Typical Residential Apartment Research Articles

A simulation-based study to evaluate the cooling potential of nocturnal radiative cooling systems for residential buildings in Egypt

During the first years of the last decade, Egypt used to face recurrent electricity cut-offs in summer. In the past few years, the electricity tariff dramatically increased. Radiative cooling to the clear night sky is a renewable energy source that represents a relative solution. The dry desert climate promotes nocturnal radiative cooling applications. This study investigates the potential of nocturnal radiative cooling systems (RCSs) to reduce the energy consumption of the residential building sector in Egypt. The system technology proposed in this work is based on uncovered solar thermal collectors integrated into the building hydronic system. By implementing different control strategies, the same system could be used for both cooling and heating applications. The goal of this paper is to analyze the performance of RCSs in residential buildings in Egypt. The dynamic simulation program TRNSYS was used to simulate the thermal behavior of the system. The relevant issues of Egypt as a case-study are firstly overviewed. Then the paper introduces the work done to develop a building model that represents a typical residential apartment in Egypt. Typical occupancy profiles were developed to define the internal thermal gains. The adopted control strategy to optimize the system operation is presented as well. To fully understand and hence evaluate the operation of the proposed RCS, four simulation cases were considered: 1. a reference case (fully passive), 2. the stand-alone operation of the RCS, 3. ideal heating & cooling operation (fully-active), and 4. the hybrid-operation (when the active cooling system is supported by the proposed RCS). The analysis considered the main three distinct climates in Egypt, represented by the cities of Alexandria, Cairo and Asyut. The hotter and drier weather conditions resulted in a higher cooling potential and larger temperature differences. The simulated cooling power in Asyut was 28.4 W/m² for a 70 m² absorber field. For a smaller field area of 10 m², the cooling power reached 109 W/m² but with humble temperature differences. To meet the rigorous thermal comfort conditions, the proposed sensible RCS cannot fully replace conventional air-conditioning units, especially in humid areas like Alexandria. When working in a hybrid system, a 10% reduction in the active cooling energy demand could be achieved in Asyut to keep the cooling set-point at 24 °C. This percentage reduction was nearly doubled when the thermal comfort set-point was increased by two degrees (26 °C). In a sensitivity analysis, external shading devices as a passive measure as well as the implementation of the Egyptian code for buildings (ECP306/1–2005) were also investigated. The analysis of this study raised other relevant aspects to discuss, e.g. system-sizing, environmental effects, limitations and recommendations.

Optimal Operation of Low-Capacity Heat Pump Systems for Residential Buildings through Thermal Energy Storage

The paper provides results from a hardware-in-the-loop experimental campaign on the operation of an air-source heat pump (HP) for heating a reference dwelling in Pisa, Italy. The system performances suffer from typical oversizing of heat emission devices and high water-supply temperature, resulting in HP inefficiencies, frequent on-off cycles, and relevant thermal losses on the hydronic loop. An experimentally validated HP model under different supply temperatures and part-load conditions is used to simulate the installation of a thermal storage between heat generator and emitters, in both series and parallel arrangements. Results relative to a typical residential apartment show that the presence of the thermal storage in series configuration ensures smoother heat pump operation and energy performance improvement. The number of daily on-off cycles can be reduced from 40 to 10, also saving one-third of electric energy with the same building loads. Preliminary guidelines are proposed for correctly sizing the tank in relation to the HP capacity and the average daily heating load of the building. A storage volume of about 70 L for each kilowatt of nominal heating capacity is suggested.

Development of window opening models for residential building in hot summer and cold winter climate zone of China

This study monitors the open/closed states of the windows in 16 residential apartments in representative cities of the hot summer and cold winter zone of China, along with outdoor air temperature, outdoor relative humidity and outdoor PM2.5 concentration in 2017, to investigate the window opening/closing behavior. Three window opening models are developed. All the models are validated by modeling a typical residential apartment to compare the predicted indoor CO2 concentration with monitored data. It is found that the window opening probability is negatively correlated to both outdoor PM2.5 concentration and outdoor relative humidity, and the probability of window opening reaches the peak value when the outdoor air temperature is 23.7 °C. In terms of season, the shortest window opening duration occurs in winter due to the cold outdoor air temperature and high outdoor PM2.5 concentration. Finally, by comparing the correlation between the measured date and simulation results of indoor CO2 concentration, this study provides an appropriate window opening model for reference.

