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[en] The speed at which many energy efficient technologies have been adopted has been very slow and the reasons why this is the case are often not well understood. An important area for New Zealand is domestic hot water which typically accounts for one-third of a household's electricity usage. We use in-depth interviews to examine the decision processes of six householders who were replacing existing hot water systems or building new homes. We also interviewed different trades people and professionals advising those households. Seven themes emerge from the interviews which demonstrate huge inertia to change. Using methods from decision sciences we also construct an information processing model describing the possible steps in the adoption decision. This model emphasises the complexity and difficulty a householder currently faces if they wish to pursue an alternative system for heating hot water. - Highlights: ► The decision process regarding the adoption of hot water systems is essentially the same regardless of context. ► Householders get no real support from suppliers and others who might appropriately advise on energy efficient systems. ► Available information on energy efficient options is seen as confusing, irrelevant and partial. ► Huge inertia exists preventing people moving away from simple and convenient technologies represented by the status quo.
[en] The aim of this paper is to explore the possibilities to reach two long-term targets regarding energy consumption and greenhouse gas emissions of the Swiss residential building stock: a reduction of the final energy consumption by a factor of 3 and of CO2 emissions by a factor of 5 until 2050. A model is constructed to describe the dynamics of the energy-relevant properties of the residential building stock. Appropriate scenarios are discussed in terms of decisions made during construction or renovation of residential buildings which affect heat demand and determine the energy carriers used for heating and hot water generation. We show that both targets could be reached, although ambitious efforts are necessary. The central element of a successful strategy is to reduce the specific heat demand of existing buildings during renovation and to substitute the heating and hot water systems by less carbon intensive ones. Our results suggest that there is more flexibility to reach the emission target than the energy reduction target
[en] By means of numerical simulations in TRNSYS v14 the influence of the solar absorption area of a system for heating water with solar energy, composed by a flat solar collector and a tank thermo-accumulator, on its energy efficiency. For the study, the solar collectors EDWARDS, ISOFOTÓN 1, ISOFOTÓN 2, MADE, ROLDAN and IBERSOLAR of absorption area 2, 1,9, 1,88, 2, 1,9 and 2,3 m2 respectively were chosen. For each collector, the energy performance was simulated for one year, setting 200 L for the accumulation volume and 50 °C for the intake temperature. Despite the different characteristics of each collector, their behavior is quite similar showing a very mature technology. (author)
[en] Sizing of domestic hot water pipes are to a large extent based on calculations of peak flow rate according to current guidelines. This article compares detailed field measurements of peak flow rates in Norwegian hotels, nursing homes and apartment buildings with calculated values according to Norwegian NS 3055, German DIN 1988-300 and European EN 806-3 code of practice. Results indicate that existing guidelines overestimate the peak flow rate by a factor of 1.2– 2.6, depending on type of building and which standard the calculations are based on. In most cases, this also resulted in oversizing the pipes. Calculations according to NS 3055 are closest to the field measurements, on average overestimating the peak flow rate by a factor of 1.6. To analyze the effect of different measurement intervals, the measured peak flow rate is also calculated as a moving average for different time steps (t). Compared to using an interval of 2 s, averaging the data over 10 s would underestimate the peak flow rate by a factor of 0.80– 1.0. Using a 30 s interval would underestimate the peak flow rate by 0.67– 0.94. (paper)
[en] Many countries are using policy incentives to encourage the adoption of energy-efficient hot water heating as a means of reducing greenhouse gas emissions. Such policies rely heavily on assumed performance factors for such systems. In-situ performance data for solar and heat pump hot water systems, however, are not copious in the literature. Otago University has been testing some systems available in New Zealand for a number of years. The results obtained are compared to international studies of in-situ performance of solar hot water systems and heat pump hot water systems, by converting the results from the international studies into a single index suitable for both solar and heat pump systems (COP). Variability in the international data is investigated as well as comparisons to model results. The conclusions suggest that there is not too much difference in performance between solar systems that have a permanently connected electric boost backup and heat pump systems over a wide range of environmental temperatures. The energy payback time was also calculated for electric boost solar flat plate systems as a function of both COP and hot water usage for a given value of embodied energy. The calculations generally bode well for solar systems but ensuring adequate system performance is paramount. In addition, such systems generally favour high usage rates to obtain good energy payback times
