Papers by Keyword: Natural Ventilation

Abstract: The current study looks at a hybrid passive cooling system that combines a solar chimney with an earth-to-air heat exchanger (EAHE) usually called Canadian Well. Numerous experimental and numerical examinations with various applied radiation heat fluxes were carried out to evaluate its ability to cool a room. Glass temperature, wall temperature, air flow mean temperature, hourly rate of air exchange (ACH), outlet airflow velocity, and rate of air mass flow were determined experimentally and numerically, and validated against previously published experimental and analytical works. It was found that the chimney's operation is dependent on the radiation intensity. The EAHE has reduced the room's temperature by improving exchanges with the solar chimney. The comparison of experimental and numerical data for different radiation intensities reveals that the best diameter of the tube of the underground heat exchanger for the proper operation of our system is d = 0.04m. The efficiency of our system increases as the radiation increases, causing an increase in the temperature of the absorber, which influences the air temperature in the chimney.

Abstract: Commercial buildings are high energy consumption buildings due to lighting system, cooling, and heating requirements (HVAC) for main corridors, shops, and other services. This research is offering an innovative environmental solution for one floor existing commercial buildings by retrofitting the design to be naturally ventilated which lead to reduce building energy consumption and Co2 production. This Research main concept is ventilating corridors and common spaces at one-floor commercial building naturally and achieving users’ thermal comfort even in the hottest day at summer.Research case study is one-floor existing commercial building in Ras El Bar, Egypt. Building model is constructed in Design Builder software to simulate building energy consumption in the current design as base case and compare different environmental solutions results with it to estimate the energy and Co2 reduction. Also, CFD simulation for different design proposals is simulated to guarantee comfort natural air flow inside the corridors for building users.In addition to visit to building site to measure temperature and wind speed by multi-functional anemometer in many focal points indoor and outdoor the building, to consider any missing data that could affect on the final decision.Finally, after simulating more than one solution, the study present solution that naturally ventilate the on-floor commercial building and achieved users’ thermal comfort at summer.

Abstract: The paper focuses on the analysis of reconstruction in terms of CO₂ concentration. The reconstruction at the university included the exchange of windows. The original windows were exchanged for the modern wood tight windows. Providing CO₂ concentration in the interiors of a university is immensely important for the students of the university. Not exceeding CO₂ concentration limits is necessary not only for the physiological needs of students but also for the required performance of students. Teaching is conducted during the whole day in the researched university schoolroom. The short-term natural ventilation during the breaks is noticeably not sufficient. After 15 minutes from the beginning of the lesson, students started complaining about the air quality and they had to open the windows. To point out the unsustainable state of the poor air quality during the day-long teaching and to be able to prove the officials the importance of the continuation of the reconstruction by building mechanical ventilation or air conditioning system, there were carried out the experimental measurements in the schoolroom. The device Testo 480 was used for the measurements. Obtained values of CO₂ concentration are presented in the charts. Interestingly, this reconstruction significantly decreased the air quality. The admissible values of CO₂ concentration were exceeded after the first hours of teaching. These values were worsening with each additional hour of teaching. Therefore, another reconstruction is needed to enable the transition from natural ventilation to the mechanical ventilation system. In the conclusion of this paper, there are principles how to design new schoolrooms. Furthermore, there are presented recommendations how to operate the existing schoolrooms.

Abstract: The present paper focuses on the evaluation of different methods for calculation of air change rates due to natural ventilation through windows. Such estimations are of utmost importance for the studies, in which the influence of window operation on thermal comfort, air quality and building performance is to be addressed. Especially, to build accurate building performance models and to develop reliable building simulation scenarios, it is crucial to predict proper values of air exchange. A number of standards and recent scientific contributions present various models for the estimation of air change rates, whereby different sets of input parameters related to room and outdoor conditions are needed. The current contribution examines the reliability of calculated air change rates obtained via a number of widely used estimation methods for a case study room with single sided windows. To this end, a number of tracer gas measurements in a variety of window state settings were conducted, and the real air change rates were calculated based on the measured concentration decay of the tracer gas. Consequently, using the resulting measured and calculated values of air change rates, the reliability of estimation methods could be extensively explored.

