MID-ATLANTIC UNIVERSITY : COLLEGE OF ENGINEERING

The main focus of this thesis was to explore ways of saving energy in laboratory buildings which inherently use large amounts for heating and cooling. The high energy use is due to the exhaust rates, high equipment loads, and internal occupant load. Laboratories have high exhaust air change rates but in many cases the exhausted equipment actually accounts for a higher exhaust rate, meaning more ventilation air that must be dehumidified and later reheated before entering the space. 

The first depth focused on how to reduce the amount of outside air required for each room by using a method called cascading air. In this method air is moved from a non-laboratory space to a laboratory makeup air. By cascading from one space to the other the following reductions were seen:

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    Overall airflow reduction

    Smaller duct sizes

    Less DOAS units

    Minimal added ductwork cost

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The second mechanical depth focused on what energy recovery methods would result in the greatest energy savings as well as what options are most cost effective. The main methods that will be tested for Mid-Atlantic University College of Engineering include the following:

   

    Heat Recovery Chiller

    Enthalpy Wheel

    Glycol Runaround Loop

    Heat Pipe - Parallel

    Heat Pipe - Series

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With cascading air a recommendation, enthalpy wheels were studied but they were less effective and more expensive than implementing cascading air. Additionally, because about half of the building contains laboratories, using the air from laboratories where toxic chemicals are being used/produced makes enthalpy wheels unsuitable for the Mid-Atlantic University project.

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The main issue with the heat pipes and glycol runaround loops were the low heat recovery effectivenesses. However, they were favorable compared to the enthalpy wheels because there is no cross contamination between air streams. Additionally, glycol runaround loops have the advantage of being able to locate the air streams away from each other but there is then the need for a separate water loop that contains glycol.

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Due to the cooling and heating load profiles the ideal energy recovery method for the Mid-Atlantic University College of Engineering building was the heat recovery chiller. It was the most effective at saving energy in the building by using the return chilled water to produce hot water and visa versa, via the refrigeration cycle. Additionally, the heat shift chiller integrated the plumbing hot water and exhaust heat recovery by making use of the additional heat to preheat the hot water and the additional cooling to collect heat from the laboratory exhaust stream.

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Currently, glycol runaround loops are implemented on only the North wing of the building but this design will be compared to a control with no glycol heat recovery as well as the other heat recovery methods laid out above. Determining the ideal heat recovery method will involve testing against the original design that used the central plant as well as a building a local plant that would require less pumping energy and less distribution losses.  

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The third portion of the mechanical depth focused on the implementation of a building central plant rather than relying on the campus central plant. The COE building is one of the furthest from the campus central plant and in analyzing the energy use associated with the building the thermal losses and pumping energy were a concern. As part of adding the central plant, geothermal was considered to work in conjunction the new central plant and the energy recovery methods. A chiller similar to the heat shift chiller would be used in conjunction with the ground loop but both would not be used simultaneously. In analysis it was found that the ground loop would be underutilized because most of the year, the heat shift operation would be preferable for this building. That would also mean the ground temperature increased exponentially because the cooling months were ideal for using the ground loop but the winter was best served with the heat shift. Ultimately geothermal was determined to be unsuitable for the College of Engineering building at Mid-Atlantic University but the building central plant consisting of two gas fired boilers, and two air cooled chillers was implemented.

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Redundancy was a concern with the College of Engineering building due to the critical research laboratories housed in the building. The campus's central plant system presented issues with distribution redundancy that could leave the COE building without cooling or heating which would potentially result in disruptions for the research. By adding cooling and heating at the building level, there is less distance to pump the chilled and hot water, no pressure reducing station to get the steam to a safe level for building use, and less thermal losses in distribution.