Energy recovery ventilation is the energy recovery process of exchanging
Energy recovery ventilation is the energy recovery process of exchanging

the energy contained in normally exhausted building or space air and
the energy contained in normally exhausted building or space air and

using it to treat the incoming outdoor ventilation air in residential and
using it to treat the incoming outdoor ventilation air in residential and

commercial HVAC systems. During the warmer seasons, the system pre-cools and
commercial HVAC systems. During the warmer seasons, the system pre-cools and

dehumidifies while humidifying and pre-heating in the cooler seasons. The
dehumidifies while humidifying and pre-heating in the cooler seasons. The

benefit of using energy recovery is the ability to meet the ASHRAE ventilation &
benefit of using energy recovery is the ability to meet the ASHRAE ventilation &

energy standards, while improving indoor air quality and reducing total HVAC
energy standards, while improving indoor air quality and reducing total HVAC

equipment capacity. This technology has not only
equipment capacity. This technology has not only

demonstrated an effective means of reducing energy cost and heating and
demonstrated an effective means of reducing energy cost and heating and

cooling loads, but has allowed for the scaling down of equipment. Additionally,
cooling loads, but has allowed for the scaling down of equipment. Additionally,

this system will allow for the indoor environment to maintain a relative
this system will allow for the indoor environment to maintain a relative

humidity of 40% to 50%. This range can be maintained under essentially all
humidity of 40% to 50%. This range can be maintained under essentially all

conditions. The only energy penalty is the power needed for the blower to
conditions. The only energy penalty is the power needed for the blower to

overcome the pressure drop in the system.
overcome the pressure drop in the system.

Importance Nearly half of global energy is used in
Importance Nearly half of global energy is used in

buildings, and half of heating/cooling cost is caused by ventilation when it is
buildings, and half of heating/cooling cost is caused by ventilation when it is

done by the "open window" method according to the regulations. Secondly,
done by the "open window" method according to the regulations. Secondly,

energy generation and grid is made to meet the peak demand of power. To use
energy generation and grid is made to meet the peak demand of power. To use

proper ventilation recovery is a cost-efficient, sustainable and quick
proper ventilation recovery is a cost-efficient, sustainable and quick

way to reduce global energy consumption and give better indoor air quality and
way to reduce global energy consumption and give better indoor air quality and

protect buildings and environment. Methods of transfer
protect buildings and environment. Methods of transfer

An energy recovery ventilator is a type of air-to-air heat exchanger that not
An energy recovery ventilator is a type of air-to-air heat exchanger that not

only transfers sensible heat but also latent heat. Because both temperature
only transfers sensible heat but also latent heat. Because both temperature

and moisture are transferred, ERVs can be considered total enthalpic devices.
and moisture are transferred, ERVs can be considered total enthalpic devices.

On the other hand, a heat recovery ventilator can only transfer sensible
On the other hand, a heat recovery ventilator can only transfer sensible

heat. HRVs can be considered sensible only devices because they only exchange
heat. HRVs can be considered sensible only devices because they only exchange

sensible heat. In other words, whereas all ERVs are HRVs, not all HRVs are
sensible heat. In other words, whereas all ERVs are HRVs, not all HRVs are

ERVs, but many people use the terms HRV, AAHX, and ERV interchangeably.
ERVs, but many people use the terms HRV, AAHX, and ERV interchangeably.

Throughout the cooling season, the system works to cool and dehumidify the
Throughout the cooling season, the system works to cool and dehumidify the

incoming, outside air. This is accomplished by the system taking the
incoming, outside air. This is accomplished by the system taking the

rejected heat and sending it into the exhaust airstream. Subsequently, this
rejected heat and sending it into the exhaust airstream. Subsequently, this

air cools the condenser coil at a lower temperature than if the rejected heat
air cools the condenser coil at a lower temperature than if the rejected heat

had not entered the exhaust airstream. During the heating seasons, the system
had not entered the exhaust airstream. During the heating seasons, the system

works in reverse. Instead of discharging the heat into the exhaust airstream, the
works in reverse. Instead of discharging the heat into the exhaust airstream, the

system draws heat from the exhaust airstream in order to pre-heat the
system draws heat from the exhaust airstream in order to pre-heat the

incoming air. At this stage, the air passes through a primary unit and then
incoming air. At this stage, the air passes through a primary unit and then

into a space. With this type of system, it is normal, during the cooling
into a space. With this type of system, it is normal, during the cooling

seasons, for the exhaust air to be cooler than the ventilation air and,
seasons, for the exhaust air to be cooler than the ventilation air and,

during the heating seasons, warmer than the ventilation air. It is for this
during the heating seasons, warmer than the ventilation air. It is for this

reason the system works very efficiently and effectively. The Coefficient of
reason the system works very efficiently and effectively. The Coefficient of

Performance will increase as the conditions become more extreme.
Performance will increase as the conditions become more extreme.

