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76 Expert Q&A

 
 

A. An electric water heater can save you money and offer you benefits that gas water heating just can’t match.

• No flames – Forget about flames because an electric water heater has none. There’s no pilot light to light—and re-light. And you don’t have to worry about children and pets coming near it or storing things around it.
• No fumes – There’s no need to worry about the odor of dangerous gas fumes or carbon monoxide.
• No flues – Because venting and combustion air circulation are not required with an electric water heater, you’ll save on venting and piping costs. And since there are no flues, you can locate the water heater almost anywhere in your home, freeing up closet and storage space. Even better, you can save energy by installing your water heater near where you use the most hot water—in the kitchen and bath.
• Economical – A family of four can have all the hot water they need for about $1.30* a day.
• Quiet & Clean – There’s no combustion noise, no fumes and no residue.

* Based on a family of four, with the following daily water heating schedule: 4 showers, 1 load of clothes, 1 load of dishes and 10 hand washes.

 

A. Geothermal heating and cooling offers the highest efficiency, greatest comfort, longest equipment life and lowest maintenance of any system available. Their advantages include:

• Energy Savings – Geothermal provides the most efficient source of heating and cooling available. Customers can save up to 50%* on their heating and cooling costs. Optional hot water units can be built-in to reduce domestic and pool water heating costs by up to 70%*.
• Greater Comfort – Geothermal ground source units provide the most consistent heating and cooling temperatures, thanks to the earth’s constant temperatures.
• Low Maintenance – Geothermal systems have fewer mechanical components and have no outdoor units, making them more reliable and less prone to failure. The ground loop has a projected life of over 50 years and requires no maintenance.
• Longer Life – Durability Geothermal closed loop systems last longer than other conventional systems because they are protected from the harsh outdoor weather. The total system is housed indoors and the loop is underground. This advantage is especially beneficial to coastal beachfront areas where salt spray corrosion occurs, reducing the normal life of the equipment.
• Quiet Operation – Geothermal ground source systems have no exposed, noisy outside units. The unit operates quietly to satisfy your needs without disturbing you or your neighbors.

* Source: Energy.gov

 

A. Surge Protectors listed under UL 1449 must meet more demanding standards. The requirements include: Thermal fuse protection, catastrophic overvoltage protection, ability to survive higher transient currents, and protection against shocks after the device fails. Look for a label that states “Listed TVSS” or is marked as “Transient Voltage Surge Suppressor.”

 

A. A home’s supply and return ducts are designed to be in balance, meaning that the amount of air supplied to the home is the same as the amount returned to the air handler, and the pressure inside the house is neutral. If either the supply or return ducts have air leaks, this balance is disrupted and the entire house pressure can be skewed. Studies show this pressure imbalance can increase infiltration up to 200% when the forced-air system operates. Most homes have leaks in the return ducts. And since most return ducts are located outside the conditioned space in the crawl space, basement, or attic, these leaks draw in outside air. This excess air increases the pressure in the home which forces conditioned air outside through cracks. The outside air drawn into the return ducts is hotter in summer and colder in winter than room air, so comfort drops and energy costs rise. Even when return ducts are located inside the house, they can draw in outside air. Often these ducts are hidden from view inside wall, floor, or ceiling cavities, but are not sealed.

If the supply ducts leak, then conditioned air is lost to the outside. Supply leaks create a negative pressure in the building which draws in outside air. This air, too, can be unhealthy and increases energy and moisture problems.

Homes usually have a combination of supply and return leaks as well as other duct problems. As a result, one area of the home may have a positive pressure while another has a negative pressure.

While pressure imbalances inside a home are bad, partially correcting duct leakage can also pose a risk. For example, equal supply and return leaks can balance each other such that the pressure in a home remains neutral. Sealing only some of the leaks can create a pressure imbalance. Of particular concern to human health is the quality of air drawn into the building by a leaky return duct. If a return duct leak is near a flue or chimney, it can draw combustion by-products into the house. Fixing return leaks without sealing supply leaks can also create an unsafe pressure imbalance. The best course is to ensure that both supply and return leaks are sealed and that the pressure inside the house is neutral.

 
Q. What does proper ventilation do?

Posted on August 2012

A. Proper ventilation controls heat and moisture buildup in attic, crawl space and uninsulated wall cavities. Good ventilation helps cool the house during hot weather and helps prevent structural damage caused by condensation in winter. Ventilation in attics and crawl spaces should not be blocked to reduce heat loss. Such blockages trap heat and moisture that can cause severe damage to the home’s structure.

 
Q. What does SIR stand for?

Posted on August 2012

A. Part of life cycle cost analysis, SIR stands for “savings to investment ratio,” and is a relative measure of cost-effectiveness. SIR represents the ratio of savings to investment. In terms of “net present value,” SIR would be the present value cost savings divided by the present value investment—accounting for additional operation and maintenance costs. Any alternative, when compared to the base case—the present value—that has an SIR greater than one is considered economically justified.

