Energy Efficiency, Questions from Home Buyers
Energy-efficient construction represents a fundamental shift in the building industry that prioritizes sustainability and long-term value. In recent years, builders and homeowners increasingly recognize the importance of minimizing energy consumption and reducing carbon footprints. Innovations in materials, technology, and design enable the creation of homes that utilize resources more efficiently, allowing for significant savings on utility costs while enhancing the comfort and livability of spaces. This commitment to energy efficiency aligns with global environmental goals and meets the rising demand from buyers who seek beautiful and responsible homes.
As a Certified Green Professional, we receive a number of questions about energy efficiency within homes. Below, we cover a few of the most commonly asked questions about green home construction.
Q: What is an energy audit?
A: Home energy audits have become popular as homeowners seek ways to lower their home energy bills. A typical audit, performed by a trained and accredited local professional for a few hundred dollars, will test the energy efficiency of your heating and cooling equipment and water heating system, identify leaks or other inefficiencies in the building envelope and ductwork, and suggest ways to reduce your energy use with lifestyle changes and home improvements.
Q: What are the most effective energy-saving products?
A: Most home energy is used for space heating, water heating, and major appliances. While upgrading to the highest-efficiency models you can afford may be an excellent strategy, their ultimate performance relies on a well-built home that is properly insulated and air-sealed.
Q: How much energy will a high-efficiency HVAC system save?
A: A high-efficiency heating and cooling system will only realize its potential in a home that's detailed to require less heating and cooling than the typical home. These details include sealing all duct seams, eliminating gaps around insulation batts, plugging envelope air leaks, installing well-sealed energy-efficient windows, etc. The small investment required for these measures will lower energy bills and make the home more comfortable and healthy.
Q: How vital is duct sealing?
A: Poorly sealed heating, ventilation, and air conditioning (HVAC) ducts can be significant energy losers. Unsealed ductwork that runs through an unconditioned attic can leak 500 cubic feet of air per minute—more than a ton of heating or cooling capacity. These air leaks occur at the seams where duct sections meet. A conscientious builder or remodeler will ensure the HVAC contractor has properly sealed these seams.
Q: What is an energy recovery ventilator?
A: An energy recovery ventilator (ERV) supplies fresh outdoor air to the house while exhausting stale indoor air. The supply and exhaust streams inside the unit pass through a heat exchanger, transferring energy from one air stream to another. This preheats incoming air in winter and pre-cools it in summer, reducing the heating and cooling load and the monthly electric bill. ERVs can be expensive, but they earn their keep in a well-insulated home.
Q: What is the R-value?
A: The R-value is a measure of energy efficiency. The higher the R-value of the insulation, windows, and even a home's structure, the better the house can block the transfer of unwanted hot or cold air through walls and ceilings. Residents of homes with high R-values experience far less temperature variation—and enjoy lower energy bills—by not having to run a furnace or air conditioner continuously to keep the house comfortable.
Q: What is SEER?
A: SEER stands for seasonal energy efficiency ratio or the cooling energy output of an air conditioner divided by the electrical energy it burns. The higher the number, the more efficient the equipment. For example, a new 15 SEER unit uses 33 percent less energy than an older 10 SEER model. All systems sold in the United States must have a minimum SEER of 13 or 14, depending on the region. The most efficient units have SEERs of 20 or more.
Q: What is thermal mass?
A: Thermal mass is the ability of a material to absorb and store heat energy. For example, a dense material like stone or concrete that helps flatten out temperature swings inside the house is said to have thermal mass. A thick tile floor next to a large, south-facing window will absorb solar energy during the day, keeping the house cooler. Then, the floor will gradually give up that heat at night, reducing the load on the heating system.
Q: What wall insulation has the best thermal performance?
A: Some homeowners wonder if switching from one insulation material to another will make their home more efficient. Still, the truth is that performance depends more on the installation than the material. Fiberglass, cellulose, rockwool, and foam can all do a great job if installed without gaps that allow heat loss. A professional builder will ensure an effective installation through an ongoing business relationship with a quality insulation company.
Q: Do photovoltaic panels convert 100% of the sun's energy into electricity?
A: No. In fact, the most efficient PV panels convert only about 20% of the solar energy they collect into usable AC electricity. That may not seem like a lot, but it is enough to generate more than 300 watts of electricity per 20-square-foot panel.
Q: How many devices will a home battery power?
A: It varies. A 4 to 6 kilowatt-hour (kWh) battery might power a refrigerator and microwave, three lights, a computer, and three extra outlets. With a 7 to 10 kWh model, you could add a television, three more outlets, and a single-zone air conditioner. An 8 to 16 kWh model might run all these, as well as a washer and dryer. These are just rough guidelines—precisely what the battery will power and for how long depends on how you use electricity.
Energy-efficient construction is poised to define the building industry's future, setting new standards for what is achievable in custom home design and construction. As a Certified Green Builder, TM Grady Builders embraces the future of green building and environmental stewardship.
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