Do-It-Yourself Home Energy Audits, Part 3: Inspecting HVAC Equipment


Conducting a four-part do-it-yourself home energy audit can help you find ways to cut cooling costs and lower your energy bills this summer. Once you’ve completed the first two parts of a DIY home energy audit — detecting and sealing air leaks and checking your home’s insulation — you’re ready to move on to part three: inspecting your HVAC equipment.

The efficiency of your home’s air conditioning system, also known as heating, ventilation and cooling (HVAC) equipment, plays a critical role in your ability to cool your home and maintain your comfort during hot summer days while keeping electricity bills from breaking the bank. To help your AC system run as efficiently as possible, you’ll need to inspect your equipment, check for leaks in your ductwork and insulate your ducts.

Inspect Your HVAC Equipment

It’s important that you inspect your HVAC equipment at least once a year. Twice a year — once before summer and once before winter — is ideal. For a summertime checkup, you’ll want to focus on your AC system.

AC Air Filters

Checking air filters and changing them out when they’re dirty is the most important maintenance task you can perform for your AC system:

  • Clogged or dirty air filters restricts normal air flow, which can make your AC system work harder to cool your home
  • Dirt that bypasses an air filter can make its way to the evaporator coil where it can reduce the coil’s ability to absorb heat
  • Clean air filters can lower your energy consumption by 5–15 percent

For central AC systems, air filters are generally located somewhere along the return duct. Filter locations can include walls, ceilings, furnaces or the air conditioner itself. If you have a room air conditioner, the filter will be mounted in the grill facing into the room.

You should clean or replace your AC system’s air filters every month during the hottest summer months, when you run your AC a lot, and about every month or two during months in which you run your AC less frequently.

AC Coils

Your AC system’s evaporator coil and condenser coil will collect some dirt over time. Even if you change out your air filters regularly, the evaporator coil will eventually collect dirt over months and years of service. Dirt that does collect will reduce air flow and insulate the coil, which will in turn reduce the coil’s ability to absorb heat. Outside condenser coils can also become dirty over time, especially if the outdoor environment is dusty or you have a lot of foliage around your unit.

Fix problems by cleaning your evaporator coil once a year before peak summer months and keeping dirt and debris near your condenser coil to a minimum. For best results, keep the area around the condenser coil clear of debris and trim foliage back at least 2 feet to allow for adequate air flow.

Coil Fins

The aluminum fins on evaporator and condenser coils can bend easily when you’re cleaning the coils, which can result in blocked air flow. Make sure to take care when cleaning your coils and consider using a fin comb (supplied by AC wholesalers) to remove dirt from the coils.

Condensate Drains

To clean your condensate drain, which can clog with dirt and debris and prevent an efficient reduction in humidity, pass a stiff wire through the unit’s drain channels. For best results, clean your condensate drains every two months.

Checking for Duct Leaks

Leaky ducts can reduce the efficiency of the air flow through your AC system and can also introduce dirt to the air flow after air has already passed through the system’s air filters. The best way to find out if your air ducts are leaking is to inspect them for dirt streaks, especially near the seams. Dirt streaks indicate air leaks. Thankfully, you can seal them easily enough with duct mastic.

Insulating Air Ducts

Insulating air ducts is a good, affordable way to preserve cooled air as it passes through ducts, especially ducts that maneuver their way through uncooled parts of your home, like your attic. Insulated air ducts will also help maintain heated air as it passes through the ducts in the cold winter months. When insulating your air ducts, make sure to use insulation with an R-value of 6 or above.

Do-It-Yourself Home Energy Audits: Air Leaks, Insulation and Lighting

Make sure to read up on the other steps involved in a four-part DIY home energy audit:

There are four steps to a fairly comprehensive do-it-yourself home energy audit. Here are the other three parts, in case you need to review them or if you missed one earlier:

Part 1: Detect Air Leaks

Part 2: Check Insulation

Part 3: Inspect HVAC Equipment

Part 4: Lighting


U.S. Department of Energy, Energy Efficiency & Renewable Energy, “Do-It-Yourself Home Energy Assessments.”

U.S. Department of Energy, Energy Efficiency & Renewable Energy, “Maintaining Your Air Conditioner.”

How to Choose, Install and Operate a Room Air Conditioner

Wednesday August 17, 2011
Posted at 08:15

Steps for choosing an energy efficient window air conditioning unit

Room air conditioners, also known as window air conditioners, can be a good choice when it comes to cooling one room at a time, especially if a central air conditioner isn’t needed. Here’s some helpful advice for choosing, installing and operating a room air conditioner.

