Buildings energy simulation using energy express a case study on sub-tropical Central Queensland University (CQU) buildings

The strategies of buildings energy management can be developed through energy audit, analysis and simulation. Currently, different end-users of CQU buildings such as heating, ventilating and air conditioning (HVAC) units, electrical appliances, etc do not take full advantage of local sub-tropical climatic conditions. Therefore, climate-responsive strategies need to be implemented in order to take full advantage of the positive climate attribute of sub-tropical climate regarding efficient energy management and conservation measures. This study is conducted on a three-story library building of CQU. HVAC systems were selected for practical operational energy conservation measures (ECM) to take advantages of hot and humid subtropical climate. A baseline energy consumption profile of the building is simulated using building energy simulation software called Energy Express (EE). The simulated results are then validated with energy audit and on-site metered data. The means to utilize environmental conditions to improve building energy efficiency is investigated. Variable air volume (VAV) system as an energy conservation option is investigated and compared with existing constant air volume (CAV) system. This study found that about 12% energy savings could be achieved by replacing CAV system with VAV system as an option for energy retrofitting, and hence recommended to CQU management for consideration

Assessment of solar assisted air conditioning in Central Queensland's subtropical climate, Australia

Australia has a very sunny climate, with a very high demand for air conditioning. Implementing solar assisted air conditioning is an ideal option to achieve a high solar fraction which leads to a significant amount of energy and greenhouse gas emission savings. Solar assisted air conditioning systems are environmentally friendly by being constructed in a way that minimises the need for chlorofluorocarbons CFC, Hydro chlorofluorocarbons HCFC or Chlorofluorocarbons HFC refrigerants and by using a low grade thermal renewable energy, therefore, making them energy efficient and environmentally safe. They can be used either as stand-alone systems or with conventional AC, to improve the indoor air quality. Solar cooling is a new and a fast growing technology compared to other fields of solar energy applications. On the other hand most of the current solar cooling applications are demonstration projects in nature; the technologies are advancing yet still need a lot of additional design, planning, development, and research efforts. To now solar assisted air conditioning’s main obstacles are the high installation costs, and the lack of knowledge and familiarity with this technology between designers, developers and architects. In this paper a feasibility study is carried out to assess a solar assisted air conditioning system for an office building under three of Queensland’s subtropical climates; Rockhampton, Gladstone, and Emerald. The technical aspects of a proposed solar cooling system are investigated. Cooling load profile for a proposed reference building was obtained using TRNSYS software under the influence of these different climates. An electric vapour compression pump, with 2.5 coefficient of performance (COP) for cooling is used as a reference system to assess the primary energy consumption, assuming 80% of primary energy consumed by the reference conventional system is replaced by solar energy. The results of analysing the proposed system indicated that an 80% of the primary energy savings can be achieved by installing 50 m2 of solar collectors and 1.8 m3 of hot water’s storage tank under the three selected climates

A comparative study of residential household energy consumption in Australia and the USA

The residential households utilise approximately one-fifth of the total energy consumed in the developed counties especially in the U.S. and Australia. The rate of household energy consumption is growing each year as the number of residential dwellings and expectation of life style has increased. The use of electricity has been rising since long [sic]. As the large proportion of the energy consumed by the residential households is electricity which is the most greenhouse gas-intensive form of delivered energy in the U.S. and Australia, the residential household is responsible for enormous greenhouse gas emissions. Therefore, the primary objective of this paper was to conduct a comparative analysis of household energy consumption pattern both in the U.S. and Australia for the period of 1990 to 2008. The study revealed that the per capita energy consumption by the residential households in Australia is significantly higher than the households energy use in the U.S. The electricity consumption has increased in both countries however the gas consumption has notably increased in Australia while the U.S. residential household gas consumption is steady

Environmental pollution generated from process industries in Bangladesh

The sources of environmental pollution in process industries in Bangladesh are discussed. Total pollution load into environment (i.e., into air, water and land) generated from process industries is determined and presented using industrial pollution projection system (IPPS) developed by the World Bank. Most polluting industries in Bangladesh are identified and ranked. The projection of this pollution load for year 2011–2012 is estimated and discussed. It was found that the food industry was the worst air polluter, whereas pulp and paper was the worst water polluter, and tanneries and leather industries were worst polluter of toxic chemicals. Industrial pollution control measures are recommended

Solar air conditioning for an institutional building in subtropical climate

Air conditioning is one of the major consumers of electrical energy. The most of the ways of generating the electricity today, as well as the refrigerants being used in traditional vapour compression cooling system, produce greenhouse gas emissions which ultimately contribute to global warming. It is therefore necessary to develop process and technology to implementing renewable sources of energy for air conditioning to reduce greenhouse gas emissions and to achieve sustainable development. The use of solar energy to drive cooling cycles for space conditioning is relatively a new and attractive concept which mostly eliminates the need for CFC, HCFC or HFC refrigerants. In this presentation an overview of a hybrid solar desiccant cooling system which has been designed and installed in an institutional building of Central Queensland University, Rockhampton campus, Australia is presented. The conceptual bases of the technology, capability and limitations are outlined. The energy demand, energy consumption, and economic and environmental problem associated with the usage of fossil fuel resources in Australian commercial buildings and the issues of indoor air quality, mould growth and indoor thermal comfort are discussed. Furthermore, experimental and computational results of the performance of installed solar desiccant cooling system is presented and discussed. The results are analysed on the basis of energy savings, solar fraction (SF), primary energy used, coefficient of performance (COP) and desiccant system efficiency. Results showed that the installed solar desiccant cooling system at Central Queensland University can achieve energy savings of 19% with maximum coefficient of performance of 0.83 and desiccant efficiency of 48%

