Indoor Air Quality Control Research Articles

Comparison of Conventional and Fuzzy Control of Indoor Air Quality in Buildings

This article compares various techniques for the control of indoor air quality in a naturally ventilated building: ON-OFF, proportional-integral-derivative PID, proportional-integral with deadband PIdb, and fuzzy control. The control system for the fuzzy controllers is a typical two input carbon dioxide concentration and its time derivative, one output change in window opening area system. Two different fuzzy controllers are modeled: one based on Mamdani's max-min inference, and the other using Gupta's multivariable structure. The results show that the fuzzy controllers and the Pldb controller are much more suitable than the PID or the ON-OFF controllers. The number of cycles of the controlled parameter i.e., the window opening fluctuations is actually much smaller. Minor differences between the two fuzzy controllers are observed.

Evaluation of Ventilation Effectiveness in the Kitchens of Beijing Flats

The effects of different kinds of room ventilation were evaluated in an experimental chamber and in kitchens of four residences in Beijing. Carbon monoxide was used as a tracer gas in the chamber, and this together with nitric oxide and nitrogen dioxide concentrations from the gas appliances were measured in the chamber and the kitchens. The ventilation styles evaluated were natural ventilation, an exhaust fan and a kitchen range hood. Their ventilation effectiveness was related to design, air flow, the distance between an appliance and air vent, and position of the appliance in the kitchen. A kitchen range hood above the appliance associated with an extra fan installed in a high window was found to be the most effective way to control indoor air quality in the kitchens.

NATO's Efforts to Set Indoor Air Quality Guidelines and Standards

The North Atlantic Treaty Organization (NATO) Committee on the Challenges of Modern Society conducted a multinational cooperative program involving about 200 experts from 15 countries during 1989–1993 to examine policy strategies in indoor air quality (IAQ) and propose a range of options that could be adopted by NATO nations. This international effort produced recommendations about a wide spectrum of issues related to IAQ. The achievement of health and comfort in the indoor environment combined with energy efficiency can be obtained by a proper control of human exposure to indoor air contaminants. The development of guidelines and standards was recognized as an essential tool in promoting the achievement of high IAQ. In particular, development of guidelines was recommended for pollutant concentration in indoor air, for ventilation, and for emission from materials. Guidelines for methods for IAQ assessment and control and for medical management of building-related complaints and illnesses also were examine...

Demand-Controlled Ventilation in a Multi-Zone Office Building

This study applies indoor air quality modelling to investigate the potential advantages and drawbacks of demand-controlled ventilation as an indoor air quality control strategy. The study uses a multiple zone pollutant transport model to evaluate the performance of several indoor air quality control strate gies under a variety of conditions. The pollutant transport model is incorpo rated into the TRNSYS simulation program to allow simultaneous calculation of both building pollutant concentrations and building energy use. A specific office building situation consisting of a main zone and a conference room was studied. The simulations showed that a carbon dioxide-based demand con trolled ventilation system can provide better control of indoor air quality than a constant outdoor airflow at the ASHRAE Standard 62-1989 prescribed level under a wide range of building conditions. The constant outdoor air approach lacks the capability of providing additional outdoor air when required by poor building conditions such as a low pollutant removal effectiveness and a high occupant density. The demand-controlled ventilation system saves energy compared to the constant outdoor air approach under all conditions consid ered. It was also found that a demand-controlled ventilation strategy consist ing of a step controller combined with scheduled 100% outdoor air purges can protect building occupants from exposure to high concentrations of non-occu pant-generated pollutants while still providing energy savings.

Cosorption characteristics of solid adsorbents

Sorptive single-blow processes which adsorb simultaneously water vapor and carbon dioxide for applications in desiccant air-conditioning systems and indoor air quality control are documented. Cosorption processes are simulated for three different adsorbents, BPL activated carbon, silica gel (grade 40), and 13X molecular sieve. The process air stream is assumed to consist of binary mixture of water vapor and carbon dioxide, and the finite heat and mass transfer rates are assumed between air stream and surface of the adsorbent. The cosorption isotherms (equilibrium equations) of water vapor and carbon dioxide, correlated from available experimental data, are utilized to simulate the sorption processes. The dynamic cosorption performance of the three solid adsorbents exhibit widely different sorption characteristics, including the roll-over effect.

Intelligent system for indoor air quality control

A new control strategy which integrates indoor air quality (IAQ) control into heating, ventilating, and air conditioning (HVAC) system is described. Based on the field tests for IAQ and HVAC operations, the control models are identified and simulated. By using an intelligence engineering approach, a conflict reasoning system for the resolution of conflict between IAQ and energy conservation is constructed and integrated into HVAC real time control system. This new control strategy simultaneously reduces energy consumption and meets indoor air quality requirements.