The Truth About the Energy-Efficiency of Room Air Conditioners

In the past, room air conditioners have had a reputation for being inefficient when it comes to using energy. However, that reputation is no longer deserved according to the Association of Home Appliance Manufacturers, which reports that the average energy efficiency of room air conditioners increased 47 percent from 1972 to 1991. Now, although slightly less efficient than central air conditioners overall, room air conditioners do a more efficient — and cheaper — job of cooling individual rooms than their central air conditioner counterparts.

A room air conditioner’s energy efficiency is measured by its energy efficiency ratio (EER), which is the ratio of cooling capacity (measured in British thermal units [Btu] per hour) to the power input (measured in watts). The higher the EER, the more efficient the unit is.

Federal standards require room air conditioners to have an EER between 8.0 and 9.8 or greater, depending on the type and capacity of the unit. ENERGY STAR–certified units have even higher EER ratings. An older room air conditioner from the 1970s might have an EER of 5. If that unit were replaced with a new room air conditioner with an EER of 10, air conditioning energy costs would be cut in half.

Selecting the Right Room Air Conditioner

When shopping for a room air conditioner, the U.S. Department of Energy recommends new ENERGY STAR–certified room air conditioners that meet the following specifications:

Energy efficiency —New units should have EERs of 10 or above.

Size — A new room air conditioner needs to be able to meet your cooling capacity requirements. Cooling capacities are measured in Btu per hour, and generally range from 5,500 Btu per hour to 14,000 Btu per hour. A ton, a common rating term for cooling capacity, equals 12,000 Btu per hour. Each square foot of room space to be cooled needs about 20 Btu per hour of cooling capacity. So, to find the correct starting point for the size of your unit, multiply your square footage by 20. The result is the necessary Btu per hour rating of your unit. However, other factors to consider when selecting the size of a unit include room height, climate, shading and window size.

Electrical system requirements — Room air conditioners operate on either 115-volt or 230-volt circuits. The standard home uses a 115-volt circuit. Shoppers need to verify the power requirements of room air conditioners and consult with an electrician if necessary to determine if they need a dedicated circuit for large 115-volt unit or a special circuit for a 230-volt unit.

Special installation concerns — If a room air conditioner is to be installed at the far end of a narrow room, shoppers should look for a fan control known as “Power Thrust” or “Super Thrust” that does a better job of sending the cooled air across the room.

Other features to look for — Shoppers should also consider units that come with a slide-out filter for regular cleaning, a digital readout for the thermostat and a built-in timer.

Installing a Room Air Conditioner

There are a couple of things to consider when installing a room air conditioner. Make sure that the unit is level so that the interior drainage system and other parts of the unit operate as efficiently as possible. Additionally, try to install the unit in a shaded spot on a home’s north or east side so that the unit receives little direct sunlight. Direct sunlight can decrease the energy efficiency of room air conditioners by up to 10 percent. To help, consider planting trees or shrubs to provide shade, but make sure they don’t obstruct air flow around the unit.

Operating a Room Air Conditioner

To operate a room air conditioner efficiently, follow these simple guidelines:

- Set the unit’s thermostat as high as possible during the summer to save money on electric bills.
- Don’t set the thermostat to a colder temperature than is needed. Doing so won’t cool a room faster but can lead to excessive cooling and higher bills.
- Set the fan speed on high, except for on humid days. When humidity is high, a low fan speed will do a better job of removing the moisture form the air.
- Don’t place appliances that give off heat, like televisions and lamps, near room air conditioners. Heat from the appliances can trigger the thermostat into thinking the room is warmer than it is and cause the unit to run longer, which will result in higher energy bills.
- Use an interior fan to help more evenly spread the cooled air from the room air conditioner throughout the space without significantly increasing electricity use.

U.S. Department of Energy: Energy Savers website, “Room Air Conditioners.”

Tips for Supervising the Installation of a New Central Air Conditioner

Monday August 8, 2011
Posted at 08:18

A new, energy-efficient central air conditioner can help you save money off monthly utility bills. In fact, a new air conditioner uses about 30 percent to 50 percent less energy than models manufactured in the mid 1970s and 20 percent to 40 percent less energy than models manufactured just 10 years ago.