Techno-economic study of thermal energy storage systems in tropical climate university building

In the heating, ventilating and air conditioning (HVAC) industry, cool thermal energy storage (TES) is the most preferred demand side management (DSM) technology for shifting cooling electrical demand from peak hour to off-peak hour. In this study, the techno-economic feasibility of TES in subtropical Central Queensland University building is studied. Cooling load profiles of existing systems are simulated first using DesignBuilder (DB) simulation software which is based on EnergyPlus (EP) simulation engine, then verified by on-site measured data and then TES systems are analysed. Under the Australian electricity tariff rates, the results show that the full chilled storage can save up to 61.3% of the electricity cost required for cooling when compared with the conventional system

Rooftop greenery systems in subtropical climates for environmental sustainability : a review

Green roofs can offer a sustainable green surface by improving urban climate, minimizing heat island effects and simultaneously protecting biodiversity. It can protect the roofing membrane from exposure to ultra violet radiation and hail damage. Green roof can reduce energy demand on space conditioning, and hence greenhouse gas emissions. It is not a cooling device rather it works as an improved insulation. Plants absorb a significant portion of solar energy through biological functions and the remaining solar radiation that would affect the internal temperature of the building is much less than that of a bare roof. In comparison with other developed countries, Australia has been slow to adopt green roofs and no solid platform has yet been developed in Australia. Due to the significant differences in climate and available substrates and plants, European and American experimental data and technology cannot be used locally (in Australia) to implementing rooftop greenery systems. However there are some scattered examples of usage of green roofs in Australia and majority of green roofs are constructed for decorative purposes. This paper presents a review and discusses the impact of green roofs on thermal transfer value, building energy consumption and environmental sustainability in subtropical climate

Review on solar assisted air conditioning for hospitals isolation units

Hospitals and hospital special units for example operation theatres, isolation units, laboratories are not like any other commercial property as they are required to operate special HVAC systems. To build an effective HVAC system design to enhance the air quality in the healthcare facilities is a great challenge. Indoor air Quality (IAQ) is more critical in healthcare facilities due to the hazardous microbial and chemical agents present and the increased susceptibility of the patients and health care staff. In certain areas, air handling unit dampers are forced to be fully open to allow for 100% of air extraction and, hypo filters are used in conjunction with dampers to ensure the quality of air during twenty four working hours seven days a week. Using no recycled air means more energy, more money and more gas emissions. Solar air conditioning systems can be constructed in a way that eliminates the need for refrigerants such as, Chlorofluorocarbon (CFC) and hydrochlorofluorocarbons (HCFC). Solar cooling systems are a nice tool for the exploitation of solar energy. They have the advantage of using absolutely harmless working fluids such as water, or a salt solution. They are energy efficient and environmentally safe. They can be used either as stand-alone systems or with conventional AC, to improve the indoor air quality of all types of buildings. The main goal is to utilize ‘‘zero emissions’’ technologies in order to reduce energy consumption as well as the CO2 emissions

Integration of carbonation process with coal fired power plant to reduce CO2 emissions

Global warming is a major issue Carbon dioxide (CO2) is the major greenhouse gas which occupies approximately 55% of the total greenhouse gases. Coal fired power plants are one of the major contributors of CO2 emission. Different carbon capture and storage (CCS) technologies are available and some are being developed and implemented to minimise CO2 emission. Mineral carbonation technology is one of the CCS technologies where CO2 is sequestered as a solid environmentally safe stable carbonated product; however, carbonation process requires additional energy for pretreatment of the feed stocks (such as grinding of mineral) and compression of CO2 before carbonation. The main advantage of this technology is its exothermic reaction process. Heat energy required for pretreatment can be supplied from this exothermic reaction if heat energy can be recovered. Sensible heat from carbonated product can also be recovered from the carbonation process. This paper presents the feasibility of integrating carbonation technology with coal fired power plant. The results of its impact on power plant efficiency arepresented and analyzed through thermodynamic energy balance

Energy recovery opportunities from mineral carbonation process in coal fired power plant

Various carbon dioxide (CO2) capture and storage (CCS) technologies are available worldwide to mitigate the effects of global warming. Mineral carbonation technology is one of the types of CCS technology. In this process gaseous CO2 is converted into geologically stable carbonates. This process has some potential advantages compared to other available CCS technologies which have attracted the attention of researchers for further development of this technology for sequestering CO2. One of the potential benefits of this technology is its exothermic reaction process. This exothermic heat energy can be recovered and used in other energy consuming components of carbonation plant. Heat energy from the products of the carbonation process can also be captured. This technology has not fully been developed yet, in particular for implementing it into power plants. In this study a thermodynamic mass and energy balance model is developed using Matlab/Simulink software for investigating energy recovery opportunities. Wollastonite mineral is used as feed stocks. The amount of heat energy which can be recovered at different carbonation temperatures is determined and analysed for a case study power plant with capacity of 1400 MW. It is found from this study that the carbonation process in case study power plant is energy self-sufficient, even only by the exothermic heat produced from the reaction and no heat recovery is needed from the products of carbonation process. It is also found that the energy required to supply to the carbonation plant (i.e. to grinder and compressor) decreases with increase in carbonation temperature. The surplus exothermic heat energy and heat energy from carbonated products can be utilized to reduce the fuel energy required for the existing power plant