[en] The present innovation relates to the coupling of a refrigerator to a cumulus to heat water and this, thanks to the heat yielded to the level of the condenser of the refrigerating system even. The heating of water is carried out thus without energy over consumption. The quantity of heat transferred by the water-cooled condenser is sufficient to raise the temperature of this latter with 60 degree at the end of five hours. This can satisfy completely or partially the requirements out of hot water of a family which can distribute its requirements out of hot water all along the day and the week. The quantity of heat recovered by water to heat rises with four multiples the power consumption by the compressor. The system thus makes it possible to save energy and to safeguard the environment
[en] Pressurized Hot Water Extraction (PHWE) is a quick, efficient and environmentally friendly technique for extractions. However, when using PHWE to extract thermally unstable analytes, extraction and degradation effects occur at the same time, and thereby compete. At first, the extraction effect dominates, but degradation effects soon take over. In this paper, extraction and degradation rates of anthocyanins from red onion were studied with experiments in a static batch reactor at 110 deg. C. A total extraction curve was calculated with data from the actual extraction and degradation curves, showing that more anthocyanins, 21-36% depending on the species, could be extracted if no degradation occurred, but then longer extraction times would be required than those needed to reach the peak level in the apparent extraction curves. The results give information about the different kinetic processes competing during an extraction procedure.
[en] Highlights: ► Circulation system heat losses were 23–70% in apartment buildings. ► The use of additional heat meters in large buildings is recommended. ► The demand for domestic hot water, space heating and ventilation should be obtained. ► Domestic hot water will constitute a major part of future energy demand of dwellings. - Abstract: The goal of this work has been to document the efficiency of domestic hot water (DHW) distribution systems and to propose more energy efficient and environmentally friendly solutions for DHW systems based on analyses of existing conditions. In the article, measurements from 13 apartment buildings and two institutions are presented, i.e. consumption of DHW, heat loss from circulation lines and efficiency of the DHW system. The heat load and the cooling of the district heating water for DHW are documented as well. Possibilities for improving the DHW system include new types of circulation pipes, which have the potential of a 40% reduction of heat losses. In addition to the reduction of heat losses inside the building, a low return temperature from the hot water system will have a large impact on the heat losses from the district heating network when the building is being heated by district heating. It is likely that the production and distribution of DHW in buildings will constitute a dominant share of both the present, and in particular, the future energy design requirements of buildings. The results of this project could influence not only future buildings, but also existing buildings when renovation of installations take place
[en] Highlights: • A triboelectric nanogenerator (TENG) with a micro and nanostructures at the interface is fabricated based on the water-assisted oxidation (WAO) process. • Optimal fabrication condition is determined to maximize the effective contact area of the TENG. • Practicality of the WAO-based TENGs is demonstrated by its application to a wind-based TENG. The performance of a triboelectric nanogenerator (TENG) was effectively enhanced by forming nanostructures at the contacting interface. The contacting interface usually consists of metal and polymer surface, but the formation of nanostructures have only been actively studied for the polymer so far. In this work, a simple and effective route to forming nanostructures on the metal surface is proposed, using a water-assisted oxidation (WAO) process. The one-step WAO process requires only hot water without any complicated equipment and treatment. Using the WAO process, densely packed micro and nanostructures were successfully formed on three target metal surfaces: aluminum, copper, and zinc. The output power of the TENG was enhanced after the nanostructure formation because of the increased contact area. The influence of the process conditions on the nanostructure morphology was additionally analyzed to maximize the output power. The simple and low-cost WAO process is advantageous in terms of practicality.
[en] To clarify the enrichment characteristics of uranium and radon in deep-buried geothermal water, 39 geothermal water samples with a buried depth of more than 800 m in the Kaifeng geothermal system in China were collected. According to the test results of uranium concentration, radon activity and other conventional chemical indicators of the water samples, the source of uranium and radon in geothermal water was obtained. Also, the influence of the redox environment, temperature and hydrochemical parameters on the occurrence characteristics of uranium and radon was analyzed. This study has indicative significance to the migration of geothermal water. (author)