If you’re considering buying a new central air conditioner, it’s important to understand how one should be properly installed. After all, a new, energy-efficient central air conditioner isn’t cheap, and when it comes to the performance, lifespan and energy efficiency of your air conditioner, quality installation is just as important as the actual air conditioner itself. In fact, a brand new, energy-efficient air conditioner that’s improperly installed can perform as poorly as the old model you’re looking to replace.

When you’re having a new air conditioner installed, make sure your contractor performs the following procedures:

- Locates the outdoor condensing unit where the noise will not keep you or neighbors awake at night, where the unit will be free of obstructions that might block air flow to it and where it will be in shade, if possible. A shaded condensing unit can save you 1 percent to 2 percent off cooling costs.
- Makes sure there are enough supply and return air registers to deliver cooled air throughout the house and return the warmed air back to the air conditioner.
- Allows enough indoor space for installation, maintenance and repair of all system components.
- Makes sure an access door is installed in the furnace or duct so that the evaporator coil can be cleaned.
- Sizes air ducts properly using industry-standard methodology such as the Air Conditioning Contractors of America (ACCA) Manual D.
- Installs air ducts within the air conditioned space and not in a hot attic whenever possible.
- Ensures that all ducts are sealed with duct mastic and, in the case of attic ducts, heavily insulated.
- Locates the thermostat away from sources of heat.
- Primes the air conditioner with the precise refrigerant charge and sets the exact air flow rate as specified by the air conditioner manufacturer.

Ensuring that these installation procedures are followed is an important part of getting the most comfort and energy-efficiency from your new central air conditioner. If the procedures are followed properly, you can expect from 15 to 20 years of quality, low-maintenance operation from you new air conditioner.


U.S. Department of Energy: Energy Savers website, “Central Air Conditioners.”

How to Buy a New, Energy-Efficient Central Air Conditioner

Friday August 5, 2011
Posted at 08:17

A few tips for buying a new energy-efficient air conditioner

Central air conditioning systems can last from 15 to 20 years. Sticking with an older unit may be less expensive in the short run, but not when it comes to helping you save money off monthly utility bills. Here’s some information to help you make a better decision when it comes time to get a new, energy-efficient central air conditioner.

A Few Facts on Air Conditioning and Energy-Efficiency

If you’re wondering whether it’s time to replace or upgrade your central air conditioning system, here are a few facts that might help:

- In the average air-conditioned U.S. home, air conditioners use more than 2000 kilowatt-hours of electricity per year.
- Producing the electricity needed to air condition the average U.S. home causes the average power plant to emit about 3500 pounds of carbon dioxide and 31 pounds of sulfur dioxide per year.
- The most energy-efficient air conditioners on the market today consume 30 percent to 50 percent less energy than models manufactured in the mid 1970s.
- Even if your air conditioner is just 10 years old, upgrading to a new energy-efficient air conditioner could save you from 20 percent to 40 percent off your cooling costs.

The Two Types of Central Air Conditioners

If you decide to replace or upgrade your central air conditioning system, the first thing you’ll need to know is whether you have a split-system central air conditioner or a packaged central air conditioner.

Split-system central air conditioners are made up of an outdoor metal cabinet containing the condenser and compressor and an indoor cabinet containing the evaporator, which in many split-system air conditioners, also contains a furnace or the indoor part of a heat pump.

Packaged central air conditioners contain the evaporator, condenser and compressor in a single outdoor metal cabinet, usually placed on a concrete slab next to a home’s foundation. From the cabinet, air supply and return ducts enter a home through its exterior wall and connect to a series of internal supply and return ducts in order to circulate cool air throughout a home. Packaged air conditioners usually include a natural gas furnace or electric heating coils and eliminate the need for a separate indoor furnace.

If your home already has a furnace but no air conditioner, then installing a split-system air conditioner is the most economical choice.

How to Judge the Energy Efficiency of a New Central Air Conditioner

When shopping for an energy-efficient central air conditioner, you’ll need to research a system’s seasonal energy efficiency ratio, or SEER, which indicates how much energy a model uses to produce a specific cooling output. If you have an older system, chances are it has a SEER rating of 6 or less.

Since Jan. 23, 2006, models have been required by the Environmental Protection Agency to have a minimum SEER rating of 13, which require 30 percent less energy to run than models manufactured with the previous minimum SEER rating of 10.

The most energy-efficient central air conditioners on the market today are ENERGY STAR–certified with SEER ratings greater than 13.