Efficiency The efficiency of an ERV system is the
Efficiency The efficiency of an ERV system is the

ratio of energy transferred between the two air streams compared with the total
ratio of energy transferred between the two air streams compared with the total

energy transported through the heat exchanger.
energy transported through the heat exchanger.

With the variety of products on the market, efficiency is unquestionably
With the variety of products on the market, efficiency is unquestionably

going to vary from product to product. Some of these systems have been known to
going to vary from product to product. Some of these systems have been known to

have heat exchange efficiencies as high as 70-80% while others have as low as
have heat exchange efficiencies as high as 70-80% while others have as low as

50%. Even though this lower figure is preferable to the basic HVAC system, it
50%. Even though this lower figure is preferable to the basic HVAC system, it

is not up to par with the rest of its class. Studies are being done to
is not up to par with the rest of its class. Studies are being done to

increase the heat transfer efficiency to 90%.
increase the heat transfer efficiency to 90%.

The use of modern low-cost gas-phase heat exchanger technology will allow for
The use of modern low-cost gas-phase heat exchanger technology will allow for

significant improvements in efficiency. The use of high conductivity porous
significant improvements in efficiency. The use of high conductivity porous

material is believed to produce an exchange effectiveness in excess of 90%.
material is believed to produce an exchange effectiveness in excess of 90%.

By exceeding a 90% effective rate, an improvement of up to 5 factors in energy
By exceeding a 90% effective rate, an improvement of up to 5 factors in energy

loss can be seen. The Home Ventilation Institute has
loss can be seen. The Home Ventilation Institute has

developed a standard test for any and all units manufactured within the United
developed a standard test for any and all units manufactured within the United

States. Regardless, not all have been tested. It is imperative to investigate
States. Regardless, not all have been tested. It is imperative to investigate

efficiency claims, comparing data produced by HVI as well as that produced
efficiency claims, comparing data produced by HVI as well as that produced

by the manufacturer.. Types of energy recovery devices
by the manufacturer.. Types of energy recovery devices

**Total Energy Exchange only available on Hygroscopic units and Condensate
**Total Energy Exchange only available on Hygroscopic units and Condensate

Return units Rotary air-to-air enthalpy wheel
Return units Rotary air-to-air enthalpy wheel

The rotating wheel heat exchanger is composed of a rotating cylinder filled
The rotating wheel heat exchanger is composed of a rotating cylinder filled

with an air permeable material resulting in a large surface area. The surface
with an air permeable material resulting in a large surface area. The surface

area is the medium for the sensible energy transfer. As the wheel rotates
area is the medium for the sensible energy transfer. As the wheel rotates

between the ventilation and exhaust air streams it picks up heat energy and
between the ventilation and exhaust air streams it picks up heat energy and

releases it into the colder air stream. The driving force behind the exchange is
releases it into the colder air stream. The driving force behind the exchange is

the difference in temperatures between the opposing air streams which is also
the difference in temperatures between the opposing air streams which is also

called the thermal gradient. Typical media used consists of polymer,
called the thermal gradient. Typical media used consists of polymer,

aluminum, and synthetic fiber. The enthalpy exchange is accomplished
aluminum, and synthetic fiber. The enthalpy exchange is accomplished

through the use of desiccants. Desiccants transfer moisture through the
through the use of desiccants. Desiccants transfer moisture through the

process of adsorption which is predominately driven by the difference
process of adsorption which is predominately driven by the difference

in the partial pressure of vapor within the opposing air-streams. Typical
in the partial pressure of vapor within the opposing air-streams. Typical

desiccants consist of silica gel, and molecular sieves.
desiccants consist of silica gel, and molecular sieves.

Enthalpy wheels are the most effective devices to transfer both latent and
Enthalpy wheels are the most effective devices to transfer both latent and

sensible energy but there are many different types of construction that
sensible energy but there are many different types of construction that

dictate the wheel's durability. The most common materials used in the
dictate the wheel's durability. The most common materials used in the

construction of the rotor are Polymer, Aluminum and Fiberglass.
construction of the rotor are Polymer, Aluminum and Fiberglass.

When using rotary energy recovery devices the two air streams must be
When using rotary energy recovery devices the two air streams must be

adjacent to one another to allow for the local transfer of energy. Also, there
adjacent to one another to allow for the local transfer of energy. Also, there

should be special considerations paid in colder climates to avoid wheel frosting.
should be special considerations paid in colder climates to avoid wheel frosting.

