Building Services Engineering Research & Technology

Absorption chillers, having thermal compressors, need a heat source at high temperature to obtain cold energy. Because thermal comfort needs are continuously growing, thermal wells placed near cities with high cooling needs might be exploited efficiently all over the year, and the payback time of these systems might be reduced. To investigate the possibility of geothermal energy utilisation for cooling, the parameters of geothermal wells were analysed in the North Great Plain region. From available geothermal wells database, some wells were chosen in order to see which the possibilities are to raise the calculated efficiency value. Based on the repartition of the temperature gradient in Hungarian territory, a diagram was developed in which the efficiency of thermal compressors variation versus well depth is presented. It was stated that deepening the analysed wells with 600–700 m, the efficiency of thermal compressor will be two to three times higher than the original value.

A potential cross-transmission route, first identified in the spread of the SARs virus in South East Asia, in which infection was spread by virus-laden aerosolised droplets entering habitable space via defective water traps is investigated. The main aim of this work was to detect norovirus in wastewater from the collection drain in a hospital Building Drainage System and attempt to trace it in the BDS vent airflow. The methodology employed polymerase chain reaction tests on waste water samples and indicated strong positives for the norovirus GII strain from the collection drain, corresponding to an outbreak in the building, confirming that the BDS is contaminated in such circumstances and poses a threat. Pathogens were not detected in the BDS vertical stack airflows; however, the methodology employed to collect samples from the airflow was considered ineffective requiring further research. An average temperature of 24.3℃ was recorded, together with an average humidity of 96.6%. This research also confirmed that inside the building drainage stack, air flow movement occurs in both the ‘up’ and ‘down’ direction. Thus, aerosolised pathogens could travel from the contaminated horizontal collection drains upwards and enter wards via defective traps or little used showers, sinks, baths and sluices.

Practical application: The detection of norovirus from raw, unprocessed samples taken from the collection drain of a hospital complex highlights the need for caution in dealing with these large contaminated systems. The obvious area affected by these findings is in the awareness by building managers and facilities managers that this contamination exists and that all appropriate measures are taken to minimise infection spread due to normal o&m operations. While it was not possible to detect the virus in the airflow itself, it is considered significant that the identification of the direction and magnitude of these airflows confirms that building drainage stacks could act as conduits for the transmission of aerosolised pathogen-laden water droplets. This research suggests that there is a need for a secure and verifiable seal between the building drainage/sewer network and habitable space within a building to minimize the likelihood of any potential cross-contamination and consequent risk to human health.

The loss of fixture trap seals presents a potential cross-contamination route for sewer-borne pathogens. The defective trap identification method was developed to assess the status of trap seals using a non-destructive ‘sonar-like’ test based on the reflected wave technique. System diagnosis, proven over several years of laboratory and sited-based validation, primarily depended on manual interpretation of system pressure responses to identify the trap location from the reflected wave return time. This paper advances the technique by introducing the developed ‘TRACER’ program which includes a time series change detection algorithm allowing automatic system diagnosis. Outputs were validated against simulations using the AIRNET numerical model which, together with the ‘PROBE’ Method, was used to determine trap pipe periods, and therefore the location of defective trap seals, with improved accuracy over those calculated theoretically. This technique thus provides a reliable and automated approach to monitoring the protective seal between habitable space and the sewer network.

Practical application: Once installed, the building drainage system is often afforded little consideration in terms of regular maintenance, due partly to the problem of the ‘out of sight, out of mind’ mentality which is so often associated with this fundamental system, but also due to the practicalities of executing such an onerous task. Armed with a greater appreciation of the health risks associated with fixture trap seal loss, due to understanding its role in the transmission of the severe acute respiratory syndrome virus in 2003, building owners, operators and regulators must take action to safeguard the integrity of this important protective seal.

