In most endeavors, striving for a score of zero is a fool's errand.
In green home building, however, it is the gold standard. The trick is to keep it from becoming fool's gold.
Despite the housing downturn and its drag on home builders, real progress has been made toward achieving the goal of building homes that consume no net energy. Unquestionably, some of this progress has been forced by the government. Still, the home building industry, battered as it has been, is taking a leading role in the movement toward reducing consumption of energy and water resources. It is realistic to expect that, over the next few years, energy use in new homes will approach zero, and water use will drop to a level one could call insignificant.
Using California as a case study, consider how far the industry has come. Homes built in the last few years use 25 percent less energy, and generate 25 percent less greenhouse gas emissions, than those built just 20 years ago. This results from relatively simple improvements in building materials, construction techniques, insulation, and appliances.
Similarly, recently constructed homes use one-third less water indoors than those built in the mid-1970s, simply due to installation of more efficient fixtures. These are production homes, using standard features. The numbers are even more impressive for homes which incorporate custom, high-efficiency features, and photovoltaic or other onsite power generation facilities.
New homes in California account for a growth of only about 1 percent of the total housing stock in a given year during strong economic times?and only a third of that during the current recession. About 60 percent of homes statewide predate any meaningful energy conservation requirements, and more than 80 percent predate water-conservation standards. Achieving significant improvements in energy and water efficiency in the residential stock would require retrofitting large numbers of those older homes. That will happen over time, driven by the utility cost savings associated with such efficiencies.
Meanwhile, new housing stock begins to demonstrate the efficiencies that can be achieved and, over time, R&D in new-home building will gradually make them more affordable.
Much of this improvement in home efficiency has been driven by changes in the California Building Standards Code, contained in Title 24 of the California Code of Regulations. What began as a set of standards and requirements related to safety and structural integrity has evolved to address environmental issues of concern to the state and its residents. This has focused most heavily on achieving greater energy efficiency.
The need for space heating and cooling has been dramatically reduced by more efficient air-conditioning units, improved wall and attic insulation, heat-resistant windows, better sealing of ductwork, and passive energy design systems. Energy use related to domestic water has been reduced through more efficient water heaters, recirculating hot water systems, and insulated pipes. Electrical demand has been further reduced by installation of more efficient lighting fixtures and domestic appliances. (On the other hand, increasing consumer desire for the newest and best in electronic gadgetry continually adds to the per-person demand for electrical power.)
In recent years, as water supply has become an increasingly critical consideration in connection with new development, Title 24 has focused on water conservation as well, setting standards for more efficient plumbing fixtures and water-using appliances.
-Tight ducts (less than 6% leakage)
-Radiant barrier roof sheathing
-Tankless water heaters
-R-30 or 38 ceiling insulation
-Photovoltaic solar panels (optional) Water conservation:
-WaterSense bath faucets
-Tankless water heaters
-Insulated hot water loop lines
-Dual-flush toilets (optional)
This trend toward increasing conservation and efficiency requirements was accelerated by enactment of A.B. 32, the California Global Warming Solutions Act, in 2006. With about 22 percent of greenhouse gas emissions in California attributable to residential and commercial buildings, clamping down further on energy consumption is vital to meeting the emissions reduction standards of A.B. 32.
That has been a prime driver behind the California Green Building Standards Code, now incorporated into Title 24. As part of a broad array of environmentally friendly building requirements, the new code includes requirements for accurate sizing of heating and cooling systems, sealing and insulation of ductwork, and sealing of openings between conditioned and unconditioned space. It also includes changes for plumbing fixtures that will result in a 20 percent reduction in potable water use, as well as weather or moisture-based outdoor irrigation controllers.
In addition to satisfying environmental regulatory requirements, these kinds of features will produce substantial cost savings for homeowners. The average California household consumes about 5,900 kilowatt hours per year. Based on typical utility rates, reducing their electrical consumption by one-third would result in an annual savings of about $375. Because electrical rates are tiered, with higher per-unit costs for higher levels of consumption, a household using 10,000 kilowatt hours per year would save nearly $1,000 annually.
Similarly, a typical new single-family home consumes about 59,000 gallons of indoor potable water and about 115,000 gallons for outdoor irrigation annually. Reducing the indoor use by 20 percent pursuant to the new code, combined with an achievable reduction of 40 percent in outdoor irrigation, would save about $300 annually. Again, because of tiered water rates, the savings would be much greater for homes with more fixtures and more landscaping.
Some home builders are taking the quest for efficiency significantly further. Brookfield Homes' Rockrose community in Carlsbad, Calif., is incorporating standard features that reduce energy consumption by 35 percent below Title 24 requirements. These features include radiant barrier roofs, more thermal-resistant windows, quality installation of insulation, insulated and tightly sealed ductwork, tankless water heaters, and highefficiency furnaces. Photovoltaic solar panels are available as an option.