Simulation-based performance analysis of residential direct evaporative coolers in four climate regions of Iran

In this paper, the effect of direct evaporative cooling (DEC) system design parameters, including the cooling pad saturation efficiency, the airflow rate, and the thermostat set-points on the system electricity and water consumption, is evaluated in four different climates of Iran according to Köppen-Geiger classification. EnergyPlus is used to perform the simulations for a typical residential apartment. The results show that using pads with a 30% higher saturation efficiency can significantly decrease the electricity and water consumption by up to 50.0% and 29.6%, respectively, because of the working time reduction. The maximum impact is in Esfahan city in cold desert climate as its wet-bulb temperature is lower than other investigated climates. Besides, increasing the airflow rate from 3000 m3/h to 6000 m3/h leads to 43.4%–55.2% reduction in electricity consumption in different climates, although the water consumption increases by 20.5%–58.8%. According to the results, by using the DEC system with 80% saturation efficiency and 6000 m3/h airflow rate, the average indoor relative humidity and CO2 concentration is 42.3%–48.5%, and 450 ppm–470 ppm, respectively, in different climates, which can provide acceptable indoor air quality. Increasing the saturation efficiency or decreasing the airflow rate increases the indoor relative humidity and CO2 concentration. The results are also compared with a typical packaged terminal air conditioner (PTAC). The total hours when the indoor relative humidity is out of comfort zone in the DEC system, with 60% saturation efficiency, are about 92% lower than the PTAC system, on average. Moreover, with 24/26 °C thermostat set-points, the PTAC system consumes 234%–265% more electricity than the DEC one with 80% saturation efficiency in different climates.

Inverse tracking of an airborne pollutant source location in a residential apartment by joint simulation of CFD and a multizone model

Prompt identification of an indoor air pollutant source location is important for the safety of building residents in gaseous contaminant leakage incidents. Using the computational fluid dynamics (CFD) method in such inverse modeling is time consuming, especially for naturally ventilated residential buildings, which have multiple rooms and require consideration both indoor and outdoor environments. This paper compares the results of the pollutant source location identification and the simulation time based on two different inverse modeling methods: the CFD method and joint modeling of the multizone and CFD methods, to discuss the consumption of the computing time, as well as the accuracy of the location identification result. An instantaneous airborne pollutant source is assumed in a typical residential apartment that utilizes natural ventilation. A CFD model with the computational domain of the whole apartment and surrounding environment is built, for which the adjoint probability method is applied to simulate the source location probability from limited sensor readings. Meanwhile, a multizone model of the apartment is built to simulate and identify the room in which the source is located using the adjoint probability method. The CFD method is applied to the identified room afterwards to identify the exact location of the source within that room. The joint simulation of CFD and the multizone model is verified by a scaled model experiment of the apartment. It is found that the joint simulation method can significantly reduce the computing time and provides a good alternative for real-time inverse tracking of the indoor airborne pollutant.

THE PECULIARITIES OF THERMAL INDUCEMENT VENTILATION SYSTEMS

Introduction. For increasing the efficiency of natural ventilation systems, it is possible to use the thermal incentives - additional heating of the exhaust ventilation duct, which allows to expand temperature difference between ambient and exhaust air and to increase the circulation effect. This method enables stable air exchange in hot period, independently of the wind direction force. However, existing systems have several limitations of application in the high-rise apartment building in countries with a cold climate. The aim of the study is to develop a thermal inducement ventilation systems, suitable for typical residential apartment buildings in russian climate. Results. The article theoretically proves the disadvantages of existing thermal inducement ventilation systems. The article also presents the results of numerical modeling of natural convection currents in the high-rise apartment building. The dependence of outlet velocity on temperature difference for various heating methods is proved on the basis of the research. Conclusion. The results of the research illustrate the high level of the heating area location influence on free convection currents in vent duct.