A Strategy for International Energy Agency Ventilation and Indoor Air Quality Research

Ventilation provides a key defence for the protection of the indoor environ ment from the adverse effects of poor air quality. However, it can also contrib ute substantially to building energy use. Furthermore, the need to install large ventilation capacity is expensive both in terms of capital cost, maintenance needs and floor space. Hence there is considerable interest in the development of efficient ventilation systems and in minimizing the emission of pollutants within buildings. The International Energy Agency's (IEA) Air Infiltration and Ventilation Centre (AIVC) has a responsibility for providing a focal point for assessing the energy and air quality implications of ventilation. This paper is aimed at introducing the AIVC's strategy on ventilation research and at outlining the work and results of related IEA annexes. Conclusions stress the need for providing practitioners and policy makers with precise guidance on the energy implications and the role of ventilation in controlling indoor air quality.

Control and Regulation of Indoor Air: An Australian Perspective

There are few standards and guidelines on indoor air in Australia, and little information is available on indoor air quality in Australian buildings. The development of existing controls has relied heavily on overseas data and often lags behind the implementation of controls elsewhere. Indoor air standards have been developed for ventilation in public buildings commensurate with U.S. standards. A recommended goal for formaldehyde exposure levels has been set at 0.1 ppm and a remedial action level for radon at 200 Bq/m3. Nitro gen dioxide, particulates and volatile organic compounds are currently under review. Other indoor issues are not yet being considered at a formal level. This paper discusses the current status of the control and regulation of indoor air quality and provides an overview of indoor air research in Australia.

Control and Regulation of Indoor Air Quality in Canada

Canadians spend over 80% of their time within the indoor environment. There has been growing concern regarding the quality of indoor air due to commonly attributed adverse effects on comfort, health and productivity. Thus several organizations have been working to develop and establish indoor air quality (IAQ) standards and/or guidelines. Two approaches have been observed for controlling IAQ: (1) set permissible levels for indoor air contami nants or (2) set minimum ventilation rates. In the residential sector, Health and Welfare Canada has published permissible levels for indoor air contami nants, while building codes, at the national and provincial levels, specify mini mum ventilation rates. Federal and provincial labor authorities, along with several other government agencies, have published standards and guidelines for nonindustrial buildings. These publications suggest maximum exposure levels for air contaminants, as well as the necessary ventilation requirements. The findings and recommendations mad...

Knowledge-based automation for energy conservation and indoor air quality control in HVAC processes

Heating, ventilating, and air conditioning (HVAC) processes provide a comfortable environment, but consume a great deal of energy. Many efforts have been put into building energy conservation since the energy crisis of 1973. On the other hand, the energy conservation efforts have led to tight building envelopes and low ventilation rates, which cause poor indoor air quality (IAQ), the so called “Sick Building Syndrome”. A conflict exists between energy saving and indoor air quality improvement. In this paper, a knowledge-based automation approach is proposed to support HVAC operations, aimed at improving energy conservation and IAQ control. The construction of an Intelligent Operation Support System (IOSS) for HVAC processes is described. It consists of expert systems for operation planning, comfort setting, conflict reasoning and some other functions. The expert system for operation planning provides recommendations of energy saving operation modes for HVAC processes. The comfort indoor setting system sets indoor temperature by a comfort strategy with the advantages of energy saving, thermal comfort and better indoor air quality, instead of thermostats. The conflict reasoning system obtains a conflict resolution for energy saving and IAQ control. An integrated distributed intelligent system framework is introduced to integrate these systems. IOSS provides a real-time integrated operation planning method and can be used to assist or train operators to achieve better operation in HVAC systems.

Control and Regulation of Indoor Air Quality in Canada

Control and Regulation of Indoor Air Quality in Canada

Immune Respiratory Disease Associated with the Inadequate Control of Indoor Air Quality

The prevalence of immunologically determined respiratory diseases is in creasing throughout the world and this has been associated with an increased mortality from bronchial asthma. Consequently, there has been considerable interest in the factors that may influence the development of allergic disor ders. The first few weeks following birth have been identified as important in determining the development of sensitivity to airborne allergens and subse quent allergic respiratory disorders. The expression of allergic diseases is both genetically determined and influenced to a significant degree by environmen tal factors related to indoor air quality. As well as possibly initiating allergic disease in the post-natal period, poor indoor air quality may cause respiratory disease in later life. These diseases may be allergic in origin (bronchial asthma or allergic alveolitis) or may be due to infections (Legionnaires' disease). The contamination of indoor air by micro-organisms may occur from the structure of th...

Immune Respiratory Disease Associated with the Inadequate Control of Indoor Air Quality

The prevalence of immunologically determined respiratory diseases is increasing throughout the world and this has been associated with an increased mortality from bronchial asthma. Consequently, there has been considerable interest in the factors that may influence the development of allergic disorders. The first few weeks following birth have been identified as important in determining the development of sensitivity to airborne allergens and subsequent allergic respiratory disorders. The expression of allergic diseases is both genetically determined and influenced to a significant degree by environmental factors related to indoor air quality. As well as possibly initiating allergic disease in the post-natal period, poor indoor air quality may cause respiratory disease in later life. These diseases may be allergic in origin (bronchial asthma or allergic alveolitis) or may be due to infections (Legionnaires’ disease). The contamination of indoor air by micro-organisms may occur from the structure of the building, the ventilation system or be introduced into the building from the outside air. The off-gassing of chemicals within buildings has attracted considerable attention over the past few years, but the evidence that this process can cause immunological disease in man is very limited. It is concluded that indoor air quality is an important potential cause of immunological respiratory disease in man which has been and still is frequently neglected.

