Room-by-room ventilation units
For a home without ducts: a unit in an outside wall of each bedroom brings fresh air in and stale air out, and keeps much of the heat. How many a bedroom needs depends on who sleeps there. Units on sale in the US, and one window unit with a waitlist.
Each bedroom needs:about 17 cfm of outdoor air per person sleeping there, to stay at 800 ppm or less. Work it out for your rooms
Before you buy one
- Worth knowing: Compare the heat-recovery airflowUnits that take turns are often sold by their ventilation-mode number. In heat-recovery mode each moves half: 30 cfm becomes 15.
- In its favour: Plan about 17 cfm for each person sleeping thereA pair of the smaller units gives about 20 to 30 cfm: one person, or nearly two. Two people (34 cfm) usually need two pairs, or a bigger unit.
- Worth knowing: Each needs an outside wall, thick enough for itHoles run from about 6 to 10½ in. Lunos needs a 12 in wall (7½ in for the short version); Zehnder’s ComfoAir 70 at least 11 in.
- Worth knowing: Few are certifiedWe found no HVI listing for a unit that takes turns. Where the energy code requires an HRV or ERV (climate zones 7 and 8, and 6 under the 2024 IECC), it must be listed with at least 65% sensible recovery at 32°F.
- Worth knowing: In a condo or a rental, ask firstA hole in an outside wall needs the board’s or the landlord’s approval.
How they work
- Plain fact: Pairs that take turnsOne unit blows in while its partner blows out, then they swap, about every minute, through ceramic cores that hold the heat.
- Plain fact: One unit, in and outA box with a fixed core moves both airstreams at once, like a small HRV or ERV. Some carry both through one hole.
- Plain fact: Compact units with short ductsA small ERV in a closet or ceiling, ducted a short way to two or three rooms: more air per hole, and certified ratings.
- Worth knowing: Real rooms do worse than the ratingsIn 60 units measured in Luxembourg homes, heat recovery averaged about 70%, and wind pushed the airflow around (Merzkirch et al., 2016).
- Worth knowing: Owners mention the noiseThe fans’ switching every minute or so, and street noise through the wall. Ask for the sound at the speed you’ll sleep with.
The units
From the makers’ and US distributors’ own pages, read October 19, 2026. Not a ranking: A to Z by maker. Airflow is per unit or per pair, as each maker states it.
Blauberg Vento Expert A50-1
Through-wall units that work in pairs, swapping in and out through a ceramic core. Pro and Wi-Fi (W V.2) versions.
- Worth knowing: About 15 cfm each in heat-recovery mode, at top speedSold as 30 cfm: that’s ventilation mode. A pair gives about 30 cfm: one sleeper, a little short of two (34 cfm).
- In its favour: Heat recovery up to 93%The maker’s figure; no HVI or Passive House listing found.
- Plain fact: 6 5/16 in (160 mm) hole, walls 9½ to 19¾ in
- Plain fact: Built-in humidity sensor; the W version adds an app
- Not stated by the maker: Sound in sones only (0.6 to 1.2), at a distance not stated
Details
- Airflow, heat recovery
- 4, 9 and 15 cfm per unit
- Airflow, ventilation mode
- 9 to 30 cfm per unit
- Power
- 3.6 to 7.1 W
- Filters
- MERV 5, MERV 13 optional
- Listing
- ETL
- Also in the range
- A85-1 S W V.2: up to 25 cfm in heat recovery, recovery up to 70%
Broan-NuTone ERV70T
A small ERV that hangs in a closet or ceiling, with short ducts to a few rooms. Sold for apartments, condos and small homes.
- In its favour: Up to 70 cfmEnough for a small home’s bedrooms through short ducts.
- Plain fact: An ERV: moves some moisture as well as heat
- Not stated by the maker: Heat recovery, sound and duct size not on the page we read
Details
- Airflow
- 70 cfm (distributor’s listing)
- Mounting
- Chain-hung
LUNOS e²
Two small fans in the outside walls, taking turns through ceramic cores. Sold in the US by 475 High Performance Building Supply.
