Residential Green Building Program Comparison
The green building industry is growing rapidly and many green building programs are now available. The four major national programs designed for single family and multifamily, custom, and production builders are: LEED for Homes, NAHB Green Building Program, Green Communities, and the DOE Building America Builder's Challenge (BABC). All of them use similar frameworks to evaluate green building practices, but they also differ in the following important ways:
Third-party Verification
LEED for Homes, NAHB Green Building Program, and BABC all require an outside verifier for worksheet compliance and building performance – Green Communities currently does not, but has plans to expand its certification protocol in 2010.
Program Rigor
It is difficult to compare programs and judge which one is more "green" because all programs provide varying levels of certification and for the most part improve on existing code – but some statistics can be telling. As an example, if all the pre-requisites for a LEED certified home – meaning they do not contribute any points – were performed under the NAHB National Green Building Standard, 80% of the points would already be satisfied for Bronze level certification (2).
In addition, LEED for Homes requires all projects to meet ENERGY STAR standards, including performance testing, while the NAHB Green Building Program base level makes performance testing optional and only requires ENERGY STAR documentation if a project is using the prescriptive path and opts out of the pre-drywall inspection. Also, only the NAHB program allows builders to use REScheck for energy modeling purposes rather than RemRate or Energy Gauge which are more comprehensive analysis tools.
The differing approaches of NAHB and LEED largely reflect differences in the intended users of each system – LEED is designed for leaders in green building, while NAHB was created to be accessible to any builder looking to improve their environmental practices. Looking briefly at the other two programs – Green Communities has similar requirements to LEED but remains the only national green residential affordable housing standard and is applicable to nearly every housing and construction type. BABC is working to create a larger market transformation towards net zero energy housing beginning with a goal of 30% energy savings.
Standards Used for Verification
The LEED for Homes and Green Communities programs have developed their guidelines from a design perspective, and therefore tend to use existing standards that provide measurable requirements for builders to meet. The NAHB Green Building Program and BABC criteria provide similar goals, but often use more prescriptive language to describe compliance methods.
A measure of a building's or product's energy performance compared with that of similar buildings or products, as determined by the U.S. Environmental Protection Agency / U.S. Department of Energy's ENERGY STARŪ Portfolio Manager. Leadership in Energy and Environmental Design (LEED) is a building rating system developed by the U.S. Green Building Council (USGBC) to measure energy efficiency. It provides a standard for environmentally sustainable construction.The ability or potential of a physical body to do work. The most common forms of energy are heat, light, mechanical (moving parts), and electrical.
Mandatory Measures
The NAHB Green Building Program currently has very few pre-requisites in comparison to LEED for Homes and Green Communities. By reducing the number of mandatory features required for compliance the NAHB system allows builders to pick and choose where to focus their attention. This can be important for addressing regionally specific issues, but may also open the door to avoidance of more difficult points for entry level certification. BABC uses a less flexible structure than the other programs, which outlines a list of mandated building practices and then provides some recommendations that do not influence compliance, but could improve overall performance.
Standard vs. Rating System
NAHB created the National Green Building Standard to act as a general code of best practices for green building. For that reason, it does not contain specific requirements for compliance with a particular program, and municipalities have the option of using the NAHB NGBS to develop their own local green building program. Compliance specifications for the NAHB Green Building Program are contained in the NAHB Research Center’s online scoring tool and verifier guidelines. LEED for Homes, Green Communities, and BABC all developed their guidelines to be used exclusively as part of their certification programs; therefore they contain all necessary compliance information.
How they fit together
Each of these programs can be used as a stand alone certification, or combined to provide a better indicator of building performance. This is especially true for the BABC because there is almost no added cost, and getting a good rating on the E-Scale can be a useful marketing tool to communicate potential energy savings with home buyers. Also, programs such as LEED and NAHB utilize regional providers who may have certifications of their own that can be done in parallel and often provide added appeal for local buyers.
COST
It is very difficult to provide a true cost comparison of the programs because they all have different compliance measures and verification involvement. Also, for any program that requires third party verification, total cost is largely based on fees for consulting and inspection services provided by the local verifier, who charges a market rate. LEED for Homes is often considered the most expensive due to a greater level of mandatory participation by project teams in the design and planning process. However, those higher front-end costs can often be recouped through fewer change orders on-site and better contractor performance. BABC is funded by the DOE, therefore they do not charge a registration or certification fee like LEED and NAHB. Green Communities does not charge fees, and the incremental cost of meeting the mandatory criteria is estimated at 1-3% of total development costs.
