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Water heating is one of the major energy‐consuming operations in the lodging sector. The purpose of the current study is to estimate the energy consumed and emission associated with hot water usage, to predict the energy cost required under different hot water systems in hotels; and to create a model for the decision‐making criteria in selecting hot water systems.

A total of 24 hotels, which use heat pumps as their main water heating systems, were investigated. A tailor‐made model for estimating the energy requirement of the water heating system was employed. Comparative studies on the energy consumption and energy costs of various types of water heating systems, including heat pumps, diesel boilers, gas boilers, and electric boilers, were conducted. Moreover, an analytic hierarchy process was used to analyze hoteliers' and lenders' selection criteria for water heating facilities.

The energy output for water heating by heat pumps was estimated at 15 GW in the lodging sector. The use of heat pumps can achieve substantial energy savings and reduction of air pollutants when compared with the energy requirements under conventional boilers. The latter accounts for 13 percent of the hoteliers' total decision weight on choosing water‐heating systems. Whereas the air pollutants generated by gas‐fired boilers are remarkably lower than those emitted in the power plants due to the use of heat pumps. Both bankers and hoteliers consider seriously the energy saving potential of hot water supply by trucks.

Due to the small number of decision‐makers in hotels participating in the analytic hierarchy process, the result can only provide an indication of the overall picture of the selection criteria adopted by hoteliers.

The analysis provides hotel owners and managers with an objective and scientific investigation of the emission prediction and energy cost estimation based on the use of different hot water systems. Hotel operators and owners can use the analytical results as reference for making green purchasing decisions.

The current study, which is based on the operational experiences of existing hotels, is a collaborative work between hospitality industry practitioners and educators. It is also the first of its kind to indicate the emission impact of various types of hotel water heating systems and the perspectives of hoteliers and bankers on these systems.

This paper aims to compute demand, consumption and other avoidance saving by replacing existing geysers with split and integrated type air source heat pump (ASHP) water heaters, to prove the potential of both ASHP water heaters in both winter and summer by virtue of their coefficient of performance (COP) during the vapour compression refrigeration cycles and to demonstrate that despite the viability of both split and integrated ASHP system, the latter exhibits a better performance in terms of its COP and achievable savings and load factor.

This research emphasised the use of the data acquisition system housing various temperature sensors, power metres, flow metre, ambient temperature and relative humidity sensor to determine electrical energy consumption and useful thermal energy gained by the hot water in a geyser and storage tanks of residential ASHP water heaters. The load factors, average power and electrical energy consumptions for the 150 L high-pressure geyser, a 150 L split and integrated type ASHP water heaters were evaluated based on the controlled volume (150, 50 and 100 L) of daily hot water drawn off.

The results depicted that the average electrical energy consumed and load factors of the summer months for the geyser, split and integrated type ASHP water heaters were 312.3, 111.7 and 121.1 kWh and 17.9, 10.2 and 16.7 per cent, respectively. Finally, the simple payback period for both the split and integrated type ASHP water heaters were determined to be 3.9 and 5.2 years, respectively. By the application of the Eskom’s projected tariff hikes over the years, the payback periods for the split and integrated ASHP water heaters could be reduced to 3.3 and 4.1 years, respectively.

The experiments were conducted in a controlled outdoor research facility as it was going to be of great challenge in conducting both experiments simultaneously in a specific home. The category of the different types of ASHP water heaters was limited to one due to the cost implication. The experiment was also conducted at a single location, which is not a full representation of all the ambient conditions of the different regions of South Africa.

The experiments were done with a specific controlled volume of hot water drawn off from each of the three hot water heating devices. The experiments was structuring controlled to a specific volume of hot water drawn off and at specific period of the day and hence to not cater for random drawers and intermittent drawn off.

The findings help to assure homeowners that irrespective of the type of ASHP water heaters installed in their residence, they can be guarantee of year-round performance and a favourable payback period provided their hot water consumption is over 200 L per day. Also, although the split type ASHP water heater performed better than the integrated system the cost of installation and maintenance will be higher in a split type in comparison to the integrated type. Finally, by successful implementation of either of the ASHP water heaters the home owner can substantially save of his hot water bill.

