Dedicated Outdoor Air Systems
Bring a breath of fresh air to any space. Expertly engineered dedicated outdoor air systems make it possible.
Fresh air for all. DOAS are commonly used in commercial buildings, high-rise residential buildings, schools, and other facilities where maintaining indoor air quality is crucial. With AAON, you can ensure a constant supply of fresh air while optimizing energy efficiency.
DEDICATED OUTDOOR AIR SOLUTIONS
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About Dedicated Outdoor Air Systems
Dedicated outdoor air refers to a ventilation system design approach in which a separate HVAC system or unit is specifically dedicated to supplying fresh outdoor air to a building's interior spaces. In this design, the outdoor air is treated independently from the recirculated air within the building.
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The Challenge
DOAS typically involve more complex equipment and controls compared to traditional HVAC systems. Maintenance and operation require trained personnel to ensure the system operates efficiently and effectively. Regular inspections, filter replacements, and proper cleaning of energy recovery devices are essential to maintain system performance.
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The Solution
Despite the challenges, DOAS units offer significant benefits in terms of ventilation control, indoor air quality, and energy efficiency. With proper design, installation, and maintenance from AAON, these challenges can be effectively addressed, resulting in a high-performance HVAC system for the building.
Dedicated outdoor air refers to a ventilation system design approach in which a separate HVAC system or unit is specifically dedicated to supplying fresh outdoor air to a building's interior spaces. In this design, the outdoor air is treated independently from the recirculated air within the building.
DOAS typically involve more complex equipment and controls compared to traditional HVAC systems. Maintenance and operation require trained personnel to ensure the system operates efficiently and effectively. Regular inspections, filter replacements, and proper cleaning of energy recovery devices are essential to maintain system performance.
Despite the challenges, DOAS units offer significant benefits in terms of ventilation control, indoor air quality, and energy efficiency. With proper design, installation, and maintenance from AAON, these challenges can be effectively addressed, resulting in a high-performance HVAC system for the building.
Dedicated Outdoor Air Applications
Industries can effectively apply DOAS solutions in the following ways:
Fresh air treatment
The DOAS unit is designed to filter, condition, and sometimes dehumidify or humidify the outdoor air before it is supplied to the building's spaces. This ensures that the air brought into the building is clean, comfortable, and meets the indoor air quality standards.
Decoupling ventilation and conditioning
With dedicated outdoor air, the ventilation needs are separated from the space heating or cooling requirements. The DOAS focuses on providing the necessary ventilation air while the space conditioning is handled by separate HVAC systems. This decoupling allows for greater flexibility in achieving energy-efficient and optimized HVAC performance.
Combined Space and Ventilation Control
Single system DOAS units are available that combine both space temperature control and ventilation humidity control in one packaged design. Fully modulating economizer can provide up to 100% outdoor air. This solution provides the benefits of simple single system control without sacrificing ventilation needs.
Energy efficiency
DOAS units can incorporate energy-saving features such as energy recovery systems. These systems recover the energy from the exhaust air to pre-condition the incoming outdoor air, reducing the overall energy consumption of the HVAC system.
Key Considerations for Dedicated Outdoor Air
Understand and comply with the ventilation standards and requirements set by local building codes and regulations.
Determine the appropriate outdoor air intake rates based on factors such as occupancy, building type, and indoor air quality requirements. Ensure that the dedicated outdoor air system (DOAS) is designed to meet these ventilation requirements effectively.
AHRI 920 Standard is one of the important industry standards for DOAS units, establishing the definition and testing requirements for DX Dedicated Outdoor Air Systems. This standard ensures manufacturers are consistent in the approach to testing DOAS units and provide trusted performance data.
Properly size the DOAS unit to handle the required outdoor air volume while considering the building's heating and cooling loads.
Ensure that the DOAS capacity is adequate to meet the ventilation needs during both peak and off-peak periods. Oversizing or undersizing the system can lead to inefficiencies, poor indoor air quality, or unnecessary energy consumption.
Design the air distribution system to ensure proper delivery of fresh outdoor air to all occupied spaces
Pay attention to air balancing, which involves adjusting airflow rates and maintaining proper pressure differentials between spaces. Properly designed air distribution helps to evenly distribute fresh air, control humidity levels, and maintain comfortable indoor conditions.
Coordinate the dedicated outdoor air system with space conditioning systems in the building.
Ensure that the DOAS integrates effectively with heating and cooling systems to maintain indoor comfort and energy efficiency. Consider strategies such as variable air volume (VAV) systems to optimize the interaction between the DOAS and space conditioning.
Incorporate solutions that provide precision temperature and humidity control for consistent comfort.
Select features like reheat coils, modulating hot gas reheat, and temperature sensors to prevent high humidity levels that contribute to poor indoor air quality.
Develop a comprehensive maintenance plan for the DOAS to ensure the continuous delivery of clean and fresh outdoor air.
Regularly inspect and clean filters, coils, and other components to maintain proper airflow and prevent the buildup of contaminants. Choose high-quality filters with the appropriate MERV (Minimum Efficiency Reporting Value) rating to effectively capture airborne particles and maintain good indoor air quality.
These considerations should be tailored to the specific requirements and goals of the building, and it is advisable to consult with HVAC professionals, engineers, and architects experienced in dedicated outdoor air solutions to ensure an effective and optimized implementation.
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