Pump Efficiency of Water Supply Systems in Buildings of Hong Kong

This paper investigates the pump efficiency of existing water supply systems in high-rise buildings in Hong Kong and provides economic justification for pump replacement by comparing the long-term energy cost savings to the initial installation costs. Energy consumptions of water supply pumps were measured with the pump efficiencies determined from the water consumptions of 20 water supply systems in buildings. The study results indicate that for typical pump motor ratings that range from 1 to 40 kW in a high-rise water system, with new pump efficiencies and annual pump efficiency drops that range from 0.68 to 0.74 and 0.012 to 0.028 respectively, a shorter replacement period can be justified on energy cost grounds for larger pumps with greater annual efficiency drops. Practical application: This paper exhibits numerical solutions of replacement period justified on energy cost grounds for typical pump motor ratings that range from 1 to 40 kW in a high-rise water system, with new pump efficiencies and annual pump efficiency drops that range from 0.68 to 0.74 and 0.012 to 0.028, respectively.

Analysis of solar chimney ventilation systems in high-rise residential buildings using parallel flow networks

The application of life cycle assessment for the optimization of pipe materials of building water supply and drainage system

Additives for PVC pipe

Preface

Introduction. The subject of research is indoor cold water supply systems of high-rise buildings. They have a complex structure due to unique architectural features, the need to pump water to higher floors and compliance with reliability requirements applicable to engineering systems. High-rise buildings are often multi-functional, and this characteristic is implemen­ted in the process of designing indoor water supply systems: it is necessary to take into account various classes of functional fire hazards typical for different areas inside a building, and equip individual rooms with automatic water extinguishing units. Of special importance is the energy efficiency of a water supply system, since pumping equipment and its mode of operation have the greatest influence on the system. The design of an indoor water supply system for any high-rise structure is always a compromise between the interests of investors (developers) and the regulations. The purpose of the study is to identify current trends in the design of indoor cold water supply systems for high-rise buildings (or complexes).
 Materials and methods. The overview is based on current regulatory and engineering documentation governing high-rise construction, as well as the research papers focused on the design of engineering systems of high-rise buildings. The author analyzed several designs of indoor water supply systems for multi-functional high-rise buildings, in respect of which positive opinions had been issued by the expert organizations.
 Results. It is established that up-feed parallel water supply systems, broken down into zones, are most widely used in the present-day projects of indoor water supply systems designed for high-rise buildings. Each water supply zone can serve 11 to 18 floors, and an increase in the number of floors within one zone reduces the energy efficiency of the system. Automatic fire extinguishing systems are an integral element of water fire extinguishing systems in multi-functional high-rise buildings. Any damage, inflicted by the false triggering of sprinklers, should be minimized at the stage of design.
 Conclusions. The author classified potential cold water supply systems for high-rise buildings, described their principle of operation, strengths, weaknesses, and applicability limits. The research project also encompasses the analysis of present-day designs of indoor cold water supply systems for multi-functional high-rise buildings.

Concrete Filled Steel Tube (CFST) columns are popular in high rise buildings due to their superior strength, seismic and fire resistance capacities and construction simplicity.Structural framing systems in high rise buildings are commonly coupled with reinforced concrete outrigger and belt systems to facilitate lateral load resistance.When axial shortenings of vertical elements occur due to time dependent phenomena of creep, shrinkage and elastic deformations, the horizontal stiff elements balance the shortening differentials in the vertical elements and cause load redistributing among them dynamically.This can result in high transfer stresses induced in the stiff outrigger and belt systems which need to be considered in design or mitigated during construction.To plan mitigation strategies such as the time to connect the shear core to the structural frame to effectively reduce time dependent transfer stresses, it is necessary to quantify current and future differential axial shortenings.This paper first quantifies the differential axial shortening (DAS) between the shear core and columns, considering effects of construction sequence, time dependent material properties and reinforcement and then quantifies the transfer stresses built up in outrigger and belt systems in CFST high rise buildings.This information will be useful in mitigating the adverse effects of these high transfer stresses.

