Kjeld Svidt

Characteristics of Airflow from Open Windows

Abstract In natural ventilation systems fresh air is often provided through opening of windows. However, the knowledge of the performance of windows is rather limited, especially with regard to their impact on thermal comfort and draught risk in the occupied zone. This paper describes and summarizes the results of a series of laboratory measurements that is performed on two different window types to determine the characteristics of the air flow in rooms. It is shown that the air flow can be described by traditional theory for jets and stratified flow and semi-empirical flow element models are developed for estimation of thermal comfort parameters in the occupied zone.

Modeling of air inlets in CFD prediction of airflow in ventilated animal houses

Abstract This study investigates different methods to model wall inlets in computational fluid dynamics (CFD) simulations of airflow in livestock rooms. The experiments were carried out in an 8.5 m long, 3 m high and 10.14 m wide test room equipped with a forced ventilation system. Four wall inlets were distributed symmetrically along an end wall 0.5 m beneath the ceiling. To obtain uniform and easily modeled boundary conditions the inlets were designed as rectangular frames with an elliptic profile in the contraction section following the ISO standard for a long-radius nozzle. Vertical and horizontal air speed profiles in the jets were measured with thermistor speed sensors at four distances from the inlets and an ultrasonic sensor was used for measurement of air velocity in the occupied zone close to the floor. CFD-simulations with the k–e turbulence model were carried out with a number of different grid constructions. Both measurement and CFD simulations showed that two different airflow patterns occurred in the test room. In airflow pattern 1 the jets beneath the ceiling turned towards the symmetry plane of the room and above the floor the air flowed away from the symmetry plane. In air flow pattern 2 the jets turned away from the symmetry plane and above the floor the air flowed towards the symmetry plane. The findings in this study indicate that assuming two dimensional (2-D) inlet conditions might be a useful way to simplify inlet boundary conditions and grid constructions for prediction of air flow in the occupied zone of livestock rooms with many wall inlets. However, more work must be done to evaluate this statement in other arrangements, including changed orientation and locations of inlets, unattached jets and non-isothermal conditions.

Ontologies to Support RFID-Based Link between Virtual Models and Construction Components

: Virtual models have in recent years proven their worth in practice in building design. Today, virtual models of a complete building project are often created before the project is carried out in practice. The immediate advantages of this new working process are great; it reduces the number of errors, it gives a better production basis, and it improves clarity and enhances communication compared to traditional 2D drafting methods. However, there is still much unutilized potential in the virtual models, especially for use in the construction and operation phases. A digital link between the virtual models and the physical components in the construction process can improve the information handling and sharing in construction and building operation management. Such a link can be created by means of Radio Frequency Identification (RFID) technology. Ontologies play an important role as the foundation for information sharing between trading partners, reuse of data from one phase in construction to the next, integration of process and product models with enterprise resource planning (ERP) systems, easy access of information, communication of data through networks, reading of data stored in electronic tags, etc. This article reviews existing ontologies relevant in relation to creating such a digital link between virtual models and the physical components. The ontologies are reviewed from an ontology consumer (system developer) point of view. The ontologies are categorized according to their applicability to specification of technical services, resources, organizational relations, business processes, and overall frameworks for ontology descriptions and their relations. It is concluded, with a few modifications for industrial use, the technical service and resource ontologies are applicable and that the meta-, organizational, and business process ontologies need further development and industrial maturity to be applicable for use in system development.

BUOYANT FLOW GENERATED BY THERMAL CONVECTION OF A SIMULATED PIG

The effects of internal occupants and supplement heating make up an essential issue for the prediction and control of fresh ventilating air distribution in an enclosure. The influence from livestock is complex, since they are mobile obstacles, producing heat and contaminants in irregular geometry. As a part of the basic studies of these influences, the investigations of air motion in a thermal buoyant flow caused by free convection around a livestock body are reported in this article. A simulated pig, made of a painted metal tube (1 m long and 0.5 m in diameter) with covered ends and heat elements inside, was used as the heat source in the experiments. The experiments were carried out in a full-scale room, 5 m iA11 m in floor area, with a 2.4 m side wall height, and sloped ceiling to center (height: 4.8 m). The simulated pig was placed near the center of the floor. The vertical temperature difference in the room space was less than 0.3iaC. The velocity and temperature in the thermal plume were measured with six sensors (each has both temperature and velocity elements) placed at 0.2 m horizontal intervals. Data were acquired at 14 levels from 0.2 to 2.4 m above the top surface of the simulated pig. The data-sampling period was 30 min in steady state for each measurement. The results show that the plume was quite thin at the beginning (yd iU 0.6 m) in the central radial plane of the model. Observations showed that the laminar flow at the beginning remained for some distance before it became turbulent and spread. When the distance from the top of the model increased (yd iÝ 0.8 m), the temperature and velocity profile of the jet fit Gaussian distributions. The temperature profiles were slightly wider than the velocity profiles. Numerical simulations (Computational Fluid Dynamics) were applied for the same experimental set-up in computing the airflow over the pig simulator. Transient simulation with fixed time stepping provided similar results to the measurements, indicating the CFD simulation method used in the study has potential for prediction of buoyant flow generated by this type heat source.

