Recent investigations on heat and mass flows through building materials in dynamical conditions show the importance of considering moisture transport and storage when analyzing the global performance of the building envelope. Lime-Hemp Concrete (LHC) is an insulation material made out of hemp chips mixed with an appropriate rich lime binder. It can be use either in old or new buildings, to cover masonry walls or to fill walls, floors or roofs in timber frame structures. This paper analyzes drying process, final density and vapour permeability of different type of LHC-wall mixtures to point out influence of mixing, implementation and water input on material’s final properties. Experiments inspired by the Nordtest project are then presented to assess moisture buffer effect in LHC material and retarded sorption effect is pointed out. Results from dry thermal conductivity measurements are also reported and influence of moisture content on this parameter is discussed. These results show why the use of LHC can help to reach high comfort feeling with low energy demand for indoor temperature and humidity regulations in sustainable buildings.
Sorption Behaviour of Lime-Hemp Concrete and its Relation to Indoor Comfort and Energy Demand
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Air Ventilation Assessment System for High Density Planning and Design
In 2003, Hong Kong was hit by Severe Acute Respiratory Syndrome (SARS) from which many people died. The Hong Kong Government subsequently set up a Team Clean Committee to investigate possible infectious disease prevention measures and policies. One of the general feelings was that SARS should be taken as a wake up call to critically examine the city for healthy living. Team Clean then charged the task to the Planning Department, HKSAR. It initiated a study titled: “Feasibility Study for Establishment of Air Ventilation Assessment (AVA) System”. In 2003, the research contract was entrusted to Professor Edward Ng of Department of Architecture, CUHK. Over the next two and a half years, a number of studies were conducted. The study eventually led to a methodology of Air Ventilation Assessment (AVA). Unlike many countries with guidelines for dealing with strong wind conditions, AVA is a guideline for weak wind conditions specifically designed to deal with congested urban conditions. The AVA system basically establishes a method for project developers to objectively assess their designs. The Government of Hong Kong has adopted the system and will require all major development projects to undertake the assessment. The first test case has been a 328 hectare old-airport site in the city centre. The scientific and implementation processes leading to the AVA system is reported in this paper.
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Integration and Formal Development of Solar Thermal Collectors
The paper presents selected results of an investigation over possible ways to improve Building Integrated Solar Thermal systems (BIST) on the formal level. It shows the results of a European survey intended to help defining quality in the architectural integration of BIST. A few criteria of integration are derived and presented as guidelines intended to support architects in their integration design work. Finally the paper describes a methodology for the formal development of solar thermal collectors responding to both energy and architectural needs.
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Shadum Evaporatis, An Autonomous and Eco-friendly Tree
The urban microclimatic conditions in the Mediterranean can become very harsh during the summer because of the intense solar radiation and the elevated air temperatures. Athens, Greece is characterised by very hot days, with temperatures, which may reach up to 38 degrees Celsius, while its urban squares are generally deprived of vegetation and water elements. This paper attempts to give an answer to these problems by proposing a multi-functional bioclimatic structure for the open spaces of Athens. It is a structure, which provides shading, cooling, and has the ability to move its parts. Shadum Evaporatis is an autonomous, eco-friendly tree, whose ambition is not to substitute real trees, but to provide, in cases where planting trees is not possible, shading and evaporation. It can also be seen as a city landmark, a path-finding element, and an object, which changes during the day and throughout the year. It is a design object for urban open spaces, which can be natural and low-tech, or sophisticated and high-tech object, depending on variations of its design.
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Transforming a low value coastal area into a high value natural and recreational area
The coastal zone in the Netherlands takes a very peculiar place in the discussion about sustainability in the Netherlands. Large areas are left unused and they remain low cost value areas due to the lack of progressive decision-making. These areas have a low value in economic, recreational and natural sense that often lead to a further degradation of the area involved. A responsible way of coping with these areas is essential for a sustainable future of the Netherlands. This downward spiral can only be broken by stepping over the boundaries of the traditional decision making pattern and by implementing sustainable design tools that lead to new forms of (urban) architecture in which sustainability is implicit. In this paper I will demonstrate that by doing the above, low value areas can be transformed into high value areas on all three aspects using an used drilling platform as a landmark and hotel in combination with a yacht harbour in a natural and recreational area in the coastal zone in Katwijk aan Zee, the Netherlands.
