Windows give homes style and beautiful views, but they also let heat and cold in and out of the home. Energy efficient windows are designed to reduce utility bills by helping to control the temperatures in the home by acting as insulation. Unlike the single function of wall insulation, which is to stop the transfer of heat from one location to the other, windows have multiple functions and require multiple ways of rating their thermal insulation performance. Here are 4 measurements you should know about that also apply to doors and skylights.
U-factor is a calculation of the entire window assembly that measures the rate of heat transfer (heat gain or loss through the glass) based on the conduction performance of the various components of the window. The lower the U-factor, the better the window will be at reducing heat transfer. Climate Zone 2 requires a U-factor of 0.40 or less and 0.65 or less for skylights.
Solar Heat Gain Coefficient (SHGC) is the amount of sun that enters through the window and creates heat inside. The lower the SHGC, the better the window is at blocking the sun from warming your home. Climate Zone 2 requires a SHGC of 0.25 or lower.
Low-e glazings lower the SHGC ratings of the window. Low-e stands for low emissivity, and these windows feature a microscopically thin transparent coating designed to reflect heat without blocking light. On the outside of the home, low-e windows reflect the sun’s heat back to the sun and on the inside, the heat from a heater will be reflected back into the home, making these windows superior energy efficient products.
Visible Transmittance (VT) is a measurement (from 0 to 1) that represents the amount of visible light coming through the window, taking into account the light that is blocked by the frame and other window components. The higher the VT, the more daylight will enter the home. Be aware that a more energy efficient window may lower the VT, so consider the tradeoff. Generally, a VT of .54 or better is good, but it could be less. It all depends on the direction the window faces, the design, and other factors. A higher VT can reduce usage of interior lights.
Air Leakage (AL) is an optional rating that may not always appear on the window label. AL represents the amount of air (heat loss or gain) passing through the whole window assembly. AL ratings are from .01 to .03 and the lower the number, the better the window is at keeping out air.
The Rio Grande Valley has one of the hottest temperatures in the nation. Here’s what you need to know about insulation. The purpose of insulation is to slow or prevent the transfer of heat. During winter it keeps the heat in and in the summer it keeps the heat out. The ability of insulation to do this is measured in R-values.
R-values rate the effectiveness of insulation materials. The higher the R-value, the more resistance to heat flow. Code laws set minimum standards, but that is not the best for the consumer. We recommend that you look for a BUILT TO SAVE™ or ENERGY STAR® builder who builds above code requirements. The insulation in their homes are inspected at the framing stage before the walls are added to insure proper installation, and that there are no missing air barriers or gaps between the air barrier and insulation.
Insulation includes many types of materials (in many forms and applications) like fiberglass, rockwool, cellulose, spray foam, and foam boards like polystyrene and polyisocyanurate, which have the highest R-value of the foam insulations.
Proper installation of insulation can reduce average home heating and cooling costs up to 50 percent. When it comes to insulation, if you hire the wrong installer, you will be paying for it every month on your
3) WATER HEATING
While you want your house to be cool, you want the water in the shower to be hot. But water heating can account for up to 20 percent of a home’s energy costs, so it pays to know what you are buying. Your choice of a water heater will depend on how much hot water you will use. And there are plenty of choices that include gas and electric options.
Water heaters are available as storage tank, tankless (on-demand), heat pump (hybrid), solar, and condensing. Each has pros and cons, and their cost will vary depending on what they offer. It is not always wise to “go cheap” where you may end up paying more in the long run to replace a water heater that did not last. For durability, you would be wise to consider Magic Valley Electric Coop’s Marathon water heater with a limited lifetime guarantee. Remember that there is also the natural gas heat pump which is among the most energy efficient options.
Since water heating is the second largest energy hog in your home, choosing the right one can mean tremendous savings for you. Make sure your builder has your budget in mind when he or she chooses the water heater for your new home.
4) HEATING, VENTILATION, AND COOLING SYSTEM (HVAC)
Most homebuyers are under the false assumption that bigger is better when it comes to heating and cooling units. That could not be further from the truth. Installing a larger unit than is required will actually cost you more money, as the over-sized unit cools the home quickly and will shut down often, stopping and starting more times than a properly-sized unit would. An over-sized unit can also, in time, create moisture and mold issues in the ductwork and the home. Choosing the right-sized unit is actually at the heart of building a home that is both energy efficient and comfortable to live in.
To calculate the right size unit for your home, many factors must be taken into account, including the size of the home, the geographical area, the ductwork system, and the ventilation system. More importantly, the installation must be done by a qualified technician—preferably one that is certified by the Air Conditioning Contractors of America (ACCA), the largest contractor organization in the nation. A 16 SEER unit, for example, could be operating as a 10 SEER or lower if other factors are ignored in the installation.