- Worth knowing: Up to about 22 cfm per pair, at top speedAbout one sleeper. Two people need about 34 cfm: two pairs, or a bigger unit. Sources differ on whether some figures are per fan or per pair.
- In its favour: Heat recovery about 90%German DIBt approval and EN 13141-8 testing; about 20 to 30% of the moisture comes back too.
- Plain fact: Sound 21 to 41 dB(A) at 1 m, 12 to 32 at 3 m
- Worth knowing: Needs a 12 in wall (7½ in for the short version)Core drill 162 mm (about 6⅜ in). A North American version (e² FR) is approved for the US and Canada.
- Plain fact: Uses very little power: 0.7 to 4 W
Details
- Airflow
- 9, 18 or 22 cfm (475); Lunos lists 15 to 38 m³/h
- Controls
- One controller runs up to 4 fans; switch sold separately
- Filters
- G3 (about MERV 5), MERV 13 optional
- Where to put them
- High on an outside wall, at least 12 in from ceilings and corners, never in a ceiling (475)
LUNOS e²60
A higher-airflow version of the e², with a control that holds its airflow against wind pressure.
- Plain fact: Up to 60 m³/h (about 35 cfm)Lunos doesn’t say whether that’s per fan or per pair, so check before counting sleepers.
- In its favour: Heat recovery 96% at low airflow, 85% at the topEN 13141-8 and DIBt approval.
- Worth knowing: Louder at the top: up to 48 dB(A) at 1 m
- Plain fact: Optional control holds airflow against up to 20 Pa of wind
- Plain fact: Core drill 162 mm, wall at least 280 mm (11 in)
Details
- Airflow
- 5 to 60 m³/h
- Sound
- 10 to 48 dB(A) at 1 m; 3 to 39 at 3 m
- Power
- 0.4 to 3.3 W
- North America
- e²60 FR model
LUNOS eGO
Two fans in one tube, taking turns: balanced fresh air through a single hole. Meant for bathrooms and kitchens.
- Worth knowing: Small: 3 to 12 cfm in heat-recovery modeUp to 27 cfm as an exhaust fan. Less than one sleeper’s 17 cfm.
- In its favour: Heat recovery about 85%Tested to the German DIBt protocol; no HVI or Passive House listing found.
- Plain fact: Sound 20 to 43 dB(A) at 1 m
- Plain fact: One 162 mm hole, wall 230 to 300 mm (9 to 12 in)
Details
- Controls
- One controller per eGO; switch sold separately
- Humidity recovery
- About 20%
Panasonic Intelli-Balance 120 (FV-12ESC1)
A compact whole-home ERV with 6 in ducts. It replaced the Intelli-Balance 100, discontinued in May 2026.
- In its favour: 30 to 120 cfmCovers several bedrooms through short ducts.
- In its favour: ENERGY STAR; sensible recovery up to 90%The retailer’s figure.
- Plain fact: Two MERV 13 filters
- Plain fact: 6 in ducts
Details
- Controls
- Optional touch-screen wall control
Panasonic WhisperComfort 60 (FV-06VE1)
A small ERV on a wall or ceiling with two short ducts. It replaced the WhisperComfort spot ERV (FV-04VE1), discontinued in January 2025.
- In its favour: 20 to 50 cfm, 60 on boostEnough for one or two bedrooms through short ducts.
- In its favour: HVI-certifiedSensible recovery 70% at 20 cfm, 60% at 60 cfm (32°F).
- Plain fact: Two 4 or 5 in portsAn optional wall cap puts both through one 7½ in hole.
- Plain fact: Quiet: about 0.9 sones at 40 cfm
Details
- Power
- 9 W at 20 cfm; 39 W at 60 cfm
- Mounting
- Wall or ceiling
- Controls
- Multi-speed selector; boost
Pioneer ECOasis 50
One through-wall unit with a sleeve that carries air both ways, a built-in CO2 sensor and Wi-Fi.
