natural ventilation

This paper describes the effect of outward opening the sash of a window on local and overall wind pressures. Wind tunnel experiments were used for the purpose of evaluation. A centre-pivot roof window on a pitched roof in a modelled scaled building was used in the analysis of wind pressures. The wind pressures were defined in terms of wind pressure coefficients. Traditionally, wind pressure coefficients are extracted from the analysis of a sealed plane surface. These wind pressure coefficients are used to estimate the natural ventilation rate through windows/openings due to wind effect.

As natural wind is continuously fluctuating in both speed and direction, quantifying instantaneous wind-driven natural ventilation rate can be difficult, and often an average effect is used to stabilize the fluctuations. This work performs an experimental investigation to assess the validity of assumptions often used in quantifying airflows through an opening under cross natural ventilation condition. In the experiment, the three velocity components are analyzed for flows approaching and through an open window exposed to natural wind.

In both, newly built and renovated buildings the building air-tightness has to be ensured. With a tight building envelope comes a low infiltration air-exchange. A minimum outdoor air exchange to ensure acceptable moisture and indoor air quality levels must be maintained. A model is introduced, that couples hygrothermal whole building simulation with a multi-zone air-flow simulation.

As the benefit of natural ventilation in reducing operational cost is well recognised, the concept of natural ventilation is becoming more received by residents and designers alike.

The thermal comfort of the “Home for Life” dwelling in Denmark, the “LichtAktiv Haus” in Germany and “Sunlighthouse” in Austria is investigated with a particular focus on the control strategies and the role of solar shading and natural ventilation (ventilative cooling). These houses are three of six buildings in the Model Home 2020 project (Feifer, 2013). They have generous daylight conditions, and are designed to be energy efficient and CO2 neutral with a good indoor environment.

This paper presents a study of the potential for the use of natural ventilation systems in Portuguese multi-family residential buildings under winter climatic conditions. The behaviour of various natural ventilation systems is tested in a standard residential dwelling, using the TRNSYS 15 and COMIS 3.1 software programs. This study leads to the conclusion that the use of hybrid ventilation systems can save a considerable amount of the energy normally spent on continuously operating mechanical ventilation systems.

Focusing on the turbulence in natural ventilation and its impact on both occupant thermal comfort and building energy consumption, this paper presents a review of existing unsteady natural ventilation envelope flow models, as well as other techniques that have potential application to further our understanding of turbulence in natural ventilation and develop models which capture the dynamics and effects on thermal comfort.

In this paper, a global map of maximum indoor operational temperatures of buildings is presented. Maximum indoor operational temperatures were evaluated around the world using both PMV and ATC.

To ascertain comfort levels and effectiveness of available adaptive opportunities for classrooms in the hot-humid regions of India, a thermal comfort field study was conducted in an undergraduate laboratory class in Kharagpur. The study, carried out between January and April 2013, had participation from 121 students and yielded 338 responses. Analysis of the results showed that comfort temperatures found in the field study had close resemblance to the predicted comfort temperatures evaluated from certain existing standard adaptive comfort equations.

Since naturally ventilated buildings respond to site conditions and microclimate, there is no ”one set of spe-cific criteria” for every naturally ventilated building. So natural ventilation should be optimized to deal with ther-mal comfort in passive buildings during hot season.