Indoor and Built Environment

This study assesses the interior air quality and infective factors in a hospital in Turkey to provide data about air quality to protect hospital workers. This study measured indoor air quality in eight different locations in a hospital, including particulate matter (PM_2.5 and PM₁), carbon dioxide, carbon monoxide, temperature, humidity and microbiological matter. The highest PM_2.5 and PM₁ concentrations were in emergency service, and the highest CO₂ was measured in the paediatric clinic. The poor interior air quality results are the most important cross-sectional data. For all participants, the prevalence of eye, upper respiratory tract, lower respiratory tract, skin and non-specific sick building syndrome symptoms were 23.0%, 40.7%, 22.5%, 36.3% and 63.7%, respectively. When sick building syndrome symptoms and environmental factors were investigated, skin symptoms increased 1.82 times in areas with stagnant air flow (p = 0.046; OR = 1.823; 95% CI: 1.010–3.290). Non-specific symptoms increased 2.17 times in locations with dry indoor air (p = 0.039; OR = 2.176; 95% CI: 1.041–4.549). Hospital workers are exposed to conditions that may increase the risk of a variety of sick building syndrome symptoms. Although the air quality measurements were not above the recommended limits in the hospital, long-term exposures should be considered for those experiencing sick building syndrome-related symptoms.

To evaluate the dispersion of a heavy gas, such as sulphur hexafluoride, with a low Froude number in a built environment, an experimental and numerical simulation study was conducted. The experiment was carried out using seven different injection inlet configurations in an experimental chamber. The release rate was found to have a great effect on the concentration in the lower part of the chamber. The obstacle in the middle of the chamber could cause a non-uniform distribution of concentration, particularly due to variations in locations and angles of the release outlets. Additionally, numerical simulations were carried out to evaluate four turbulence models: the standard k-ε model, the realizable k-ε model, the re-normalization group (RNG) k-ε model and the shear stress transport (SST) k-ω model. Four indicators were used to evaluate the turbulent model performance. In general, the SST k-ω model performed the best, with geometric mean bias (MG) = 0.968 and geometric variance (VG) = 1.09 at 0.055 m height, and with MG = 0.384 and VG = 2.80 at 0.6 m height. The standard k-ε model was the next best in performance, followed by the realizable k-ε and the RNG k-ε model.

Overheating in buildings is one of the increasing concerns related to climate change and can lead to an increase in heat-related health issues and higher energy consumption due to the use of air conditioning systems. Literature shows that internal conditions and demand on environmental control systems can vary with height within buildings. However, an architectural trend towards highly glazed façades for tall buildings suggests the vertical gradient of performance is not always considered in the design process. By simulating a high-rise residential building in London, a comparative analysis of the overheating risks and daylighting at different levels in the building was conducted. In this study the model was able to consider the influence of surrounding built environment on solar gain and so influence of urban location on overheating risk was taken into account. Simulations were conducted using typical reference years as well as meteorological data for specific heat-wave periods experienced in London and that are expected to become more intense and frequent due to climate change. Passive mitigation options (external shading) are demonstrated to help reduce overheating occurrence by 74%, at the same time the impact of decreased daylighting (30%) is less problematic at higher levels where daylight factor is greater.

Titanium dioxide (TiO₂) is a known photocatalyst with a capability of decomposing organic substances. However, the photocatalysis of the pure TiO₂ is not effective for the indoor environment due to a lack of the ultraviolet irradiation inside a building. Doping TiO₂ with substance such as C, N, or metal can extend the threshold of the absorption spectrum to the visible spectrum region. Thus, doped-TiO₂ is able to decompose volatile organic compounds (VOCs) under an indoor environment. To date, most experimental works reported on photocatalytic kinetics were conducted inside small-scale devices. The performance of air purification function under the actual indoor application scenery need to be further clarified. For this purpose, it is crucial to predict the performance of autogenous air quality improvements by visible light-driven photocatalyst for the actual applications. This work has developed a model to evaluate the performance of functional coating with photocatalyst in removing VOCs. Factors such as the effects of coating designs and indoor ambient conditions on the air purification efficiency were studied. This work demonstrates that doped-TiO₂ photocatalytic coating is effective to improve the indoor air quality.

