Implementation of the Laboratory Air Handling Unit Systems (LAHU)

The LAHU system has been designed, installed, and commissioned in a large university research building. This paper provides detailed information about the demonstration project, including the specific LAHU system mechanical design, optimal airflow control schedules, and measured LAHU energy and indoor air quality (IAQ) performance. The measured energy and IAQ performance are also compared with the conventional operation and theoretical predicated values. INTRODUCTION Most laboratory buildings have both office and laboratory spaces. Conventional AHU designs for laboratory buildings use two separate AHUs, one for the office section and another for the laboratory section. The laboratory section AHU uses 100% outside air to satisfy the requirement of the laboratory exhaust airflow rate. The discharge air temperature of the cooling coil is controlled at 55°F (12.8°C) to maintain a suitable humidity level. A significant amount of cooling and heating, especially re-heat, is consumed due to high supply airflow rate required by the fume hood exhaust. At the same time, the office section draws minimal outside air intake to satisfy indoor air quality requirements. The total building outside air intake is higher than necessary, which causes excessive heating and cooling energy consumption. To improve the energy performance of the conventional systems, a number of energy conservation measures have been developed and implemented in laboratory facilities. These measures are the air-to-air heat recovery heat recovery [1-7], the run-around coils [18, 19], the variable air volume (VAV) fume hoods [8-16] and the usage-based control devices (UBC) [17]. These measures have effectively reduced the cooling energy, preheat energy and fan power consumption, and sometime, improved indoor relative humidity control. To maximize AHU energy performance efficiency in laboratory buildings and improve office section indoor air quality (IAQ), the Laboratory Air Handling Unit (LAHU) has been developed [20, 21, 22]. The theoretical investigations have found that the LAHU uses less outside air during summer and winter, improves the indoor air quality (IAQ) of the office section, and saves up to 30% of annual thermal energy when the optimal airflow control schedules are used [23]. This paper presents the implementation of the LAHU in a chemistry engineering education facility, which includes the facility and LAHU design and construction information, optimal airflow control schedules implemented, and measured energy savings and indoor air quality improvements. EXPERIMENT FACILITY The experimental facility is a three-story chemistry engineering research laboratory building located at Lincoln, Nebraska (See Figure 1). The building has a total floor area of 12,077 m (130,000 ft). Figure 2 presents the typical floor layout. Office spaces are on the perimeter of the building with windows. Some offices and classrooms are located in the interior zone. Laboratory spaces are located in the interior zone as well. Figure 1: Experimental Facility