What Is It and How Does It Work?

There are many different types of heating, ventilation, and air- conditioning (HVAC) systems that you can choose from for your home. Heating and cooling account for about 50 percent of energy used on average in a U.S. home, so choosing the right kind of HVAC system can mean big cost and energy savings. It is especially important to view your HVAC system comprehensively. It is more than just the mechanical equipment that you have installed outside, but also includes ductwork, thermostats, supply and return registers, and more. All of these components need to be maintained in order to capitalize on the efficiency of a new heating and cooling system. Ducts must be properly insulated and sealed, thermostats should be set at appropriate temperatures, and other components regularly monitored and serviced. 

Types of HVAC Systems:

AC: Central air conditioners cool your entire home and are more efficient; however, room air conditioners are less costly to install and operate if you only need a few rooms cooled. For room air conditioners, consult Energy  Star sizing guidelines to make sure that your system operates at maximum efficiency.   If you are unsure as to what cooling system would be best for your home, a heating and cooling contractor can perform several calculations to determine which system is best for you.

Circulating fans: Ceiling fans and other kinds of circulating fans create a wind-chill effect by moving air through the rooms in your home. Fans can make your home more comfortable even if it is also cooled with natural ventilation or an air conditioner. Although the fan does not make the circulating air any cooler, the increased air movement across your skin causes evaporation, which creates a perceived cooling effect.

Heat Pumps: An electric air- source heat pump is an efficient tool for both heating and cooling that is most effectively used in moderate climates. Air- source heat pumps can be integrated into your home’s heating and cooling system much like conventional HVAC – either distributing conditioned air through ducts, or in a ductless system – but are much more efficient than conventional HVAC systems because instead of using fuel to either heat or cool air inside your house, heat pumps simply move heat either into or out of your house (depending on the season). Because they move heat, rather than generate it, heat pumps can provide four times as much energy as they use.

Water Heating
Furnace
Space Heaters
Natural Gas

Why Should I Consider It?

If your current HVAC system is getting old, replacing it with an Energy Star– certified system can help you start saving money and energy. Energy Star– qualified heat pumps and air conditioners can use up to 20 percent less energy than standard new models. If your existing system requires frequent maintenance or if you have noticed your energy bills going up, you are probably ready for a new system that can start saving on maintenance and energy bills right away.

Inconsistent heating or cooling patterns from room to room may be a sign of leaky ducts or poor insulation. You may think of your ductwork and insulation as separate from your air- conditioning or heating unit, but they all work together to keep your home comfortable, so you should think of them as a system. A great way to control that system is with a programmable thermostat. You can save money by setting the thermostat at different settings when you are away from home or asleep.

There are other factors that may signal a need for a new HVAC system, such as humidity and dust problems. Inadequate ventilation caused by leaky ducts or malfunctioning equipment can lead to dry air in the winter or moist air in the summer. Leaky ducts and dirty filters can also spread excess dust particles throughout your home.

What Are the Options?

Your options for installing a new HVAC system will depend somewhat on what your current system is. The easiest kind of upgrade is to simply replace your existing HVAC system components with new models of the same type. Replacing an air- conditioning unit, furnace, or boiler with an Energy Star –labeled upgrade is one good way to improve the energy efficiency of your home. However, you should consider whether upgrading your existing system will provide the best cost- benefit ratio versus seeking out a new, higher efficiency system.

The options, if you are considering a full replacement, are broad, and the factors that you should consider include the fuel sources available (electric, natural gas, etc.), the type of distribution (ducts or room units), costs (purchase, installation, and maintenance), efficiency, and sizing. Your local utility company can provide you with rates and availability of different types of fuel sources. If your existing HVAC system uses central air conditioning with ductwork, it could make sense to make use of that existing infrastructure – but make sure you also seal and insulate your current ducts. If your current system does not use ducts, you could consider adding a centralized system with ducts if cost and installation are reasonable. If not, baseboard hot water heaters and room air conditioners or heat pumps may be better options. Also, don’t neglect the opportunity to use free heating and cooling resources from the wind and sun. If you live in a moderate climate, simply opening the windows for cross ventilation can remove heat that has built up inside your house. On clear, cool days, opening your window shades on south-facing windows can bring warmth from the sun into your home and reduce the strain on your HVAC system.

Correct sizing of your HVAC system is critical to optimizing the efficiency of whichever system you choose. Factors to consider include climate, size and shape of your home, amount of insulation, window size and type, infiltration rates, number of occupants, time of occupancy, and the types of other heat-generating appliances. Your contractor should use an accurate sizing calculation and should show you the results as part of his or her bid – and don’t sign a contract until you know the details. The Air Conditioning Contractors of America (ACCA) has created two separate guides to HVAC sizing and ductwork design (Manual J and Manual D). Your contractor’s bid should be based on calculations using these forms.

No matter what type of system you end up selecting, keep in mind that it will only operate as effectively as possible if you consider the energy efficiency of your entire home, including windows, insulation, lighting, and the potential to integrate passive heating and cooling strategies.

How Is It Installed?

Each type of HVAC system has different installation requirements. Before you make a decision on what type of system to use, make sure the installation is compatible with your home. If you can integrate ductwork into your attic, floors, or dropped ceiling, a centralized system could provide the most efficient solution. If you do not have the option to add ducts, use a room-based system instead.

What Are the Potential Benefits?

The benefits of installing a new HVAC system range from greater thermal comfort to lower energy bills. A properly installed HVAC system with a programmable thermostat can keep all of the rooms in your house at comfortable temperatures and adequately ventilated for a lower cost than an outdated or improperly installed system.

Are There Health and Safety Concerns?

It is important to remember that your HVAC system does more than just heat and cool your home, it also provides ventilation. If your home is inadequately ventilated, moisture problems can develop that may lead to mold, so make sure you keep filters clean and replace them when necessary.

How Much Does It Cost?

Each type of HVAC system has a different set of cost implications. Check the Energy Ideas Fact Sheets for the systems that you are considering in order to get a detailed sense of how much you should expect to spend, what the cost premium will be for energy-efficient products, and how quickly these initial higher costs will be repaid due to energy savings.

There are several online tools that you can use to calculate the long-term energy cost savings that you can expect to receive by choosing energy-efficient HVAC equipment:

Lawrence Berkeley National Laboratory Home Energy Saver
Energy Experts

What Else Should I Know?

When considering your options for HVAC systems, remember to maximize energy efficiency for the whole house. Even a high- performance HVAC system will operate inefficiently in a poorly insulated, leaky home.

Where Do I Start?

The first step is to find out what your current HVAC system is, how old it is, and whether it is operating efficiently. You may already have an Energy Star HVAC system that just needs proper maintenance or service in order to save money and energy. If you decide that you do need an upgrade.

Where Can I Get More Information?

Energy Ideas Incentives Database

Department of Energy
Energy Star
Lawrence Berkeley National Laboratory Home Energy Saver