Radium, which is naturally present in many rocks, decays to the radioactive gas radon, which is then exhaled from the surface of underground tunnels and other underground buildings and is a major source of human exposure to radioactivity. A mathematical model for the migration of radon from a circular tubular emanation medium was established based on the seepage–diffusion migration theory for radon in porous emanation media, such as artificial retaining walls and the surrounding rocks in these locations. An analytical solution for the distribution of radon concentrations and the calculation formula for the radon exhalation rate under steady-state conditions were then obtained. An experimental device was designed to determine the radon exhalation rate under different pressure gradients. The theoretical calculation values for the radon exhalation rate and the total amount of radon exhalation are in good agreement with the experimental results. The radon exhalation rate at the low-pressure side increases with an increase in seepage velocity (pressure difference), while the radon exhalation rate at the high-pressure side is on the contrary. The total amount of radon exhalation increased over time with an increase in the seepage velocity and tended towards a maximum value.

Liquid-desiccant dehumidification system in building air-conditioning has high energy efficiency in comparison to traditional dehumidification technology that needs to cool air below the dew point temperature. Since the dehumidification process dominates the performance of a liquid-desiccant system, this study aims to develop a deeper understanding in the dehumidification performance of some liquid desiccants. Then, an experiment test was conducted to determine the CaCl₂-LiCl mixed liquid-desiccant system in a dehumidification system. The effects of the pure and mixture liquid desiccant solution on the moisture removal rate, refrigerating capacity and dehumidification performance were compared and analysed. Results show that with the increase in the LiCl concentration, the dehumidification capacity and dehumidification coefficient first increased rapidly and then increased slowly after 30% LiCl concentration. According to the economic analysis of mixed salt solution, the mixed LiCl and CaCl₂ solution with a mixing ratio of 3:1 would achieve the best optimal dehumidification efficiency and would incur a low system cost under the working conditions of a dry-bulb temperature at 26°C and a relative humidity of 60% of fresh and return air.

The major segment for energy consumption is found in industry, transport, agricultural, residential and commercial sector. The main part of the energy consumption in residential and commercial buildings is due to the use of mechanical devices to maintain a comfortable indoor environment. Thermal conductivity of building materials is one of the factors which influence the heat transfer in buildings. Thermal conductivity can be reduced by the use of materials with low density. The present paper reports the development of a sustainable thermal insulating external wall panel and its mechanical, thermal and durability properties. The wall panel was prepared using foam concrete and rice husk and replacing the cement by fly ash. Strength of panel was tested by conducting in plane bending test and compressive strength test. Thermal conductivity was tested using guarded hot plate apparatus. Durability properties were tested by conducting water absorption test, drying shrinkage and acid resistance test. The test results showed that the rice husk and fly ash content had a major influence on the thermal conductivity and durability properties of the developed wall panels.

Considering the importance of thermal comfort in decision-making in tourism, a transverse study involving micrometeorological measurements and questionnaires was performed at a popular coastal destination during the seasons of spring, autumn and winter. We examined the thermal sensation and thermal acceptability using the physiological equivalent temperature (PET). The results indicate that tourists’ thermal sensations varied with the season and the neutral PETs were 19.2°C, 23.8°C and 23.3°C in winter, spring and autumn. The 90% acceptable ranges of the PET affected by the local climate were 19.6–29.5°C during the entire three-season survey period, 21.4–27.1°C in the spring, 19.2–32°C in the autumn and more than 15.9°C in the winter. The analysis of microclimate parameters that affect thermal comfort in three seasons reveals that people expected weaker solar radiation, stronger wind and lower humidity with the air temperature rising, and vice versa. The acceptable range of wind speed was 0.6–2.5 m/s in winter, 0.6–3.5 m/s in spring and autumn. The acceptable range of solar radiation was 0–150 W/m² in autumn and 0–250 W/m² in winter. These findings contribute to the better designs for coastal facilities and the thermal comfort of tropical areas.

The annual thermal evaluation of an open double-glazing unit (ODGU) is presented. The ODGU was modelled using two double-glazing configurations: DCC (clear glass + air + clear glass) and DCA (clear glass + air + absorbent glass). Numerical simulations were performed for the warmest design-day on each month of 2016 in four different climatic conditions in Mexico. The pseudo-transient simulations were carried out using an in-house code based on the finite volume method. To obtain the results, 5856 computational runs were necessary. From the results, the DCA configuration was observed to show the best thermal performance to reduce heat flux that passes through the inside space in the extreme warm dry climate with average reductions of 97 W/m², followed by the semi-arid climate with 84 W/m² and the tropical wet and dry climate with 82 W/m² on a yearly basis. On an annual average, the DCA configuration in the extreme warm dry climate reached almost twice the mass flow rates than those observed in the temperate climate. From the numerical simulations, we have concluded that the use of the low-cost DCA configuration in warm climates was the best solar passive strategy for saving energy in buildings throughout the year.