature profile at the exhaust outlet can be used as a reliable and quick method to detect frosting. The frosting limit temperature of the energy exchanger is found to be 5℃ to10℃ lower than the frosting limit of the heat exchanger under the same air flow rate and exhaust air relative humidity. Testing the exchangers under both frosting and defrosting conditions shows that the frost accumulation rate is nearly linear with time, while the frost removal rate decreases exponentially with time. Moreover, the frosting rate in the heat exchanger is found to be three times higher than that of the energy exchanger. A theoretical model to predict the frosting limit using the design parameters of the exchangers and the operating conditions is developed. The model is verified with experiments. Both the experimental and theoretical results show that the indoor air moisture content and the outdoor air temperature have significant effects on the frosting limit. Finally, a method to calculate the energy impact of frosting is introduced. Comparison between different frost control strategies in exchangers shows that frost prevention is preferred over repeated cycle of frosting followed by defrosting

Creep behaviour of densified wood

Due to the reproducibility, good workability, suitable mechanical properties, and attractive aesthetic appearance, timber is widely used in the building industry. Among those properties, mechanical properties are important for the useability of timber in construction applications. It is well known that there is a positive relationship between wood density and its mechanical properties. That means the thermo-hydro-mechanical (THM) densification, i.e. transverse compression of the wood cells only by using additional temperature, moisture and mechanical action to increase its density without structural fracturing is a practicable method to increase the performance of low-density species and thereby improve its mechanical properties. The previous studies on wood densification mainly focused on the influence of process parameters on wood physical and mechanical properties and how to use post-treatment to reduce the set recovery. This study is in the field of increasing the use of densified timber in construction applications and thereby strengthen the competitiveness of wood as a construction material. In construction, however, densified timber normally needs to be exposed to long-term loading which may lead to creep deformation and reduction of load-bearing capacity. There is an obvious risk of reduced serviceability and safety of constructions containing densified wood. Studies of creep characteristics of densified wood are rare, and therefore the purpose of this study was to fill the gap in knowledge if the field of densified under bending load. Scots pine specimens subjected to THM densification, THM densification with a post-heat treatment, and THM densification combined with phenol resin impregnation were loaded under 3-point bending under the 35% of maximum stress level at 20℃ and 65% RH. Results from these tests will be presented.Finansiär: Republic of Slovenia</p