Cumulative impacts of polluted urban streams on property values: A 3-D spatial hedonic model at the micro-neighborhood level

Urban streams could concurrently bring about both positive amenities accruing to the view of waterscape and negative disamenities associated with water pollution. In this paper, we focus on a specific question that has not yet been explicitly answered in the extant literature: how to estimate the cumulative impacts of urban streams (which refer to the combined impacts of amenities and disamenities of multiple sources) in high density and high-rise urban contexts. A typical residential apartment complex (comprised of a number of apartment units located in dozens of mid- to high-rise commercial apartment buildings on a contiguous land parcel) in Guangzhou, south China, is used as a case study. A detailed palette of natural amenities and environmental disamenities of two bifurcated streams are quantified via the generalized spatial two-stage least squares (GS2SLS) model. In this model, an originally constructed 3-D spatial connectivity matrix, cube contiguity, is applied to address, in a sophisticated manner, an array of endogenous, exogenous, and error interactions along both horizontal and vertical dimensions that inherently exist in the spatial context of high-rise housing markets. Our results from spatial hedonic models at the micro-neighborhood level demonstrate that homebuyers tend to evaluate urban streams’ chemical, physical, and ecological features holistically. A cumulative impact is also found, as homebuyers would like to pay an extra premium for an apartment located farther away from both polluted streams. This study advances the extant literature by contributing to a novel and effective extension of the conventional two-dimensional spatial matrix which can capture the long-ignored spatial correlation existing amongst apartment units located on contiguous floors, as well as a robust estimation of the demand of urban natural and environmental amenities in the gradually rising mid- and high-rise housing market in both developing and developed countries.

Harmonic current emission level assessment of residential loads based on impedance-gathering trend

Summary Because of the widespread application of new energy and power electronic–based residential loads in distribution networks, the impact of collective harmonics cannot be ignored. The harmonic impedance should be evaluated when determining the harmonic responsibilities at the point of common coupling. This paper presents a new noninvasive method to quantify the harmonic current responsibilities of the utility side and customer side on the basis of impedance-gathering trend. The method is compared with another noninvasive resistance-sign–based method. In addition, the emission level of the residential loads is calculated. The presented results of a field test conducted in a typical residential apartment in Shanghai, China, prove that the method works well in practical conditions.

Spatial and temporal analysis of urban heat island and global warming on residential thermal comfort and cooling energy in Taiwan

Urban heat island (UHI) and global warming effects will raise the ambient temperature of cities and increase building energy consumption. This paper discusses the residential cooling energy variations imposed by urban warming in the present and future. Data from a dynamically downscaled hourly meteorological model with a grid resolution of 5km and for time slices 1979–2003, 2015–2039, and 2075–2099 were used for dynamic building energy simulation against a typical residential apartment in the central Taiwan region. The meteorological grids were classified as 4 city grids, 25 town grids, and 31 countryside grids based on their urban morphology attributes. The values from 20 countryside grids with lower average ambient temperatures during cooling seasons were selected as reference. The spatial and temporal distributions of the impact of indoor overheating risk and annual cooling energy consumption by UHI and global warming effects were quantified against the reference value. Furthermore, because the energy penalty can be used to rapidly estimate the urban warming impact on total cooling energy consumption of a given city, the linear correlation of the energy penalty and the magnitude of the UHI effect was also established and discussed.

