Buildings In Hot-humid Climates Research Articles

Thermal performance assessment of opaque ventilated façades for residential buildings in hot humid climates

In this paper, the thermal performance of opaque ventilated façades (OVFs) in the Mediterranean climate zone, where passive cooling is a priority, was examined using computational fluid dynamics (CFD). Simulations were carried out to analyse the behaviour of OVF components under different geometric configurations, using weather data for three cities in Turkey that reflect the climatic conditions of a first-degree day region. These data include the air cavity thickness, outlet size, and air cavity height. Unlike in previous literature, two-way outlet ventilation is employed in this study in the analysis of different façade systems for the Mediterranean climate region, and its performance in reducing solar gain is determined. According to the samples examined within the scope of the criteria outlined herein, it was determined that the rate of heat transferred indoors through the façade can be reduced within the range of 69 % to 75 %.

The Impact of Internal Courtyard Configuration on Thermal Performance of Long Strip Houses

A courtyard is an essential space for natural lighting and natural convective ventilation of residential buildings in hot-humid climates. This study focuses on the internal courtyard configuration on the thermal performance of long strip houses (LSH) in the hot-climate area of Hainan Island, China. The aim is to identify the best design parameters for the courtyard to improve thermal comfort in modern LSH design. Appropriate strategies, including Mahoney table, field investigation, and CFD simulation, are used to determine thermal performance. As a result, the design guidelines of the courtyard are proposed to optimize the thermal comfort towards energy saving. The study reveals the spatial characteristics and climate regulation of internal courtyards in traditional LSH. In addition, the simulation results show that the enclosure with a shaded cover and a high ratio of H/D is conducive to thermal environment and ventilation, and the section of contracted shape from bottom to top is a preferred option in the internal courtyard configuration. This study should, therefore, be of value in designing practical projects with an interior courtyard for architects.

The Impact of Degradation on a Building’s Energy Performance in Hot-Humid Climates

To date, energy consumption in buildings accounts for a significant part of the total amount of energy consumed worldwide. The effect of ageing and degradation of various building components is one of the least studied reasons for the possible increase in energy consumed in buildings over time. In addition, there is a clear lack of practical guidelines that would help specialists take this factor into account. In this paper, an attempt is made to assess a possible change in the energy performance of buildings due to the degradation of their various components (insulated glass units, thermal insulation, airtightness, solar reflectivity of the building envelope, and photovoltaic modules). Detached and apartment buildings in hot-humid climates with reference to the United Arab Emirates (UAE) were considered. The study was based on simulation research using EnergyPlus, in which the initially collected data on the possible deterioration of the properties of various building components was used for dynamic thermal simulation of selected buildings. The results showed an increase in energy consumption for cooling in detached houses might reach up to 9.53–38.4% over 25 years for more airtight and insulated buildings and 12.28–34.93% for less airtight and insulated buildings. As a result, certain patterns of changes in energy consumption for cooling buildings were established, based on which a set of guidelines was developed. These guidelines can help specialists in various fields better understand the trends in the energy performance of buildings under the influence of degradation processes and take appropriate measures.

Sustainable active cooling strategies in hot and humid climates – A review and a practical application in Somalia

Providing spaces with thermal comfort is a critical need, particularly in hot-humid regions, where more than a third of the world's population are settled. In terms of space cooling technologies, the global market is largely dominated by window air conditioners and ductless mini-splits. However, numerous other options are available and require more exploration to clearly identify their advantages against conventional systems. In this regard, there are plenty of studies about active cooling systems, but still little is known about the best choices for their application in high-density buildings in extreme humid climates, where latent loads are dominant. In such a framework, this paper briefly examines and identifies possible solutions for space cooling in non-residential buildings in hot-humid climates. In this sense, an all-air system with heat recovery and a radiant ceiling coupled with air handling were identified as the most recommended options for such environments, based on their working principles. Furthermore, the study includes a detailed assessment of the application of these solutions on a case-study building in Mogadishu, Somalia, from the point of view of the cooling demand to the energy consumption of the selected cooling systems. The findings of this work can be extrapolated to be then applied in other developing cities, and outline the path future research should follow to improve the systems.

