Evaluation of the performance of demand control ventilation system for school buildings located in the hot climate of Saudi Arabia

The advantages of the demand control ventilation system(DCV)have been widely discussed in previous research studies.However,the literature has not addressed the benefits of DCV on controlling indoor CO_(2)concentration and minimizing cooling energy consumption for school buildings located in extremely hot climates.Therefore,this paper contributes to the development of DCV and mechanical ventilation systems through a comprehensive evaluation of these systems to maintain acceptable indoor air quality(IAQ)while minimizing cooling energy demands for school buildings located in the harsh hot climate of Saudi Arabia.The evaluation is based on a calibrated whole-building energy model and validated IAQ predictions using field data obtained from a school case study in Jeddah.The results of this research study confirm that hourly and sub-hourly monitoring of indoor CO_(2)concentration is required to ensure optimal design and operation of the ventilation systems in schools.In addition,the analyses indicate that a 13%increase in cooling energy end-use can result for any additional 0.1 students/m^(2)density increase in the classrooms.However,the energy penalties related to ventilation needs can be reduced by up to 25%using DCV instead of conventional mechanical ventilation systems for school buildings located in Saudi Arabia’s hot climate.

Experimental Investigation of Demand Controlled Ventilation Systems： A Suitable Alternative for Controlling Ventilation in Dwellings

Indoor CO2 concentration depends on the number of persons, their metabolic rates, other sources of indoor pollution, ventilation rate and ventilation efficiency. These factors are not considered by the Spanish technical building code since ventilation is set only by a fixed air change rate. This paper aims to explore the possibilities of DCVS （demand controlled ventilation systems） to ensure adequate and sustainable ventilation. It is based on a research project carried out by the University of the Basque Country （EHU-UPV） and Euskadi Public Housing and Soil Join-Stock Company （VISESA）： the living rooms of 90 dwellings were provided with DCVS, where CO2 sensors were used to dynamically control the ventilation rate. Tests were carried out using tracer gas techniques, with results showing the air age to be adequate at every point of the occupied zones and free of stagnant areas, therefore proving the system＇s effectiveness and rapid response, and its energy savings.

Determination of Effectiveness of Energy Management System in Buildings

Building Energy Management Systems(BEMS)are computer-based systems that aid in managing,controlling,and monitoring the building technical services and energy consumption by equipment used in the building.The effectiveness of BEMS is dependent upon numerous factors,among which the operational characteristics of the building and the BEMS control parameters also play an essential role.This research develops a user-driven simulation tool where users can input the building parameters and BEMS controls to determine the effectiveness of their BEMS.The simulation tool gives the user the flexibility to understand the potential energy savings by employing specific BEMS control and help in making intelligent decisions.The simulation is developed using Visual Basic Application(VBA)in Microsoft Excel,based on discrete-event Monte Carlo Simulation(MCS).The simulation works by initially calculating the energy required for space cooling and heating based on current building parameters input by the user in the model.Further,during the second simulation,the user selects all the BEMS controls and improved building envelope to determine the energy required for space cooling and heating during that case.The model compares the energy consumption from the first simulation and the second simulation.Then the simulation model will provide the rating of the effectiveness of BEMS on a continuous scale of 1 to 5(1 being poor effectiveness and 5 being excellent effectiveness of BEMS).This work is intended to facilitate building owner/energy managers to analyze the building energy performance concerning the efficacy of their energy management system.

Assessing ventilation control strategies in underground parking garages

Enclosed parking garages require mechanical ventilation fans to dilute concentrations of pollutants emitted from vehicles,which contributes to energy use and peak electricity demand.This study develops and applies a simulation framework combining multi-zone airflow and contaminant transport modeling,fan affinity laws,and realistic assumptions for vehicle traffic patterns and carbon monoxide(CO)emissions to improve our ability to predict the impacts of various ventilation control strategies on indoor air quality and fan energy use in parking garages.The simulation approach is validated using measured data from a parking garage case study and then applied to investigate fan energy use,peak power demand,and resulting CO concentrations for four different ventilation control strategies in a model underground parking garage under a variety of assumptions for model inputs.The four ventilation control strategies evaluated include one simplistic schedule(i.e.,Always-On)and three demand-based strategies in which fan speed is a function of CO concentrations in the spaces,including Linear-Demand Control Ventilation(DCV),Standardized Variable Flow(SVF),and a simple On-Off strategy.The estimated annual average fan energy consumption was consistently lowest with the Linear-DCV strategy,resulting in average(±standard deviation)energy savings across all modeled scenarios of 84.3%±0.4%,72.8%±3.6%,and 97.9%±0.1%compared to SVF,On-Off,and Always-On strategies,respectively.The utility of the framework described herein is that it can be used to model energy and indoor air quality impacts of other parking garage configurations and control scenarios.