Influences of ambient air PM2.5 concentration and meteorological condition on the indoor PM2.5 concentrations in a residential apartment in Beijing using a new approach

PM2.5 concentrations in a typical residential apartment in Beijing and immediately outside of the building were measured simultaneously during heating and non-heating periods. The objective was to quantitatively explore the relationship between indoor and outdoor PM2.5 concentrations. A statistical method for predicting indoor PM2.5 concentrations was proposed. Ambient PM2.5 concentrations were strongly affected by meteorological conditions, especially wind directions. A bimodal distribution was identified during the heating season due to the frequent and rapid transition between severe pollution events and clean days. Indoor PM2.5 concentrations were significantly correlated with outdoor PM2.5 concentrations but with 1–2 h delay, and the differences can be explained by ambient meteorological features, such as temperature, humidity, and wind direction. These results indicate the potential to incorporate indoor exposure features to the regional air quality model framework and to more accurately estimate the epidemiological relationship between human mortality and air pollution exposure.

Natural ventilation in Beirut residential buildings for extended comfort hours

This paper examines the effectiveness of natural ventilation in Beirut for the purpose of extending comfort periods within living and sleeping zones of the residential buildings. A field survey is conducted to estimate the common window opening and degree profiles. A base case model representing a typical residential apartment located in Beirut was then adopted in integrated environmental solutions (IES) software and calibrated by experimentation through monitoring simulated and measured data indoor. The calibrated IES model was used to evaluate typical wall layering and building local materials and their role in improving indoor comfort with natural ventilation. The simulation results showed that an optimal wall configuration of higher insulation and capacitance, comprised of a 5 cm layer of strawboard sandwiched between a 2 cm × 10 cm wall of masonry Hempcrete units, achieved the highest degree of thermal comfort and enhanced comfort in winter season when compared to the base case.

Radiant floor cooling coupled with dehumidification systems in residential buildings: A simulation-based analysis

The development of radiant cooling has stimulated an interest in new systems based on coupling ventilation with radiant cooling. However, radiant cooling systems may cause condensation to form on an active surface under warm and humid conditions during the cooling season. This phenomenon occurs when surface temperature falls below dew point. To prevent condensation, air humidity needs to be reduced with a dehumidification device or a mechanical ventilation system. There are two main options to achieve this. The first is to use dehumidification devices that reduce humidity, but are not coupled with ventilation, i.e. devices that handle room air and leave air change to infiltrations. The second is to combine a mechanical ventilation system with dehumidifying finned coils.This study analyzes the floor radiant cooling of a typical residential apartment within a multi-storey building in three Italian climate zones by means of a detailed simulation tool. Five systems were compared in terms of both indoor thermal comfort and energy consumption: radiant cooling without dehumidification; radiant cooling with a soft dehumidification device; radiant cooling with a dehumidification device which also supplies sensible cooling; radiant cooling coupled with fan coils; and radiant cooling with a mechanical ventilation system which dehumidifies and cools.

Feasibility of Underfloor Heating Using Solar Energy

This study explores the economic feasibility of the underfloor heating system in North Cyprus. A case study of typical residential apartment 150m to compare the annual cost savings during the winter season between first the apartment depending only on split unit and second use solar energy to heat the underfloor. The initial investment or new life cycle investments are 10000TL with 4 solar collector units. The solar energy is cost effective, therefore as a result of the comparison the annual cost savings were 3260TL.The Solar panels which were used to collect 33.88kWh/day of energy. The feasibility of this study was determined by criteria like Net Present Value NPV, Simple Payback period SPB, Savings-to-Investment Ratio SIR, Internal Rate of Return IRR. NPV which was obtained greater than zero, IRR percentage was larger than the discount rate. The utilize of solar energy reduced the electricity cost and energy consumption.

