Proposed Design Solutions to Take a Marine Biology Laboratory to Net Zero
John Weale, Integral Group
Joshua Gassman,
RA, LEED AP®, Lord, Aeck & Sargent, Inc.
The St. Croix Marine Research and Education Center presented a few deceptively simple challenges that required an innovative design to overcome, including providing a net zero humidity-controlled laboratory space and housing for dozens of residents, while remaining fully off the water and sewer grid. The solar availability at the site is excellent for photovoltaic power systems, making a net zero facility a natural design target.
During this presentation, the third in the series on this project, the speakers will focus on the technical solutions proposed for the project.
Net metering will be used to minimize the size of battery storage onsite to backup requirements only, with site loads such as daily compression of air for SCUBA operations and filling of a seawater cistern for laboratory use designed to allow extensive demand control, so operations can be scheduled for peak solar hours.
The laboratory space is not ventilation driven, but is presented almost-continuous dehumidification throughout the year to meet the desired conditions and a significant equipment plug load. A very efficient dehumidification system that was robust enough for the marine environment with somewhat limited local maintenance capabilities was critical, so a solar based desiccant system was developed. Ductwork is an active maintenance problem in the Caribbean environment, so a radiant slab system was used to provide the bulk of sensible cooling in a very robust and low-maintenance manner.
The presence of full-time residents adds a significant water and sewer demand, which must be met entirely by onsite resources. Several waste water treatment approaches were investigated, and the team ultimately settled upon an option that requires minimal maintenance while providing a large stream of treated water for secondary reuse. The ability to reuse treated sewage water for toilet flushing, landscape use, and potentially wash down of marine equipment at the dock is a critical factor in maximizing the carrying capacity of the site.
Beyond those features, achieving the net zero electricity and water footprint required careful attention to and implementation of the "standards" of naturally conditioned (ASHRAE adaptive comfort model), including full daylighting, extensive natural ventilation, and application of the full suite of passive design techniques available to allow the residence areas and auxiliary education and outreach space to be naturally conditioned space.