By 2020 the housing industry will adopt a “house-as-a-system” perspective addressing energy-efficient, healthy, durable, water-conserving, and disaster-resistant performance. As a result, new homes will be built zero-net-energy ready, with energy loads so low that small renewable energy systems will offset most or all of the balance of annual energy demand. Manufacturers, architects, and builders will collaborate to deliver these ultra-high-performance homes in markets across the country. This market transformation process will be driven by codes, standards, and rating systems working together to embrace proven innovations.
The residential sector is a critical segment of the U.S. economy driven by a diverse set of codes, standards, and rating systems. At this time, model energy codes and voluntary rating systems are paving a path to increasingly more stringent thermal enclosures that have important related impacts on the durability, indoor air quality, and safety of our homes.
Greater insulation levels reduce thermal flow through construction assemblies, which in turn make them substantially less tolerant to drying. This leaves new high-performance homes more sensitive to bulk moisture and vapor flow.
Increased air tightness levels reduce the amount of dilution of interior moisture and pollutants. In addition, tighter construction potentially intensifies pressure imbalances caused by operation of internal fans, and this in turn can lead to combustion safety issues. Thus, a house-as-a-system approach is becoming increasingly important to minimize the risk of failure in new high-performance homes.
And high performance is the future based on the U.S. Department of Energy’s (DOE) goal for zero-net-energy-ready new homes by 2020. These are homes so energy efficient, a small renewable energy system can offset most or all annual energy consumption. Additional enhancements addressing indoor air quality, water conservation, and disaster resistance will go hand in hand with these homes to ensure efficiency, health, and durability.
The journey to these ultra-high-performance homes involves a myriad of codes, standards, and rating systems that must work together delivering whole-house system solutions.
A SENSE OF URGENCY
The housing industry is too important to our economy and environment to get it wrong. And we are at significant risk of getting it wrong if related health and durability issues are not addressed in high-performance homes. Why is housing so significant to our economy? It begins with recognition that residential investments account for nearly 5% of the U.S. Gross National Product (GNP), and together with housing services nearly 20% of GNP. And its economic significance is even greater when tangential impacts are taken into account, including the purchase of housing products and services and substantial local government tax revenue. Homes also create significant environmental impacts directly associated with their energy use. This is because the residential sector accounts for more than 20% of our nation’s total annual energy consumption.
These impacts suggest the nation would be best served by affordable zero-net-energy homes that minimize or eliminate energy requirements, minimize or eliminate outdoor pollution associated with residential energy use, minimize the risk of indoor air quality problems, ensure meaningful and persistent manufacturing and construction jobs, and provide more economically viable communities.
Considering that new homes are likely to last at least 100 years, there is a profound urgency to develop codes, standards, and rating systems that enable this path to zero-net-energy homes.