What is an Energy Recovery Ventilator (ERV)? Ultimate Resource

There are many types of heating, cooling, and ventilation systems for a home, and you may have heard of an ERV. What is an energy recovery ventilator (ERV)?

An energy recovery ventilator (ERV) is an efficient whole-house ventilation system that helps keep the air in your home healthy. It provides fresh air when you want it while minimizing energy loss from conditioned indoor air leaving your house.

The ERV’s true innovation lies in its ability to use the warm exhaust air from inside your home to preheat the incoming fresh air.

ERVs recover and return up to 95% of the energy used to condition outdoor air, making them 30-60% more efficient than traditional ventilation systems.

What is an Energy Recovery Ventilator (ERV)?

The ERV cools and dehumidifies the exhausted indoor air with a heat-exchange process that uses water as a working fluid.

The ERV then draws in fresh outdoor air, which is pre-cooled by the heat exchanger.

The ERV has a balanced design that provides the same supply of conditioned air to all areas of your home.

Related Article: An ERV can help reduce humidity levels in a home. Can High Humidity in a Home Cause Mold? Protect Yourself

Here are some common questions about ERVs:

Can I combine an ERV with my current heating and cooling system?

An energy recovery ventilator (ERV) can work with an existing heating, ventilation, and air-conditioning system.

The function of the existing equipment will change because an ERV supplies outdoor air to the HVAC system.

This can be beneficial if only one unit is required to heat or cool your home.

How big should an ERV be?

A typical home should have an ERV that is between 3,000 to 5,000 cubic feet per minute (cfm).

The size of the unit depends on many factors including the type of HVAC system the home has, how well-sealed your house is and how much heating or cooling you need.

If you are unsure of the size of ERV to select, a qualified HVAC contractor can help you determine the best system for your home.

Will adding an ERV increase my energy bills?

One of the most common questions about energy recovery ventilators (ERVs) is whether or not they will increase your energy bills.

The answer depends on many factors which are discussed in this article, including home size, number of occupants, types of appliances used in the house, and climate.

Related Article: Does Humidity Affect Hardwood Floors? Protect Your Investment

An ERV is not the same thing as a heat pump or air conditioner. Heat pumps and air conditioners transfer heat from one place to another (similar to how your refrigerator works).

ERVs recover waste heat, which makes them 30-60% more efficient than heat pumps and air conditioners.

Although ERVs are most frequently used in moderate climates, they work in all climates.

ERVs help control humidity levels by adjusting how much outdoor air is drawn into your home.

Too much humidity can be uncomfortable for some people, especially when the weather is warm.

ERVs help ensure your home is comfortable, even during extreme weather.

ERVs can be installed as part of a new construction project or added to an existing home.

How does an Energy Recovery Ventilator (ERV) Work?

OK, so now we know what an energy recovery ventilator (ERV) is. But how does an energy recovery ventilator work?

An energy recovery ventilator (ERV) works by providing continuous ventilation and replacement of stale air with fresh outdoor air. The indoor unit sends the dirty, moist air through metal ducts to the outdoor unit where it passes over plates that are cooled by the wind and rain.

The cool outdoor air causes water vapor to condense on the metal plates.

The moisture is collected and removed along with odors, heat, dust, and other contaminants that might be airborne.

Clean air is then recirculated back into the home through dedicated system ductwork.

Energy recovery ventilators (ERVs) are also known as Air-to-Air Energy Recovery Ventilation (A-AERV).

An energy recovery ventilator (ERV) is a type of mechanical ventilation that provides continuous outdoor air.

The air enters an intake and passes through a heat exchanger. If the home is cooler than the outside air, such as at night, the warm indoor air will pass over one set of metal plates.

The heat in the indoor air is transferred to the outdoor air passing over other cooler metal plates.

Clean air with low humidity, odors, and contaminants is then recirculated through dedicated system ductwork into the home.

The energy recovery ventilator (ERV) also traps heat from stale air that would otherwise escape out of the exhaust.

The heat energy is transferred to the next air mass that comes into the home, so it can be used instead of using electricity or gas to heat incoming outdoor air.

What is the Difference Between an HRV and an ERV?

HRVs and ERVs each have their own advantages. So what is the difference between an HRV and an ERV?

The difference between an HRV and an ERV is that an HRV (Heat Recovery Ventilator) is a type of ventilation system that captures indoor pollutants and odors, such as chemicals, pollen, and smoke particles. An ERV (Energy Recovery Ventilator) works on a similar principle as an HRV but also captures humidity.

The HRV uses an air-to-air heat exchanger to transfer energy from the stale exhausted indoor air to the incoming new supply air.

This process eliminates individuals’ exposure to the pollutants being exhausted from a home.

An HRV is commonly found in homes with forced-air heating systems.

A major distinction between the two appliances is that an ERV does not require ductwork.

Additionally, because an ERV does not transfer heat energy it is considered much more efficient.

One final difference between the appliances is that an HRV captures only particulate matter whereas an ERV captures both solid particles and water vapor molecules.

The latter makes them suitable for use in homes with humidifiers or dehumidifiers.

So if the issue is about the two devices then we can say that both of them are different types of ventilation systems.

Are Energy Recovery Ventilators (ERVs) Worth It?

An Energy Recovery Ventilator (ERV) is a smart and efficient way to conserve energy by recycling the same air in your home or business.

