Effect Of Natural Ventilation Research Articles

A simple greenhouse climate control model incorporating effects of ventilation and evaporative cooling

A greenhouse climate model, incorporating the effects of natural ventilation and evaporative cooling (fog-system), is proposed and discussed. Linearization of the greenhouse heat and water balance equations leads to a simple system of two equations with two unknowns (the temperature and humidity differences between inside and outside air) which represent quite well the complex coupling mechanisms between ventilation and fog observed in situ. The model predicts that a minimum inside temperature can be reached for a certain combination of these cooling processes. Crop temperature and transpiration were also estimated using the Penman-Monteith approach and the energy balance of the crop. Good agreement between measured and computed values of air temperature, air humidity, crop temperature and transpiration was observed. From a practical point of view this approach may permit improvement in on-line climate control.

The Effect of Natural Ventilation on Radon and Radon Progeny Levels in Houses

The Effect of Natural Ventilation on Radon and Radon Progeny Levels in Houses

The Effect of Natural Ventilation on Radon and Radon Progeny Levels in Houses

The Effect of Natural Ventilation on Radon and Radon Progeny Levels in Houses

Positive Pressure Ventilation with Fire Suppression: Effective Reduction of Toxic Gas Exposures

Abstract The risks to firefighters and building occupants during fire suppression operations are intuitively obvious. However, little objective information about the relative effects on these risks of various fire suppression technologies is available. This study used a series of similar fires in a fire training building to compare the effects of natural ventilation (Scenario 1), positive pressure ventilation (PPV) before fire extinguishment (Scenario 2), and PPV applied after fire extinguishment (Scenario 3). Carbon monoxide concentrations were measured at five locations throughout the building. The number of 20-second intervals at which carbon monoxide levels were at or above 400 parts per million (ppm) during 10 minutes of monitoring after the temperature in the fire room reached 260°C were analyzed. The mean number of intervals of elevated carbon monoxide was 14.4 for Scenario 1, 4.9 for Scenario 2, and 16.5 for Scenario 3. The difference between Scenario 2 and the other two scenarios was significant (p = 0.017). This effect was noted at all five monitoring positions but was most significant at locations away from the fire. The use of PPV before and with fire suppression efforts may significantly reduce the duration of toxic exposure to firefighters and victims in structural fires.

Gases in forage tower silos.

Measurements of hazardous gas concentrations in forage tower silos are described. The problems associated with sampling in silos, the identity and distribution of gases and their rate of evolution, and the effects of forced and natural ventilation are considered. Particular attention is given to conditions at times when entry to the silo by farm personnel is likely and the possibility of farmers carrying out gas measurements is discussed.

The effect of vertical location on thermal performance of multistorey apartments in Riyadh, Saudi Arabia

During the recent large-scale development that has taken place throughout the Kingdom of Saudi Arabia in various sectors (e.g., agriculture, industry, transportation, education, and health), many multistory buildings have been constructed with little or no concern for their thermal performance. This paper investigates the effect of exposed roofs on thermal performance during the hot season of the year, by comparing the indoor climate of two apartments, one located on the top floor and the other located on the ground floor of the same building. The internal surface temperatures of the four walls, the surface temperature of the roof, and the indoor air temperature of the selected apartments were recorded automatically, when no air-conditioning was used and the openings were tightly closed to eliminate the effects of natural ventilation and to minimize the effect of infiltration. The surface temperatures of the four walls and the roof were then converted to mean radiant temperature values. The computed mean radiant temperature and indoor air temperature values were then combined into environmental temperature, and these values are presented graphically to quantify the effect of the vertical location on thermal performance. Thermal comfort requirements are also presented for comparison purposes. The results indicated that there is a considerable difference in the thermal performance of the selected apartments due to their vertical location. The indoor air temperature and internal surface temperatures of top floor apartments are relatively higher than the values recorded for apartments located on lower levels, mainly due to the exposure of the roofs of the top-floor apartments to the intense heating effect of the direct solar radiation. Some of the design alternatives for roof construction which have been recently introduced into the Kingdom of Saudi Arabia in an attempt to improve a roof's thermal performance are briefly analysed. The U-values of these alternatives are computed and compared with the U-value defined by the Gulf Cooperation Council (G.C.C.) and the U-value of the roofs of the apartments in this case study.

A monitoring exercise for a school atrium

At a time when great importance is being attached to making more efficient use of resources, there is a strong case for considering ways in which buildings may be improved and extended to meet new and changing requirements. The Martin Centre investigated the potential which was offered in these respects by the addition of glazed roofs to existing courtyards and lightwells. The investigation aimed at carrying further the current knowledge of the environmental performances of glazed courts and so revealing the potential of the glazing of existing courts. The work was carried out in collaboration with Essex County Council and the emphasis was on school buildings. Part of the study involved the monitoring of a primary school fitted with a glazed courtyard. This paper presents an analysis of the temperatures recorded both in the atrium space and in the adjacent classes. The stratification phenomenon is discussed as well as the effect of natural ventilation on overheating conditions.

A Study on Combined Passive Cooling Effect of Roof Spraying and Natural Ventilation

A Study on Combined Passive Cooling Effect of Roof Spraying and Natural Ventilation

Wind Tunnel Investigations of Natural Ventilation

Requirements for similarity of natural ventilation in wind tunnel models and experimental methods for evaluating its effectiveness are reviewed and tested in a 1:25 wind tunnel model of the Florida Solar Energy Center Passive Cooling Laboratory (PCL). The experiments indicate that, in addition to the requirements for simulation of external flows around the building, an internal Reynolds number based on the maximum velocity and minimum dimension of each room should be larger than 2×104. Internal to external velocity ratios are shown to give a detailed unbiased picture of the local internal climate. Dimensionless pressure difference coefficients, based on pressure measurements on the external envelope of the building model, and dimensionless dilution rates, based on tracer concentration decay measurements, can be used to evaluate the relative integral effectiveness of natural ventilation in different configurations. The advantages and limitations of each method, as demonstrated in the study of the PCL model...

Thermal Performance of Perforated Brick, Hollow and Light-weight Block Construction in Tropics

ABSTRACT This paper deals with a study on the effect of thermal properties of hollow, perforated and lightweight block building components on the indoor climate. The experimental data collected during the severest days of summer and winter seasons of 1967 are reported. The effect of natural ventilation during night and the fan circulation during day on the indoor conditions has also been discussed. Results indicate that the observed data fits in well with the curve relating thermal damping and thermal time constant for insulated masonry structures which was given earlier.

Casa en Alahurín, Málaga

This set of buildings on a single floor level, is constructed on a hillside, at Alahurin de la Torre. It follows the typical layout of Andalusian country houses, consisting as it does of two parallel, long, low roofed buildings, with windows and doors opening onto the interior precinct. The enclosed patios have shallow ponds, whose object is to cool the inner zone and establish temperature gradients within the building that will induce an effective natural ventilation. This project is especially distinguished because of its sober style, sense of spaciousness and its continuity with the natural environment. The external walls are in cut stonework, which provides a very rustic and continuous texture. On the inner side, by contrast, the walls are lightly, and ellaborately, constructed, and enclose cool patios and ample porches.