Meeting stringent requirements while prioritizing Indoor Air Quality (IAQ) and operational efficiency, this healthcare facility, Claremore Indian Hospital (CIH), took a proactive stance on maintaining a healthy environment. Beyond providing world-class medical care, the hospital prioritizes energy efficiency and building performance. Discover how precision airflow management is pivotal in reducing the spread of healthcare-associated infectious (HAI) diseases and enhancing IAQ.
> Download: Meeting Ventilation Requirements, Achieving IAQ and Operational Efficiency
An integrated “all-airflow” control strategy uses airflow measurement at key measurement locations to provide the minimum ventilation requirements for IAQ and the proper intake/exhaust differentials to maintain the pressurization airflow between exterior or interior adjacent pressure zones. The technique has numerous advantages over static pressure control strategies.
A Florida community college prioritizes student and staff health for exceptional education. The College places the relationship between comfort and productivity at the core of its priorities. Installing thermal dispersion airflow measuring stations within every campus at the College makes it possible to accurately measure outdoor air ventilation in real-time, even from a smartphone. The college staff collaborated with Original Solutions Company Inc., a Manufacturer’s Representative of Engineered HVAC Products, to furnish a network of airflow measuring stations at the college campuses. The installation successfully achieved the desired Indoor Air Quality (IAQ) goal and energy savings. Users can easily access real-time data from every airflow measuring station via the BACnet integrated Building Management System or the EBLink App on their smartphone.
> Download: Improved Air Quality for a Healthier Environment
The increasing requirement for intelligent cities and energy-efficient facilities with enhanced security systems fuels the Building Automation Systems (BAS) industry. The global BAS market size was valued at USD 86.8 billion in 2022, and it is projected to reach USD 148.6 billion by 2027, growing at a compound annual growth rate (CAGR) of 11.4%. 1
Thermal dispersion airflow measurement stations with BACnet communication protocols address the industry’s need for data integration and operational transparency. Advanced BAS systems use extracted data for decision-making, trend analysis, interoperability, and issue resolution. The advantage of using a BACnet airflow sensor is that it allows for more actionable data with the option of using analog for the local controller.
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The aftermath of the COVID-19 pandemic is a challenge for establishments to maintain high indoor air quality (IAQ) standards for occupants. The ASHRAE Epidemic Task Force (ETF) has guided ventilation and air filtration systems and protocols during the pandemic. ASHRAE Standard 241, Control of Infectious Aerosols, is an improved approach to creating infection-resilient buildings. The standard can assist designers, facility managers, engineers, and building owners in making informed decisions regarding IAQ protocols.
> Download: Making Buildings Healthy
Wildfires in Canada and the Western United States have sparked a renewed discussion about indoor air quality (IAQ). Building codes and ASHRAE’s Ventilation and IAQ Standards (62.1, 62.2) basis for achieving IAQ is through dilution (ventilation) and air cleaning (filtration). Ensuring air enters or leaves a building in a controlled and intended manner (pressurization control) is essential to maintaining indoor contaminant levels. The contaminants outdoors may be higher than indoors, universally measured by the air quality index (AQI), and differ by country. Wildfires generate gases and particulate matter that the AQI measures; it is a good indicator to determine when the outdoor air is at risk.
> Download: Wildfires Have Increased Advocacy for Better Indoor Air Quality and Building Codes
Outdoor air is essential to dilute airborne contaminants. The COVID-19 pandemic demonstrated that inadequate outdoor air ventilation increased transmission between occupants. Under-ventilation of outdoor air also affects building pressure, increasing moisture levels in the building envelope and ventilation zone. Excessive moisture is a prerequisite to mold and fungal growth and contributes to poor IAQ and thermal comfort. Mechanical codes, including the IMC and UMC, and energy codes, including the IgCC and California’s Title 24, specify outdoor air ventilation rates for compliance. However, most buildings are deficient in code-required ventilation during operation.