It helps you control climate issues while keeping utility costs low, but are they worth it?

It’s easy to see why an ERV would be beneficial on the surface – after all, recycling the same air means you’re not constantly replacing it and therefore removing waste.

However, there are a few factors to consider when trying to determine if an ERV would be beneficial for your particular needs.

For example, if you happen to live in an area that has particularly humid or moist weather then using an ERV may cause more harm than good, as it would be recycling already moist air and adding even more moisture to a space.

It’s also important to consider the level of insulation in your home. If you’re unsure, there are plenty of ways to test insulation levels.

If your home needs added insulation then an ERV may not be worth the initial investment if it will be used in a well-insulated space.

On the surface, an ERV does not sound like it would cost much to operate, but it’s important to keep in mind that running one comes with its own energy usage that must be taken into account when determining if the unit is truly worth the initial investment.

There are plenty of other factors to consider when determining if an ERV is right for you, but don’t let this deter you from giving it a second thought.

An ERV comes with its own set of pros and cons that should be considered alongside your other home comfort options.

How Long do Energy Recover Ventilators (ERVs) Last?

Energy recovery ventilation (ERV or ERVs) is a type of mechanical ventilation in which the heat energy from the outgoing exhaust air is transferred to the incoming fresh air via an air-to-air heat exchanger, substantially improving energy efficiency.

In an effort to improve indoor air quality, energy recovery ventilators are being installed in an increasing number of commercial buildings.

A properly maintained unit will provide many years of reliable service.

Due to the fact that ERVs are mechanical devices, they can be subject to failure at any point in time depending on maintenance and other factors.

However, the average lifespan is roughly 10 years.

It’s important to keep in mind that the “Lifespan” is influenced by many factors, such as climate, humidity levels, quality of electricity, etc.

• Outgoing air flow rate: the minimum airflow for efficient operation is about 600 CFM (cubic feet per minute).
  
• Size matters. Before setting up an Energy Recovery Ventilation system, it is important to know the heat and humidity loads in your home. Determining these factors will help determine the correct size unit that you need.
  
• There are three types of energy recovery ventilators: single-pass, multi-pass, and cross-flow. The choice of the type may determine the service life and maintenance requirements.
  
• ERVs are mechanical devices, so they can be subject to failure at any point in time depending on maintenance and other factors. The more often a unit is maintained, the longer it will last.
  
• Temperature and humidity can affect how long an Energy Recovery Ventilator lasts. Units in temperate climates, such as California or Italy, should last up to 16 years. whereas units operating in tropical environments may only get 8 years.
  
• The operating environment is another key factor in the average lifespan of an energy recovery ventilator. A unit will last nearly twice as long if it’s used in a commercial application versus residential use.
  
• Other factors – Depending on the installation, airflow or lack thereof can affect how long your Energy Recovery Ventilation system lasts. The more open the building is, the easier it will be for your unit to exchange air with fresh outside air.

Benefits of an Energy Recovery Ventilator

An energy recovery ventilator (ERV), which is essentially an air-to-air heat exchanger that recovers sensible and latent energy from one airstream to another, can be used in residential homes to improve indoor air quality by supplying fresh outdoor air while also decreasing the heating or cooling load.

It offers several other benefits as well.

The energy used to provide the heating or cooling of an indoor space is usually produced by burning fuel, which releases gaseous emissions.

These emissions can escape into the outside air or recirculate within the building, depending on how systems are designed.

Either way, these gases can pollute indoor air quality by making it less breathable.

ERVs have an integrated heat exchanger, which collects sensible heat from one airstream and transfers it to the other, increasing the overall quality of indoor air.

Because fresh outdoor air is introduced into a home or building through ERVs, these devices also help improve energy efficiency by lowering energy consumption for heating and cooling, as more exhaust gas is not being used.

Additionally, the use of ERVs in buildings reduces energy demand by lowering the air conditioning load required to maintain acceptable indoor conditions during the summer months.

Finally, the constant replacement of outdoor air with fresh air helps eliminate odors and keep humidity levels low, preventing moisture problems such as mold growth that can result from excess moisture in the air.

An energy recovery ventilator, or ERV, is an efficient way to assure indoor comfort without excessive heating or cooling costs.

Reduced energy demand also lowers the carbon footprint of a building, thus benefitting the environment as well.

How Much Does an Energy Recovery Ventilator (ERV) Cost?

The average cost of an energy recovery ventilation system for a 3,000-square-foot home with two bathrooms is $2,500. The price varies according to the size of the home and the number of bathrooms.

What is Better, an HRV or an ERV?

An HRV (heat recovery ventilator) and an ERV (energy recovery ventilator) both increase the quality of air in a room.

The difference between them is that an ERV can recover more energy and therefore improves indoor environmental quality more than an HRV can.

An HRV can recover about 70% of heat from air exhausted from a room while an ERV can recover up to about 90%.

For this reason, if someone is concerned with improving indoor air quality more than energy savings, they would want to purchase an ERV.

Trina Greenfield, Author
SmackDown Media LLC
LinkedIn

About the Author:
Trina Greenfield, the owner of SmackDown Media LLC, is passionate about providing information to those interested in the air quality in and around their homes. Trina writes content about things she’s passionate about, such as safe, in-home air, educational platforms for children and adults, as well as all things family-related.