Suchergebnisse

The potential for recovery and reuse of waste heat from cooling London's underground train tunnels as a heat source for district heating systems has been investigated. Cooling of London's underground system is needed to maintain the future underground environment at safe temperature levels. Cooling methods currently being applied across the network include the use of cooling coils in ventilation shafts, air handling units (AHUs) and cooling pipes in tunnels, although the latter method has only been applied on a theoretical basis. These systems use chilled water to cool the air in the tunnels by means of heat exchangers. The chilled water is normally generated using chillers and heat is rejected to atmosphere. District heating networks currently account for only about 2% of total heat used in the UK. However, there are a number of local government managed district heating schemes operating in London, at present. Heat is generally supplied by combined heat and power (CHP) generating plant, but it is planned to expand these schemes and to make use of secondary waste heat sources in the future. The present project, which is funded by Innovate UK, investigates the potential benefits of combining cooling of London's underground train tunnels with the transfer of heat to district heating networks. Instead of using air cooled chillers to cool the water to provide cooling to the air in the underground tunnels, it is planned to use water to water heat pumps to transfer the heat to a district heating network. This should significantly reduce the total energy input required for both the cooling and heating of the respective networks. It has been estimated that there is at least 15 MW of waste heat available from cooling London's underground system. To evaluate the benefits of the proposed approach, an energy, carbon and whole life costing calculator model will be developed to estimate energy, carbon and cost savings for a range of configurations and operating conditions. An inter-seasonal analysis will also be carried out to determine how the benefits vary during the year. Details of the model and the results of preliminary calculations of the potential benefits based on a case study are reported, and the configuration of the planned heat recovery system is presented. The results from the current project will be used to inform the design of a pilot scale trial. This heat recovery approach could be extended to other secondary waste heat sources.

The scarcity of water resources has led researchers to investigate and develop mechanisms for the good use of saline and brackish waters to produce drinking water. In Brazil, the water crisis has always been a reality. The objective was to carry out desalination through a prototyped system with sustainable supplementary heating, to help supply drinking water to residents who face precarious living conditions. The research is aimed at the Bailique Archipelago and Sucuriju District, located in the extreme east of the State of Amapá and bathed by the Atlantic Ocean. It presents a quali-quantitative analysis, as it involves the construction of the prototype and temperature and physical-chemical tests of water samples. Regarding the results, desalination was carried out using a prototype, with subsequent analysis of the physical-chemical conditions of the interstitial waters to correlate with the potability parameters. The supplementary heating positioned on the sides of the system converged solar rays towards the greenhouse that contains salt water inside, and a device on the glass slope collected the condensed water. The 50cm x 50cm model desalinated 890mL and the 25cm x 25cm model desalinated 190mL of water in one day, reaching a maximum temperature of 91 ºC.

China is the world's largest market for solar water heating systems, installing 13 million square meters of new systems in 2004, mostly in large cities. Municipal authorities, however, are sensitive to quality and visual impact issues created by this technology deployment. Therefore, there is currently a trend toward developing building integrated systems as well as upgrading building codes, establishing testing and certification programs, and educating building architects and developers. The use of photovoltaics for urban and grid-connected applications has lagged behind the solar water-heating market; however, in 2003, a 1 MW photovoltaic-rooftop system was constructed in Shenzhen in southern China and several demonstration building integrated systems have since been installed. There is also an emerging interest in photovoltaics for distributed generation and grid support in China. Trends and requirements for developing solar urban applications in China will be presented in this article.

The paper investigates the European space heating (SH) and domestic hot water (DHW) market in order to close knowledge gaps concerning its size. The stimulus for this research arises from incongruences found in SH and DHW market&rsquo ; s data in spite of over two decades of scientific research. The given investigation has been carried out in the framework of the Hotmaps project (Horizon 2020&mdash ; H2020), which aims at designing an open source toolbox to support urban planners, energy agencies, and public authorities in heating and cooling (H& ; C) planning on country, regional, and local levels. Our research collects and analyzes SH and DHW market data in the European Union (EU), specifically the amount of operative units, installed capacities, energy efficiency coefficients as well as equivalent full-load hours per equipment type and country, with a bottom-up approach. The analysis indicates that SH and DHW account for a significant portion of the total EU energy utilization (more than 20%), amounting to almost 3900 TWh/y. At the same time, the energy consumption provided by district heating (DH) systems exceeds the one of condensing boilers. While DH systems applications are growing throughout the EU, the replacement of elderly, conventional boilers progresses at a slower pace.

