C.L. Cheng

Evaluating water conservation measures for Green Building in Taiwan

Green Building evaluation is a new system in which water conservation is prioritized as one of its seven categories for saving water resources through building equipment design in Taiwan. This paper introduces the Green Building program and proposes a water conservation index with quantitative methodology and case study. This evaluation index involves standardized scientific quantification and can be used in the pre-design stage to obtain the expected result. The measure of evaluation index is also based on the essential research in Taiwan and is a practical and applicable approach.

An empirical approach: Prediction method of air pressure distribution on building vertical drainage stack

Abstract Pressure fluctuation control in vertical drainage stacks has been identified as important to insure sanitary drainage performance in early empirical studies. Chaotic plumbing and over‐design are common in utility services within building envelopes from domestic investigations in Taiwan. Considerable progress has been made in predicting the air pressure distribution within vertical drainage stacks. Following previous research, this paper focuses on an empirical approach to air pressure prediction in vertical drainage stacks. An experimental device that simulates a medium high apartment was set up to provide empirical parameters and model verification. Comparisons between the measured data and calculated values reveal that this prediction model can reproduce the mean air pressure distribution value in a vertical drainage stack given single point discharge and steady flow conditions.

An evaluation tool of infection risk analysis for drainage systems in high-rise residential buildings

This study proposes a simple risk analysis tool and evaluation level for the probable infection due to a contaminated drainage stack in residential high-rise buildings in some Asian cities which have equivalent drainage systems. The methodology would follow the conception of FMEA (Failure Mode Effects Analysis). In particular, key risk factors including connections between appliance and stack, the plumbing system, ventilation, equipment life and maintenance were surveyed and used to evaluate the overall risk associated in high-rise residential buildings with Monte Carlo simulations. With the proposed tool, regional risks of infection due to the building drainage systems were estimated, with respect to the city building age and height profiles. The results showed that a city with a high-rise environment would associate a higher spreading risk due to the drainage system. Practical applications: Following the outbreak of SARS (Severe Acute Respiratory Syndrome) in early 2003, the operational performance of drainage systems in high-rise residential buildings has become a major concern. The assessment system would be practical and sensible for evaluating the infection risk in building drainage systems for both existing buildings and new construction. The assessment tool may provide the government, designers and the occupants a source of reference to judge drainage system performance in either new construction or the existing building, so that improvements would be conducted.

Air Pressure Fluctuations of Drainage Stacks at a High-rise Office Building

This study examines air pressure variations along a discharging stack with unsteady discharging flow rates, including the fluctuation frequency, the maximum and average pressures with their respective standard deviations at a drainage stack of an in-use office building. With a modified constant, the maximum air pressure at the drainage stack could be described by the probability density function of the measured data using earlier proposed mathematical expressions for steady discharging flow rates. The average prediction and the maximum under-prediction of the absolute peak pressure were determined with the margin of errors taken within certain confidence levels. The results would be useful for understanding the air pressure in drainage stacks and help increase the potential of installing a real-time monitoring system in a high-rise drainage stack.

An urban drought-prevention model using raft foundation and urban reservoir:

The main purpose of this research is to develop a practical operation model for water conservation, in responding to the challenges of climate change, to propose a solution for urban drought period. This paper presents an urban drought-prevention model with allocation to prevent-drought using abundant idle raft foundation of existing buildings and the information of urban reservoir implemented by linear programming. The proposed model is developed to provide substantial demand for residential water utilisation during a period of urban drought. This operation model is of adaptable system underpinned by sustainable water management principles. The simulation and validation assumed that the water used is the rainwater and just to flush the toilets. According to the results of this research, the proposed model has been proven to be practicable and feasible for urban drought-prevention solution. Practical implications: This research illustrates the important contribution of abundant idle capacity in existing building raft foundations. This paper also shows the sustainable water management technologies and the solution for the designer, which has the opportunity to implement and adapt to the best benefit for water conservation and sustainability.

A physical study of plumbing life cycle in apartment houses

Abstract We know that extending the life span of a building can reduce environmental impact, and also save money with the viewpoints of life-cycle cost. But due to the complex system construction of buildings, if we apply the concept of life-cycle cost to design, we must consider it in coordination with the life spans of subsystems in order to avoid unreasonable wastage and problems of utility function. Concerning corrosion of piping, past documents mostly direct investigation and analysis to the physical or chemical characteristics of materials. This paper focuses on the plumbing system of a building, by matching up the investigation of practical cases, we determined the life span of a plumbing system in a building and try to offer an assessment system for a life-cycle model. This could be of use in life-cycle architectural planning and design.

