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What are the right Ventilation strategies adopted by HVAC Consulting Companies ?

Article By MG Cooling Solutions In HVAC - May 8, 2019

HVAC Consulting Companies refer to ASHRAE code  62.1–2016 which talks about Ventilation for Acceptable Indoor Air Quality. It talks about reducing the amount of necessary outside air that needs to be conditioned for acceptable indoor conditions, and there are several ways by which HVAC Consulting Companies can do this as per ASHRAE Standard.

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Below mentioned are some ways and strategies HVAC Consulting Companies deploy to save energy and money

Occupant diversity

People inside a room will contaminate indoor air by activities like exhaling carbon dioxide, sweating, coughing, etc. Again the premises have contamination that comes from paint, carpet, upholstery, and other fixtures, furniture, which emit minute particles and vapors, all of which are already mentioned into the mathematic formulas found in ASHRAE 62.1-2016, the standard that regulates outdoor air.

For example, a large office space with a capacity for 100 people and five conference rooms accommodating up to 20 occupants each and a cafeteria accommodating 50 people will be used throughout. Hence, a building which has a total of 100 employees those 100 people are either at a desk, in a private office, in the cafeteria, or sitting in a conference room, but not occupying two spaces at once.


Hence, it is not necessary to design a building for every person that every room is designed to accommodate, but the HVAC Consulting Company must include a reasonable approximation of the expected use of the building by every occupant and employee.

Time Averaging

ASHRAE 62.1-2016 Section allows HVAC Consulting Companies to account for situations where the occupancy matters as a period of time. For example, depending on the nature of the organization and its employees, some people may occupy a space for a short period of time or vice versa. Time averaging is the process through which  HVAC Consulting Companies solves this problem. For example, a conference room often sits completely empty but is occasionally full for a short period of time. Imagine, a meeting will last for only 30-45 minutes, requiring occupied outdoor-air ventilation for those 30-45 minutes. However, the prescriptive formulas would indicate the need for full ventilation resulting in an overventilated room. By focusing on the amount of time people are staying in space, the required outdoor-air requirements can be reduced anywhere from 30% to 50%.

Similarly, retail spaces and restaurants are the places where the occupancy varies depending on the day or time. Hence, it is imperative for  good HVAC Consultancy Companies to derive meaningful energy savings by designing the right system for space

Hence, there is a cost saving approach as there is a huge potential for a reduction in electrical system design sizing, such as smaller wire sizes, smaller circuits ampacity, reduced electric operating demand kilowatts, as well as electrical energy-consumption reductions.

Real-time air monitoring using CO2 sensing

Referring  ASHRAE 62.1-2016 Section 6.2.7, it talks about the use of sensors that collect data in a specific zone and communicate the information in real time to the HVAC control system, which then makes immediate adjustments in the ventilation airflow. The most common application of Demand Control Ventilation ( DCV) uses carbon dioxide (CO2) sensors to determine if people who are occupying a room are creating a condition of excessive carbon dioxide and negative oxygen and, if so, remediate it immediately with increased outdoor air, and is constantly being sampled and treated, not allowing CO2 a chance to concentrate above a predetermined “high value. ASHRAE 62.1-2016 describes the allowance for outdoor airflow reset in response to system population. When using a DCV system, the HVAC Consulting Companies must determine what airflow range is appropriate for the zone and for the system.


Often, a value of 1,000 parts per million (ppm) CO2 is considered adequate for the dynamic-reset high CO2 value. However, in urban areas, the ambient outdoor-air CO2 concentration may be much closer to 1,000 ppm, and in such cases, the HVAC Consultancy Company should consider how this higher ambient CO2 may impact the high-value setpoint as well as the reset values for outdoor airflow.

Ideally, these CO2 sensors are used in areas that have the potential of being densely but intermittently occupied, such as in cafeterias, auditoriums, gymnasiums, and conference rooms. The sensors may not provide a quantifiable benefit for other spaces, such as open-office or reception areas, due to the smaller number of occupants per unit of area

Real-time monitoring through occupancy sensing

The final strategy is using DCV with occupancy sensors. These devices are always monitoring. When there is motion in a space that triggers the sensors, the building automation system responds accordingly. Motion sensors are commonly used in other applications, such as lights that trigger automatically when a customer enters a store restroom or security lights that turn on or brighten when a person walks by.


The savings that can be realized upon implementation of any or all of the strategies described above can be in first cost ( i.e. capital expenditure) and operating cost. Smaller outdoor-air ventilation system size can result in a smaller heating or cooling plant and smaller equipment. Smaller equipment leads to smaller duct and/or piping as well as reductions in electrical wire sizing and circuit breakers.  Operationally, the reduced outdoor airflow saves costs throughout the life of the equipment and the building through smaller operating horsepower of pumps and fans supplying and conditioning the outdoor air.  Hence, implementing these strategies by HVAC Consulting Companies maximize energy efficiency in HVAC systems can add up, quickly resulting in appreciable savings for its clients.

MG Cooling Solutions, an HVAC Consulting Company makes sure that it uses all the strategies or in their combination for better results.

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