Analysis of indoor set-point temperature of split-type ACs on thermal comfort and energy savings for office buildings in hot-humid climates

In hot-humid climates, particularly in sub-Saharan Africa (SSA), ambient temperatures and relative humidity are as high as 35 °C and 84%, respectively, requiring the use of mechanical cooling systems for indoor thermal comfort. Split-type vapor-compression air-conditioners (SVAC) are mainly used for space cooling in SSA and consume 60–80% of total energy consumption in commercial and public buildings. Appropriate control strategy of the indoor set-point temperature of SVAC can result in significant energy savings in these buildings. In this study, modeling and dynamic simulation have been conducted using EnergyPlus to predict the energy saving potential and indoor thermal comfort of buildings in hot-humid climates by controlling set-point temperature of the SVAC. In a case study, climatic data for Ghana, was used to predict the energy saving potential and indoor thermal comfort. The study results revealed that, to ensure indoor thermal comfort at high outdoor temperature condition of 35 °C, the least and optimum set-point temperatures of the SVAC should be 21 °C and 25 °C, respectively. On the other hand, for low outdoor temperature condition, the least and optimum set-point temperatures were 22 °C and 26 °C, respectively. Considering 1-star and 2-star rated SVACs which are dominantly used in Ghana, operating at 21–25 °C in the case of high outdoor conditions, and 22–26 °C for low outdoor conditions relative to the least temperatures resulted in energy savings of 8–33% and 12-44%, respectively.

Analysis of Incorporating a Phase Change Material in a Roof for the Thermal Management of School Buildings in Hot-Humid Climates

Strategies to reduce energy consumption are presently experiencing vigorous development. Phase change materials (PCMs) are novel materials that can reduce indoor temperatures via the change in material phase. Regarding the situation in Taiwan, there is no practical utilization of PCMs in school buildings at present, especially in combination with rooftops. In this paper, we discuss the feasibility and utilization potential of installing PCMs in the rooftops of school buildings. School buildings located in northern and southern Taiwan (Taipei and Kaohsiung) were selected to analyze the energy-saving potential and optimization of indoor thermal comfort by installing PCMs with different properties in rooftops over two time periods, including the air conditioning (AC) and natural ventilation (NV) seasons. Based on the simulation results, the feasible patterns of PCM simultaneity are found to be appropriate for improved indoor comfort and energy saving during the different seasons. Specifically, the efficient phase change temperature (PCT) for different PCM thicknesses is clarified to be 29 °C. The economic thickness of PCM was clarified to be 20 mm for Taipei and Kaohsiung. Through the recommendations proposed in this study, it is expected that the PCMs may be efficiently implemented in school buildings to realize the goal of energy conservation and improve thermal comfort.

Indoor thermal comfort assessment in office buildings in hot-humid climate

This paper aims to assess the user’s perception of thermal comfort and air conditioning in office buildings in Batu Pahat, Johor area. Field experiments were conducted utilizing environmental measurement and Post Occupancy Evaluation (POE) in Batu Pahat District Land Office (Pejabat Daerah) and (C2 and ORICC) office buildings in the Universiti Tun Hussien Onn Malaysia (UTHM). The environmental measurement was conducted using thermal comfort station BABUC A, whereas the POE was based on the ASHRAE 55-2010 standard. The environmental parameters included relative humidity, air temperature, and air velocity. They were measured and compared with MS-1525, ASHRAE 55, and ISO 7730 standards. Results indicated that indoor air temperature in C2 has good compliance with MS-1525, ASHRAE 55, and ISO 7730 standards and criteria with a measured comfort range of 24 °C-26 °C. Whereas for ORICC and Pejabat Daerah, temperatures were a bit lower than the suggested range. At the same time, the range of relative humidity was found to be higher than ASHRAE limits but complied with other standards. Moreover, adequate air velocity standards were not met in the three office buildings, in which they were measured within 0.4-0.5 m/s range. Furthermore, thermal comfort levels and the POE survey results indicated that users’ in hot tropical office buildings could acclimate to a higher indoor environment than what was suggested by standards.

Peak indoor air temperature reduction for buildings in hot-humid climate using phase change materials

A hot-humid climate, which is characterized by uniform diurnal temperature throughout the year, can provide a year-round opportunity to benefit from phase change materials (PCMs) for buildings' application. However, the small diurnal temperature fluctuation might restrict the PCMs' performance and efficiency. This paper investigates the capability of PCMs to decrease the peak indoor air temperature (Tᵢ) of naturally conditioned buildings in a hot-humid climate region by storing night coolness. To this end, field measurement has been conducted in existing buildings to identify the appropriate transition temperatures' range for PCM. Then, a macro-encapsulated PCM with different transition temperatures and quantities has been numerically examined. The results showed a considerable reduction in peak Tᵢ, particularly when using PCMs with lower transition temperatures and higher quantities. Although uncompleted PCM freezing was observed when lower transition temperatures were used, it was tackled by combining night ventilation. Moreover, the PCMs showed effective year-round performance and achieved a reduction in the peak Tᵢ reached up to 4.87 °C. The optimal performance was achieved when using a combination of NV and PCMs with the lowest transition temperature that ensured complete PCMs freezing. Therefore, the PCMs’ freezing temperature should be considered when selecting PCMs for such conditions.