AN EMPIRICAL APPROACH TO DETERMINE PEAK AIR PRESSURE WITHIN THE 2-PIPE VERTICAL DRAINAGE STACK

Abstract Following the massive outbreak of SARS (Severe Acute Respiratory Syndrome) in early 2003, the drainage systems in high‐rise residential buildings have become a major concern. Inappropriate drainage system design may cause pressure fluctuations and depletion of the water trap seal. In Taiwan, most vertical drainage stack pipes serving medium‐height apartment blocks are designed as 2 or more vertical pipe systems. A prediction method to determine the air pressure distribution within the single‐stack vertical drainage system with a single discharge has already been established. This paper expands this prediction method to allow the air pressure distribution of the 2‐pipe vertical drainage and vent system, which is widely used in Taiwan, to be predicted. Comparisons between the measured data and calculated values reveal that the prediction method can reproduce the negative and positive peak air pressure values within the 2‐pipe vertical drainage stack given single point discharge and steady flow conditions. A prediction model based on empirical parameters offers a reference for drainage system designers designing and maintaining water trap functions in buildings. This prediction method can be easily applied to drainage system design.

Empirical approach to main drain system design and solid transportation performance in buildings

Water-saving facilities were constructed in response to the sustainability and global issues all over the world. However, the performance of drainage systems must be ensured as the volume of flush water is reduced. Otherwise, it might cause sanitary problems to indoor environments and interrupt building functions. According to the methodology of investigation and observation, this paper categorized parameters that dominate the solid transportation performance of main drains. An empirical experiment was executed to clarify the quantitative influence of these parameters. A calculation model for estimating the boundary condition of main drain design is conducted. Furthermore, an estimation interface is validated and proposed as an assessment tool for practical application. Practical implication: This paper offers an evaluation tool by statistic methodology to ensure solid transportation performance. An estimating model and regulation proposal of solid transportation in main drains of buildings that can guide the designer and engineer to confirm the performance of drainage system is validated and proved to be practicable. Furthermore, this research conducted an estimation interface to validate the solid transportation performance, which can offer an assessment tool for practical application. The results can contribute to building code guidelines and lead to new technical development of building drainage systems.

Empirical study on drainage stack terminal water velocity

A building drainage network is an essential provision of each developed city all over the world. The terminal velocity at discharging drainage stack is a crucial issue as it provides the permitted flow rate of a building drainage system. The National Plumbing Code (NPC) of the US has specified the permitted flow rate for drainage systems. Mathematical expressions for terminal velocity were reported in research studies since the 1920s but discrepancies among calculations remained. This study proposes an empirical approach in determining the terminal velocity in a drainage stack using the air pressure distribution mechanism. New experimental observations of the stack terminal velocity using a digital high-speed video camera were presented as a validation database. The proposed model was validated in terms of the measured terminal velocities and the locations of the maximum air pressure in a discharging stack at a steady water flow rate (1.0, 2.0, 3.0 and 4.0 L/s). This article offers an empirical approach and validation for terminal velocity instead of using the existing deductive approach. Practical applications: This article proposes an empirical approach with experimental validation for terminal velocity at a drainage stack. New evidence presented would lead to a review of the terminal velocity in drainage stacks in future drainage network designs. Due to the importance of terminal velocity, it is anticipated that this result would be used to lead the new technical development of building drainage system.

Relationship between building hot water usage and energy and carbon reduction

This article proposes a calculation model for estimating the energy consumption and CO2 emissions resulting from hot water usage and for evaluating the potential for carbon reduction by using a water efficiency strategy. The model revealed a reciprocal relationship between hot water usage in daily life and energy consumption and carbon footprints. From 1990 to 2010 in Taiwan, hot water accounted for approximately 20%–30% of daily water consumption, and the use of hot water indirectly caused an average emission of 6.19 (kg-CO2/m3) and a 1.83% contribution to carbon emissions per capita. The potential influence of hot water usage on the issue of carbon reduction and the importance of strategies for saving water are thus highlighted in this study. Practical application :The proposed calculation model clarified the relationship between hot water usage and carbon emissions. Through the investigation and simulation of domestic hot water usage, the carbon reduction potential of a hot water-savings strategy was validated. This study can make various organizations in both the public and private sectors aware of the importance of building a society based on the concept of water conservation, and various policy-making processes are anticipated to be initiated as a result. Efforts to save hot water could be consolidated to achieve synergy with carbon reduction policies and benefits to building service engineering.