5292280 Method and apparatus for controlling ventilation rates and indoor air quality in an HVAC system

1995 ◽  
Vol 21 (3) ◽  
pp. III
Author(s):  
J. Janu George ◽  
W. Tellier Mark
Keyword(s):  
Air Quality ◽  
Indoor Air Quality ◽  
Indoor Air ◽  
Hvac System ◽  
Ventilation Rates

scholarly journals Mitigation Strategies for Overheating and High Carbon Dioxide Concentration within Institutional Buildings: A Case Study in Toronto, Canada

Buildings ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 124 ◽  
Author(s):  
Claire Tam ◽  
Yuqing Zhao ◽  
Zaiyi Liao ◽  
Lian Zhao
Keyword(s):  
Carbon Dioxide ◽  
Air Quality ◽  
Indoor Air Quality ◽  
Air Temperature ◽  
Indoor Air ◽  
Indoor Environment ◽  
Thermal Conditions ◽  
Co2 Concentration ◽  
Hvac System

Indoor air quality and thermal conditions are important considerations when designing indoor spaces to ensure occupant health, satisfaction, and productivity. Carbon dioxide (CO2) concentration and indoor air temperature are two measurable parameters to assess air quality and thermal conditions within a space. Occupants are progressively affected by the indoor environment as the time spent indoors prolongs. Specifically, there is an interest in carrying out investigations on the indoor environment through surveying existing Heating, Ventilation, Air Conditioning (HVAC) system operations in classrooms. Indoor air temperature and CO2 concentration in multiple lecture halls in Toronto, Canada were monitored; observations consistently show high indoor air temperature (overheating) and high CO2 concentration. One classroom is chosen as a representative case study for this paper. The results verify a strong correlation between the number of occupants and the increase in air temperature and CO2 concentration. Building Energy Simulation (BES) is used to investigate the causes of discomfort in the classroom, and to identify methods for regulating the temperature and CO2 concentration. This paper proposes retro-commissioning strategies that could be implemented in institutional buildings; specifically, the increase of outdoor airflow rate and the addition of occupancy-based pre-active HVAC system control. The proposed retrofit cases reduce the measured overheating in the classrooms by 2-3 °C (indoor temperature should be below 23 °C) and maintain CO2 concentration under 900 ppm (the CO2 threshold is 1000 ppm), showing promising improvements to a classroom’s thermal condition and indoor air quality.

Energy Conservation, Ventilation and Acceptable Indoor Air Quality

1978 ◽  
Vol 22 (1) ◽  
pp. 538-538
Author(s):  
James E. Woods
Keyword(s):  
Air Quality ◽  
Indoor Air Quality ◽  
Indoor Air ◽  
Energy Use ◽  
Renewable Energy Resources ◽  
Construction Techniques ◽  
Consumption Rates ◽  
New Codes ◽  
Current Concerns ◽  
Ventilation Rates

In response to current concerns about the depletion rates of non-renewable energy resources, new codes and standards have been promulgated which require improved construction techniques and reduced ventilation rates. While implementation of these codes and standards has reduced energy consumption rates, degradation of indoor air quality has also been reported. These complaints indicate that arbitrary reduction of ventilation rates can result in deleterious effects to the occupants. Thus, a compromise solution is required with the objective to provide a safe, healthy, and comfortable indoor environment by using materials and methods that optimize efficiency of energy use.

scholarly journals Impacts of Energy Retrofits on Ventilation Rates, CO2-levels and Occupants’ Satisfaction with Indoor Air Quality

2016 ◽  
Vol 96 ◽  
pp. 260-265 ◽  
Author(s):  
Virpi Leivo ◽  
Mari Turunen ◽  
Anu Aaltonen ◽  
Mihkel Kiviste ◽  
Liuliu Du ◽  
...  
Keyword(s):  
Air Quality ◽  
Indoor Air Quality ◽  
Indoor Air ◽  
Co2 Levels ◽  
Ventilation Rates

scholarly journals FACTORS AFFECTING VENTILATION, INDOOR-AIR QUALITY AND ACOUSTICAL QUALITY IN ‘GREEN’ AND NON-‘GREEN’ BUILDINGS: A PILOT STUDY

2011 ◽  
Vol 6 (3) ◽  
pp. 168-180 ◽  
Author(s):  
Alireza Khaleghi ◽  
Karen Bartlett ◽  
Murray Hodgson
Keyword(s):  
Mechanical Ventilation ◽  
Air Quality ◽  
Indoor Air Quality ◽  
Indoor Air ◽  
Natural Ventilation ◽  
Sound Pressure ◽  
Low Frequency ◽  
Green Buildings ◽  
Noise Levels ◽  
Ventilation Rates

This paper discusses a pilot project involving the direct monitoring of ventilation, indoor-air quality and the acoustical conditions in selected nominally ‘green’ and non-‘green’ buildings located on a university campus. The objectives were to measure parameters quantifying these three aspects of indoor environmental quality, determine the relationships between them and the building-design concepts, and evaluate the implications of the results for ventilation-system design, especially in ‘green’ buildings. Measurements were made in rooms, with and without acoustical treatment, in buildings with natural ventilation or mechanical (displacement and/or mixed-flow) ventilation systems. Measurements were made of ventilation rates (air changes per hour), indoor air quality (respirable-fibre, total-VOC and ultrafine-particulate concentrations), and the acoustical conditions (noise levels and reverberation times). Correlations between the environmental results, the building concept, the ventilation concept and the building window status were explored. In rooms with natural ventilation, low-frequency noise and total sound-pressure levels were lower; however, the rooms had higher ultrafine-particulate counts and lower ventilation rates. Rooms with mechanical ventilation had higher low-frequency and total sound-pressure levels, higher ventilation rates and fibre concentrations, but lower concentrations of ultrafine particulates. It was concluded that, in general, mechanical ventilation can provide better indoor air-quality, but that HVAC noise is an issue if the system is not properly designed. In ‘green’ buildings, noise levels were acceptable when the windows were closed, but increasing the ventilation rate by opening the windows resulted in higher noise levels. The results suggest that the acceptability of environmental factors in buildings depends on the degree of compliance of the design and its implementation with standards and design guidelines (i.e. for ventilation, air quality, thermal comfort, etc.), whether the original design concept is ‘green’ or non-‘green’.