Environmental evaluation of pump replacement period in water supply systems of buildings

Indoor domestic water demands are increasing rapidly in many cities of China, among the causes, water wastage due to overpressure outflow (OPO) at water distribution points in buildings, especially in high-rise buildings, is a factor that has not gained much attention. Field tests in 23 high-rise public buildings and laboratory tests were conducted to quantitatively evaluate the influence of water pressure on water consumption in buildings. The water-saving potential by adopting pressure reducing measures was theoretically analyzed and verified based on a case study. Results indicated that water consumption is closely related to water pressure and overpressure outflow is a very common culprit of water wastage in high-rise buildings. Pressure management measures, such as branch pipe pressure-reducing valves, can reduce water consumption in buildings and improve the comfortability of use as well. Based on the laboratory pressure–outflow characteristics study of different water appliances, water-saving potential of pressure reducing measures can be theoretically evaluated. Case study demonstrated a theoretical reduction of 19.4% in water consumption by adopting branch pipe pressure-reducing valves, an actual 14,773 m3 water (11.9% reduction) and 15,955 kWh embodied energy was saved in 2015 after the implementation of branch pipe pressure-reducing valves retrofitting measure. Therefore, despite the current measures of adopting high-efficiency water appliances and/or utilization of unconventional water resources in buildings, implementation of pressure management measures is highly recommended in designing water supply system for new high-rise buildings and reconstruction of water supply system in existing high-rise buildings, thereby, promoting water, energy saving, and development of green building. Practical application: Water and energy saving in building is gaining more and more attention, however, water wastage due to overpressure outflow in buildings has not gained much attention. Based on field and laboratory tests, the water and energy saving potential in building water supply system were evaluated theoretically and further verified by a case study. Results indicate that pressure management measures such as branch pipe pressure reducing valves (PRVs) can reduce water and energy consumption in buildings. We strongly suggest that pressure management measures should be implemented in buildings, thereby, promoting water, energy saving, and development of green building.

The paper selects distributed solar water heating system of certain high-rise house in Jinan City as research object, its field performance test and energy efficiency assessment are made, obtains annual solar guarantee rate and conventional energy substitution quantity of solar water heating system of the building, makeseconomic benefit assessment, analyzes energy saving effect and economic benefit of the system, and gives out energy saving index and economic index. Research results show distributed solar water heating system of the high-rise building has good energy saving effect and economic benefit.

Factors influencing the airflow rate of kitchens in cooking exhaust shaft system of high-rise residential buildings

This paper discusses an energy-efficient LED lighting distribution system in high-rise buildings based on 48Vdc bipolar ELVDC distribution nano-grid fed from a centralized AC/DC converter. The paper first introduces the LED lighting system performances and its associated challenges. It then introduces the preference for ELVDC distribution system in the built environment. The paper then presents the mathematical model of the two different ELVDC distribution systems: the unipolar and the bipolar systems and their associated electrical component models. An approximated analysis was done using a constant power load model on the two distribution systems with voltage drop and power loss as the main indices. Simulations were carried out to determine the voltage level and system efficiencies at each node point. Experimental results of the two ELVDC LED lighting systems are verified and are compared with theoretical results. The 48Vdc bipolar ELVDC distribution system has reduced voltage drop and better system efficiency compared to the 24Vdc unipolar system.

The energy efficiency of water supply systems in high-rise residential buildings has become a significant concern for sustainable development in recent times. This work presents a numerical investigation on the influence of diffuser vane height on flow variation and hydraulic loss in the volute for a water supply centrifugal pump. Experiments and numerical simulations were conducted with four different vane height ratios. The numerical results were validated against experimental data. The hydraulic losses of different flow components were numerically evaluated at varying guide vane blade heights. The changes in flow patterns within the volute and the resulting discrepancies in hydraulic losses due to variations in the inlet flow conditions at different blade heights were studied. The findings indicate that the total pressure drop within the volute is affected significantly. Compared to traditional guide vanes, the reduced height vanes can reduce the hydraulic loss in the volute by nearly 75%. Once the vane height is reduced, the high-pressure gradient is improved, and the small-scale vortex vanishes. The influence area of the large-scale vortex in the volute outlet pipe decreases, leading to a weakening of the deflection of the main flow and ultimately resulting in reduced hydraulic loss.

High-rise buildings have a significant impact on the surrounding environment. Building-integrated solar water heating (SWH) systems are effective ways to use renewable energy in buildings. Impediments, such as security concerns, aesthetics and functionality, make it difficult to apply SWH systems in high-rise buildings. At present, only China uses SWH systems on a large scale in such buildings. What are China’s experiences and lessons learned in applying SWH systems in high-rises? Are these experiences scalable to other countries? This study used a combination of field investigation, literature review and case study to summarize 36 systems that had been in operation for 1–14 years. System types, collector types, installation methods, types of auxiliary heat sources, economic performance and various basic principles were summarized. The economic performance of SWH systems in high-rise buildings was analyzed and verified by a case study in Shanghai. The results show that the installation of SWH systems in high-rise buildings is feasible and reliable as long as appropriate design, construction, operation, and maintenance measures are employed. China's unique practical experience gives a reference for other countries in their efforts to make high-rise buildings more sustainable.

A methodology to simulate peak water demand for water supply systems using semi-direct methods: A case study for a residential building in Mexico