In the beginning of this decade, the Portuguese Program E4 – Energy Efficiency and Endogenous Energies have proposed an ambitious goal of 1 million m2 of solar collector area in Portugal until 2010. To cope with this, it was implemented in 2001 by Portuguese Government the National Program Solar Hot Water for Portugal (IP-AQSpP). The Portuguese new Thermal Regulations (RCCTE) opens to all constructions partners a new opportunity for implementing more strongly renewable energy technologies in buildings.

Publisher Copyright: CCBY ; Lately, the European Union has reinforced the targets set to cut back carbon emissions. The energy generation sector and particularly, the district heating (DH) system, is still prevailed by combustion of fossil fuels that heavily contributes to such emissions. This paper presents a system-based approach to study the coupling between electricity and DH sector for effective mitigation of emissions. A mixed integer linear programming framework is proposed that aims to exploit the flexibility of electricity cogeneration together with partial electrification of the DH system by investing in renewable technologies. The objective is to simultaneously minimize the investment cost and emissions. Both the electricity and DH load profiles are segregated into critical and flexible types. Comprehensive demand response (DR) framework of thermostatically controlled loads and electric vehicles is considered while preserving the chronology. The framework is applied to the Finnish energy system considering the generation mix. Results prove that coordinating the electricity cogeneration with renewable generation combined with partly shifting from DH to electrified heating has a great potential in reducing the emissions. For an average weather scenario under DR, the least-cost solution guarantees an annual emission reduction of 12.04% relative to the total emissions of Finland against the total investment of €13.24Bn in wind and solar power generation. ; Peer reviewed

The basic issue of this thesis concerns one of the fundamental problems of the future of our society: How to meet the energy requirements for a large and growing world population while preserving our environment? This question is important for the world and the answers are complex and interwoven.Conventional energy sources, fossil and fissile, are polluting in the present and in the future: they erode the environment and their resources are limited. Renewable energy (hydro, wind, solar, geothermal) constitutes a minimum of pollution in the different energy systems. The technologies for using renewable energy are well known though further development and progress are made. This development also requires behavioural change, adaptation, and above all political will. The transition from an economy based on fossil energy to an economy based on renewable energy appears necessary for the protection of the environment. The cost of renewable energy is often represented as an obstacle but remains competitive in the long run.The development and availability of renewable energy, which varies because of its spatial and temporal distribution, require an adaptation of lifestyle, habits, habitat design (passive bioclimatic houses), urban planning and transportation.The focus of this thesis was to apply renewable energy in an area with hot summers and cold winter, a climate like that in the northwest of Algeria. In order to provide improved comfort in the buildings and also economic development in this area, the energy demand for heating and cooling was analyzed in the ancient city of Tlemcen. To supply domestic hot water and space heating, water must be simultaneously available at two different temperature levels. Cold water temperature, close to that of the atmosphere, and hot water between 50 and 60°C. An interesting feature of the preparation of hot water is the small variation of requirements during the year, unlike that to heating. The preparation of hot water is one of the preferred applications of solar energy in the building for several reasons. For this reason an experimental study of the thermal behaviour of a domestic hot water storage tank was undertaken. The phenomena that affect the thermal behaviour of tank especially the coupling between the solar collector and storage tank was studied. This study included concentrating solar collector in which optical fibers were used to transport the energy to the storage tank. Another technology was introduced and developed for the heating and cooling of buildings in the desert involving an existing ancient irrigation system called Fouggara. The novel idea is to use the Fouggara as an air conditioner by pumping ambient air through this underground system. Then air at a temperature of about 21°C would be supplied to the building for heating in the winter and cooling in the summer. This study shows the feasibility of using this ancient irrigation system of Fouggara and contributes to reducing and eliminating the energy demand for heating and cooling buildings in the Sahara desert. ; Godkänd; 2011; 20110920 (sofama)