Assessment of microbiological indoor air quality in an Italian office building equipped with an HVAC system

2009 ◽  
Vol 161 (1-4) ◽  
pp. 473-483 ◽  
Author(s):  
Sa. Bonetta ◽  
Si. Bonetta ◽  
S. Mosso ◽  
S. Sampò ◽  
E. Carraro
Keyword(s):  
Air Quality ◽  
Indoor Air Quality ◽  
Indoor Air ◽  
Office Building ◽  
Hvac System

Evaluation of comfort levels in office space equipped with HVAC system based in personalized ventilation system using energy produced in DSF systems

2020 ◽  
pp. 65-74
Author(s):  
Eusébio Conceição ◽  
Mª Inês Conceição ◽  
Mª Manuela Lúcio ◽  
João Gomes ◽  
Hazim Awbi
Keyword(s):  
Air Quality ◽  
Numerical Model ◽  
Thermal Comfort ◽  
Indoor Air Quality ◽  
Indoor Air ◽  
Numerical Study ◽  
Ventilation System ◽  
Airflow Rate ◽  
Hvac System ◽  
Personalized Ventilation

In this study the numerical simulation of a Heating, Ventilating and Air Conditioning (HVAC) system, based in a personalized ventilation system, installed in an occupied office desk is made. The energy is produced in a Dual Skin Facades (DSF) system installed in the outdoor environment. The personalized ventilation system, placed above and below the writing area, installed in the desk central area. The office desk is occupied by eight virtual manikins. The numerical simulation is made in a winter typical day. This numerical study considers a coupling of a differential numerical model and an integral numerical model. The differential numerical model simulates the Computational Fluids Dynamics (CFD), evaluates the air velocity, air temperature, turbulence intensity and carbon dioxide concentration and calculates the indoor air quality. The integral numerical model simulates the Multi-Node Human Thermo-physiology Model, evaluates the tissue, blood and clothing temperatures distribution and calculates the thermal comfort level. The HVAC system, based on a DSF system, is built using three DSF unities, is equipped with internal venetian blinds. Each one, installed in a virtual chamber, is turned to south. The personalized ventilation system, made with eight upper and eight lower air terminal devices, is installed in the desk central area. On each table top two upper and two lower air terminal devices are considered in the left and right manikin area, while on each side of the table two upper and two lower air terminal devices are placed between the manikins. The office desk is occupied by eight virtual manikins, one sitting on each table top and three sitting on each side of the meeting table. In this numerical study, carried out in winter conditions, the occupants’ clothing level is 1 clo. In these situations a typical activity level of 1.2 met is considered. The evolution of indoor environmental conditions, in the DSF and in the office room, are calculated during a full winter typical day. The thermal comfort, the indoor air quality, the effectiveness for heat removal, the effectiveness for contaminant removal and the Air Distribution Index (ADI), are evaluated. In accordance with the obtained results the thermal comfort levels increase when the air renovation rate increases and the indoor air quality level increases when the air renovation rate increases. However, the ADI is quite constant when the inlet airflow rate increases, because the thermal comfort number decreases when the inlet airflow rate increases and the air quality number increases when the inlet airflow rate increases.

scholarly journals Investigation of HVAC Operation Strategies for Office Buildings During COVID-19 Pandemic

2021 ◽  
Author(s):  
Cary A Faulkner ◽  
John E Castellini ◽  
Wangda Zuo ◽  
David M. Lorenzetti ◽  
Michael D Sohn
Keyword(s):  
Air Quality ◽  
Indoor Air Quality ◽  
Indoor Air ◽  
Virus Transmission ◽  
Mitigation Strategies ◽  
Virus Concentration ◽  
Hvac System ◽  
Operational Cost ◽  
Outdoor Air ◽  
Indoor Contaminants

To minimize the indoor transmission of contaminants, such as the virus that can lead to COVID-19, buildings must provide the best indoor air quality possible. Controlling indoor air quality is largely achieved by running the building’s HVAC system to dilute any concentration of indoor contaminants. However, doing so has practical downsides on the HVAC operation that are not always quantified in the literature. This paper develops a temporal simulation capability that is used to investigate the indoor virus concentration and operational cost of an HVAC system for two mitigation strategies: 1) supplying 100% outdoor air into the building and 2) using different HVAC filters, including MERV 10, ASHRAE minimum-recommended MERV 13, and highly rated HEPA filtration. These strategies are applied to a hypothetical medium office building consisting of five occupied zones and located in a cold and dry climate. We modeled the building using the Modelica Buildings library and developed new models for HVAC filtration and virus transmission to evaluate COVID-19 scenarios. We show that the ASHRAE-recommended MERV 13 filtration reduces the average virus concentration by about 10% when compared to MERV 10 filtration, with negligible additional operational cost. In contrast, the use of 100% outdoor air or HEPA filtration reduces the average indoor concentration by about an additional 3% compared to MERV 13 filtration, but significantly increases building operational cost. This is due to the significant increase in energy consumption when supplying 100%outdoor air and the higher cost of purchasing a HEPA filter.

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