BIM-based techno-economic assessment of energy retrofitting residential buildings in hot humid climate

Buildings in hot humid climates are energy intensive to operate. Energy consumption in Saudi Arabia is almost three times higher than the global average, and one of the major contributors to that is the residential sector. Increasing environmental and economic concerns, in the form of Saudi Vision 2030, mean that the existing unsustainable residential building stock has to be energy retrofitted. This study examines the techno-economic feasibility of retrofitting existing homes in Eastern Province, Saudi Arabia. A Building Information Modelling (BIM)-based retrofit framework has been adopted and investigated on two case studies. Eight Energy Efficiency Measures (EEMs) have been implemented including increasing cooling set point temperature, using energy efficient appliances, replacing conventional lights with more efficient lights, applying window shading, improving glazing type, improving air tightness, using more efficient air conditioning system, and adding envelope insulation. A three-level energy retrofit plan is proposed. Results indicate that annual energy consumption in a villa is reduced by 13.79%, 19.27% and 56.9%, and in the apartment building by 22.84%, 28.85% and 58.5% through a level 1, 2 and 3 retrofit respectively. Compound Payback Period (CPP) was computed to assess the economic viability. For the villa, investing in a level 1, 2 and 3 retrofit will pay back in 0.92, 8.37 and 25.15 years respectively, while for the apartment building, the payback period is 0.60, 11.28 and 24.60 years respectively. Thus, energy retrofitting of existing homes has the potential to significantly reduce energy consumption, however, it is economically not viable in the existing scenario. Electricity tariffs need to be further increased and coupled with incentive programs to render deep energy retrofits feasible. Furthermore, the investigated BIM-based approach can be adopted to investigate energy retrofitting in other climate zones of Saudi Arabia and other countries in the region, and eventually be adopted to efficiently effectuate the colossal task of retrofitting the whole existing residential building stocks of these countries.

A Review of Retrofit Interventions for Residential Buildings in Hot Humid Climates

A Review of Retrofit Interventions for Residential Buildings in Hot Humid Climates

High efficiency ‘low-lift’ vapour-compression chiller for high-temperature cooling applications in non-residential buildings in hot-humid climates

Over the last decade, building engineers have begun implementing sensible-latent de-coupled air-conditioning systems in non-residential buildings in hot-humid climates. Typically, a de-coupled system consists of a dedicated outdoor air sub-system for ventilation and high-temperature radiant cooling sub-system for space cooling. This approach has lowered cooling energy demands and fan energy consumption in buildings. However, the complete energy saving potential of de-coupled systems, specifically high-temperature space cooling sub-systems, can only be realized by using low-lift chillers that supply chilled water which matches the high-temperature radiant cooling application.This paper discusses the results of a retro-installation of a prototype modular low-lift chiller to provide high-temperature chilled water (at 17 °C) to the radiant cooling units. The paper presents temperature and cooling load profiles, control methodology and energy efficiency improvements of the low-lift cooling system. The paper also further discusses the influence of various parameters on the performance of the chiller. Despite having a cooling capacity of only 20 kW, the modular low-lift chiller is consistently able to achieve a Coefficient of Performance (COP) of 8. By operating at a low-lift (20 K) compared to a high-lift (29 K), the sensible cooling electrical consumption (at the chiller) is reduced by 23% despite being compared to a high-lift low-temperature chiller with 100 x higher cooling capacity. When normalized for cooling capacities, this reduction is between 29–30%. The project is the first known installation of low-lift cooling for building comfort control in hot-humid climates, and first reported publication of low-lift cooling in a real-life scenario - i.e., non-laboratory conditions or modelling exercise.

Assessment of net energy contribution to buildings by rooftop photovoltaic systems in hot-humid climates

Abstract The study aims to investigate the overall impact of rooftop photovoltaic (PV) systems on the energy performance of residential buildings in hot-humid climates. The study area spans over 100 km2 encompassing 33,000 residential units in the city of Al-Khobar in Saudi Arabia. It examines the restrictions towards the utilizability of building rooftops for PV application. The total building rooftop area and its corresponding PV output at the urban scale level has been estimated with the help of geographic information systems and PV simulation tools. The secondary contribution by PV in terms of heat gain reduction has also been investigated through EnergyPlus simulation engine. It is found that villas and apartment buildings respectively offer 21% and 28% of their rooftops for PV application. Results suggest that solar PV can offset 19% of the electricity demand when 25% of the building roof is utilized, in addition to a cooling load reduction of 2% due to the shading effect of panels. For the total study area, the annual electricity generation potential for tilted and flat application of PV with the existing roofs conditions turns out to be 797 GWh and 757 GWh respectively.

