Building Services Engineering Research & Technology

Recognizing high-rise building water-use maneuver should be helpful for developing some practical strategies when indoor room space safety becomes a crucial feature in the building operation. This paper presents a data-processing approach for exploring the water-use maneuver of high-rise building. This approach combines the empirical mode decomposition and statistical analysis to process the mezzanine-floor air-pressure data measured in the drainage stack system of Li Ka-Shing building at PolyU of Hong Kong on 28th of April of 2008. Because the mezzanine-floor air-pressure signals in the building drainage system are recorded within about 10 hours with a recording rate of one signal per second, data re-sampling is obviously needed. Otherwise, the direct application of empirical mode decomposition should be unavailable because the mezzanine-floor air-pressure data are too massive. Statistical analysis is further encompassed after the empirical mode decomposition to seek the influences of re-sampling time interval and the empirical mode decomposition index so that the building water-use maneuver can be understood in detail.

Practical application : From the viewpoint of Building Services Engineering, any occupied space should be safeguarded, because the depletions of the trap seals ¹ and the bathroom floor drain traps ² can result in cross-contamination via the drainage system. This suggests that it is crucial to investigate building water-use maneuver when indoor room space safety becomes urgent. To explore the water-use maneuver, an indirect way is by analyzing the mezzanine-floor air-pressure in the drainage stack system in terms of an appropriate approach. Since the mezzanine-floor air-pressure in the drainage stack system of an 18-floor building, i.e. Li Ka-Shing building at PolyU of Hong Kong has been recorded, ³ it can be used to propose the water-use maneuver approach which is helpful for developing some practical strategies for indoor room space safety when the safety should be carefully and urgently faced.

Siphonic roof drainage systems are an efficient method of removing rainwater rapidly from roofs. Siphonic roof drainage systems are designed to run full-bore, resulting in sub-atmospheric system pressures, higher driving heads and higher system flow velocities. Hence, siphonic roof drainage systems normally require far fewer downpipes, and the depressurised conditions also mean that much of the collection pipework can be routed at high level, thus reducing the extent of any underground pipework. But, they work properly at only one roof run-off rate and therefore suffer from sizing and operational problems that limit their performance. Climate change is creating situations where normal ranges of rainfall intensity are being frequently exceeded, and this may have an impact on the performance of siphonic roof drainage systems. A multiple parallel pipe siphonic roof drainage system appears to offer benefits and avoids sizing problems associated with current siphonic roof drainage systems. A movable cap covering the inlet to a small bank of parallel pipes has the potential to avoid noise associated with making and breaking siphonic action through flow modulation. Laboratory scale tests demonstrate the basic feasibility of the multiple parallel pipe system and indicate that handover of flow between pipes occurs smoothly and that the flow modulation cap functions reliably. This technology includes moving parts and smaller diameters (19 mm ID) than are currently accepted (32 mm ID) in the British Standards and product development will be required.

Practical application: Original research detailing an innovative development of a multi-pipe siphonic roof drainage system. This provides a wide design flow rate range and flow modulation caps reduce noise significantly by avoiding priming failure. Potentially extends the technique to a smaller building size than with current siphonic systems and offers climate change resilience potential.

This paper concerns the impacts of future climate change under two forcing scenarios on energy demand of commercial building and residential buildings with different energy-saving levels in Tianjin. Heating load of commercial building will decrease under the two scenarios in the next 90 years but increase of cooling load is found. All residential buildings will decrease heating load in the future 90 years. In particular, the decreasing rate of energy demand during 2011–2100 by the residential building slows down from the first- to the third-stage energy-saving levels. Additionally, the difference in energy demand between the two scenarios becomes smaller as the energy-saving level increases. These suggest that higher energy-saving levels are beneficial for decreasing not only energy consumption but also its sensitivity to climate change.

Practical application : Climate change in the future causes the large and significant increase in cooling energy demand but decrease in heating energy demand. This would be helpful for the adjustment of energy use strategy by government. Also, the possible changes in future energy demands for heating and cooling will be of interest to energy providers. The responses of heating energy demand to the future climate change show large difference among the residential buildings with different energy-saving levels. This will provide useful information for policy makers and building industry managers on how to make appropriate measures keep occupants comfort and reduce energy use.

In the past, the building energy consumption was surveyed without distinction of air-conditioning system types, which caused large dispersal of the energy consumption of the same building type. To study energy consumption of office buildings using air-source heat pump, six office buildings using air-source heat pump in Shanghai were investigated through energy audit and field test. The energy use intensity (EUI) per annum ranged from 102 to 139 kWh/m², with an average value of 126 kWh/m². The EUI range of office buildings using air-source heat pump is much smaller than the EUI of office buildings according to the literature. Based on field test of the air-conditioning (A/C) system, it was found that the present main problem of A/C system included insufficient refrigeration capacity of A/C system, low A/C system energy efficiency, and small cold water temperature difference. Countermeasures were brought forward to solve the problems, including ① retrofitting part of the present air-source heat pumps to water-cooled cold water air-conditioners, ② retrofitting present air-source heat pumps into new air-source heat pumps, and ④ pump variable frequency renovation. The A/C load is estimated by Bin method. According to the case study in this paper, the pay back period are about two years for the first measure, five to seven years for the second measure, and 0.65–2 years for the third measure.

