Airflow Simulation Helps Retrofit Schools for AC

By DE Editors

Thermal image produced using FloVENT software showing the introduction of cooled air, body heat displacement from class students, and the projected convection paths using the proposed thermal displacement ventilation (TDV) technique.

AECOM (Los Angeles, CA) consultants used FloVENT computational fluid dynamics (CFD) software from the Mentor Graphics Mechanical Analysis Division (formerly Flomerics) to determine the viability of and guidelines for the use of thermal displacement ventilation (TDV) for schools in Southern California. AECOM used FloVENT CFD software, which is designed specially for building interior spaces, to simulate the use of TDV in various classroom configurations. TDV demonstrated the ability to provide comfortable classrooms at energy consumption levels considerably lower than conventional air conditioning systems.

TDV works by introducing cool air at around 65°F, compared to 55°F for a standard mixed system, at low velocity at a low level by using either a raised floor or terminals around the perimeter of the space. Sources of heat such as people and equipment warm the air, causing it to rise and take with it moisture and contaminants such as carbon dioxide from people. Compared to a standard mixing system, TDV reduces energy consumption because it is only necessary to cool the occupied zone. The hours in the year when free cooling is available are also far greater for a TDV system than for a mixed system with economizer. The reason is that the supply air temperature is considerably higher than in a mixed system.

FloVENT was used to analyze otherwise identical classrooms with different ceiling heights to establish a minimum that could be used as a filtering process for which schools, or classrooms within schools could use this technology.

After developing guidelines for the use of TDV, AECOM installed TDV in a few pilot schools. TDV demonstrated the ability to provide comfortable classrooms at energy consumption levels considerably lower than conventional air conditioning systems. With the guidelines in place, competitive bidding will be used to select contractors to install TDV in the remaining schools based on the guidelines.

For more information, visit Mentor Graphics.

For previous DE coverage, see “Mentor Graphics Acquires Flomerics Group PLC,” (Nov. 2008).

Sources: Press materials received from the company and additional information gleaned from the company’s website.