Tips for Buying a New Central Air Conditioner

Buying a new central air conditioning system doesn’t have to be intimidating. Here are a few tips on what you should look for in a new system:

- Size matters when it comes to a new central air conditioner. If your unit is too small, it will have to work too hard to cool your home, which can result in higher electric bills and damage to components. It may not even be able to reach comfortable temperatures on hot days. If your unit is too big, it will cycle on and off too quickly, which will prevent the unit from removing humidity from the air and can also damage components. Only a right-sized unit will provide the performance, operating life and energy efficiency you expect. Know your home’s square footage and consult with an HVAC contractor before you make a purchase.
- Partial replacement may not be ideal. Although you can replace the outdoor compressor on an older model with a modern, high-efficiency unit, you should consult a local HVAC contractor to make sure that the compressor is properly matched to the rest of the older system. Even if it is, changes in refrigerants and air conditioning designs over the years usually mean it’s a wiser decision to replace the entire system.
- Look for an air conditioner with an EER rating of 11.6 or greater. An air conditioner’s EER rating is different from its SEER Rating. EER is an air conditioner’s thermal expansion valve and a high-temperature rating and determines how efficiently the unit runs when the weather is at its hottest.
- Make sure the system runs quietly.
- Look for systems that have a variable speed air handler for new ventilation systems, an automatic-delay fan switch that turns off the fan a few minutes after the compressor turns off and a fan-only switch so you can take advantage of nighttime ventilation that can significantly reduce cooling costs.
- Find a system that has a check filter light to remind you to inspect the filter after a certain number of operating hours.

Ideal Thermostat Settings for Combining Comfort with Savings

Here are some tips for the best thermostat settings in the summer and winterRunning your air conditioner too much during the summer and your heater too much during the winter can end up costing you a lot of money. But following these simple rules can help ensure that you’re comfortable when you need to be while saving money off your residential electric bills.

Save About One Percent off Your Electric Bill for Each Degree of Setback

You should allow your home to get warmer during the summer and cooler during the winter when you’re not home. Setting your thermostat back 10–15 degrees for 8 hours a day can save you about 5 percent to 15 percent on your electric bill for the year, or about one percent for each degree of setback.

Preferred Summer Thermostat Settings

When you’re home, set your thermostat to 78 degrees.

When you’re away at work or know you’ll be gone for a while, raise your thermostat temperature to around 88 degrees.

Preferred Winter Thermostat Settings

When you’re home, set your thermostat to 68 degrees.

When you’re away at work or know you’ll be gone for a while, decrease your thermostat temperature to around 58 degrees.

Use a Programmable Thermostat

Programmable thermostats can help you easily and conveniently manage your home and away temperature settings by setting up a schedule. In the winter, a programmable thermostat can lower the temperature just after you leave and warm it back up right before you return. Likewise, in the summer, it can allow the temperature to increase after you leave and lower it back down to a comfortable level before you arrive home.


Energy Savers website, “Thermostats and Control Systems.”

5 Ways to Keep Cool Without Your Air Conditioner

Thursday May 19, 2011
Posted at 08:18

Five ways to keep cool without air conditioning

The vast majority of U.S. homes — 84 percent, to be exact — use air conditioners. And air conditioners can be a big expense when it comes to paying your bills. While you may be able to buy cheaper electricity by switching to an alternative retail electricity supplier, you can also reduce your electricity bills by simply using your air conditioner less often. To help, we’ve put together a list of five ways you can keep cool while using your air conditioner less often.

1. Use Windows and Shades Smartly

The way you use your windows and shades can play a big role in helping keep your home cool without using your air conditioner, or at least using it a lot less:

- Open your windows at night if it’s cooler outside than inside so that the house can cool naturally while you’re sleeping.
- In the morning, close all windows and shades on the east side of your home, but leave open the windows and shades on the west side of your home — the ones that are in the shade — to continue cooling your home for a little while longer.
- If you live in a cool climate, switch in the afternoons — open the windows and shades on the east side while closing those on the west side. Otherwise, close all windows when the outside temperature warms in order to capture the cool air already in your home.

