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The Energy Star Home Drew Tepper Overview What is an energy star home? New Homes Existing Homes Windows HVAC Insulation Plumbing Conclusion What is an energy star home? “More home for less money than standard homes.” Energy Star labeled homes are at least 30% more energy-efficient than standard homes. Use reliable and established technologies and building practices to operate significantly more efficiently than homes built to the Model Energy Code. These technologies and practices save the owners of Energy Star homes money on their utility bills. They provide a home that’s more comfortable, more durable, environmentally friendly, and cheaper to own. To receive an Energy Star label, homes must undergo a third party evaluation of their energy efficiency. Standard Home Energy Star Labeled Homes $200,000 List Price $203,000 $1,654 Monthly Mortgage $1,679 $155 Monthly Utilities $100 $1,809 Total Monthly Costs $1,779 Monthly Savings $30 Model Energy Code The Energy Star standard for new homes is measured by the Home Energy Rating System (HERS) scoring. The HERS rating is a calculation of the energy efficiency of a home compared to an identical ‘house’ that meets the minimum requirements of the Model Energy Code (MEC). The HERS score will be between 0 and 100. The reference ‘house’ will have a score of 80. Each 5% reduction in energy usage will result in an additional point on the HERS scale. An Energy Star home must receive a score of at least 86 on the HERS score. Builder Option Packages (BOP Ratings) BOPs are a set of construction specifications for a specific climate zone. These specifications include performance levels for the thermal envelope, insulation, windows, orientation, HVAC systems, and water heating efficiency. The United States has been divided into 19 climate zones for purposes of BOP. A home built to BOP specs is not rated by the HERS system but still is subject to third party verification. BOP homes either pass or fail as Energy Star homes. New Construction Tight Construction. There are hundreds of holes that penetrate the outside of a house. These occur due to gaps and holes from framing and penetrations for wiring, plumbing, and ducts. Air sealing combined with proper ventilation can reduce energy bills and eliminate unwanted drafts and pollutants. New Construction Cont. Tight Ducts. Duct Sealing – typically ducts leak more than 35% of the air traveling through them before reaching a destination. Duct tape does not seal ducts adequately. Duct location – should only be placed where the air will be heated and cooled. Attics can reach above 150 F. Duct insulation – if used outside the living area. Duct Sizing. New Construction Cont. Insulation. A continuous boundary of insulation is necessary between the inside and outside for a home to maintain temperature efficiently. Insulation must be installed carefully with no gaps, crimping, or compression, as these can allow unwanted air and heat exchange between the outside and inside. Old Construction Existing houses can be modified to meet Energy Star standards. Not necessary. Improvements can be made to increase efficiency. Windows. High-efficiency heating and cooling systems. Replacement Windows Windows typically make up 10 – 25% of a home's exterior wall area. Energy Star labeled windows are twice as efficient as the average window produced just ten years ago. U-factor, R-value and Solar Heat Gain Coefficient U-factor is the measurement of heat transfer through a given building material (such as glass). R-value depicts the resistance a material has to heat transfer. U-factor = 1/R-value The solar heat gain coefficient (SHGC) is a measure of the amount of solar energy that a glazing material allows to pass. Window Facts In heating-dominated climates, windows account for up to 25% of a typical house’s heating load. In cooling-dominated climates, windows account for up to 50% of the same house’s cooling load. In recent years, many technological advances have improved the thermal performance of windows. These advances include low-emissivity and solar control coatings, low-conductance gas fills, improved thermal breaks and edge spacers, and better edge sealing techniques. What’s a good window? Windows can improves the thermal performance of homes by minimizing heat loss in heating- dominated climates and by minimizing solar heat gain in cooling-dominated climates. Windows with lower U-factors (higher R-values) perform better in heating-dominated climates while windows with lower solar heat gain coefficients (SHGC) perform better in cooling- dominated climates. “Vacuum” can be filled with other gases Thermal Window Windows Cont. Air tightness (unconditioned air leakage into a house). A rating of 0.2 cfm/ft (cubic foot per minute of air leakage per linear foot of window edge) or lower is considered good. The best windows have a rating of 0.1 cfm/ft or lower. High-Performance™ Low Emissivity, Argon Blend Filled Window: Air Leakage: 0.15 cfm/ft U-Factor: 0.28. Solar Heat Gain Coefficient (SHGC): 0.43 Insulation (R-values put to use) Insulation Specs Insulation Material R-value per inch of Thickness Batt-type 3.1 to 3.5 Loose fill 2.9 to 3.7 Board stock 3.5 to 6.2 Spray-type 3.5 to 6.0 Rigid Foam Insulation HVAC The average air conditioned home uses 2000 kWh per year. The efficiency of Central A/C units is governed by U.S. law and regulated by the U.S. Department of Energy. The Seasonal Energy Efficiency Ratio (SEER) is defined as the total cooling output (in Btu-British thermal units) provided by the unit during its normal annual usage period divided by its total energy input (in Watt-hours) during the same period. The minimum SEER allowed by law for a central A/C is 10. The best available SEER is about 18. Water (not addressed in the energy star program) When buying shower heads, look for low GPM (gallons per minute). Toilets Light Bulbs – Compact Florescent Bulbs (CFLs) 25 watts used is the equivalent of a 100 W bulb Conclusion New construction Energy Star Homes make sense because during construction upgrade costs are nominal. Upgrades to existing homes have a cost benefit if the life of the product is taken into account. Keep in mind that Energy Star Homes take advantage of current technologies used in efficient ways; no solar or wind power (but maybe back at the power plant!) Energy Star improvements will increase resale value of homes. With a hybrid in the driveway and an energy star home, who wouldn’t want to be your friend?!
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