- Worth knowing: Up to about 35 cfmPioneer doesn’t say whether that’s the fresh air it brings in while recovering heat, and recommends two units, so check before counting sleepers.
- Worth knowing: Heat recovery “up to 97%” is the maker’s claimNo test standard or certification named.
- In its favour: Built-in CO2 sensor and an app
- Plain fact: Wall 8½ to 14⅛ in; 6¼ in duct
- Not stated by the maker: Whether the airflow takes turns isn’t stated
Details
- Airflow
- 11.8 to 35.3 cfm
- Sound
- Up to 32.7 dB(A), distance not stated
- Power
- 6 to 8 W
- Filter
- F7 (about MERV 13), sold separately
SWERV V2 window ERVNot on sale yet
Sits in an open window: no hole in the wall, so it can suit a rental. Early: waitlist only, and not yet UL-certified.
- In its favour: No wall holeFits double-hung, single-hung or sliding windows 23 to 48 in wide.
- Plain fact: 5 to 110 cfm; 28 to 75 in typical use
- Worth knowing: Heat recovery claims vary (70 to 92%)No independent test data yet.
- Worth knowing: Louder at the top: 59 dB(A) at 1 m35 dB(A) at its lowest speed.
- Worth knowing: Waitlist only; not yet UL-certified
Details
- Power
- About 10 W typical, 42 W maximum
- Filters
- MERV 13 plus carbon, $49 each
- Controls
- Dial; optional sensor pack with indoor and outdoor CO2 and an app
VENTS-US Micra 150
A larger single-room box, with a schedule and a filter alarm.
- In its favour: Up to 71 cfm at its top speedAbout four sleepers’ worth; slower speeds are quieter.
- Not stated by the maker: Heat recovery not stated on the seller’s page
- Plain fact: Sound 36 dB(A), distance not stated
- Plain fact: Two 5 in ducts
Details
- Power
- 51 W
- Controls
- LCD panel, remote, weekly schedule, boost timer, filter alarm
VENTS-US Micra 60
One box on the wall with a fixed core and two 5 in ducts through it: fresh air in and stale air out at the same time.
- In its favour: 17.7 to 35.3 cfmAbout two sleepers at its top speed.
- Plain fact: Sensible recovery 79% at low speed, 70% at high
- In its favour: Thin walls are fine: 2½ in minimum
- Plain fact: An HRV: heat only, no moisture
- Plain fact: Quiet: 0.38 to 1.0 sones at 10 ft
Details
- Power
- 4.2 to 15.4 W
- Filters
- Two MERV 8 (G4)
- Controls
- 3-speed wall control; freeze-protection thermostat
VENTS-US TwinFresh Comfo RA1-50-2
A through-wall unit that takes turns through a ceramic core; run two as a pair to balance the room.
- Worth knowing: About 15 cfm each in heat-recovery mode, at top speedSold as 30 cfm: that’s ventilation mode. A pair gives about 30 cfm.
- In its favour: Heat recovery up to 88%The seller’s figure (91% in VENTS’ 2013 data); no certification named.
- In its favour: Thin walls are fine: 4¾ in minimum
- Plain fact: Quiet: 0.2 to 0.5 sones at 10 ft
Details
- Airflow, ventilation mode
- 12, 19 and 30 cfm per unit
- Duct
- 6 in telescopic
- Power
- 4.5 to 7 W
- Controls
- Wireless remote
VENTS-US TwinFresh Expert RA1-50-2
A through-wall unit with a humidity sensor and Wi-Fi, linked with a second as a pair, taking turns through a ceramic core.
- Worth knowing: About 15 cfm each in heat-recovery mode, at top speedSame specifications as Blauberg’s Vento Expert A50. A pair gives about 30 cfm: one sleeper, a little short of two (34 cfm).
- In its favour: Heat recovery up to 93%The seller’s figure; ETL listed.