Water consumption is reduced further by the use of dual-flush toilets, looped and insulated hot water lines, high-efficiency irrigation controllers, and drought-resistant landscaping.
Other builders are trying different approaches.
Toll Brothers is introducing a variety of energy-saving options but is focusing particularly on renewable energy generation. The company is making photovoltaic solar panels available on homes in several projects, including in the Vista del Verde community in Yorba Linda, Calif., at no increase in sales price, by having the panels owned by a third party and leased to homeowners, who then receive lower-cost electricity. Toll similarly is making available geothermal heating and cooling systems in projects such as the Hills at Southpoint in Durham, N.C. KB Home is installing solar panels as a standard feature in several new projects. Pacific Housing is taking this a step further in a Sacramento project, installing a battery storage system as a backup to rooftop solar panels.
Surprisingly, these kinds of features are not significantly impacting housing affordability. Taking into consideration all rebates and tax credits available, construction costs in the Brookfield project are only increased by $1.50 per square foot on a net basis, allowing it to remain one of the most affordable new housing developments in San Diego County. This project also benefits from the moderate, coastal Southern California climate; such energy efficiency improvements would cost considerably more in the warmer inland climate zones.
In Phoenix and other markets, Meritage Homes has been able to include an array of energy-saving features, including solar energy, while keeping sales prices under $230,000 for a 3,000-squarefoot home, by incorporating these elements into their standard design rather than adding them as options. Moreover, as an optional upgrade, they are offering sufficient additional solar panels to eliminate electrical service costs.
As these kinds of offerings become more commonplace in the home building industry, the question will be how far such efficiency can be taken, particularly by production builders. The goal of many developers, consumers, and environmentalists is to be able to produce homes that are net zero with regard to resource impacts, i.e., homes with on-site features that reduce consumption to zero, through some combination of efficiency and renewable energy generation.
To achieve such net zero results with regard to energy will require taking significant additional steps in most cases. These might include thicker exterior walls, heat-resistant roof tiles, higherefficiency heating and cooling equipment, conditioned attic space, passive heating and ventilation features, fewer and better insulated windows, strategic orientation of the structure, and planting of deciduous trees. In all likelihood, it also will require installation of on-site energy generation facilities, particularly photovoltaic solar, geothermal, solar water heating, and/or wind turbines. This is all readily doable now, but at a cost of $40,000 to 50,000 for a typical new detached home.
At the same time, an energy savings greater than that available from a full range of green building features can be obtained by simply locating homes in walkable communities or transit-oriented locations, as energy use and greenhouse gas emissions associated with vehicular transportation typically exceed those of the house itself. Such locational considerations will be increasing in significance in California, in particular, as the state implements not only the mandates of A.B. 32 but also other statutory requirements for reduction of vehiclerelated environmental impacts.
Bringing water consumption down to net zero is more challenging. Significant reductions can be achieved by using the lowest-flow fixtures indoors, planting the most drought-resistant landscaping, and using both collected stormwater and domestic gray water for irrigation. However, in the absence of onsite water treatment capability, net zero will not be achievable.
Individual zero-energy custom homes are popping up, especially in areas with temperate climates, and a handful of zero-energy subdivisions are being built. These homes typically also receive LEED certifications and come with a certain cachet of environmental consciousness.
It is reasonable to ask, however, whether achieving zero-energy status and near-zero water status is a particularly worthwhile goal.
Noted new urbanist architect Andres Duany has taken the lead in criticizing LEED and other similar programs for requiring large expenditures to meet extreme standards, when nearly the same level of environmental gain can be achieved at far less cost. Achieving that last increment comes with a highly disproportionate price tag. Just as a given level of energy reduction can be achieved through retrofitting older homes at one-eighth the cost of achieving the same reduction in already more-efficient new homes, the cost of taking a standard new home to a zero net energy level could instead pay for signifi- cant energy reductions in several new homes. Furthermore, new urban, infill, and transitoriented developments already substantially reduce their energy use footprint simply by virtue of their locations, and therefore should be viewed as effectively below net zero compared with new homes in locations that generate high vehicle miles traveled.
Zero net energy is a lofty goal, and its application to even a small percentage of new homes serves as a proving ground for new technologies and new design methods, some of which can be applied to production homes. It is not, however, a feasible or practical approach for all new housing. Nor should it be.
We can accomplish far more in the way of reducing our energy and water use by applying more cost-effective methods on a larger scale, to both new housing and the existing housing stock. This will take political courage, however, because new homes do not have a political constituency, while existing homes certainly do.
Until conservation and efficiency become real goals for the general public throughout the country, new housing alone will bear the financial burden, to the detriment of both housing affordability and environmental goals.
BB Steve Doyle is president of Brookfield Homes, San Diego. Cary Lowe is a San Diego land use lawyer and planning consultant.
Learn more about markets featured in this article: Los Angeles, CA.