> Download: The Importance of Airflow Measurement
This paper clarifies industry misconceptions regarding DCV and exposes the significant uncertainties associated with CO2 -DVC. The paper also offers two improved methods for those who want to use CO2 as a method of demand control ventilation. Both methods use outdoor airflow measurement either at the air handler (recirculating air systems) or ventilation zone (DOAS). Finally, the paper suggest that the industry considers using direct occupancy measurement, rather than CO2 , as a method of DVC when feasible.
> Download: Improve Traditional CO2-DCV
Outdoor air ventilation in schools promotes health and well-being. Ventilation is typically through mechanical HVAC systems. The state, provincial, and municipal codes determine the amount of ventilation. Studies reveal that increased ventilation boosts health and academic performance. Conditioning and filtering the air for indoor use can be costly if not accurately monitored and controlled. That’s why efforts to scale back ventilation during lower occupancy is crucial. But it’s not that austere – internal and external environments and HVAC system wear and tear influence the ventilation. This constant flux means actual ventilation rates are constantly changing. Integrating a method to measure and control ventilation within every system is essential to ensure the right balance of fresh air without wasting resources. It’s time to prioritize accurate and efficient ventilation rates for healthier, smarter school spaces.
> Download: The Importance of Controlled Ventilation in Schools
Outdoor air ventilation is essential to providing a healthy indoor environment. The COVID-19 pandemic caused by SARS-CoV-2 brought attention to building ventilation design and operation. A safe and healthy building is dependent on dilution ventilation and maintaining proper pressurization. A building’s ventilation system during normal operation strives to achieve acceptable indoor air quality (IAQ) based on building codes. The setup and operation of ventilation systems has variances and limitations. When a ventilation system fails to provide adequate ventilation, the effects of this are not immediately known. Unless the rate of outdoor airflow is actively measured, determining under-ventilation may only come after it is too late to prevent the outcome.
> Download: Ventilation Control for COVID-19 & Beyond
Proper control of building pressure is critical for maintaining acceptable indoor air quality (IAQ), thermal comfort, and structural integrity. Inadequate pressurization can lead to the infiltration of untreated outdoor air, bringing in contaminants and moisture, which may cause humidity control issues, mold growth, and temperature regulation problems. Additionally, improper building pressure can damage the building envelope, create door operation issues, and increase energy costs. Understanding and implementing effective building pressurization strategies, such as analyzing pressure zones and using accurate airflow measurement devices, ensures stability and efficiency in HVAC systems, ultimately safeguarding the building’s environmhttps://ebtron.com/wp-content/uploads/2016-using-your-hvac-system-to-improve-iaq.pdfent and structural health.
> Download: Pressure Control for Today’s High-Performance Green Buildings
In a joint report, Lawrence Berkley National Laboratory and the U.S. Department of Energy (2000) estimated that improving indoor air quality would yield up to $208 billion annually through decreased healthcare costs and improved productivity. The good news is that these savings can be achieved with minimal investment and with readily available technology. Dilution air and building pressure control go hand‐in‐hand. Buildings require outdoor air for both dilution ventilation and pressurization. Many attempts to conserve energy by reducing the outdoor air result in negatively pressurized compartments with high moisture envelopes, especially in humid climates. A sound strategy ensures that the air handling unit’s minimum outdoor airflow rate will meet IAQ’s ventilation and flow requirements for the individual pressure compartments.
> Download: Using Your HVAC System to Improve IAQ
The control of the building or room’s net pressure is essential to maintaining acceptable indoor air quality (IAQ), thermal comfort, and structural integrity. Negatively pressurized spaces transport untreated outdoor air through any intentional, temporary, or unintended opening into the occupied space. Untreated outdoor air will transport dirt, dust, other contaminants, and moisture in humid climates (climates where the outside dew point exceeds 60⁰ F). Humidity control issues result from the transport of untreated moisture and mold growth in and near the building envelope resulting from untreated moisture transport. Perimeter temperature control problems result when the outdoor air temperature varies significantly from the indoor air temperature. In addition, improper space pressure flow may damage the building envelope, create door open/close issues, increase owner liability (Americans with Disabilities Act – ADA), and increase energy costs when excessive pressure results in the undesired ejection of conditioned building air into the outdoor environment.
