Study On Architectural Models Designed For Natural Ventilation By Finite Element Method

With people's health status according to statistics getting worse and worse, improving the quality of health is an inevitable need that many researchers are interested in. In addition to improving through eating, improving the living environment in homes and workplaces is also essential. Nowadays, many countries around the world have implemented many house models that apply natural ventilation instead of artificial air conditioning system, because natural wind is better and also feels more comfortable. Therefore, the study of controlled natural wind-catching architecture is necessary and consistent. Research in this field can help improve the living environment for people. The objective of the paper is to simulate ventilation solutions based on experience in construction works by finite volume method through ANSYS software to consider and evaluate the feasibility of these solutions. If the simulation results match or approximate the actual verified results, they can be applied to the improvement of natural ventilation structures to create a better indoor living environment, meeting the requirements of the environment. more comfortable diagnostics.

Research on the Indoor Thermal Environment of Attached Sunspace Passive Solar Heating System Based on Zero-State Response Control Strategy

The application of attached sunspace passive solar heating systems (ASPSHS) for farmhouses can improve building performance, reduce heating energy consumption and carbon dioxide emissions. In order to take better use of the attached sunspace to prevent heat transfer or promote natural ventilation, this paper presented a zero-state response control strategy for the opening and closing time of active interior window in the ASPSHS. In order to verify the application of this strategy, an attached sunspace was built in an actual farmhouse. A natural ventilation heat exchange model was built based on the farmhouse with attached sunspace. The proposed zero-state response control strategy was implemented in TRNSYS software. Field measurement in living lab was carried out to inspect the distribution of the thermal environment in the farmhouse with attached sunspace under a zero-state response control strategy in the cold region of northern China. The experimental results show that, even under −5.0–2.5 °C ambient temperature, the application of zero-state response control strategy effectively increases the internal temperature to an average of 25.45 °C higher than the outside, with 23% indoor discernible temperature differential in the sample daytime. The whole-season heating performance was evaluated by simulating the model for the heating season in 2020–2021. The simulation demonstrates that the ASPSHS under zero-state response control strategy can maintain a basic indoor temperature of 14 °C for 1094 h during the heating season, with a daytime heating guarantee rate of 73.33%, thus ensuring higher indoor heating comfort during the day. When compared to a farmhouse with an attached sunspace under the zero-state response control strategy, the energy savings rate can be enhanced by 20.88%, and carbon emissions can be reduced by 51.73%. Overall, the attached sunspace with the zero-state response control strategy can effectively increase the indoor temperature when the solar radiation is intensive and create a suitable thermal environment for the farmhouse in the cold region of northern China.

Numerical Assessment of Zebra-Stripes-Based Strategies in Buildings Energy Performance: A Case Study under Tropical Climate

Urban growth has increased the risk of over-heating both in the microclimate and inside buildings, affecting thermal comfort and energy efficiency. That is why this research aims to evaluate the energy performance of buildings in terms of thermal comfort (operative temperature (OP) levels, satisfied hours of natural ventilation SHNV, thermal lag), and energy efficiency (roof heat gains and surface temperatures) in an urban area in Panama City, using superficial-heat-dissipation biomimetic strategies. Two case studies, a base case and a proposed case, were evaluated using the Designbuilder software through dynamic simulation. The proposed case is based on a combined biomimetic strategy; the reflective characteristics of the Saharan ant applied as a coating on the roofs through a segmented pattern such as the Zebra’s stripes (one section with coating, and another without). Results showed that the OP decreased from 8 to 10 °C for the entire urban zone throughout the year. A reduction of 3.13% corresponding to 8790 kWh per year was achieved for cooling energy consumption. A difference of 5 °C in external surface temperature was obtained, having a lower temperature in which the biomimetic strategy was applied. Besides, it was evidenced that a contrasted-reflectivity-stripes pitched roof performed better than a fully reflective roof. Thus, the functionality of Zebra stripes, together with the reflective characteristics of the Saharan ant, provide better performance for buildings’ thermal regulation and energy needs for cooling.

Effects of Future Climate Change and Adaptation Measures on Summer Comfort of Modern Homes across the Regions of the UK

The global climate is warming rapidly, with increasing frequency of severe events including heatwaves. Building insulation standards are improving to reduce emissions, but this can also lead to more overheating. Historically, UK house designers have not included adaptation measures to limit this. Most studies of the problem have had limited geographical or future climate scope. This study considers the comfort performance of a small modern house, in detached, semi-detached, and terrace (row) forms, but otherwise identical. Overheating is evaluated according to established criteria, including night-time bedroom hours over 26 °C. Simulations are carried out using median future weather years for current, 2030s, 2050s, and 2080s climates under medium- and high-emission scenarios for 14 regions of the UK. The results show a very large increase in overheating by the 2080s in all regions. With solar shading and natural ventilation, overheating is reduced considerably, maintaining comfort in most northern regions in the 2050s and a few northern regions in the 2080s. Differences between medium and high emissions are generally less than between different decades. Terraced (row) houses consistently overheat slightly more than semi-detached, with detached showing the least overheating.

