Natural Systems International

NSI CAN CONTRIBUTE TO YOUR LEED PROJECT

INTEGRATED AND HISTORICALLY JUSTIFIED DESIGN

Natural Systems International can help your project earn up to 9 LEED credits through an integrated water program.  NSI develops long-range, site-specific water demand models integrating

• historic climate data (rainfall, snowfall, and temperature),
• building occupancy and fixture data,
• landscape and greenroof plans,
• stormwater management plans,
• rainwater harvesting options,
• graywater harvesting options,
• blackwater harvesting options, and
• proposed irrigation schedules and plans (if known)

The water balance typically includes 30 years of daily data and allows the design team to analyze rainwater harvesting options, graywater and/or blackwater treatment and reuse options, and potential indoor and outdoor water savings. The water balance provides the basis of design for a holistic reclamation program. The following LEED-NC credits are achievable as part of the integrated design:

WE Credit 1.1 – Water Efficient Landscaping (reduce water use by 50%) – 1 Credit
Depending on the type of building, landscaping may be the majority of water use in a project.  Reducing landscape water consumption by 50% is worth one LEED point.  NSI will use the water balance to determine the best, most cost-effective solutions to reduce potable demand and will make recommendations and provide drawings showing the elements of the design.  In some cases, NSI has worked with the landscape designer to reduce demand by selecting more appropriate landscape species, including natives and xerics.  Typical components of the system include one or more storage cisterns and low-energy-use treatment elements such as sand filters, rooftop wetlands, trickling filters, and disinfection processes. 

WE Credit 1.2 – Water Efficient Landscaping (no potable water use) – 1 Credit
This credit takes the benchmark of credit WE1.1 and extends it to total reuse or zero-water use landscape.  Landscapes can be, and often are, designed as zero-water use.  In many cases, aesthetic goals for the project lead to landscapes which still require watering.  Rainwater and gray/blackwater harvesting is a preferred option in these cases.  The historical water balance can show the range of water required on a yearly basis, and includes unusually dry years, to give a complete picture of the likely performance of the system over time.

WE Credit 2.0 – Innovative Wastewater Technologies – 2 Credits w/ Innovative Design credit
Where on-site gray and/or blackwater treatment is desirable, NSI designs a treatment system capable of meeting the requirements for this LEED credit.  In most cases, reuse of the treated water is desirable, linking the creation of a problem (sewage) to a beneficial solution (treatment and reuse).  Again, the water balance and other site-specific information guides the design of the treatment and reuse system.  NSI designs with energy-efficiency in mind, and the treatment systems we propose reflect our principal of mechanical simplicity and biological complexity.  Common treatment elements are integrated rooftop wetlands, below-grade sand filters, and trickling filters.  Treatment elements can be hidden out of sight, or prominently displayed as educational and aesthetic features, depending on the needs of the project.  WE Credit 2 is often used as the basis for an additional ID (Innovative Design) credit.  NSI often designs systems to treat 100% of the onsite sewage generated to tertiary standards, doubling the level of treatment required by LEED.

WE Credit 3.1 – Water Use Reduction (20% Reduction) – 1 Credit
The water balance model will document long-term potable water use reductions due to rainwater and gray/blackwater harvesting, along with the use of efficient fixtures.  NSI will work with the MEP engineer and project manager to document all efficient fixtures and compile a baseline and design-case version of the water balance, clearly showing a reduction in onsite water use.  Many projects NSI works on have been awarded LEED credit for documenting a better than 60% reduction in water use from a similar, but not ecologically-designed, building.

WE Credit 3.2 – Water Use Reduction (30% Reduction) – 2 Credits with the Innovative Design credit
The approach to this credit uses the same principals of long-term design used in WE Credit 3.1.  The following table is a summary of a water balance NSI completed as part of a LEED design for a mixed-use residential and commercial building in Michigan.  The example shown below represents a 63% reduction in water use from the baseline (conventional) plan through reuse of treated graywater and rainwater for flushing toilets and irrigating a greenroof.  This example is also eligible for an Innovative Design credit, as the water savings from the baseline case are more than twice the 30% required by LEED.

SS Credit 6.1 – Stormwater Design: Quantity Control
An integrated water design aims for maximum impact with minimal capital and technological requirements.  Reducing the quantity of rainwater leaving the project site to pre-development levels is worth a LEED credit, and is also a natural effect of using onsite rainwater harvesting to meet the LEED credits already described.  When an integrated water harvesting and reuse system is in place, improving the stormwater runoff quantity and quality is low-hanging fruit.

SS Credit 6.2 – Stormwater Design: Quality Control
As before, an integrated water plan already includes improvement in stormwater runoff characteristics.  NSI will prepare plans and documentation, including any additional controls necessary, to meet the intent and requirements of this LEED credit.