> Download Pressure Flow Control for Today’s High-Performance Green Buildings, and learn the essentials to IAQ, thermal comfort, structural integrity, and the energy footprint of a building.
Maintaining the required minimum ventilation rates using only CO2 inputs is impossible. By “efficiently,” we mean that we want to bring in just the right amount of outdoor air that meets professional ventilation standards and code requirements without exceeding or falling short. This ensures the health and productivity of the occupants and minimizes energy waste during the operation. Many professionals in the engineering and construction industry support the idea of controlling CO2 inputs because the concept of a single set point control, similar to a thermostat, is easy to understand. Instead of regulating room temperature, the aim is to maintain a predetermined interior or differential CO2 concentration level. Buildings’ differential CO2 set point and airflow rates must be compared more frequently and accurately with reference measurements. Therefore, any deviations that occur can be overlooked, minimized, or dismissed.
> Download: The CO2 Riddle: Precision & Savings?
Selecting the right airflow measurement devices is crucial for optimal performance of HVAC control systems. Comparing similar products through published literature alone may not reveal all the differences. Accuracy and repeatability can vary significantly between instruments, influenced by technology, manufacturing quality and field conditions. This paper offers an overview of airflow measurement technologies for HVAC designers and operators that enhance ventilation control in buildings.
> Download: Permanently Installed Airflow Measurement Devices.
Building pressurization can only be created and maintained by a building’s mechanical system. The mechanical system is, therefore, central to controlling pressurization to a predetermined, practical, and energy-efficient level. The mystery to most people is how to accomplish these objectives simultaneously. This paper provides an understanding of building pressure, problems with pressure control, pressure flow control, determination of the pressurization airflow required in the building, accuracy, AHU control of single zone pressure, and dilution ventilation, closing with a summary and conclusion.
> Download: Energy Efficient Pressure Control for Recirculating Systems.
The application of CO2 sensors for indirect control of minimum ventilation rates continues to create contradictions and controversy due to the lack of specificity in ASHRAE Standards (62.1‐2013; 90.1‐2013 and previous versions). Numerous studies have highlighted significant deficiencies in the Steady-State-based methodology and CO2 sensor performance when used for ventilation control. Assuming a direct linkage between associated elements has fogged the logic and shrouded the key variables: actual ventilation rates and actual space population. Claims of operational adequacy are supported mainly by
theoretical analysis, computer modeling, energy simulations, and spot measurements. How much airflow set point uncertainty can we expect?
> Download: CO2 and Ventilation Reset Precision.
EBTRON, a company with 30 years of experience designing air control applications, has set a new benchmark for performance in airflow measurement used in commercial HVAC controls. Despite the numerous design innovations and product excellence, the company’s basic manufacturing philosophy remains unchanged. In this paper, we have presented facts that demonstrate the superiority of EBTRON’s designs compared to competing alternatives and basic standards and methods used for air performance determination. We have outlined the many differences and achievements that allow these products to outperform all others and summarized the facts and conclusions under appropriate categories.
> Download: EBTRON Airflow Measuring Technology
It is important to note that the AFMS (Air Flow Measuring Station) cannot be solely blamed for any differences when comparing measurements taken with handheld instruments. Several factors could be responsible for these differences, such as external sources and the quality of the handheld or airflow station. Therefore, taking time to assess and eliminate other possible causes is highly recommended before concluding that adjustment of the UUT (Unit-Under-Test) output is the only solution. To evaluate the AFMS performance, users can refer to Proposed ASHRAE Standard 215, which provides additional information on measurement with permanent instruments in Annex B. Before deciding to adjust the output, it is crucial to consider the potential impact of the adjustment by comparing the statistical uncertainty of the field reference being used to that of the permanently installed AFMS.