Assessment of Indoor Air Quality in Residential Buildings of New England through Actual Data

Several studies on indoor air quality (IAQ) and sick building syndromes have been completed over the last decade, especially in cold countries. Efforts to make homes airtight to improve energy efficiency have created buildings with low ventilation rates, resulting in the build-up of indoor pollutants to harmful levels that would be otherwise unacceptable outdoors. This paper analyzed the infiltration rates, indoor temperatures, and variations in CO2, 2.5 μm particulate matter (PM2.5), and total volatile organic compound (TVOC) concentrations over the fall of 2021 in several homes in New England, USA. A relationship between outdoor and indoor conditions and ventilation strategies has been set using the results from blower door tests and actual indoor air quality data. Although all case studies lacked mechanical ventilation devices, such as those required by ASHRAE Standard 62.2, natural ventilation and air leakage have been enough to keep VOCs and PM2.5 concentration levels at acceptable values most of the studied time. However, results revealed that 25% of a specific timeframe, the occupants have been exposed to concentration levels of CO2 above 1000 parts per million (ppm), which are considered potentially hazardous conditions.

Experimental Methods of Investigating Airborne Indoor Virus-Transmissions Adapted to Several Ventilation Measures

This study introduces a principle, which unifies two experimental methods for airborne indoor virus-transmissions adapted to several ventilation measures. A first-time comparison of mechanical/natural ventilation and air purifiers with regard to infection risks is achieved. Effortful computational fluid dynamics demand detailed boundary conditions for accurate calculations of indoor airflows, which are often unknown. Hence a suitable, simple and generalized experimental set up for identifying the spatial and temporal infection risk for different ventilation measures is required. A trace gas method is suitable for mechanical and natural ventilation with outdoor air exchange. For an accurate assessment of air purifiers based on filtration a surrogate particle method is appropriate. The release of a controlled rate of either trace gas or particles simulates an infectious person releasing virus material. Surrounding substance concentration measurements identify the neighborhood exposure. One key aspect of the study is to prove that the requirement of concordant results of both methods is fulfilled. This is the only way to ensure that the comparison of different ventilation measures described above is reliable. Two examples (a two person office, several classrooms) show how practical both methods are and how the principle is applicable for different types and sizes of rooms.

Guidance to assess ventilation performance of a classroom based on CO2 monitoring

Since the COVID-19 pandemic, the ventilation of school buildings has attracted considerable attention from the general public and researchers. However, guidance to assess the ventilation performance in classrooms, especially during a pandemic, is still lacking. Therefore, aiming to fill this gap, this study conducted a full-scale laboratory study to monitor the CO2 concentrations at 18 locations in a classroom setting under four different ventilation regimes. Additionally, a field study was carried out in two Dutch secondary schools to monitor the CO2 concentrations in the real classrooms with different ventilation regimes. Both the laboratory and field study findings showed that CO2 concentrations varied a lot between different locations in the same room, especially under natural ventilation conditions. The outcome demonstrates the need of monitoring the CO2 concentration at more than one location in a classroom. Moreover, the monitored CO2 concentration patterns for different ventilation regimes were used to determine the most representative location for CO2 monitoring in classrooms. For naturally ventilated classrooms, the location on the wall opposite to windows and the location on the front wall (nearby the teacher) were recommended. For mechanically ventilated classrooms, one measurement location seemed enough because CO2 was well-mixed under this ventilation regime.

A study on the temperature profile of bifurcation tunnel fire under natural ventilation

This study simulated a series of bifurcation tunnel fire scenarios using the numerical code to investigate the temperature profile of bifurcation tunnel fire under natural ventilation. The bifurcation tunnel fire scenarios considered three bifurcation angles (30°, 45°, and 60°) and six heat release rates (HRRs) (5, 10, 15, 20, 25, and 30 MW). According to the simulation results, the temperature profile with various HRRs and bifurcation angles was described. Furthermore, the effects of bifurcation angles and HRRs on the maximum temperature under the bifurcation tunnel ceiling and the temperature decay along the longitudinal direction of the branch were investigated. According to the theoretical analysis, two prediction models were proposed. These models can predict a bifurcation tunnel fire’s maximum temperature and longitudinal temperature decay in the branch. The results of this study could be valuable for modelling a bifurcation tunnel fire and benefit the fire engineering design of bifurcation tunnels.

Measurement of indoor environmental parameters and analysis of the condensation phenomenon in urban utility tunnels

Condensation is a major issue in the safe operation of utility tunnels. To address the condensation problem, the indoor air temperature, relative humidity (RH) and surface temperature in an urban utility tunnel in Jining were continuously measured, and the condensation conditions were surveyed and analysed. The results indicated that under natural ventilation conditions, the air temperature in the comprehensive cabin varied from 23.4°C to 24.5°C, the RH fluctuated between 86.4% and 95.3%, and the corresponding air dew point temperature (DPT) remained in the range of 22.2°C–22.9°C. The surface temperature of the water supply pipeline ranged from 17.8°C to 18.5°C, which was far lower than the DPT in the tunnel, resulting in serious condensation. A water supply pipeline with an anti-condensation design was developed based on environmental test data. A 25-mm-thick rubber plastic sponge insulation layer was used to thermally insulate the water supply pipeline, preventing further dew condensation. Furthermore, mechanical ventilation had little effect on reducing the RH in the tunnel and may actually cause dew condensation; therefore, a ventilation control mode was proposed in this study. These results are expected to provide basic data for further research and reference for the safe management of utility tunnels.