System description

The HVAC system considered provides heating and cooling to a university classroom of about 1,500 m3 and a maximum occupancy of 400 students. The AHU operates around 2,000 hours per year and it has been in operation since 1991. It is an all-air system, supplying 10,000 m3/h and returning 8,000 m3/h in nominal conditions, of which 2,000 m3/h are lost due to the overpressure of the classroom. The air supply fan has a nominal power of 5.5 kW and the return air fan has 2.2 kW of installed power. The fans work at fixed speed, with no inverter, and as a result the clogging of the air filters causes a variable air flow rate. The system can operate with 100% outdoor air, partial recirculation or total recirculation.

Some of the data available include:

• Power consumption for ventilation;
• Fans pressure rise;
• Supply, return, outdoor and exhaust air flow rate;
• Indoor air quality (supply and return air): CO2, temperature, RH%;
• Pressure drop across the air filters;
• Heating and cooling power;
• Particle concentration upstream and downstream of the fine filter unit.