English

Recently, in the Polish building sector, there has been a conflict between ventilation techniques and a strong tendency toward increasing building airtightness. Despite this increasing airtightness, the ventilation process in the majority of these buildings still depends on the uncontrolled supply of air through gaps in windows combined with natural exhaust air ducts. To improve energy efficiency in the building sector, more airtight envelopes constructed of modern materials of low air leakage coefficient are being constructed.

During the past few years, the research team of the University of Michigan has developed techniques to solve problems associated with designing a performance evaluation tool environment. This paper describes the development of a system (Web-IBEDO) that makes use of emerging communication technology. The system is being used as a model for a larger implementation of distributed multi-simulation environment that provides quantitative data for bioclimatic building design.

This paper presents a new simplified method to measure the air entrainment ratio of an active chilled beam or induction unit. The method uses a single anemometer and a simple purpose built measurement venturi together with the primary airflow rate. The new method is described and its calibration procedure is explained. Measured results are compared with results obtained according to European Standard prEN15116 with two extra sensors measuring the after coil air temperature. Results show that the new rectangular venturi method produces reliable and consistent results.

Real-time control of comfort in indoor spaces needs models of temperature distribution and the air velocity field. Complete models, based on CFD, give this information but, because of processing time limitations, cannot be applied to real-time calculations. Therefore, a reduced model is needed. This study proposes to reduce the complexity of a CFD model by first considering a fixed velocity field and solving only the energy balance equation, then putting this equation in the form of state-space and finally by reducing its order by Proper Orthogonal Decomposition (POD).

The innovation of computational simulations at the design stage can provide a more accurate prediction of building characteristics. Presenting information about practical cases is essential to validate the usefulness of computed predictions. This paper focuses on the coupling of computational fluid dynamics (CFD) and flow network model simulations, and their validation by means of field measurements. An energy-saving building was designed and built. In the building, natural ventilation is utilized incorporating unique and challenging concepts.

The suction cylinder described in this paper is a device to increase the ventilation flow rate, especially in naturally ventilated buildings. Outdoor wind is the driving force. The principle of operation is the development of a pressure drop created by the relative increase in flow velocity as wind driven air flows through a nozzle. This paper basically describes how this pressure drop and resultant momentum can be used to provide exhaust ventilation.

The purpose of ventilation is to dilute indoor contaminants that an occupant is exposed to. In a multi-zone environment such as a house, there will be different dilution rates and different source strengths in every zone. Most US homes have central HVAC systems, which tend to mix conditions between zones. Different types of ventilation systems will provide different amounts of dilution depending on the effectiveness of their air distribution systems and the location of sources and occupants.

The amount of energy used to heat and cool buildings is a significant concern that impacts on issues from national policies to personal desires of cost and comfort. The key to achieving optimum performance is the control of the energy flows in the building and its environment. Such control is secured through monitoring and altering the driving sources to maintain the desired thermal and air quality conditions in a space while external and internal conditions (e.g. seasonal climate, indoor heat gains, pollutants etc.) change over time.

This paper addresses the process of optimising the benefits of the natural (air) environment in the case of a high density city in which the amount of building volume is ultimately constrained. It is hypothesised that, in densely built cities, the amount of vertically placed gaps, permeability and porosity of the cityscape will affect the ventilation and wind environment. Wind tunnel experiments are described in which different amounts and positions of gaps were applied to a simplified city layout.

The potential for prediction error when using computational fluid dynamics (CFD) for investigating internal building airflows is assessed in the current paper. The ability of a proprietary CFD code, CFX, to simulate buoyant and forced airflow regimes, typical of a naturally ventilated building, are investigated using two experimental case studies from the literature. Comparisons are then made between simulated and measured airflows for a naturally ventilated building.