2. Circulate Air with Ceiling and Floor Fans

Running ceiling fans can make the ambient air temperature in a room feel up to four degrees cooler; floor fans can also help a lot:

- Make sure to run ceiling fans counterclockwise so they push air down from the ceiling to cool you with a “wind chill effect” which, in turn, forces cooler air along the floor back up toward the ceiling.
- When running a floor fan, place a bucket of ice in front of it. As the warm air runs over the top of the bucket, it’s cooled by the evaporating ice. The process is just like an air conditioner, only a lot cheaper.
- If you run a floor fan in tandem with a ceiling fan, place the floor fan in a corner, with the bucket of ice, and let the cooled air blow into the center of the room, where it can be pulled to the ceiling and become part of the circular cooling effect.

3. Replace Your Hot Light Bulbs

Incandescent light bulbs get really warm and contribute to increased temperatures in your home. So, too, can energy-efficient halogen lights, which can get blisteringly hot. To help, change out your incandescent and halogen bulbs for compact florescent light (CFL) bulbs or light emitting diode (LED) bulbs, which not only save energy, but operate with very little heat. In fact, LEDs are about 25 times cooler than an incandescent bulb.

4. Paint Your Roof White

It may sound silly, but painting your roof white will prevent a lot of the sun’s heat energy from radiating into your attic and down into your living space. While black and dark colors, like those of many roof shingles, are great radiators — which means they allow heat to easily pass through — light colors like white are really bad radiators, which means heat has a harder time passing through.

Painting roofs white is becoming a common option to keep heat out of homes in places like New York, California, and Hawaii. White roofs can cut air conditioning costs by as much as 20 percent and Steven Chu, the U.S. Secretary of Energy, even says that white roofs can help with global warming by reflecting the sun’s light back into space.

5. Seal Windows and Doors and Insulate Your Attic

All these ideas for making and keeping cool air in your home without using your air conditioner won’t amount for much if the cool air escapes through cracks in doors and windows or out into your attic. But there are a few easy things you can do to effectively seal the cool air inside your home and make the rest of these tips really count:

- Perform a few simple tests to determine where your home is leaking air. Then grab some weather stripping and caulk and seal off the offending areas.
- In order to prevent cool air from escaping into your attic and warm air from radiating down into your living space, increase the insulation in your attic.

To get even more ideas for things you can do to keep your home cool without using your air conditioner, consider a home energy audit for a more thorough, professional account of how your home uses energy.


eHow website, “How to Cool Your Home Without Air Conditioning.”

Yahoo! Green website, “14 Ways to Keep Cool in Your Home Without Air Conditioning.”

Huffpost Green website, “8 Ways To Keep Cool Without Air Conditioning.”

White Roofs Catch On as Energy Cost Cutters,” The New York Times, July 29, 2009.

Saving Money by Keeping Your AC Filters Clean

Thursday May 5, 2011
Posted at 08:17

Change your air conditioner filter frequently

Like any piece of machinery, an air conditioning system needs regular maintenance if it’s to perform at peak efficiency. The most important maintenance you can provide for your air conditioning system is changing or cleaning its air filters. Clogged or dirty air filters can block air flow and impair an AC system’s efficiency, and dirty air that gets past a filter can be carried into the evaporator coil and reduce the coil’s ability to absorb heat and cool your home.

Whether you have central air conditioning or room air conditioners, keeping the air filters clean can lower your AC unit’s electricity use by 5 percent to 15 percent, according to the U.S. Department of Energy. And since cooling your home is a big source of energy consumption, keeping your AC filters clean can help save money on your monthly electric bill.

Types of Air Conditioner Air Filters

There are several different kinds of air filters for AC units. Central and room AC units typically use washable or disposable filters. Disposable fiberglass filters are the cheapest, but usually the least effective at keeping out dust, particles and microorganisms. Washable filters can often be a step up in terms of quality, but need regular bi-weekly maintenance to keep them going strong.

Location of Air Conditioner Air Filters

Air filters for central AC units will typically be found along the length of the return duct, in a wall, ceiling, furnace, or even in the AC itself. The filter for room AC units is mounted in the grill facing into the room.

Changing and Cleaning AC Filters

Disposable AC filters will need to be changed every month or two during the cooling season, or more often if you run your AC a lot. For best performance, washable AC filters should be cleaned every two weeks by letting them soak for an hour in a tub or basin filled with a solution of one part water and one part vinegar. Washable AC filters should be changed out every three to six months, depending on how much you use your AC unit.


Energy Savers website, “Maintaining Your Air Conditioner.”

Air Conditioning Filters website, “The Importance of Maintaining Air Conditioner Filters.”