Choosing the best LEED for the job

Deciding between LEED NC, LEED CI, LEED EB isn’t a simple matter
Monday, October 3, 2011
By Michael Driedger

There are multiple green building rating systems available to projects in Canada. While these ratings systems are effective and offer tools for measuring green building, the added rigour and rapid early adoption of LEED (Leadership in Energy and Environmental Design) has helped make it the most widely used rating system in North America.

In the past 12 years, the U.S. Green Building Council (USGBC) and Canada Green Building Council (CaGBC) have expanded their offering of what they call LEED products – LEED certification rating systems for differing building types. In addition to LEED for New Construction (NC) and LEED for Commercial Interiors (CI), these products now include LEED for Core and Shell (CS) for speculative commercial development and LEED for Existing Buildings: Operations and Maintenance (EB:O&M) for facility operations. With the proliferation of these products, choosing the one most appropriate for each project can be challenging.

LEED EB:O&M versus NC and CI
Choosing a rating system is most difficult when a project involves the renovation of an existing building. While LEED EB:O&M, NC and CI are all possible options, there are two major factors that determine which LEED product is most appropriate: what the owner wants the certification to represent; and the extent of alteration and scope of the project.

Both LEED NC and CI attempt to capture the design and construction process of a project. As such, both rating systems use predictive energy models and water calculations to estimate how well a building will perform once occupied. Given the nature of occupant interaction with buildings, the actual energy and water performance of a facility can vary greatly from initial projections.

The only LEED product that judges a building on its actual performance is LEED EB:O&M. Formerly LEED EB in the U.S., the CaGBC adopted this rating system in 2010. Ever since, there has been tremendous uptake in the product, especially in the Greater Toronto Area. While there are credits within this product to address facility alterations, most credits are geared to tracking ongoing operational issues.

LEED NC was written for owner occupied buildings, LEED CI for tenants wishing to fit-out a space and LEED EB:O&M for facility managers to monitor occupant impact. While the LEED NC and CI products can be used in multi-tenanted buildings, doing so becomes more challenging in this scenario as both were meant to address a more limited scope of design and construction.

LEED EB:O&M advantages and disadvantages
Advantages include:

  • Greater range of credits that match various strategies of relevance;
  • USGBC LEED online management software available; and
  • Quicker documentation process (two reviews rather than three).

Disadvantages include:

  • Documentation is based on actual rather than modelled performance (delaying certification);
  • No credits available that capture design intent;
  • Not ideal for phased construction; and
  • Not appropriate for greater than 50 per cent fit-out.

LEED NC advantages and disadvantages
Advantages include:

  • More credits are available for recognizing building reuse (shell and structure); and
  • Durable building credit is available.

Disadvantages include:

  • Best suited for an entirely owner occupied building;
  • Many site credits are available that may not apply to project scope or budget; and
  • Not ideal for phased construction (no certification until the end of all construction).

LEED CI advantages and disadvantages
Advantages include:

  • Allows project certification in isolation from other tenants (one floor at a time);
  • Fewer site credits;
  • Good for phased construction; and
  • Allows for the greatest number of credits (highest certification).

Disadvantages include:

  • Fewer materials credits are available that recognize building retention.

Selecting the right rating system
The selection of a LEED product typically comes down to what a client is attempting to measure. If the goal is to measure ongoing operations and the odd small renovation, then LEED EB:O&M is the best selection. If the project requires a major renovation with landscape work and changes to the building envelope, then LEED NC may be the preferred option. If, however, the client is attempting to capture the design and construction of a significant interior renovation, then LEED CI may be the appropriate choice.

Regardless of which rating system is selected, if members of the consulting team are not sure about the choice, they can always contact the CaGBC to help validate the decision-making process.

Michael Driedger is a sustainable building advisor in the Vancouver office of Perkins+Will Canada.

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