The experimental design and methodology is the first of its kind to be conducted in South Africa. The results and interpretation were obtained from original data collected from the set of experiments conducted. Also, the authors are able to show that the introduction of back up element in an ASHP unit to run simultaneously with the vapour compression refrigeration cycles of the ASHP can reduce the COP of the overall system.

Present research focus on using solar energy as a renewable option for office buildings in different climatic conditions in Iran. To seeking a way to use clean solar energy and reduce current expense in buildings an investigation carried out. Nine office buildings in various climatic regions selected as case studies. Through a precise examination, buildings specifications, energy demand and climate information carried out. In the first step based on the buildings type and hot water demand, solar water heater systems designed for each case. In the second step, a cost-benefit analysis is done to detriment the economic aspects of implement aforementioned type of solar system. A cost-benefit analysis is done from saving energy and return time of investment point of view. Results indicate that solar water heater with low investment about US$500 and payback time between 2 and 5 years can be noticed as a desirable renewable option in case studies. Furthermore, analysis reveals that thermal load of building is more effective on fuel saving in building, while solar radiation intensity has more effective on the payback in solar water heater utilization.

In this study based on thermal load of nine building office and radiation of different part of Kermnashah province, the possibility of solar water system is investigated.

Analyses reveal that the thermal load of building is more effective on fuel saving, while solar radiation intensity has more effective on the payback in solar water heater utilization. The main originality goes back to consideration of different meteorological conditions in solar water heater selection.

The purpose of this paper is to evaluate the energy, economic and environmental performance of commercial water heating systems in Hong Kong special administrative region (SAR), China.

The research team contacted 50 facilities managers in Hong Kong, and 16 of them agreed to participate in this territorial-wide survey. The overall efficiency of different water heating systems was determined through measurements of inlet water temperatures, outlet steam/water properties, the amount of steam/water produced and the amount of energy consumed. The cost effectiveness and the amount of greenhouse gases produced per megajoule (MJ) output were also determined.

Results show that electric water heating systems had the highest mean overall efficiency, followed by gas- and oil-fired systems. However, the difference between the mean overall efficiency of the three types of water heating systems was not statistically significant, as the systems had been inspected and maintained regularly. Oil-fired systems were found to be the most cost-effective when taking fuel prices into consideration. Environmental analysis showed that gas-fired systems produced the least amount of greenhouse gases per MJ output.

Water heating is one of the major uses of energy in buildings. Hence, the efficiency of a water heating system can have a significant effect on the overall performance of a building. This paper not only provides insight on the energy performance but it also evaluates the economic and environmental performance of water heating systems.

The purpose of this paper is fourfold: to experimentally determine the standby thermal energy losses in various hot water cylinders in both scenarios, without isotherm blanket installation and with isotherm blanket installation; to analytically evaluate the performance of either the geyser, split- or integrated-type ASHP water heaters based on the number of heating up cycles and total electrical energy consumptions over a 24-h period without isotherm blankets and with isotherm blankets installed; to demonstrate the impact of the electrical energy factors of the split- and integrated-type ASHP water heaters under both the scenarios (without and with the isotherm blankets installed); and to use statistical tests (one way ANOVA and multiple comparison procedure tests) to verify whether any significant difference in the standby thermal energy losses occurred for each of the heating devices under both the scenarios.

The methodology was divided into monitoring of the performance of the electrical energy consumptions and ambient conditions of the hot water heating technologies without isotherm blanket installation and with isotherm blanket installation.

The results reveal that the average standby thermal energy loss of the geyser without the installation of an isotherm blanket was 2.5 kWh. And this standby loss can be reduced to over 18.5 per cent by just installing a 40-mm thick isotherm blanket on the tank. The statistical tests show a significant mean difference in the group electrical energy consumed to compensate for the standby losses under both scenarios. In contrast, the average standby thermal energy losses for the split- and integrated-type ASHP water heaters were 1.33 kWh and 0.92 kWh, respectively. There was a reduction of 15.5 per cent and 3.5 per cent in the electrical energy consumed in compensating for standby losses for both the split and integrated types, respectively, but there was no significant mean difference in the standby losses under both scenarios for the two systems. Again, without any loss of generality, the electrical energy factor of both the ASHP water heaters decreased upon installation of the isotherm blanks.