> Download: Set Up and Verify Airflow Measurement Device Operation.
Many myths are created about substitutions for products used in the design process. “Value Engineering” exercises often lead to owners accepting lower quality products for a lower cost, resulting in future issues and higher utility bills. Remember, the quality of input determines the effectiveness of your control system and the performance of your building’s mechanical system. Keep reading if you have concerns about your project’s design integrity, quality, and reputation.
> Download Myths and Reality of ‘Strong’ Specs.
Reducing the amount of outdoor air entering a space when an HVAC system is mechanically cooling or heating and an air-side economizer is inactive has distinct advantages. For some spaces, demand-controlled ventilation (DCV) based on changes in occupancy may be desirable. According to one method of DCV, the ventilation rate is adjusted based on carbon dioxide (CO2) level. Unfortunately, many designers do not clearly understand the relationship between CO2 and ventilation and the requirements for proper ventilation control. This article will clarify the relationship between CO2 level and ventilation rate and offer suggestions for improving traditional single-setpoint CO2 DCV by adding a direct outdoor-airflow-measuring device.
> Download: Single-Zone, CO2-Based Demand Control Ventilation.
Spaces with high occupant densities and variable populations present a unique challenge to designers struggling to meet the requirements of both ASHRAE Standards 62.1-2010 and 90.1-2010, plus the 2009 International Mechanical Code on Ventilation. Energy, rather than occupant health and productivity, has become the focus of most owners and engineers concerning HVAC design. Can systems using demand controlled ventilation (DCV) strategies to conserve energy comply with today’s ventilation standard for acceptable indoor air quality (IAQ) and our national energy standard? This paper will demonstrate the potential uncertainties associated with several methods of demand controlled ventilation, including traditional CO2-based DCV, DCV using population estimates from CO2, and direct occupancy counting systems.
> Download: Reliable DCV Methods – Meeting Ventilation Requirements While Minimizing Energy.
Over the past 15 years, studies concerned with the energy implications of ventilation rate increases have found sufficient benefits and insufficient negative economic impacts. Standard 62-1989 was adopted and included requirements for effectively increasing the dilution ventilation rates required previously in the 1981 version by about three times. Multiple government and private studies have shown that productivity improvements, ranging from 3% – 20%, can be expected due to improvements in a worker’s indoor environment (National Contractors Study, et. al. 1990, 1993, 1995, LBNL-1997, 2000, 2002, 2003, 2011). Recently, some have reduced that range to a more realistic 5% – 10%. This is the magnitude of the benefit that might be captured with help from improved dynamic intake control through HVAC instrumentation and ventilation design. It will be shown that even a significant fraction of 1% is sufficient to justify the needed equipment and energy to implement ventilation control changes economically. The body of this paper will summarize the findings of relevant studies over this period that reflected on the impact of different levels of dilution ventilation.
> Download: Relationships Between Ventilation and Occupant Productivity, Energy and Other Societal Costs.
ASHRAE Standard 62 -1989 was adopted for “Ventilation for Acceptable Indoor Air Quality”. However, research showed that increased ventilation rates may be needed under many conditions to ensure acceptable indoor air quality. Economic projections on the energy implications of increasing ventilation rates are being considered with little consideration for the expected benefits. We should find design methods and technologies to minimize negative financial impacts and explore some of the many technical justifications for optimal dilution ventilation. The paper will provide potential methods of
minimizing the costs of providing the needed outdoor air while simultaneously providing flexibility in controlling changes in space usage and dynamic environmental effects.
> Download: Productivity and Energy Conservation are Not Mutually Exclusive Objectives.