Renewable energy can play an important role in meeting the ultimate goal of replacing parts of fossil fuels to generate sustainable, inexhaustible, clean and safe energy. One of the promising applications of renewable energy technology is the installation of wind turbine that has been identified as having potential for wide-scale application in Hong Kong. Locally, wind turbines are seldom installed in building developments. The barriers include limited installation space available, the heavily obstructed external environments and noise and vibration problems. The apposite places for the installation would be on the roof/rooftop of low-rise buildings located in low-density zones. Relevant wind data and output power generated on-site, which may be quite site-dependent, are essential for modelling and evaluating the wind energy conversion system. Long-term measured wind data are crucial to the study of wind energy potential. This work studies the wind data and micro-wind turbine used in dense urban terrain and low-density area. Technical data including wind speed and output power were analyzed and reported. To achieve 1% of total building energy consumption generated from wind power, 17 micro-wind turbines are required to be installed in this institutional building located in low-density zone.

Practical application: Wind turbine is one of the typical applications of renewable energy technology. However, micro-turbines are not popularly installed in building developments. This work analyses the measured wind data and the energy performance of micro-wind turbines installed in an institutional building. The findings provide the on-site measured data for design and assessment of micro-wind turbines installed in building blocks.

This article presents the effect of envelope measures on thermal environmental conditions of a naturally ventilated building block in composite climate of India. Envelope measures such as roof U-value, wall U-value, glass U-value and glass solar heat gain coefficient, roof reflectance and two combinations of these measures (total seven cases) are analysed as recommended by National Energy Conservation Building Code-India (ECBC) through prescriptive route. Subject building is modelled and simulated using dynamic thermal simulation tool. Two approaches of thermal comfort have been used in this study such as heat balance model based on laboratory study and adaptive model of thermal comfort based on field findings. Thermal environmental conditions are evaluated based on operative temperature with and without considering the effect of thermal adaptation. This study found that comfortable temperature varies from 20.3℃ to 31.5℃ based on calculation of comfortable temperature through comfort temperature equation during winter to summer season in warm climatic conditions. This study concludes that envelope with ECBC specifications offer 60% hours under comfort state which were not comfortable with conventional practiced envelope specifications of India. The same methodology is also used to investigate the effect of ECBC envelope specifications in other climatic conditions such as hot and dry, and warm and humid climate of India.

Practical applications: The thermal performance of building envelope varies from climate to climate therefore care should be taken to choose particular envelope measure. This study aims to improve comfort conditions in naturally ventilated building block considering building code with/without thermal adaptation. This research would be helpful to architects, engineers and building constructors to choose the most effective or climate responsive envelope option for better thermal environment quality of the proposed building design. Use of thermal simulation tool is also recommended to examine the effect of envelope options on thermal comfort.

The performances of combined cooling, heating and power (CCHP) system are greatly dependent on its design, operation strategy and thermal and electric demands. This paper illustrates how the use of a genetic algorithm can provide speedy optimization, by applying it to two styles of buildings operated in different operation strategies. The primary energy consumptions of CCHP system following electric demand management (EDM) and thermal demand management (TDM) are firstly analyzed respectively. Then, sixteen hypothetical buildings are constructed to represent various energy demands. Primary energy saving (PES), annual total cost saving (ATCS), and CO₂ emission reduction (CO₂ER), are weighted to evaluate the integrated performances of CCHP system in comparison to separation production system. Finally, the optimized CCHP system for sixteen scenarios using GA are compared.

Practical application: This paper provides an optimization design method for CCHP system. The performance analysis of CCHP systems running different operation modes for different buildings is believed by the authors to contribute to a significant guide for the fundamental design of CCHP systems. Although sensitivity to a number of other important design considerations such equipment performance, possible future changes in operating conditions, changes to the price or carbon intensity of grid-supplied energy etc are not addressed, the conclusions present a simple and effective direction and the proposed optimization algorithm and the evaluation method for CCHP system can be extended to other buildings.

To reduce work in assessing alternative system structures in low-energy design, a Branch and Bound method is proposed. The bound is based on exploiting the thermodynamic constraint of exergy destruction along a heat flow path. A novel derivation of exergy in a flow system is provided and used to show its fundamental relationship with temperature and primary energy. The method is applied to two simple systems.

Practical application: In novel low-energy design, there can be many structural solutions that meet the client brief, especially at early stages in design, before full simulation/optimisation can be efficiently applied. The technique presented offers an application of the Branch and Bound algorithm that can be implemented on a spread sheet and which usually reduces the number of full structural solutions that have to be produced. It relies on working in exergy as the metric rather than temperature, and the work explains why this approach, common in optimising services components, can be applied to heating systems.