The 2012 edition of the ICC 700 National Green Building Standard (NGBS) helps residential building professionals develop, build and remodel higher performing projects in a more sustainable manner. Each week, Get to Know the NGBS explores a selected topic within the standard to learn more about this robust tool and the guidance it offers today’s building professional.
This Week: Chapter 11: Remodeling, A Chapter Overview
No matter what the economy is doing, the number of new residential buildings added in any given year will always represent a tiny fraction of the built environment. Collectively, green building protocols like the NGBS can only do so much to reduce the environmental impact of building and occupying homes if they are only applicable to new construction.
For any meaningful aggregate improvement to occur in the residential sector, attention must be paid to improving the performance of the millions of existing buildings that predate current green protocols and energy codes. During a remodel is an ideal time to make these improvements.
The 2012 NGBS provides a standalone chapter (Chapter 11: Remodeling) of mandatory and discretionary practices that earn points toward NGBS compliance and improve the performance of an existing building as a whole. (Chapter 12 provides guidance for smaller remodeling projects.) The individual practices of Chapter 11 will be considered in more detail in future editions of Get to Know the NGBS.
Just as with new buildings, remodeling compliance requirements are given in Chapter 3 of the NGBS. And like new construction, a NGBS-compliant remodel considers the lot on which the building sits, the materials used in the project, the indoor environmental quality (IEQ), owner education, and energy and water use.
Unlike new construction, however, the lot, building material, IEQ and education-related provisions don’t reside in their own chapters, but are organized in related sections within Chapter 11.
The requirements for energy and water usage differ even further for remodeling projects. In lieu of a prescriptive approach with a combination of mandatory provisions and point-weighted options, the energy and water requirement are wholly performance based. The straightforward approach requires that upon project completion, anticipated use of both energy and water must be reduced by percentages that increase as higher compliance levels are sought.
Here are the tiered reduction requirements:
In both cases, reduction estimates can be determined either by third-party audit or through utility consumption data. Post-remodel calculated reductions must consider whole-house usages, so even if living space is added during the remodel, the same reduction thresholds still apply.
The prescriptive site, material, IEQ and education measures for remodels reside in Chapter 11. Similar to the requirements for new homes, any applicable mandatory items are required, and other measures are selected and implemented to accrue enough points to satisfy the point requirement for the level sought.
To achieve any level of compliance, a project must reach all three thresholds for that level. For example, a project striving for Silver-level compliance must demonstrate at least 25% improvement in energy usage, at least 30% in water usage and accrue at least 125 points from Chapter 11 (in addition to the mandatory levels.)
While the inherently rigorous performance improvements Chapter 11 requires help ensure meaningful reductions in the natural resources a home consumes following an NGBS-compliant remodeling project, the standard maintains sufficient flexibility so that achieving targeted thresholds can be as cost-effective as possible.