Impact of Varying Blower Opening Degrees on Indoor Environment and Thermal Comfort

At present,air handling units are usually used indoors to improve the indoor environment quality.However,while introducing fresh air to improve air quality,air velocity has a certain impact on the occupants’thermal comfort.Therefore,it is necessary to explore the optimization of air-fluid-body interaction dynamics.In this study,the indoor air flow was changed by changing the opening and closing degree of the blower,and the thermal manikin is introduced to objectively evaluate the human thermal comfort under different air velocities.The main experimental results show that the air change rate increases with the increase of the opening and closing degree of the blower considering an ACH(air changes per hour)range between 3.8 and 10.For a better prediction,a linear correlation with a coefficient of 0.995 is proposed.As the blower’s opening is adjusted to 20%,25%,30%,35%,and 40%,the air velocity sensor positioned directly beneath the air inlet records average velocities of 0.19,0.20,0.21,0.28,and 0.34 m/s over four hours,respectively.Observations on thermal comfort and the average sensation experienced by individuals indicate an initial increase followed by a decline when the blower’s operation begins,with optimal conditions achieved at a 35%opening.These findings offer valuable insights for future indoor air ventilation and heat transfer design strategies.

Plus Energy Buildings:A Numerical Case Study

The feasibility of Plus Energy Building for a sample relevant case is investigated.After a literature review aimed to identify key aspects of this type of buildings,a preliminary evaluation of the thermal performance of a building constructed using conventional material is presented together with a parametric analysis of the impact of typical influential parameters.Solar domestic hot water(SDHW)and photovoltaic systems(PV)are considered in the study.Numerical simulations indicate that for the examined sample case(Beirut in Lebanon)the total annual energy need of conventional building is 87.1 kWh/y.m^(2).About 49%of energy savings can be achieved by improving the building envelope and installing energy efficient technologies.Moreover,about 90%of energy savings in domestic hot water production can be achieved by installing a SDHW system composed of two solar collectors connected in series.Finally,the addition of a grid connected PV array system can significantly mitigate the energy needs of the building leading to an annual excess of energy.

The Impact of Sun Radiation on the Thermal Comfort in Highly Glazed Buildings Equipped with Floor Heating Systems

Occupants of highly glazed buildings often suffer from thermal discomfort during the mid-seasons when no shadings are used in such buildings,especially when inertial heating systems are used.The present study is devoted to evaluating the impact of long solar beam exposure on the internal thermal discomfort in glazed spaces when heating is implemented through a floor system.A comprehensive experimental study is carried out using an experimental bi-climatic chamber which is fully monitored and controlled,allowing realistic simulations of the dynamic movement of the sun patch on a heated slab.The findings show that a period of discomfort as long as 8 h can occur,and persist far after the sunbeam exposure stops.During this period,the heating slab’s surface temperature,considered from an average point of view,can attain 34°C while the indoor temperature reaches 26°C.Simulations conducted using a previously developed model display a good fit with the measurements.

Thermal comfort of Frail People under dynamic and non-uniform thermal environments using a thermal manikin with thermoregulatory control:An experimental study

The thermal comfort of frail people has to be considered carefully,mainly because of the high thermal sensitivity of this population and the negative influences that unsatisfactory thermal conditions have on their health.Most existing thermal comfort works have been conducted under steady-state,uniform thermal environments,with far fewer being performed in dynamic and non-uniform thermal environments,and even less for frail people.This study aimed at assessing the thermal responses of frail people under transient and non-uniform thermal environments,using a thermal manikin and a climatic test cell.Thermal responses were investigated and discussed in both genders.The analysis of variance showed a significant difference in thermal comfort and thermal sensation between females and males over time,under hot exposure.Under cold exposure,results showed a significant difference in thermal sensation between females and males over time,but no significant difference was observed in term of thermal comfort.Analysis revealed also significant differences in the dynamic thermal sensation between the sexes under cold exposure,while results confirmed that there is no significant difference in the dynamic thermal sensation between sexes under hot exposure.