Practical application: Generally, the energy consumption survey gives a wide range of data. To some extent, it is caused by the survey method which does not take the air-conditioning type into consideration. The work stresses on the energy consumption of office buildings using air-source heat pump. The result showed that the energy consumption was in a relatively small range, which will be more meaningful to industry. Energy saving measures concerning air-conditioning system is studied on the basis of the survey.

Balconies are green features commonly used in residential buildings to improve natural ventilation and air quality. Small vents, if mounted with an acoustic silencer, can reduce noise penetration while still allowing natural ventilation to occur. In this study, the computational fluid dynamics method is used to investigate numerically the effect of balconies with small upper and lower vents on the ventilation and air quality of the 4th, 5th and 6th floors of a 10-storey building. The results show that balconies can significantly increase the natural ventilation on these floors and generally have a more positive effect on the improvement of natural ventilation and the reduction in pollutant concentration on the floor on which they are located rather than on the levels above or below.

Practical application: This study will help designers and engineers understand more about the effect of balconies and lower and upper vents on natural ventilation and indoor air quality in buildings. This study will also help them to incorporate with confidence the design of balconies with lower and upper vents.

It is important to limit dwelling infiltration to reduce energy demand and help meet national climate change commitments while concurrently providing sufficient ventilation to deliver adequate indoor air quality. DOMVENT3D is a model of infiltration and exfiltration that assumes a linear pressure distribution over any number of uniformly porous facades and integrates the airflow rate in the vertical plane to predict the theoretically correct airflow rate through them. DOMVENT3D is a new development of an existing two-dimensional model of infiltration that provides more opportunities for investigating a greater number of dwellings than was previously possible. Initial testing suggests that DOMVENT3D is mathematically robust and is suitable for modelling a wide variety of dwelling types and geometries to assist engineers and policy makers.

Practical application: The modern building services engineer may be required to model airflow networks in a building to balance the conflicting needs of energy consumption reduction and occupant health. Limiting exfiltration is one method of reducing heat losses from a building and so there is a need to model it accurately. This article presents a new model of infiltration and exfiltration through a uniformly porous facade that can be incorporated within advanced complex airflow network tools or applied using a simple spreadsheet.

This paper presents an approach towards enhanced building-integrated wind harnessing. It uses building forms and profiles to trigger continuous air entrainment to power turbines. Computational fluid dynamics is used for evaluating, testing, and optimizing proposed designs. Wind separation around buildings is modeled alongside an investigation into the parameters of a wing-profile to accelerate wind. Computational fluid dynamics provides a good tool for modeling, designing, and optimizing aerofoil shapes. The main parameters affecting the wing’s wind harnessing capabilities are the distance between the wing and the building and the angle of attack of the wing. The aerofoil can magnify wind velocity by a factor ranging from 0.53 to 3.5; that is, from just below Betz limit to over six times the limit, depending on incident velocities.

Practical applications : The approach presented in this paper can be implemented directly into optimization of new designs of buildings to integrate wind energy harnessing. Furthermore, new proposed wing shapes or profiles can be investigated by the same procedure presented in this study. Computational fluid dynamics investigations to building-mounted wind technologies, such as the ones presented here, are becoming increasingly adopted in the design process in practice, in university courses and future research.

Lift traffic design can employ calculation or simulation methods. Calculation can be split into main categories: analytical equation-based methods and numerical methods. Simulation can be split into discrete event simulation and time-slice simulation. These methods vary in the level of computational complexity, as well as their ability to arrive at a value for the required performance parameters with acceptable accuracy and under the general case. Moreover, the repeatability of the results is an important consideration, as well as the simplicity and calculation time of the method used. This technical note provides a general overview of each of the four methods. It also discusses the suitable areas of application of each of the methods, showing the strengths and weaknesses of each of the four methods. This technical note concludes by outlining the current hybrid method used by designers in lift traffic design, whereby one of the calculation methods is used to find a starting arrangement and then the design is fine tuned using one of the simulation methods (e.g. changing speed, capacity of the lifts as well as the group control algorithm) in order to achieve the required average passenger waiting time and average passenger transit time.

Practical application: This technical note provides a blueprint to lift traffic designers for the lift traffic design process. It emphasises the fact that calculation and simulation are not mutually exclusive methodologies, and shows how they complement each other, where the former provides a starting design and the latter allows the designer to fine tune the lift traffic design.