A numerical modeling approach to evaluate energy-efficient mechanical ventilation strategies

This paper investigates design features that can potentially reduce the energy consumed in attaining appropriate thermal comfort levels in typical residential buildings. A numerical model coupled with a PID controller is developed to predict the indoor air temperature that is adjusted via mechanical ventilation. The model is used to simulate and evaluate various scenarios of building wall layouts and materials. From the various simulation runs, the wall configurations and materials were refined to combinations that rendered the mechanical ventilation a feasible option for attainment of comfort for the largest number of hours per year. The runs were conducted for a typical residential apartment located in the city of Beirut, Lebanon, which is characterized by mild coastal climatic conditions. Different wall configurations were assumed for each of the living zone and the bedroom zone of the apartment. The simulation results suggest an optimal wall configuration comprised of a 5cm layer of insulating strawboard sandwiched between a 2cm×10cm wall made of masonry units consisting of Hempcrete (mixture of Portland cement, aggregates, and industrial hemp fibers) for the living zone, whereas the wall for the bedroom zone consists of a 10cm of Hempcrete.

Valuing the health benefits of improving indoor air quality in residences

Unlike commercial premises, the indoor air quality of residences is more dynamic, uncontrolled, and prone to human behavioral changes. In consequence, measuring the health benefit gains derived from improving indoor air quality in residences is more complicated. To overcome this, a human thermal comfort model was first integrated with indoor microenvironment models, and subsequently linked with appropriate concentration–response and economic data for estimating the economic benefit gains derived from improving indoor air quality in residences for an adult and an elderly person. In this study, the development of the model is illustrated by using a typical residential apartment locating at the worst air quality neighborhood in Hong Kong and the daily weather profiles between 2002 and 2006. Three types of personal intervention measures were examined in the study: (i) using air cleaner in residence, (ii) changing time spent in residence, and (iii) relocating to a better air quality neighborhood. Our results revealed that employing air cleaners with windows closed in residence throughout the entire year was the most beneficial measure as it could provide the greatest annual health benefit gains. It would give a maximum of HK$2072 in 5-year cumulative benefit gain for an adult and HK$1700 for an elderly person. Employing air cleaners with windows closed in only cool season (October through March) could give the highest marginal return per dollar spent. The benefit gains would become smaller when windows were opened to a greater extent. By contrast, relocating to a better air quality neighborhood and changing the time spent in residence did not appeal to be beneficial intervention measures.

Effect of an Ionic Air Cleaner on Indoor/Outdoor Particle Ratios in a Residential Environment

We tested a leading commercially available ionic air cleaner in a typical residential apartment to study the effect of the device on indoor/outdoor airborne particle number and mass concentration ratios. In addition, we also determined the indoor ozone and ion concentration levels. When measured during normal daily activity, the average indoor/outdoor mass concentration ratio was reduced from 1.03 to 0.73 and the number concentration ratios underwent reductions for most of the particle size fractions. However, due to a substantial inter-and intra-measurement variation in particle ratios, the observed average reductions were not statistically significant. When measurements were performed in a still room, the indoor/outdoor particle mass concentration ratio decreased from 0.9–1.4 to 0.3–0.4 in eight hours when the air cleaner was operating. Ambient ozone concentrations measured in the middle of the apartment were between 13–19 ppb during normal daily activity and the ozone levels increased to 77 ppb when me...

96/05491 A critique of estimates of the cost of damage to building material due to atmospheric attack

The development of radiant cooling has stimulated an interest in new systems based on coupling ventilation with radiant cooling. However, radiant cooling systems may cause condensation to form on an active surface under warm and humid conditions during the cooling season. This phenomenon occurs when surface temperature falls below dew point. To prevent condensation, air humidity needs to be reduced with a dehumidification device or a mechanical ventilation system. There are two main options to achieve this. The first is to use dehumidification devices that reduce humidity, but are not coupled with ventilation, i.e. devices that handle room air and leave air change to infiltrations. The second is to combine a mechanical ventilation system with dehumidifying finned coils.This study analyzes the floor radiant cooling of a typical residential apartment within a multi-storey building in three Italian climate zones by means of a detailed simulation tool. Five systems were compared in terms of both indoor thermal comfort and energy consumption: radiant cooling without dehumidification; radiant cooling with a soft dehumidification device; radiant cooling with a dehumidification device which also supplies sensible cooling; radiant cooling coupled with fan coils; and radiant cooling with a mechanical ventilation system which dehumidifies and cools.