Abstract: The present contribution, reports on the results of ongoing research efforts on performance assessment of a number of buildings designed by the Austrian architect, Konrad Frey. He is a pioneer of energy-efficient architecture, and his designs, those dating back to the 1970s, adapted the principles of modern solar houses. The current study focuses on the Kindergarten Hart, which was especially designed focusing on the availability of cross ventilation option in building. For the purpose of analyzing thermal comfort, indoor air quality, and the occupants’ adaptive actions with respect to natural ventilation, we conducted long-term monitoring under summer and winter conditions. The monitoring efforts covered indoor and outdoor environmental conditions, as well as the state of windows. Thereby, study of the monitored dataset provides a better understanding of the building performance. Moreover, it makes it possible to examine whether the architect’s expectations in terms of thermal comfort and indoor air quality levels are fulfilled or not. In addition, investigation of the occupants’ interactions with windows, together with indoor and outdoor environmental conditions, assists understanding of possible associations between the window opening/closing and environmental parameters, as well as potential optimization of the control-oriented actions.

Abstract: Despite growing interest in sustainable office buildings and technological advancements, often either comfort or energy is sacrificed at the expense of the other in the conventional approach. Designers and architects tend to lean towards fully glazed buildings in a multi-floor office building due to its light structure, transparency and more access to daylight compared to traditional buildings. However, their energy efficiency and impact on occupant comfort – thermal, glare and visual – are questioned. Some practitioners, therefore, prefer a fully sealed façade with a low glazing ratio to reduce energy consumption. This paper argues that wellness and energy savings are not contradictory aspects of design. It is shown that measures to create an exceptional, healthy environment for occupants drive conservation and energy efficiency. Such design needs special considerations at the early stages that significantly affect decisions regarding passive strategies. To help drive first decisions, an accurate and fast simulation tool that considers dynamic thermal, daylight and airflow models is required. However, some passive measures such as natural ventilation are more difficult to simulate and validate due to the complex, non-linear relationship between wind forces and thermal buoyancy. The aim of this paper is to demonstrate the use of TRNLizard, an integrated thermal, daylight and airflow simulation tool based on Rhinoceros 5, Grasshopper, TRNSYS18, DaySIM and TRNFlow to develop and validate the concept for an energy efficient office building with a healthy, comfortable environment. The office building is located in Germany with a highly glazed façade and night ventilation for passive cooling. It is shown that night flushing reduces annual end-use cooling energy and peak cooling load of mechanical air conditioning systems by 55% and 15%, respectively.

Abstract: Within an ongoing project, we explore the potential of double skin facades to provide both noise control and natural ventilation capability. Three strategies are investigated: i) Manipulation of sound paths via offset of the openings in the two shells of the façade; ii) Application of absorbing materials in the interstitial space of the façade; iii) Active noise cancelling methods utilizing wave-destructive interference. This contribution describes the overall project but focuses primarily on the active noise cancellation approach. Aside from a comprehensive background research on existing technology, we undertook the design of an actual setting for noise cancellation testing with suitable low-cost components as a proof-of-concept. Results of the experiments are expected to inform subsequent efforts to include noise-cancelling technology in double skin facades.

Abstract: One of the optimal and most economic ways of completing a thermal assessment of a building is with a precise dynamic thermal simulation, where a building envelope and its systems are simulated and evaluated in a virtual climate using real meteorological data. The simulation parameters can be exported to a Building Management System for a particular building, as simulation problems of natural ventilation reflects the real behaviour of a building. Instability of dynamic thermal simulation is a typical issue for certain conditions, as window operations can cause excessive interior temperature fluctuations and even trigger the heating system if the common ON/OFF or simple linear operation function is used. To solve the problem, reduction of the simulation time-step is usually used, though the principle of the air flow is not handled. Additionally this solution multiplies the simulation complexity, though the instability of the model is significantly reduced. The case model clearly showed a negative contribution of AOVs operated by linear function related to temperature or CO₂ at initial simulations, by increasing the energy consumption of the building.

Abstract: The paper presents a computer model, developed in the software programme Comsol, for studying the influence of the ventilation apertures on low voltage (LV) switchboard heating. Results have been obtained, concerning the distribution of the LV switchboard thermal field and air velocity field in cases of closed LV switchboards and switchboards with ventilation apertures both at natural and forced ventilation. The influence of the ventilation apertures location, as well as of the air velocity at forced ventilation, on heating the current carrying circuits in the LV switchboard has been studied.

Abstract: The article is focused on the theoretical calculation of double-skin façade without effect of wind. Each algorithm needs entry figures for initiation, so that the computing could be started. Incoming data entry of this computing program consists of two parts - geometric and physical parameters of double-skin façade. Calculation of the mass flow in inter-space is a highly complex matter. Particular unknown quantities in heat computing and air mass flow are unknown and interdependent to each other. Algorithms of their specification by iteration method are processed for designation of these values.