An engineering approach to controlling indoor air quality.

Evidence is accumulating that indicates air quality problems in residential and commercial buildings are nearly always associated with inadequacies in building design and methods of operation. Thus, the very systems depended on to control the indoor environment can become indirect sources of contamination if diligence is not exercised at each stage of a building's life: a) planning and design, b) construction and commissioning, c) operation, and d) demolition or renovation. In this paper, an engineering perspective is presented in which the existing building stock is characterized in terms of its environmental performance. Preliminary data indicate that 20 to 30% of the existing buildings have sufficient problems to manifest as sick-building syndrome or building-related illness, while another 10 to 20% may have undetected problems. Thus, only about 50 to 70% of the existing buildings qualify as healthy buildings. Two methods and three mechanisms of control are described to achieve "acceptable" indoor air quality: source control and exposure control. If sources cannot be removed, some level of occupant exposure will result. To control exposures with acceptable values, the primary sensory receptors of the occupants (i.e., thermal, ocular, auditory, and olfactory) cannot be excessively stimulated. The three exposure control mechanisms are conduction, radiation, and convection. To achieve acceptable occupant responses, it is often practical to integrate the mechanisms of radiation and convection in heating, ventilating, and air conditioning systems that are designed to provide acceptable thermal, acoustic, and air quality conditions within occupied spaces.(ABSTRACT TRUNCATED AT 250 WORDS)

An Engineering Approach to Controlling Indoor Air Quality

An Engineering Approach to Controlling Indoor Air Quality

Ventilation for control of indoor air quality: A case study

Dilution of indoor air contaminants with less contaminated outdoor air is the most common strategy for control of indoor air quality. Unfortunately this strategy frequently imposes a substantial energy burden. If the contaminants are associated with occupants and their activities, a ventilation control system based on the carbon dioxide level in the controlled space is shown to relieve this energy burden. A test was carried out in the Fridley, MN, Junior High School Music Department to obtain air quality, energy, and subjective response data on an Automatic Variable Ventilation System. A control system with both CO 2 and temperature inputs was devised to control the use of outdoor air. Infiltration measurements lead to a quantitative measure of ventil3tion efficiency. This in turn led to recommendations for air circulation patterns in rooms. The measured ventilation efficiency enabled energy and CO 2 models to fit measured data. Energy savings of approximately 20% were found for this application. Subjective response of the occupants also was measured. A special questionnaire, subjected to statistical analysis, showed that the subjects felt warmer with increased CO 2 in the room air.

Methods for control of indoor air quality

This report presents results of a review of available methods for control of environmental hazards applied to indoor air pollutants. Indoor air pollution originates from transport of ambient outdoor air contaminants into occupied spaces by natural infiltration ventilation, or by mechanical ventilation using outdoor makeup air, plus contributions from indoor emission sources. When air exchange with the external ambient environment is reduced to conserve energy, contributions from indoor emission sources may dominate indoor air pollutant levels. This paper identifies alternative methods available to control indoor air pollutant exposures. The performance characteristics of ventilation systems and of air cleaning devices used in mixed modes for ventilation of occupied spaces are described. Models for predicting effectiveness of several alternative modes are reviewed, with field trial validation results cited where available. Results of previous confined-space studies are briefly reviewed as points of departure for consideration of necessary air quality, ventilation, and air cleaning. Understanding of indoor air contaminant generation and controls is aided by examination of earlier studies of indoor air quality, using modern perspectives on occupational environmental health and hygiene.

The splash of a liquid drop : F. H. Harlow and J. P. Shannon, J. Appl. Phys., 38 (10) (1967) 3855–3866; 15 figs., 18 refs.

In the modern era, people spend approximately 90% of their time in indoor settings, such as offices and residential buildings. As prolonged exposure to indoor environments can significantly impact health outcomes, it is important to ensure that good indoor air quality (IAQ) is achieved. The main obstacles to achieving effective control of IAQ are twofold. First, it is very difficult to monitor the values of IAQ parameters, especially within a person's breathing zone. Second, current heating ventilation and air conditioning systems are unable to rapidly predict and optimize IAQ. This study aims to obtain accurate indoor environmental parameters for rapidly predicting and optimizing IAQ. To achieve this, a computational fluid dynamics (CFD)-based back propagation neural network (BPNN) combined with a particle swarm optimizer (PSO) algorithm is proposed. Notably, the BPNN-PSO algorithm can rapidly predict and optimize IAQ while using a limited number of CFD runs. In comparison with other state-of-the-art methods for controlling IAQ, such as the artificial neural network (ANN)-genetic algorithm (GA), the BPNN-PSO algorithm further reduces the concentration of indoor air pollutants by up to 6.44% and computational costs by as much as 23.53%. The use of CFD ensures that the information obtained is accurate and allows for rapid prediction of indoor environmental conditions. The BPNN-PSO algorithm has the potential to contribute very effective and intelligent control strategies for ventilating indoor environments.