Techno-economic analysis of a hybrid solar PV-grid powered air-conditioner for daytime office use in hot humid climates – A case study in Kumasi city, Ghana

Air-conditioners are the highest energy consuming appliances in the offices of businesses, public and commercial buildings in hot humid climates. In Ghana, survey conducted indicates that 60–80% of electricity used in offices of public and commercial buildings is for air-conditioning. Many hot climates, and Ghana in particular, are endowed with high solar irradiations. The need for daytime office space cooling is actually as a result of high solar radiation levels.In the present work, studies have been conducted on the performance of a hybrid solar PV-grid powered air-conditioner for daytime office cooling in hot humid climates with a case study in Kumasi city, Ghana. A standard office of 30 m2 floor area (105 m3 office space) in a building with three of the sides sharing walls with adjacent offices, and the front side facing north was used for the study, with the air-conditioner set at a temperature of 20 °C. In the experiment, the pure sine wave hybrid inverter with integrated PWM charge control system was set to solar energy priority and supported by utility grid electricity when solar energy is not sufficient.It has been determined that for daytime office cooling, a 1040 Wp solar PV system with 200 Ah, 24 V battery configuration has a monthly mean solar fraction of 51% ± 9% for an air-conditioner with nominal cooling capacity of 2.5 kW and maximum power consumption of around 1.19 kW. The energy generation of the 1040 Wp solar PV system has been determined to be around 1211 kWh per year. Financial analysis has revealed that for the hybrid solar PV-grid powered air-conditioner, there is potential savings of US$ 1600 compared to 100% utility grid electricity in 10 years. It has also been estimated using available data that there is a potential of about US$ 3300 savings when the air-conditioner is powered with 100% solar energy compared to 100% utility grid electricity in 10 years, for daytime office use.

An Innovative Smart Liquid Desiccant Air Conditioning System for Indoor and Outdoor Cooling using Seawater Bittern

The design and construction of buildings in hot-humid climates requires high energy consumption typically for air conditioning due to higher thermal loads. In hot-humid climates, there is a rising concern on the current rate of energy consumption due to air conditioning. Considering the wider impacts of carbon emissions on our climate, and the need to reduce these emissions, effective energy efficiency solutions are necessary to achieve the overall goal of reducing carbon emissions. Conventional energy resources continue depleting and the energy demands of a growing global population continue to increase. Ventilation rates to buildings must be increased to ensure occupants healthy indoors environment. This more outdoors air gave the designers a much bigger load to be removed especially in humid climates. Outdoor cooling remains a challenge but will have lots of social and economic benefits. This paper presents the design and performance of a fully integrated liquid desiccant air conditioning system that could be used for indoor and outdoor cooling. The superefficient packed liquid desiccant evaporative air conditioning system can provide 22000 m3/h treated fresh air at supply temperature of 16°C with 50% reduction in energy consumption compared to conventional systems.

Energy and Economic Evaluation of Green Roofs for Residential Buildings in Hot-Humid Climates

Green roofs may be considered a passive energy saving technology that also offer benefits like environmental friendliness and enhancement of aesthetic and architectural qualities of buildings. This paper examines the energy and economic viability of the green roof technology in the hot humid climate of Saudi Arabia by considering a modern four bedroom residential building in the city of Dhahran as a case study. The base case and green roof modelling of the selected building has been developed with the help of DesignBuilder software. The base case model has been validated with the help of 3-month measured data about the energy consumption without a green roof installed. The result shows that the energy consumption for the base case is 169 kWh/m2 while the energy consumption due to the application of a green roof on the entire roof surface is 110 kWh/m2. For the three investigated green roof options, energy saving is found to be in the range of 24% to 35%. The economic evaluation based on the net present value (NPV) approach for 40 years with consideration to other environmental advantages indicates that the benefits of the green roof technology are realized towards the end of the life cycle of the building.