SEER and AFUE Ratings: Seasonal Energy Efficiency Ratio (SEER) for air conditioners and the Annual Fuel Utilization Efficiency (AFUE) rating on furnaces indicate how well these units are performing. The higher the rating, the less wasted energy and the more cold or warm air.
Manual J, Manual S, and Manual D Calculations: “Manual J” calculations on your house are used to figure out the cooling load, and “Manual S” calculations are used to select the optimal system. Manual D calculations take into account the duct design and airflow pressures from room to room throughout the home. These calculations take the guesswork out of choosing the right-sized unit for your specific home. Ask your builder if these were performed on your new home. With the BUILT TO SAVE™ and ENERGY STAR® programs, an independent home energy rater makes sure the calculations are in compliance, thereby insuring that the home has a properly-sized HVAC system.
Variable Speed Blower Technology and Whole-House Ventilation: When purchasing a new air conditioner, look for one with variable speed blower technology, which uses the fan motor inside the air handler located inside the home to move cooled or heated air through the ductwork. Variable speed motors use less energy and allow you to control the comfort of your home from room to room. In addition to saving energy, these blowers also help remove moisture and circulate air slowly, which allows your home’s air filters to remove dust and other contaminants from your indoor air. While an over-sized air conditioning unit is bad, one with a variable speed blower will only run to the load that will keep it from cycling on and off.
The ENERGY STAR® label on an appliance means that the product has been tested and meets the criteria of performing 10 to 50 percent more efficiently than a similar product on the market. While ENERGY STAR® products are generally more expensive, their upfront costs are more than recovered over time by savings on utility bills. Visit the ENERGY STAR® website at energystar.gov to see a list of all qualified products. Gas appliances offer additional benefits of their own including the benefit of uninterrupted use even when the power goes out.
6) PROGRAMMABLE THERMOSTATS
Programmable thermostats allow you to automatically adjust the temperature in your home during the day. You can program the thermostat to keep your house warmer while your family is away and cooler when you are sleeping. There are even smart thermostats that work with smartphone apps to adjust your home’s temperature from anywhere. As of September 1, 2016, all new homes are required to have programmable thermostats in Texas. When used correctly, this can save up to $180 per year according to EnergyStar.gov.
In general, 20 percent of your utility bill goes to lighting your home. Changing from old incandescent light bulbs to compact fluorescent bulbs (CFL) or LED lights means using less energy to create light—not to mention that most incandescent light bulbs are no longer being manufactured. CFL bulbs use 75 percent less electricity, produce 90 percent less heat, and last 10 times longer than traditional incandescent. LEDs use 80 percent less energy than CFLs, last 10 times longer, and are cool to the touch. Minimum code in the State of Texas requires that 75% of the lights in new construction consist of energy efficient lighting.
Your roof keeps rain out, but you also want it to keep heat out and climate-controlled air in. Just as you insulate the walls in your house, you also want to make sure the roof is properly insulated. Radiant heat is what makes a car in the sun so hot inside. When an attic is not well insulated, radiant heat warms the attic, which in turn warms the air ducts traveling through the attic and the cool air within. A radiant barrier works by reducing radiant heat gain. To be effective, the radiant barrier must face the air space it is trying to cool. There are also solar reflecting shingles available in a variety of light colors and are engineered specifically to lower attic temperatures, for cooler interiors and lower utility bills.
9) HERS Score / ERI
Whether buying a new home or upgrading your current one, you want to know its Home Energy Rating System (HERS) score or Energy Rating Index (ERI). These scores are calculated using specialized equipment and software implemented by licensed third-party inspectors and are designed to predict the energy efficiency of a home. The lower the score, the greater the energy efficiency and savings. In Texas, homes built after September 1, 2016, must have an ERI of 65 or lower to comply with code. If you prefer a better built and more efficient home, the BUILT TO SAVE™ and the ENERGY STAR® programs are designed to build homes that are above code requirements.
10) HOME CERTIFICATIONS
If you are looking at buying a new home, understand that energy certifications such as ENERGY STAR® and BUILT TO SAVE™ indicate that a house is built to a higher standard of energy efficiency and quality. These certifications require third-party home energy inspectors to check and inspect the home during construction, and upon completion to guarantee the home’s certification. When you buy a BUILT TO SAVE™ and ENERGY STAR® certified home, you will have peace of mind knowing your home will be comfortable and save you money on utility bills and maintenance, with the added bonus of providing a higher resale value in the future.