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No description available.

Thesis (M. Sc.)--University of Hong Kong, 1995. / Includes bibliographical references.

published_or_final_version / Environmental Management / Master / Master of Science in Environmental Management

published_or_final_version / Environmental Management / Master / Master of Science in Environmental Management

M.Sc. / South Africa is in the midst of an energy crisis. The national energy provider is unable to provide the capacity currently demanded in South Africa. Although the construction of new electricity plants is planned, it does not solve the immediate problem. A large amount of energy is used to provide thermally comfortable indoor environments using conventional methods such as air-conditioning units. Energy efficiency is an environmentally friendly solution for South Africans to reduce the demand for electricity. In the context of the current situation in South Africa, significance can be given to investigations that explore viable methods of reducing energy consumption in buildings, while maintaining or improving thermal performance through passive energy interventions. This study was conducted with the goal of quantifying and demonstrating technologies that simultaneously attempt to improve energy efficiency (through avoiding the use of energy intensive heating/cooling units) and improving the physical learning environment in prefabricated classrooms in South Africa, through the use of passive energy retrofits. This study forms one of the initial case studies conducted within the framework of the Enerkey Sustainable Megacities pilot programme. Reflective roof coatings and ceiling insulation were used to retrofit eight prefabricated classrooms at Garsfontein Primary School, Tshwane. Monitoring was performed of temperature conditions in two control and eight experimental classrooms. The resulting data were used to compare the thermal performance of the altered classrooms to the control classrooms. Empirical data sets included hourly average temperature readings in ten prefabricated classrooms and an externally located weather station. Average diurnal temperatures and temperature difference plots were created. A pre-retrofit questionnaire to determine occupants’ perceptions on the thermal indoor environments was distributed. Spot measurements of illumination levels in all ten classrooms were taken with a Lux meter. A cost-effectiveness analysis of the passive energy interventions was performed, using as a reference case an electrically powered air conditioning unit, specified to cool a 50 m2 classroom. Overall, the reflective roof coatings were not effective at reducing peak summer temperatures. A 50 mm thick plastic fibre insulation layer installed in the ceiling spaces consistently reduced peak indoor temperatures by ~2°C, while 50 mm thick expanded polystyrene ceiling boards were the most effective of the retrofits, consistently reducing peak indoor air temperatures by ~3°C. An analysis of the cost-effectiveness of passive interventions showed that, in comparison to the proposed alternative of installing electrically powered air-conditioning units, ceiling insulation is cost effective in varying extents, depending on the assumptions. However, in all cases considered, the cost advantage, expressed as Rand per degree Celsius comfort improvement, is considerable compared to the air conditioning unit. Light measurements indicated non-uniform illumination in the tested classrooms, from severe glare next to south facing windows, to dark areas well below minimum recommended levels. The overall illumination situation is unsatisfactory. Opportunities exist for improving illumination using passive and active energy efficient interventions. The hypothesis for this study was that passive energy interventions in prefabricated classrooms are energy- and cost-efficient means for improving the physical learning environment in South African schools. Ceiling insulation makes a valuable contribution towards improving indoor thermal environments in prefabricated classrooms. Ceiling insulation by itself, however, does not provide a comprehensive solution – the entire building envelope needs to be taken into consideration. A building energy digital simulation model could explore a range of interventions, to derive the overall most costeffective solution to improving indoor thermal environments in South African schools. Investigations of this nature will be conducted as part of the ongoing larger Enerkey project.

In 2006, over 160 countries have ratified the Kyoto Protocol, which is an international agreement concerning the climate change. It sets binding targets for reducing greenhouse gas (“GHG”) emissions (UNFCCC, 2006) and these countries were committed to do so. Reduction on GNG emission becomes a common but differentiated responsibility over these countries, including China and Hong Kong. In Hong Kong, The Government of the Hong Kong Special Administrative Region (“HKSAR”) was also committed to reduce GHG emissions by implementing difference measures (EPD, 2010). In view of 60 percent of GHG emission in Hong Kong is generated by electricity generation, reduction on electricity consumption for building operations is the main means of achieving reduction on GHG emissions. Since Hong Kong had been treated as international financial centre, over 60 percent of the total electricity consumption was contributed by the commercial sector. To promote energy efficiency so as to accomplish reduction on electricity consumption, both HKSAR and other green organization, such as BEAM Society and U.S. Green Building Council, had set up numerous reference guidelines. However, these guidelines may applicable to new buildings but not in most commercial building in Hong Kong which were aged and multi-owned. In these aged and multi-owned commercial building, the concern of energy efficiency was not involved during design stage. In view of durable nature of commercial building, energy efficiency hardly be achieved unless substantial implementation of measures. However, capital cost and alteration work were needed to be considered for such implementation which causing difficulties for most of the single block building. As advised by Electrical and Mechanical Department, the Building Manager is one of the key persons in building energy efficiency and conservation as it is the one who operate all building services installation so as to suit the needs of the occupants. This dissertation is an attempt to evaluate the feasibility of implementing energy efficiency measures in these commercial buildings in Hong Kong from the management point of view. / published_or_final_version / Housing Management / Master / Master of Housing Management

No description available.

No description available.

M.Eng. (Engineering Management) / The residential and commercial urban sprawl towards green future is governed by the ability to overcome the challenges facing the high rise buildings sustainability. This research is dedicated to assess the high rise buildings’ energy towards near net-zero energy consumption from the point of view of production (the on-site energy generation via renewable technologies) and consumption (the usage of low consumption products). The features of the high rise buildings limit the on-site renewable energy production to solar energy, therefore the integration of solar application in the building’s facade plays a major role in the on-site energy production. Since, the relative roof area compared to the height of the high rise buildings is much less than the single family houses. Therefore, the use of the facade in high rise buildings for clean energy production becomes a major element towards its sustainability. There are several solar energy production techniques of which the most feasible and effective one is the combined electricity generation and heat collection via integrating PV and thermal collector system this system is denoted as solar Photovoltaic and Thermal (PVT) system. PVT system produces both electricity and heat at a higher efficiency from one integrated system on the same surface area exposed to the sun. For instance, PVT system produces approximately 43% more primary energy than a conventional solar thermal collector per unit surface area, and even around 96% more than a conventional Photovoltaic PV system (PVTwins, n.d). The concept of the PVT system was generated based on the fact that Photovoltaic (PV) system has typically 14-17% efficiency, so the rest of more than 80% is a lost energy; this lost energy goes in a form of heat. This heat could reach as high as 50oC above the ambient temperature resulting in structural damage as well as reducing the system efficiency by 25%. Recovering this harmful heat could reach up to five times thermal energy more than electricity from PV array (Hollick, 2011). From the energy consumption perspective, the air conditioning and ventilation system (HVAC) is considered as one of the highest energy consumer in the overall high rise buildings energy consumption (around 40%). This makes it an essential part of any high rise buildings energy solution therefore several low energy consumption HVAC systems has been developed recently. As such, absorption chiller presents one of the greenest HVAC system whereby it has no moving part, no electricity required, thermal driven system (use heat to produce cold) and could be operated by solar thermal energy. In this sense, the enterprise should respond to the increasing demand of the high efficiency buildings mainly by developing new solutions that enhance the latest green technologies and overcome the recent energy challenges.