Reducing energy usage in mechanically ventilated buildings without violating minimum dilution and pressurization requirements demands greater outdoor air control precision. Precision can be improved by avoiding unwanted and unnecessary uncertainties from multiple design or operating assumptions. Indirect methods of outdoor air rate determination with multiple uncertainties propagate control errors. An undiscovered total uncertainty in control may prevent the satisfaction of minimum ventilation requirements, energy constraints, and the concurrent requirements of ASHRAE Standards 62.1, 90.1, and 189.1. Direct outdoor air intake rate and space population determination methods can minimize control uncertainties and improve air system repeatability for enhanced comfort and energy control. Design considerations and appropriate component selections are keys to successfully applying direct methods.
> Download: Reduction of Errors in Ventilation Rate Determinations
Airflow-measurement-device selection is critical to the performance of today’s state-of-the-art HVAC control systems, as accuracy and repeatability can vary dramatically between instruments. Many of the requirements and limitations of one measurement technology, however, often are thought to apply to all.
This article discusses functional and performance differences between the two most popular technologies for permanently duct-mounted measurement systems in commercial buildings: velocity-pressure devices (Pitot arrays, probes, Piezo rings, and other delta-P methods) and thermal-dispersion (TD) devices (microprocessor-based instruments using some form of thermistor sensor). It excludes vortex shedding and resistance-temperature-device-type instruments, which generally are applied in contaminated and/or high-temperature industrial environments.
> Read online: Evaluating Airflow-Measuring Devices | HPAC Engineering
The proper selection of airflow measurement devices is critical to the performance of today’s state-of-the-art HVAC control systems. As with most things promoted as nearly identical, true operational or lab comparisons of products may not provide similar results. Many of the requirements and limitations of one measurement technology are often mistakenly thought to apply to every other, especially when the comparison involves two similar technologies.
Accuracy and repeatability vary dramatically between measurement instruments. They are most significantly influenced by the inherent advantages and disadvantages of the basic technology, the manufacturer’s understanding of the technology employed, the quality of basic components used, consistency in the manufacturing process, and the conditions found at the measurement installation location. Nothing unexpected is revealed in this article if you only take a few seconds and use common sense when thinking about it.
This article offers an overview of the functional and performance differences in currently available instrumentation technology used to improve the control of ventilation systems in buildings worldwide. Beyond the analysis, it offers practical information to be used when comparing or specifying these products, providing the means to ensure that the level of performance you need is provided.
Read online: Evaluating-Airflow-Measuring-Devices-TAB-Journal
In a joint 2000 report, Lawrence Berkley National Laboratory and the U.S. Department of Energy estimated that improving indoor air quality would yield up to $208 billion annually through decreased healthcare costs and improved productivity. The good news is that savings can be achieved with minimal investment and readily available technology. Since the annual cost for employees per square foot is typically 150-250 times the cost
for indoor ventilation, even significant percentage increases in yearly ventilation costs are small compared to the employer benefits. Although every building will require a uniquely engineered solution depending on its construction, location, and use, practically every design should accurately control the dilution (outside) airflow rates and pressurization airflow rates to achieve acceptable IAQ.
> Download: Using Your HVAC System to Improve IAQ.
Spaces with high occupant densities and variable populations present a unique challenge to designers struggling to meet the requirements of both ASHRAE Standards 62.1-2007 and 90.1-2007, plus the 2006 International Mechanical Code on Ventilation. Energy, rather than occupant health and productivity, has become the focus of most owners and engineers concerning HVAC design. Can systems using demand controlled ventilation (DCV) strategies conserve energy and comply with today’s ventilation standard for acceptable indoor air quality (IAQ) and our national energy standard? This paper will demonstrate the potential uncertainties associated with several methods of demand controlled ventilation, including traditional CO2-based DCV and DCV using population estimates from CO2 and occupancy counting systems.
> Download: Reliable DCV Methods Meet Ventilation Requirements While Simultaneously Minimizing Energy.