Water heating is a main consumer of energy in households, especially in temperate and cold climates. In South Africa, where hot water is typically provided by electric resistance storage tank water heaters (geysers), water heating energy consumption exceeds cooking, refrigeration, and lighting to be the most consumptive single electric appliance in the home. A recent analysis for the Department of Trade and Industry (DTI) performed by the authors estimated that standing losses from electric geysers contributed over 1,000 kWh to the annual electricity bill for South African households that used them. In order to reduce this burden, the South African government is currently pursuing a programme of Energy Efficiency Standards and Labelling (EES&L) for electric appliances, including geysers. In addition, Eskom has a history of promoting heat pump water heaters (HPWH) through incentive programs, which can further reduce energy consumption. This paper provides asurvey of international electric storage water heater test procedures and efficiency metrics which can serve as a reference for comparison with proposed geyser standards and ratings in South Africa. Additionally it provides a sample of efficiency technologies employed to improve the efficiency of electric storage water heaters, and outlines programs to promote adoption of improved efficiency. Finally, it surveys current programs used to promote HPWH and considers the potential for this technology to address peak demand more effectively than reduction of standby losses alone

Trabajo presentado en la IEEE Conference on Decision and Control (CDC), celebrada en Miami Beach (FL, USA), del 17 al 19 de diciembre de 2018 ; A model predictive control (MPC) framework is developed in the present study, with the final objective to improve the energy flexibility of building thermal loads through demand-side management. Three different configurations are tested and tuned, with the following objective functions: minimizing the delivered energy to the building, the electrical energy used by the HVAC system (heat pump) or the cost of this electricity use. To validate these MPC configurations, a Matlab-Trnsys co-simulator is also created, in order to run the MPC on a virtual plant composed of a detailed building model. The MPC strategy manages to run effectively on the chosen study case (a residential building with heat pump in Spain), and the differences between configurations are discussed. ; This project has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 675318 (INCITE). Part of this work stems from the activities carried out in the framework of the IEA-EBC Annex 67 (International Energy Agency – Energy in Buildings and Communities program) about Energy-Flexible Buildings. ; Peer reviewed

This paper presents a comparative analysis of different space heating and hot water systems for a social housing project in Santurtzi, Spain. The building, comprising 32 apartment units and currently under construction, has been designed to minimize thermal energy demand, while ensuring comfort and quality of the internal environment for the social housing occupiers. The selection of the heating and hot water energy systems has been carried considering a life cycle perspective both for environmental and economic impacts. Different alternatives have been analysed which compare conventional gas boiler installation, which has been the norm for this type of social housing for the last decades, with various options based on heat pump technology. Life cycle analysis of the environmental effects of electrification of the thermal energy demand through heat pumps show a potential for reducing life cycle CO2 emissions. The economic evaluation done through life cycle costing, comparing investment, maintenance, replacement and operational costs of gas boiler with aerothermal and geothermal heat pump solutions, have shown however that gas heating solutions are still the most competitive economically. Increasing the overall efficiency of those heating and hot water systems that include heat pump technology, while reducing their uncertainty in operation is a key element to ensure competitiveness of heat pumps in the current market. ; The work presented in this article is part of an analysis carried within AZEB project 'Affordable Zero Energy Buildings', which has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 754174.

Within the European Union, buildings account for around 40% of the energy use and 36% of CO2 emissions, thus representing a significant challenge in the context of recent EU directives that require all new buildings to be nearly zero-energy by 2020. Reduced consumption of water, and hot water in particular, provides a significant opportunity to reduce energy consumption. While there have been numerous studies pertaining to the water-energy nexus of residential buildings, the complexity of water networks in larger buildings has meant that this area has been relatively unexplored. The paper presents a comprehensive investigation of the hot water use profile, associated energy use, on-site pumping energy use, carbon emissions, and solar energy harvesting potential in an Irish university building over periods before and after water conservation efforts. Total water-related energy consumption (including the heating and pumping losses) were analysed using the WHAM model and modified pumping energy expressions. The results revealed that water heating including losses contributed to as high as 30% of total building energy consumption, and stringent water conservation measures reduced the average hot water use rate by 8.5 m3/day. It was found that 10% of the total pumping energy was constituted by pump start-ups. Simulation results for solar harvesting potential in the study site found that around 60% of water heating energy demand could be met by solar energy in the new water demand scenario. The study results can act as a benchmark for similar buildings, and the model combination can be emulated in future studies.