Significance of Operational and Climatic Parameters in Laboratory HVAC System Selection

Shreshth Nagpal, Atelier Ten

Laboratories are far more energy intensive than typical commercial buildings, but not all laboratories consume energy for the same reasons. Most available design guidance for laboratories provides a list of energy efficiency strategies that include reducing design air change rates, decoupling cooling and ventilation systems and employing variable air volume fume hoods. However, there are quite a few parameters that need to be evaluated for each project's unique requirements to assess the value of any particular strategy. Utilizing detailed design analysis results from actual laboratory projects, the authors will make a case that based on their functional requirements and location, different projects respond very differently to the same strategies.

Savings with ventilation airflow reduction vary greatly with climate, sensible and ventilation system decoupling offers savings only if the internal loads are higher than a certain threshold, an all air system can be more efficient than a hydronic system if air side economizer is effective for that climate, stricter humidity control requirement with chilled beams might result in an overall energy penalty, variable air volume fume hoods are effective only if the program allows for airflow modulation, reheat energy gets affected not just by airflow rates but also by humidity control and supply air temperature reset, a higher capacity all-air distribution system operating at an efficient part load might consume less fan energy than a smaller primary-only air system.

These are some actual project examples where computer based simulation showed that the selection of energy efficiency strategies in a laboratory project requires a thorough understanding of ventilation rates, sensible and latent loads, operational airflow and humidity control requirements, envelope heat transfer and the climate. If not carefully assessed for their application in the particular project, any of the generally recommended measures, which usually come at an additional first cost, might offer little or no operational energy savings, or even result in an energy penalty.

This paper will present results from multiple energy simulation runs for multiple projects and attempt to assess relationships between the functional requirements, loads, operational flexibility, climate and the effectiveness of various energy efficiency measures. The goal would be to compile a matrix of strategies that also identifies the effectiveness of each strategy based on the project's specific functional, operational and climatic parameters.

Learning Objectives

  • Identify the effectiveness of efficiency strategies based on the project's specific functional, operational and climatic parameters
  • Understand various operational parameters including ventilation rates, sensible and latent loads, airflow and humidity control requirements, envelope heat transfer and the climate.
  • Understand that if not carefully assessed, the generally recommended measures which usually come at an additional first cost, might offer little or no operational energy savings, or even result in an energy penalty

Biographies:

With over a decade of experience in the field of high-performance building design, Shreshth is an expert in the application of building performance simulation and analysis for architectural design and systems optimization. A key member of the Atelier Ten Energy Analysis practice, he brings to the team his experience in building energy analysis including renewable energy systems and optimization of high-performance building envelope, mechanical, and electrical systems.

 

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