Reliability in the whole life cycle of building systems

Purpose – The purpose of this research is to show that reliability analysis and its implementation will lead to an improved whole life performance of the building systems, and hence their life cycle costs (LCC). Design/methodology/approach – This paper analyses reliability impacts on the whole life cycle of building systems, and reviews the up-to-date approaches adopted in UK construction, based on questionnaires designed to investigate the use of reliability within the industry. Findings – Approaches to reliability design and maintainability design have been introduced from the operating environment level, system structural level and component level, and a scheduled maintenance logic tree is modified based on the model developed by Pride. Different stages of the whole life cycle of building services systems, reliability-associated factors should be considered to ensure the system's whole life performance. It is suggested that data analysis should be applied in reliability design, maintainability design, and maintenance policy development. Originality/value – The paper presents important factors in different stages of the whole life cycle of the systems, and reliability and maintainability design approaches which can be helpful for building services system designers. The survey from the questionnaires provides the designers with understanding of key impacting factors

Chemotherapy followed by low dose radiotherapy in childhood Hodgkin's disease: retrospective analysis of results and prognostic factors

PURPOSE: To report the treatment results and prognostic factors of childhood patients with Hodgkin's disease treated with chemotherapy (CT) followed by low dose radiotherapy (RT). PATIENTS AND METHODS: This retrospective series analyzed 166 patients under 18 years old, treated from January 1985 to December 2003. Median age was 10 years (range 2–18). The male to female ratio was 2,3 : 1. Lymphonode enlargement was the most frequent clinical manifestation (68%), and the time of symptom duration was less than 6 months in 55% of the patients. In histological analysis Nodular Sclerosis was the most prevalent type (48%) followed by Mixed Celularity (34.6%). The staging group according Ann Arbor classification was: I (11.7%), II (36.4%), III (32.1%) and IV (19.8%). The standard treatment consisted of chemotherapy multiple drug combination according the period of treatment protocols vigent: ABVD in 39% (n-65) of the cases, by VEEP in 13 %(n-22), MOPP in 13 %(n-22), OPPA-13 %(n-22) and ABVD/OPPA in 22 %(n-33). Radiotherapy was device to all areas of initial presentation of disease. Dose less or equal than 21 Gy was used in 90.2% of patients with most part of them (90%) by involved field (IFRT) or mantle field. RESULTS: The OS and EFS in 10 years were 89% and 87%. Survival according to clinical stage as 94.7%, 91.3%, 82.3% and 71% for stages I to IV(p = 0,005). The OS was in 91.3% of patients who received RT and in 72.6% of patients who did not (p = 0,003). Multivariate analysis showed presence of B symptoms, no radiotherapy and advanced clinical stage to be associated with a worse prognosis. CONCLUSION: This data demonstrating the importance of RT consolidation with low dose and reduced volume, in all clinical stage of childhood HD, producing satisfactory ten years OS and EFS. As the disease is highly curable, any data of long term follow-up should be presented in order to better direct therapy, and to identify groups of patients who would not benefit from radiation treatment

Generalized theoretical model of combined heat, air and moisture transfer in porous media

Combined heat, moisture and air transfer in porous media is a complicated phenomena. In addition to energy liberated during phase conversion, heat is transferred not only by conduction, but by advection as well. Similarly, moisture transfer occurs by vapor diffusion and advection due to air pressure gradients. Moisture is accumulated and stored in porous media as a function of the material sorption isotherm. A generalized theoretical model combining all influences of heat and mass transfer in porous media is presented in this paper. The \u27evaporation and condensation theory\u27 is modified to include the advection terms. The air pressure equation is derived without the typical isothermal assumption and liquid moisture diffusion is included to account for capillary forces

Contextual prerequisites for the application of ILS principles to the building services industry

Purpose – This paper proposes assessing the context within which integrated logistic support (ILS) can be implemented for whole life performance of building services systems. Design/methodology/approach – The use of ILS within a through-life business model (TLBM) is a better framework to achieve a well-designed, constructed and managed product. However, for ILS to be implemented in a TLBM for building services systems, the practices, tools and techniques need certain contextual prerequisites tailored to suit the construction industry. These contextual prerequisites are discussed. Findings – The case studies conducted reinforced the contextual importance of prime contracting, partnering and team collaboration for the application of ILS techniques. The lack of data was a major hindrance to the full realisation of ILS techniques within the case studies. Originality/value – The paper concludes with the recognition of the value of these contextual prerequisites for the use of ILS techniques within the building industry

Modeling the interactions between air distribution systems, building envelopes, and the outdoor environment in a typical hot, humid climate residence

Air leakage and duct wall conduction in forced air distribution systems often waste 20% to 40% of the energy used to condition residences in hot, humid climates. The simulation of these forced air distribution system leakages, their attendant uncontrolled airflows within the building system, and their consequential energy uses may be achieved by treating building spaces as pressure vessels (nodes) that are interconnected with the forced air distribution system, the outdoors, and each other through the basic laws of pressure and airflow. A detailed, hourly building energy simulation program, subjected to rigorous analytical and theoretical evaluation and validated against high-quality, empirical data, is used in this study to simulate these complex interactions in a typical residence located in Miami, Florida. Since energy uses related to forced air distribution systems are dependent on a number of factors, including duct system location and insulation level and the rate and location of the air leakage, a parametric simulation analysis that varies these factors across a range of typical values is used to conduct this investigation. The simulations quantify and disaggregate the typical residential energy uses for a peak summer day in Miami, Florida. The individual components of the predicted energy use that are related to the forced air distribution system include the duct wall conduction, the sensible and latent energy uses resulting from supply and return leaks, and the mechanically induced infiltration caused by the unbalanced forced air distribution system. Delivery and distribution efficiencies for the forced air systems on the peak summer day are calculated for each parametric case as compared with an ideal forced air system that experiences no air leakage and no duct wall conduction. By including accurate pressure and airflow models in the building simulation, the model can provide more accurate prediction. Simulation results show increased energy use in the typical Miami, Florida, residence by between 33% and 42%

Comparison of duct computer models that could provide input to the proposed thermal distribution standard method of test

ASHRAE Research Project 852 aimed to provide a firmer rational basis for the selection of a public-domain software to simulate the complex behavior of ducted air distribution systems for space conditioning in residential and small commercial buildings. The project was accomplished by: identifying candidate duct computer models based on the project criteria; determining the accuracy of the pertinent numerical solutions and algorithms employed by each model; and investigating the remaining models by comparing results from a group of parametric simulations where the problems consisted of a series of interconnected pressure vessels interacting with a leaking forced-air distribution system and the outdoor atmospheric environment

Comparison of a duct system computer model with measured data in a residential attic with a duct system

The purpose of this study was to compare a large set of high-quality laboratory measurements with computational predictions made by the FSEC 3.0 simulation model for air distribution systems located in building spaces, specifically attics in this study. Duct system tests were performed with controlled attic ventilation in a residential attic test module (RATM) located in a large-scale climate simulator (LSCS). The duct system in the RATM was attached to an independently controllable supply of conditioned air. Both summer and winter conditions were used in the LSCS, with the corresponding supply to the duct system either cool or warm air. Holes simulating air leakage sites at typical duct joints at the beginning, middle, and end of the duct system were opened and closed selectively to study the effect of air leakage into the attic space. Tests were conducted using both uninsulated and insulated ducts. Airflows and pressures in the duct system and temperatures in and around the RATM were monitored in all the tests. The comparison shows that the model predicts duct air temperatures, pressures, and leakage airflows well. The model can be used with good confidence to simulate the thermal performance of air distribution systems