Case study: Museum HVAC upgrade requires precision control
The Art Institute of Chicago incorporated pressure-independent control valves to improve energy efficiency
The Art Institute Chicago has been proactive in reducing its energy usage and operating its systems efficiently. Maintaining both temperature and humidity is critical when storing and displaying artwork as they can affect the physical and chemical properties of the materials used in the artwork.
High temperature and humidity can cause materials to expand, contract, warp and degrade, leading to permanent damage to the artwork. High temperatures can accelerate chemical reactions and cause paint to crack, fade or become brittle. Low humidity can cause materials to dry out and become brittle, while low temperatures can cause condensation and damage to delicate surfaces.
Maintaining temperatures within an appropriate deadband requires precision control of the cooling, heating and humidification systems.
Additionally, energy costs have only increased and demand charges by the local utility company represented approximately 22% of the energy cost in 2013 and was projected to be approximately 42% in 2016. Opportunities to reduce energy usage and increasing energy efficiency were a driving factors by the decision makers.
With a chilled water temperature difference of 7°F to 9°F and even worse during unoccupied hours, any increase in temperature difference would save both pumping energy and potentially reduce the quantity of operating chillers. The chilled water plant operated at an average of 0.93 kW/ton before any changes were made to the system.
Pressure-independent control valves were introduced to the operating team as an opportunity to increase energy efficiency and reduce energy consumption. As a result, an implementation cost of approximately $350,000 was met with a simple payback of 2.4 years before any utility incentives. The operation of the plant was reduced to an average of 0.73 kW/ton. Temperature differences were also greater than originally specified for the system.