By 2020 most of the United States will build under the 2015 and 2018 energy codes. Improvements in the International Energy Conservation Code (IECC), driven by a combination of federal mandates and superior construction methods pioneered by volunteer green rating systems such as the Department of Energy’s Build America Program, the Environmental Protection Agency’s Energy Star, and private efforts such as LEED have already paved the way toward dramatic improvements in the energy profile of new housing.

However, new housing represents a fraction of the U.S. housing stock. We currently build about 500,000 new units annually, the superior energy efficiency of which cannot offset the 130 million units of existing housing that averages 34 years old, according the American Housing Survey of the U.S. Department of Commerce. This is why, despite all of the energy efficiency advances made in new home construction, the total amount of energy consumed by the sector has remained flat.

This is not bad news. Total U.S. energy consumption in homes has remained relatively stable for so many years precisely because the energy efficiency of new homes has offset the increase in the number and average size of housing units, according to newly released data from the Residential Energy Consumption Survey (RECS). This data shows a downward trend in average residential energy consumption over the last 30 years despite increases in the number and average size of homes plus increased use of electronics. Nevertheless, this improvement does not get us to the 60% overall reductions in energy consumption envisioned in the 2030 Challenge, which sets goals for existing buildings as well as new:

• All new buildings, developments, and major renovations shall be designed to meet a fossil fuel, GHG-emitting, energy consumption performance standard of 60% below the regional (or federal) average/median for that building type.

• At a minimum, an equal amount of existing building area shall be renovated annually to meet a fossil fuel, GHG-emitting, energy consumption performance standard of 60% of the regional (or federal) average for that building type.

While the focus on advancing green codes and rating systems for new homes has made astonishing progress, proving to the industry how much better we can build, the focus on improving the existing housing stock seems to have lost steam. The Architecture 2030 web site offers only two pages of case studies under the existing buildings category vs. seven pages under new construction. Considering the relative number of new and existing buildings, the project categories should be reversed with more effort devoted to existing buildings. Likewise, of the 11,014 LEED certified projects in the U.S., only 1,617 are LEED EB.

In the residential arena, when the proposed Home Star legislation fell under political pressure, the national weatherization effort stalled. Home Star was legislation designed to create jobs in existing industries by providing strong short-term incentives for energy efficiency improvements in residential buildings. Homeowners have only financial incentives to perform energy upgrades, and these were provided largely through government and utility incentives that have been reduced or eliminated. The dollars saved through energy conservation alone, especially with cheap natural gas and electricity cannot offset the capital expense required to make the needed upgrades.

Some code provisions promise to have a direct, if unheralded impact on existing housing. One of the most important updates came with the 2009 International Building Code (IBC), chapter 419, the first attempt to address live-work in a prescriptive manner. The integration of live-work into the IBC allows builders and developers to actually build zero commute housing, rather than just advocate for it.

Continued progress in green codes and rating systems for new construction is by no means assured. This year we have seen serious pushback on Energy Star v.3, movement in several states to slow the adoption of new model codes from three- to five-year cycles, and most recently strong opposition to LEED v.4. If this sort of industry and political repositioning continues, as it is likely to, the optimistic predictions we’ve made beyond 2012 may not materialize. However, we can still make significant progress, and with strong construction industry support, by focusing more intently on developing aggressive goals for greening our huge stock of existing houses.

Doing this will require engaging the remodeling community more vigorously through the DOE’s Build America and the EPA’s Energy Star programs. Rating systems like the California Build It Green’s, GreenPoint Rated Existing Home certification exist because utility companies, PG&E in this case, realize the overwhelming benefit of retrofit green. On a national basis, the USGBC should further develop LEED credits for remodeling. The LEED for Homes rating system currently includes gut rehabs but not other remodeling projects that encompass less than the entire structure. The NAHB Model Green Home Building Guidelines score major remodeling projects. The association would be a strong advocate for focusing on remodeling and rehabilitation since here low-hanging fruit remains, and the activity would bolster the beleaguered housing industry.

To wit, the ANSI National Green Building Standard (often referred to as NAHB Green) offers the most robust path to date to have a single-family home or multi-unit building remodeling project green certified. But as more jurisdictions throughout the U.S. adopt the 2012 IgCC and future updates, green remodeling of residential and commercial structures should become easier through prescriptive guidelines and gain market legitimacy through the municipal blessing of adopted codes.