Semantic Web Supported Knowledge Management System: An approach to Enhance Collaborative Building Design

This paper focuses on a lightweight ontology-based knowledge management system, which is a main component of IT-CODE, a Semantic Web based virtual workspace for enhancing the collaboration at an early building design stage. Technologies with respect to de facto standards that are proposed by industry group W3C are implemented to develop this knowledge management system. Resource Description Framework (RDF) associated with its Schema (RDFS) is selected as ontology language of the system. RDF(S) with its embedded reasoning techniques provides a rich set of constructs to facilitate the generation of ontologies so that the annotated information can be machine readable. Initiatives taken in the building industry for the evolution of the Semantic Web will be overviewed in this paper. Potential benefits offered by the RDF(S)-based knowledge management system to the building industry will be explained. Approaches of how the knowledge is represented in RDF-based ontology, is shared and retrieved among actors participating in the early design phase of a building project will also be described and illustrated. The paper will conclude with a description of how the early design phase may benefit from IT-CODE and its innovative knowledge management system.

Engineering Education in Higher Education in Europe

The present chapter concerns engineering education in higher education in a European context. It comprises two main strands: in the first, we present an overview of engineering education in Europe from historical and sociological perspectives, and in the second, we present country-specific examples of engineering education from three European countries—Denmark, Turkey, and the UK, representing three different traditions of engineering education. This chapter contributes to research on the cultural dimension of engineering education, while it may also inform stakeholders on the history, politics, and diverse practices in the European context. We provide a short comparison of the engineering education systems in Denmark, Turkey, and the UK across several criteria. We conclude these different European countries’ innovation levels may stem from their differences in their educational programs and teaching methods: diverse and interdisciplinary in Denmark and the UK and uniform and traditional in Turkey. Finally, we provide recommendations for policy makers, educators, and researchers based on our review.

In Search of Sustainable Design Patterns: Combining Data Mining and Semantic Data Modelling on Disparate Building Data

Cross-domain analytical techniques have made the prediction of outcomes in building design more accurate. Yet, many decisions are based on rules of thumb and previous experiences, and not on documented evidence. That results in inaccurate predictions and a difference between predicted and actual building performance. This article aims to reduce the occurrence of such errors using a combination of data mining and semantic modelling techniques, by deploying these technologies in a use case, for which sensor data is collected. The results present a semantic building data graph enriched with discovered motifs and association rules in observed properties. We conclude that the combination of semantic modelling and data mining techniques can contribute to creating a repository of building data for design decision support.

Towards data-driven sustainable design: decision support based on knowledge discovery in disparate building data

ABSTRACT Sustainable building design requires an interplay between multidisciplinary input and fulfilment of diverse criteria to align into one high-performing whole. BIM has already brought a profound change in that direction, by allowing execution of efficient collaborative workflows. However, design decision-making still relies heavily on rules of thumb and previous experiences, and not on sound evidence. To improve the design process and effectively build towards a sustainable future, we need to rely on the multiplicity of data available from our existing building stock. The objective of this research is, therefore, to transform existing data, discover new knowledge and inform future design decision-making in an evidence-based manner. This article looks specifically into this task by (1) outlining and distinguishing between the diverse building data sources and types, (2) indicating how the data can be analysed, (3) demonstrating how the discovered knowledge can be implemented in a semantic integration layer and (4) how it can be brought back to design professionals through the design aids they use. We, therefore, propose a performance-oriented design decision support system, relying on BIM, data mining and semantic data modelling, thereby allowing customized information retrieval according to a defined goal.

Development of an Information Delivery Manual for Early Stage BIM-based Energy Performance Assessment and Code Compliance as a Part of DGNB Pre-Certification

The evolvement of integrated practices utilizing Building Performance Simulations has made it possible to address the growing needs of the building design. Furthermore, including a sustainability rating system in the early stages ensures a superior environmental performance and a common goal for all parties involved. However, the persistent lack of early collaboration and process standardization prevent reaching the full potential of BIM-based performance evaluation. By following buildingSMART’s methodology for development of Information Delivery Manual/Model View Definition, this paper presents a framework for BIM-based energy performance assessment and code compliance, as required by the Danish Building Regulations and the DGNB rating system. Standardization of the information exchange would increase efficiency and reduce manual data input, duplication of work and errors due to miscommunication.

Integrating Virtual Reality and BIM for End-User Involvement in Design: A Case Study

The outcome of projects within Architecture, Engineering, and Construction is highly dependent on the quality of the collaboration between the involved actors. The end-users occupy the buildings on a daily basis, and therefore their involvement in the design process is essential to the output. However, traditional practices place the responsibility of decision-making mostly in the architectsO hands. Virtual Reality technologies coupled with Building Information Modelling have the potential to improve the collaboration and data visualization in the building design.This paper presents the findings from a case study on the integration of Building Information Modelling and Virtual Reality for user-centred participatory interior furnishing of a new university building. Besides a significant reduction in the time for generation of alternative proposals, the end results show an increased attachment of the employees to their future workplace and a high level of acceptance towards the technology. Finally, the authors present suggestions for further work, which could improve future design processes utilizing the Virtual Reality technology.