Systems can avoid frosting by modulating wheel speed, preheating the air, or
Systems can avoid frosting by modulating wheel speed, preheating the air, or

stop/jogging the system. Plate heat exchanger
stop/jogging the system. Plate heat exchanger

Fixed plate heat exchangers have no moving parts, and consist of alternating
Fixed plate heat exchangers have no moving parts, and consist of alternating

layers of plates that are separated and sealed. Typical flow is cross current
layers of plates that are separated and sealed. Typical flow is cross current

and since the majority of plates are solid and non permeable, sensible only
and since the majority of plates are solid and non permeable, sensible only

transfer is the result. The tempering of incoming fresh air is
transfer is the result. The tempering of incoming fresh air is

done by a heat or energy recovery core. In this case, the core is made of
done by a heat or energy recovery core. In this case, the core is made of

aluminum or plastic plates. Humidity levels are adjusted through the
aluminum or plastic plates. Humidity levels are adjusted through the

transferring of water vapor. This is done with a rotating wheel either
transferring of water vapor. This is done with a rotating wheel either

containing a desiccant material or permeable plates.
containing a desiccant material or permeable plates.

Enthalpy plates were introduced 2006 by Paul, a special company for ventilation
Enthalpy plates were introduced 2006 by Paul, a special company for ventilation

systems for passive houses. A crosscurrent countercurrent air-to-air
systems for passive houses. A crosscurrent countercurrent air-to-air

heat exchanger built with a humidity permeable material. Polymer fixed-plate
heat exchanger built with a humidity permeable material. Polymer fixed-plate

countercurrent energy recovery ventilators were introduced in 1998 by
countercurrent energy recovery ventilators were introduced in 1998 by

Building Performance Equipment, a residential, commercial, and industrial
Building Performance Equipment, a residential, commercial, and industrial

air-to-air energy recovery manufacturer. These heat exchangers can be both
air-to-air energy recovery manufacturer. These heat exchangers can be both

introduced as a retrofit for increased energy savings and fresh air as well as
introduced as a retrofit for increased energy savings and fresh air as well as

an alternative to new construction. In new construction situations, energy
an alternative to new construction. In new construction situations, energy

recovery will effectively reduce the required heating/cooling capacity of the
recovery will effectively reduce the required heating/cooling capacity of the

system. The percentage of the total energy saved will depend on the
system. The percentage of the total energy saved will depend on the

efficiency of the device and the latitude of the building.
efficiency of the device and the latitude of the building.

Due to the need to use multiple sections, fixed plate energy exchangers
Due to the need to use multiple sections, fixed plate energy exchangers

are often associated with high pressure drop and larger footprints. Due to their
are often associated with high pressure drop and larger footprints. Due to their

inability to offer a high amount of latent energy transfer these systems
inability to offer a high amount of latent energy transfer these systems

also have a high chance for frosting in colder climates.
also have a high chance for frosting in colder climates.

The technology patented by Finnish company RecyclingEnergy Int. Corp. is
The technology patented by Finnish company RecyclingEnergy Int. Corp. is

based on a regenerative plate heat exchanger taking advantage of humidity
based on a regenerative plate heat exchanger taking advantage of humidity

of air by cyclical condensation and evaporation, e.g. latent heat, enabling
of air by cyclical condensation and evaporation, e.g. latent heat, enabling

not only high annual thermal efficiency but also microbe-free plates due to
not only high annual thermal efficiency but also microbe-free plates due to

self-cleaning/washing method. Therefore the unit is called an enthalpy recovery
self-cleaning/washing method. Therefore the unit is called an enthalpy recovery

ventilator rather than heat or energy recovery ventilator. Company´s patented
ventilator rather than heat or energy recovery ventilator. Company´s patented

LatentHeatPump is based on its enthalpy recovery ventilator having COP of 33 in
LatentHeatPump is based on its enthalpy recovery ventilator having COP of 33 in

the summer and 15 in the winter. References
the summer and 15 in the winter. References

External links .com/heat-recovery-efficiency-d_201.html
External links .com/heat-recovery-efficiency-d_201.html

Designing Dedicated Outdoor Air Systems, Stanley A. Mumma
Designing Dedicated Outdoor Air Systems, Stanley A. Mumma

http:www.lowkwh.com, Energy Recovery methods and publications
http:www.lowkwh.com, Energy Recovery methods and publications

http:www.UltimateAir.com Energy and Heat Recovery Ventilators
http:www.UltimateAir.com Energy and Heat Recovery Ventilators

Heat Recovery Ventilation TANGRA Heat Recovery Ventilaton Recovery
Heat Recovery Ventilation TANGRA Heat Recovery Ventilaton Recovery