 

A. An energy investment’s simple payback period is the amount of time it will take to recover the initial investment in energy savings, dividing initial installed cost by the annual energy cost savings. For example, an energy-saving measure that costs $5,000 and saves $2,500 per year has a simple payback of 5000 divided by 2500, or two years. While simple payback is easy to compute, its weakness is that it fails to factor in the time value of money, inflation, project lifetime or operation and maintenance costs. To take these factors into account, a more detailed life-cycle cost analysis must be performed. Simple payback is useful for making ball-park estimates of how long it will take to recoup an initial investment.

 
Q. What is a geothermal system?

Posted on August 2012

A. Everyone knows it’s cooler underground in the summer and warmer underground in the winter. Geothermal systems take advantage of the earth’s constant temperatures to provide the highest efficiency available today. Special plastic piping is buried below the ground’s surface which allows heat to be transferred to and from the earth. Water is simply re- circulated to and from the underground piping where it is warmed by the earth in the winter and cooled by the earth in the summer. In order for any system to work properly, it must be sized, designed and installed correctly. Make sure your contractor is manufacturer-certified to install closed loop Geothermal systems.

 
Q. What is an air-change rate?

Posted on August 2012

A. The air-tightness of a home is often indicated by air-change rate—the number of times the home’s air changes over with outside air. For example, if the amount of air that enters and exits in one hour equals the total volume of the heated part of the house, the house is said to undergo one air change per hour. Air change rate is very difficult to pin down because it depends significantly on how the house is used, as well as the wind and temperature differentials it experiences during the year. Even if the rate were determined with some precision, which is established with a blower-door test, there is no assurance that value would apply under other conditions. For this reason, rough estimates are generally used when referring to a home’s air tightness.

The national average of air change rates, for existing homes, is between one and two per hour, and is dropping with tighter building practices and more stringent building codes. Standard homes built today usually have air change rates from .5 to 1.0. Extremely tight new construction can achieve air change rates of .35 or less. Most homes with such low air change rates have some form of mechanical ventilation to bring in fresh outside air and exchange heat between the two air streams.

To get an idea of what your home’s air change rate might be, consider that a tight, well-sealed newly constructed home usually achieves .6 air changes per hour or less. A reasonably tight, well-constructed older home typically has an air change rate of about 1 per hour. A somewhat loose, older home with no storm windows and caulk missing in spots has an air change rate of about 2. A fairly loose, drafty house with no caulk or weather-stripping and entrances used might have an air change rate as high as 4, and a very drafty, dilapidated house might have an air change rate of as high as 8.

 

A. Federal law requires that EnergyGuide labels be placed on all new refrigerators, freezers, water heaters, dishwashers, clothes washers, room air conditioners, central air conditioners, heat pumps, furnaces and boilers. These labels are bright yellow with black lettering. EnergyGuide labels for major appliances feature the estimated annual energy consumption, in kilowatt-hours per year (electric) or therms per year (gas). The estimated yearly operating cost is provided toward the bottom of the label. Each label provides the following information:

1. The manufacturer, model number, type of appliance, and capacity at the label’s top
2. How that particular model compares in energy efficiency with other models on the market of comparable size and type

For refrigerators, freezers, water heaters, dishwashers, and clothes washers, the range shows energy consumption in kWh/year or therms/year. The most efficient models will have labels showing energy consumption (“This Model Uses”), at or near the left-hand end of the range, close to the words “Uses Least Energy.”

For room air conditioners, central air conditioners, heat pumps, furnaces and boilers, the range is not energy consumption, but rather, the energy efficiency ratings for these products—EER, HSPF & SEER, and Annual Fuel Utilization Efficiency (AFUE), respectively. Therefore, labels on the most efficient models will show “This Model’s Efficiency” at or near the right-hand end of the range, close to the words “Most Efficient.”

The labels showing estimated annual energy consumption also show estimated annual operating costs, near the bottom of the label. This estimated cost is based on recent national average prices of electricity and/or natural gas, and assumes typical operating characteristics.

New furnaces and boilers must now carry EnergyGuide labels showing their annual fuel utilization efficiency (AFUE); past labels for this equipment only offered suggestions for conserving energy. EnergyGuide labels on heating and cooling equipment still refer customers to manufacturer’s fact sheets available from the seller or installer. These fact sheets give further information about the efficiency and operating costs of the equipment under consideration.

EnergyGuide labels are not required on kitchen ranges, microwave ovens, clothes dryers, demand-type water heaters, portable space heaters, and lights.

 

76 Expert Q&A