Recently, LEED guidelines and ASHRAE Standard 62 have emphasized the direct monitoring of outside air intake flow rates for continuous control. However, some trade journals have published misleading information for consulting engineers, undermining the importance of direct outside airflow monitoring and control. This article aims to clarify the correct method for controlling outside air intake flow rates for non-densely and densely occupied spaces.
> Download: Outside Air Intake Flow Control.
ANSI/ASHRAE Standard 62.1-2004 is an often misunderstood document outlining ventilation requirements to provide acceptable indoor air quality for new buildings or those with significant renovations. Because the rate-based nature of both procedures allowed for compliance, this analysis focuses on the need for reliable intake rate control and the risks of some popular indirect controls. Design recommendations are intended to increase the potential for both predictable compliance and flexibility to accommodate future changes while providing the most significant control reliability with the most energy-efficient methods. This paper summarizes ASHRAE Standard 62.1-2004, Ventilation for Acceptable Indoor Air Quality (IAQ) in Commercial, Institutional, Industrial, and High Rise Residential Buildings, as it impacts and is influenced by ventilation control requirements, methods, and equipment.
> Download: Update, Analysis, and Recommendations.
The following article was published in ASHRAE Journal, in October 2004. © Copyright 2004 American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc. It is presented for educational purposes only. This article may not be copied and/or distributed electronically or in paper form without permission of ASHRAE.
Energy conservation strategies often distract attention from
other core design objectives, including occupant health, productivity, and avoiding threats to the building structure’s long-term integrity. CO2-based demand control ventilation (DCV) is an energy-conserving strategy that, in some cases, has sacrificed several of these fundamental design objectives. Instead, we have embraced short-term energy cost savings and accepted greater risks to occupant health, diminished worker productivity, increased maintenance costs, and life-cycle costs for the structure.
> Download: CO2-Based Demand Control Ventilation, Do Risks Outweigh Potential Rewards?
ASHRAE Standard 62 – 1989 was adopted 15 years ago, and it focused on ventilation for acceptable indoor air quality. Before its approval, the construction industry was mainly concerned about the energy implications of tripling the ventilation rates. However, studies showed that the benefits outweighed the costs, leading to the adoption of the standard. Subsequent research has shown that even greater ventilation rates may be required under many circumstances. Instead of focusing solely on energy costs, we should explore design methods and technologies that minimize or eliminate any negative financial impacts while providing healthier indoor environments for people.
> Download: Productivity and Energy Conservation are not Mutually Exclusive Objectives
Properly choosing the airflow measurement devices is crucial for the optimal performance of modern HVAC systems. It is a common misconception that the requirements and limitations of one technology apply to all others. However, different technologies offer varying levels of accuracy and repeatability, depending on installation location, airflow rates, and system turndown required.
Electronic thermal dispersion and differential pressure-based pitot arrays are the two most commonly used airflow measurement technologies in HVAC systems. It is important for designers to understand the advantages and limitations of each technology before selecting a device for a specific application.
> Download: Airflow Measurement for HVAC Systems – Comparing Technologies.
This article published by ASHRAE Journal documents the key reasons why ASHRAE Standard 62-1989. “Ventilation for Acceptable Indoor Air Quality” recommends measuring and documenting outdoor air intake flow on constant volume and variable air volume (VAV) systems. It also analyzes the most critical portion of the fan system control algorithm, which controls the minimum outdoor air during mechanical refrigeration (cooling coil operation). The results demonstrate that intake air cannot be controlled on either constant volume or VAV systems with a fixed-position minimum outdoor air damper (or even with a minimum position damper, reset by supply airflow, on VAV systems). The lack of minimum ventilation air control is due to the system’s operational characteristics and boundary conditions, such as wind and stack effect. The focus on Indoor Air Quality (IAQ) has finally stimulated systematic engineering evaluation of the control of outside air intake rates in constant volume and VAV systems.
