ASHRAE Journal - June 2011 - 85

It is common for residential dwellings to have 0.5 ach leakage. Better sealed homes can reduce leakage to 0.1 ach, which provides significant energy cost savings. In cold weather climates such as Duluth, Minn., reduced air leakage saved $187 per year, and in somewhat milder Chicago, savings were $124 per year. In Atlanta, which has a warm climate, reduced air leakage saved $55 per year. Savings were calculated for an 1,800 ft2 (167 m2) house using gas heat, during heating months, and do not include space cooling.17

longer, with the shorter payback periods occurring in a colder climate with higher cost fuel.

references
1. LaFrance, M. and J. Deringer. 2009. “U.S. DOE building windows and envelope R&D—Retrofit focus.” http://tinyurl.com/LaFrance-Der. 2. Amberix. 2011. “Envelope and Windows.” http://tinyurl.com/ Amberix. 3. ANSI/ASHRAE Standard 90.2-2007, Energy-Efficient Design of Low-Rise Residential Buildings. 4. Energy Efficiency and Renewable Energy. 2010. 2009 Buildings Energy Data Book. U.S. Department of Energy. http://buildingsdatabook. eere.energy.gov/. 5. “Exterior wall insulation.” 2007. Madison Gas & Electric. http:// tinyurl.com/MGE-Exterior. 6. U.S. Census Bureau. 2010. United States Selected Housing Characteristics: 2005 – 2009: American Community Survey. http://tinyurl. com/US-Housing-Survey. 7. Arasteh, D., et al. 2006. “Zero energy windows.” http://tinyurl. com/arasteh. 8. Coler Natural Insulation. 2006. “BioBased.” www.coler.com/ biobased.asp. 9. Straube, J. and J. Smegal. 2009. “Building America Special Research Project: High-R Walls Case Study Analysis.” http://tinyurl.com/ High-R-Walls. 10. Perkins, D. 2008. “Retrofitting an insulated cold roof.” Journal of Light Construction. http://tinyurl.com/cold-roof. 11. Kosny, J., et al. 2011. “Sustainable retrofit of residential roofs: Using metal roofing panels, thin-film photovoltaic laminates and PCM heat sink technology.” Journal of Building Enclosure Design. http:// tinyurl.com/Kosny-roof. 12. “New Construction Replacement Windows vs. Retrofit Windows.” 2011. Replacement Windows IC. http://tinyurl.com/replacement-retrofit. 13. “Technology Development in Support of Next Generation Fenestration.” 2010. U.S. Department of Energy. http://tinyurl.com/ DOE-fenestration. 14. Mukerji, S. 2010. “Closer look: More construction to incorporate triple glazing.” Glass Magazine. http://tinyurl.com/triple-glazing. 15. U.S. Environmental Protection Agency (EPA). 2009. “ENERGY STAR Program Requirements for Residential Windows, Doors, and Skylights—Version 5.0.” http://tinyurl.com/Residential-Requirements. 16. “Advanced Air Sealing: Air Leakage in Homes.” 2010. Oikos. http:// tinyurl.com/Advanced-Air. 17. “Remodel project—deep energy retrofit: insulation, air sealing, & HVAC offer chances to slash energy bills.” 2010. Green Building Advisor Green Building Encyclopedia. http://tinyurl.com/Remodel-Project. 18. Moe, R. 2009. “This Old Wasteful House.” New York Times 158. http://tinyurl.com/WastefulHouse. 19. “Recovery Through Retrofit.” 2009. U.S. Council on Environmental Quality, Middle Class Task Force. http://tinyurl.com/Recovery-Retrofit. 20. “Retrofit Measures for Wood Stud Wall.” 2010. National Renewable Energy Laboratory. National Residential Efficiency Measures Database. http://tinyurl.com/RetrofitMeasures. 21. National Renewable Energy Laboratory. 2010. National Residential Efficiency Measures Database. http://www.nrel.gov/ap/retrofits/ group_listing.cfm.

energy savings
Homes built before 1939 consume 50% more energy than those built in 2000. It has been calculated that retrofitting 300,000 homes per year would result in saving 200 million barrels of oil energy equivalent (approximately 1 quad) over 10 years.19 Additionally, if existing technology were used to retrofit an older house (envelope and other house systems), energy savings of up to 40% could be achieved. Such retrofits carried out across the housing sector could result in savings of $21 billion per year.20

market Factors
Replacement windows are available from a range of vendors in a variety of quality and styles, at installed prices ranging from $300 to $1,500 per average-size window. When replacing poorly performing, leaky windows, annual heating cost savings on the order of $500 can be obtained. At the low end of the replacement window cost range, replacing 15 windows in an average house would cost $4,500, yielding a nine-year simple payback. Often, window replacement is motivated by additional factors besides energy savings alone. The cost of the advanced window technologies will exceed that of base level components. Windows having a U-value of 0.10 are estimated to cost $5 more per square foot than standard double pane low-e coated windows. It is projected that in 10 years this price differential will drop to $3. Dynamic windows average $20 more per square foot than a standard insulated glass unit; it is projected that the price differential will drop to $5 in 10 years. Thus, the marketability of the latter technology will improve when the price premium falls.2 The cost of installing R-19 fiberglass batt is less than that of low-density spray foam, which is less than that of high density spray foam.10 Improving from an insulated wood stud wall with 16 in. (406 mm) cavities to an R-13 insulated wall with either cellulose or fiberglass costs on average $3 per square foot of wall. Moving from an R-3 fiberglass insulated wall with 24 in. (610 mm) cavities to R-21 costs on average $4.20 per square foot of wall.21,22 For an average house with 2,000 ft2 (186 m2) of wall area, the cost would be $6,000 to $8,000. Heating cost savings range from $500 to $1,000 per year depending on climate and fuel source. Simple payback periods are generally six years and
June 2011

John Dieckmann is a director and Alissa Cooperman is a technologist in the Mechanical Systems Group of TIAX LLC, Cambridge, Mass. James Brodrick, Ph.D., is a project manager with the Building Technologies Program, U.S. Department of Energy, Washington, D.C.
ASHRAE Journal 85

ASHRAE Journal - June 2011

Table of Contents for the Digital Edition of ASHRAE Journal - June 2011