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The laboratory air handling unit (LAHU) system for laboratory buildings has been developed and optimized. Theoretical study has concluded that the LAHU with optimal outside air control and optimal heat recovery control significantly reduces thermal energy use, saves pump power consumption and improves office indoor air quality. This paper presents validation experiments of the LAHU energy performance for the winter operation in a large university research building including detailed experimental methodology, procedures and experimental energy savings results. The experiments establish that the LAHU can reduce annual heating energy consumption by over 30% and can reduce heat recovery pump power by over 50%peryear for this typical laboratory building. The experimental validation of the LAHU for the summer operation will be reported in a followup paper.

Optimal operation and control of heat recovery in an integrated Laboratory Air Handling Unit (LAHU) system differs substantially from that in conventional dedicated AHUs for laboratory buildings with a 100% outside air AHU for laboratory spaces, since the LAHU allows economizer operation for both offices and laboratories. Optimal operation and control schedules of the heat recovery systems in the LAHU have been developed to minimize the total thermal energy cost. This paper presents the procedure, methodology, and results of generic optimal heat recovery control schedules for the LAHU and investigates its impact on the LAHU potential thermal and pump energy savings. The optimal control schedule can potentially save 14% to 27% thermal energy and 17% to 100% pump energy during the winter under weather conditions that prevail in Omaha, Nebraska. The findings discussed in this paper also apply to any heat recovery system, where AHU has an economizer function.

The Laboratory Air Handling Unit (LAHU) system conditions both the office section and the laboratory section. It improves indoor air quality by maximizing outside air intake to the office section and minimizes thermal energy consumption by re-circulating the office section air to the laboratory section. This paper presents a theoretical linear optimization method and results of optimal outside air control in LAHUs. The optimal outside airflows are expressed as functions of the weather conditions (outside air temperature and enthalpy), office and laboratory airflow rates, office and laboratory supply air temperatures, and four dimensionless parameters that describe the building system and energy characteristics. The optimization method used in this paper can be used to identify the optimal control schedules in other HVAC systems.

Constant speed fan exhaust systems are the most popular exhaust system in laboratory buildings since they satisfy building architectural requirement, and have low initial costs with reliable performance. The constant speed fan exhaust system maintains constant stack exit velocity to prevent toxic exhaust air downwash back to occupied areas near the building or on the roof top. To achieve constant velocity when the exhaust airflow is less than the design value, makeup air is introduced to the system at the inlet of the exhaust fan. Since the laboratory exhaust airflow is often significantly less than the design airflow, exhaust fans consume significantly more energy than is necessary. Multi-stack and Variable frequency drive techniques can reduce both the make-up airflow rate and fan energy in the constant speed fan exhaust system retrofit. This paper introduces the application principles, describes the optimal methods of stack sizing, and presents an example. The application example showed that the average annual fan power is 50% of the design fan power for a two-stack system, and 47% for a three-stack system.