The experiments were conducted only for a 150-L geyser and 150-L split- and integrated-type ASHP water heaters. The category of the different types of ASHP water heaters was limited to one because of the cost implication.

The experiments were not conducted with various hot water storage tanks installed in different positions (roof, inside or outside of a building wall, etc.) so that actual real-life observations could be obtained. The challenges of easy disassembling and deployment of systems and DAS to different positions were also a real concern.

The findings can help homeowners and ESCO in deciding whether to install isotherm blankets on storage tanks of ASHP water heaters on the basis of the impact of standby losses and its potential viability.

The experimental design and methodology are the first of its kind to be conducted in South Africa. The results and interpretation were obtained from original data collected from a set of experiments conducted. The findings also show that the installation of isotherm blanket on an electric geyser can result in a significant mean reduction in the standby losses. In contrast, an installation of the isotherm blankets on the storage tanks of ASHP water heaters can reduce the standby losses, but there exists no significant mean difference.

Reviews the application and design of systems using sealed expansion vessels from circa 1967 to the present day, incorporating all types of systems. Discusses the fundamental differences and characteristics between open vented and sealed expansion vessel systems, and also the attitudes of water authorities to both commercial and domestic systems. Compares this with other western countries. Investigates whether there have been any inherent disadvantages of using sealed systems and concludes by considering current appropriate British standards and codes of practice together with the terminology used in some instances, which tend to create unfavourable impressions of sealed systems.

In the current economic recession — one of the worst ever to affect this country — we have all become particularly conscious of the cost of living. Turning on a tap and getting hot water, for example, can no longer be taken for granted. Heating water uses energy, and energy costs money. Industry in general should be acutely aware of this, since it uses over 40 per cent of the country's energy, nearly half this consumption being related to heating.

Introduction Changes to the UK's Model Water Byelaws will permit, subject to their adoption by the regional Water Authorities, the use of hot water storage systems of more than 50 litres capacity which are connected directly to the mains water supply (storage systems of less than 50 litres are exempt from the Building Regulations), removing the need for a cold water storage cistern. Systems of this type have been in widespread use throughout the world for many years but have not been allowed in the UK. The new Building Regulations for England and Wales, published in November 1985, include safety requirements for these unvented systems. The Approved Documents supporting the Building Regulations state that such systems should be covered by an Agrment Certificate and should be fitted only by BBA Approved Installers, as defined in the Certificate. Similar requirements are likely to be introduced in due course into the Building Regulations for Scotland and Northern Ireland.

Low flow bikini solar combisystems and high flow tank‐in‐tank solar combisystems have been studied theoretically. The aim of this paper is to study which of these two solar combisystem designs is suitable for different houses. The thermal performance of solar combisystems based on the two different heat storage types is compared.

The thermal performance of Low flow bikini solar combisystems and high flow tank‐in‐tank solar combisystems is calculated with the simulation program TRNSYS. Two different TRNSYS models based on measurements were developed and used.

Based on the calculations it is concluded that low flow solar combisystems based on bikini tanks are promising for low energy buildings, while solar combisystems based on tank‐in‐tank stores are attractive for the houses with medium heating demand and old houses with high heating demand.

Many different Solar Combisystem designs have been commercialized over the years. In the IEA‐SHC Task 26, twenty one solar combisystems have been described and analyzed. Maybe the mantle tank approach also for solar combisystems can be used with advantage? This might be possible if the solar heating system is based on a so‐called bikini tank. Therefore, the new developed solar combisystems based on bikini tanks is compared to the tank‐in‐tank solar combisystems to elucidate which one is suitable for three different houses with low energy heating demand, medium and high heating demand.

The use of fossil fuels in developing countries places increasing economic, health, and environmental costs on the population. In decentralized and rural communities without existing grid systems, direct solar technologies provide the basis for electricity production, for water pumping and hot water, and for heating of houses. Examples and case studies for each of these direct solar technologies are presented which may be directly applicable or potentially modified for rural development in countries such as Uzbekistan and Turkmenistan, which have ample direct solar resources. Related design involving both daylighting and passive cooling are described as part of the incorporation of passive solar heating techniques.