Potential of shading devices and glazing configurations on cooling energy savings for high-rise office buildings in hot-humid climates: The case of Malaysia

Abstract Rapid growing of energy use has raised critical concerns over energy supply difficulties and negative environmental impacts globally and among ASEAN countries. Malaysia is experiencing a high average annual energy demand growth rate of approximately 2.3% which large portion of that energy is used by office buildings. Under the hot-humid climatic conditions in Malaysia, high-rise office buildings with large or fully glazed facades are facing a major problem of overheating due to high solar radiation through the glazed facades. This has caused high cooling energy requirements. The aim of this study is to investigate the potential of three types of shading devices on cooling energy savings when applied at different facade orientations. The aim also extends to investigations on different cooling energy savings when shading devices are applied on facade glazing with different configurations and thermal performances. This was done through a case study of a high-rise office building in Kuala Lumpur, Malaysia using IES (VE) building thermal simulation software. Twenty simulation building models were applied with different shading devices at different facade orientations and with high and low performance facade glazing. The simulation results indicate that high-rise office buildings in Malaysia use approximately 45.9% of total building energy for cooling purposes. The results also suggest that use of various shading devices on low-e double glazed facades will result between 1.0% and 3.4% annual cooling energy savings, depending on the types of shading devices and facade orientations. The estimated annual cooling energy savings increase to between 5.0% and 9.9% when the shading devices are applied to all orientations of low-e double glazed facades. The estimated annual cooling energy savings further increase to between 5.6% and 10.4% when the facade glazing is replaced by single clear glazing. This study recommends prioritizing shading devices on the East and West facades for optimized annual cooling energy savings. The simulation results show that egg-crate shadings are able to produce the highest annual cooling energy savings compared to vertical shadings and horizontal shadings. It is recommended to use shading devices on low performance glazing compared to high performance glazing since the energy savings are more significant when shading devices are used on low performance glazing. In conclusion, the use of shading devices is more effective in achieving cooling energy savings compared to the use of high performance glazing under the hot-humid climate of Malaysia.

Thickness Optimization of Kapok Fibre Insulation below Roof Pitch of Residential Buildings in Hot-Humid Climate with Mathematical Formulation

Kapok fibre possesses high thermal resistance and can retard the rate of heat flow into the building through the roof. Reduced heat flow into the building leads to reduction in the use of room air-conditioners that improves indoor thermal comfort, leading to lower electricity bills. Additionally, the cost of insulation increases with its thickness. Therefore, determining the optimum thickness of insulation is essential to maximize the cost savings over the service period of insulation. In this study, a house model design with a floor dimension of 3 m by 3 m, room height of 2.5 m and roof slope of 45° is employed to determine the optimum thickness of kapok fibre insulation for a placement below roof pitch of residential buildings under hot-humid climate and it is associated with cost savings. The findings suggested that a maximum cost savings of RM1148.84 can be obtained at the optimum thickness of 0.0604 m.

Environmental Design Consideration for Courtyards in Residential Buildings in Hot-humid Climates: A Review

This paper discusses environmental design considerations for courtyards in residential buildings in hot-humid climates through a literature review by contrasting with those in hot-dry climates. The main focus of discussion is on shading and ventilation effects of courtyards. The results of the analysis revealed that the form and orientation of a courtyard were less significant in its environmental design considerations for the hot-humid climates. Although these factors were reported to be the most important design considerations in the case of hot-dry climates. Mean-while, natural ventilation has been commonly utilized in wooden-structured traditional build-ings in hot-humid climates. However, most of the urban houses in Southeast Asian regions are becoming heavy-weight brick-walled buildings nowadays. It could be seen that the required environmental effects of a courtyard and its design considerations in the case of high thermal mass buildings in hot-humid climates are still uncertain and need to be investigated further.

Strategi Double Skin Fasade pada Bangunan Kampus National Central University dalam Menurunkan Kebutuhan Energi Pendinginan

Building facade plays significant role in building energy efficiency and sustainability. Double Skin Facade (DSF) strategy comes as one of solution in advance building facade design technology. The aim of this study is to observe the performance of DSF configuration (air gap width) and materials in terms of reducing cooling energy for energy efficiency in case study buildings in hot humid climate in Taiwan. DesignBuilder- EnergyPlus was used as simulation tool in this study. Two scenario based on the placement of DSF strategy were conducted. The results show that combination of 1.2m air gap and double glazed Low E could reduce the cooling energy demand up to 31.28%. This study proved that DSF strategy is possible to be applied on hot humid climate such as Taiwan.

Comparative Study of Indoor Environment in Residential Buildings in Hot Humid Climate of Malaysia

Comparative Study of Indoor Environment in Residential Buildings in Hot Humid Climate of Malaysia