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Theory and Practice of Natural Ventilation in a Theatre
We report on a detailed monitoring exercise and an analogue experimental study of a naturally ventilated theatre in operation in the UK which can take audiences up to 300 people. The theatre has a raked seating area, and two outflow stacks, with a ring of air inflow vents on the floor which supply air naturally from an underfloor plenum. Detailed temperature measurements over a period during the winter 2003/2004 broadly indicate that the air within the theatre is stratified in temperature, with a relatively cool zone near the lower inflow vents and a progressive increase in temperature up to the roof space, where the temperature decreases again. A series of analogue laboratory experiments designed to simulate the natural convective flow, to help understand this thermal profile and the air flow pattern, identifies a series of fascinating flow regimes which depend on the inflow opening area at the base of the theatre. In general, the raked seating leads to a large scale circulation upwards and backwards across the audience which then spreads across the roof space and partially vents. The remaining flow rising from the seating zone recirculates in the upper part of the air space creating a weakly stratified upper layer. Lower in the theatre, the inflow of relatively cold air through the floor develops small inflow jets which mix with some of the warm air in the theatre and then spread laterally to form a cooler lower layer of air. This is mixed by the convective plume rising over the raked seating area and heated up as it is then carried into the upper part of the theatre. The experiments point to some design rules in order to achieve satisfactory ventilation within the space, without leading to excessive or insufficient cooling.
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Engaging Engineering and Architectural Students in the Integrated Design Process (IDP) for a Competition Entry Demonstration House – the Solar Decathlon
Since April of 2003, a group of students from Concordia University and Université de Montréal has been preparing their entry to the Second Solar Decathlon competition to be held in September 2005. Their goal is to design, build and operate the most attractive and effective solar-powered house that also sets a considerable standard in sustainable design. Some of the technologies to be integrated into the architectural design include solar electricity (photovoltaics), advanced windows, solar domestic hot water and battery storage; at the same time, other less high tech concepts (such as buffer zone spaces, Trombe wall, thermal mass, and natural daylighting) are to be transparently incorporated. Additional ecological strategies include the attempt to reduce embodied energy, recuperate and recycle rainwater, and design for growth and change. This paper will present the experience from the first year design process. The complexity of bringing together students from totally different backgrounds and institutions is not unlike the situation of some architect-engineer forced-relationships found in practice, and the interaction process will be described and analyzed.
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“In town without my car!”: a new urban soundscape
In order to promote a more sustainable mobility society, the French government initiated a few years ago a “Car free day” (In town without my car!). Since the year 2000 this initiative has become an overall European action. In the framework of this policy the city of Bordeaux has made the choice to ban the cars from its centre area every first Sunday of the month. Besides a decrease of the air pollution during this period, acoustic measurements show a big change in the noise environment. To verify this effect, we made a comparison between the audio recordings of the soundscape, of the first Sunday and the normal Sunday of the month. The “sound walk” followed a trajectory with different urban forms. It started on the Place des Quinconces (a very large square), passed the Place de la Comédie, followed the Cours de l’Intendance (a broad avenue), rue Vital Carles (a narrow street) and finished in front of the St André cathedral. We used for the recordings a “dummy” head with Digital Audio Tape recorder. In order to compare the different acoustical ambiances of the first Sunday and the normal ones, we analysed them on sound level.
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Passive Downdraught Cooling: hybrid cooling in the Malta Stock Exchange
The use of cooling in buildings is continuing to increase in Europe. This is raising concern that it will undermine the European Community’s drive toward reducing CO2 emissions. To counter this trend, there is increasing interest in evaporative cooling in general and passive downdraught evaporative cooling (PDEC) in particular. However, there are many locations in southern Europe where the relative humidity is sometimes too high for evaporative cooling to be viable. This in turn has led to the proposal for energy efficient hybrid cooling systems. This paper will present a case study of a hybrid downdraught cooling system within the new Malta Stock Exchange.
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Analyzing the microclimatic influence of urban canyon geometry with an open-air scale model
A novel approach is developed for modeling the influence of street canyon geometry on microclimatic conditions within the urban canopy. A physical scale-model of an urban roughness array was constructed in open-air conditions to enable the measurement of climatic parameters with natural turbulence effects, potentially overcoming some of the limitations common to more conventional research techniques. Energy balance in the urban canopy is quantified using a pedestrian-centered model which allows for the computation of energy exchange between a hypothetical human body and the urban environment, based on data measured within the scale-modeled street canyons and taking into account the effects of dimensional scaling. The proposed technique is demonstrated under typical hot-arid summer conditions in a desert region, and relative pedestrian energy exchanges are compared with previous findings from full-scale measurements in a climatically-similar actual urban setting. Results show that a compact street canyon geometry may reduce pedestrian heat gain during most summer hours, if attention is paid to design aspects such as street axis orientation. The model shows the ability to reproduce patterns observed in full-scale, and to reveal distinctions which are impractical to quantify using field studies alone.
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