- Plain fact: Humidity sensor, schedule, Wi-Fi
- Plain fact: 6 5/16 in hole, walls from 5⅞ in
Details
- Sound
- 0.6 to 1.2 sones at 3 ft
- Airflow, ventilation mode
- 9, 18 and 30 cfm per unit
- Power
- 3.6 to 5.2 W
- Filters
- MERV 5, MERV 14 optional
VENTS-US TwinFresh Expert RW1-85-2 V.2
The larger TwinFresh Expert: a through-wall unit with Wi-Fi, linked with a second as a pair.
- Plain fact: Up to 25 cfm each in heat-recovery modeA pair gives about 50 cfm, enough for two sleepers.
- Plain fact: Heat recovery up to 70%The seller’s figure; ETL listed.
- Worth knowing: Louder at top speed: up to 4.3 sones at 3 ft
- Not stated by the maker: Hole size isn’t statedWalls from 5⅞ in.
Details
- Sound
- 0.7 to 4.3 sones at 3 ft
- Airflow, ventilation mode
- 9 to 50 cfm per unit
- Power
- 3.3 to 9.7 W
- Controls
- Wi-Fi app; units chain together
Zehnder ComfoAir 70
One through-wall box with an enthalpy core, moving air in and out at the same time. Passive House certified.
- In its favour: Up to 60 m³/h (35 cfm)About two sleepers at its top speed; 40 m³/h (24 cfm) a step below.
- In its favour: Passive House certified (component 0826vs03)Heat recovery 90% at low speed, 71% at the top; moisture recovery 84% to 54%.
- In its favour: Quiet at night: 11 to 29 dB(A) at 3 m up to its third speed36 dB(A) at the top.
- Worth knowing: A big hole in a thick wallAbout 270 mm (10½ in) core, wall 275 to 900 mm (11 to 35 in).
- Plain fact: Optional CO2, humidity and VOC sensors
Details
- Airflow
- 15, 25, 40 and 60 m³/h (9 to 35 cfm)
- Power
- 4 to 17 W
- Also
- An optional duct can serve an adjoining room
Read next
Have ducts, or room for small ones?
Three or four sets of room units can cost as much as a ducted system, and a ducted one keeps the fans out of the bedrooms. HRV and ERV units
Sources
- Blauberg North America: Vento Expert A50-1 Pro
- Blauberg North America: Vento Expert A50-1 Pro data sheet (July 2024)
- Blauberg North America: Vento Expert A50-1 W V.2 data sheet
- Blauberg North America: Vento Expert A85-1 S W V.2 data sheet (April 2025)
- Hercules Industries: Broan ERV70T
- LUNOS: e² product page
- LUNOS: e² data sheet E254 (February 2020)
- 475 High Performance Building Supply: Lunos FAQ (2016)
- 475 High Performance Building Supply: ventilation (prices)
- LUNOS: e²60 product page
- LUNOS: e²60 technical data (January 2022)
- 475 High Performance Building Supply: Lunos eGO
- SupplyHouse: Panasonic FV-12ESC1
- SupplyHouse: Panasonic FV-10VEC2 (discontinued)
- Panasonic: WhisperComfort 60 catalog
- SupplyHouse: Panasonic FV-06VE1
- SupplyHouse: Panasonic FV-04VE1 (discontinued)
- Pioneer: ECOasis 50
- Pioneer help center: ECOasis 50 overview
- Sylvane: Pioneer ECOasis 50
- SWERV: V2 product page
- SWERV: ductless and single-room ERV buying guide
- Green Building Advisor (November 2025): Introducing the SwervAir energy recovery ventilator
- HVACDirect: VENTS-US Micra 150
- Rise: VENTS Micra 60
- The Home Depot: VENTS-US Micra 60
- VENTS: Micra 60 specifications (2013)
- Rise: VENTS TwinFresh Comfo
- The Home Depot: VENTS-US TwinFresh Comfo
- VENTS: TwinFresh Comfo performance (2013)
- Rise: VENTS TwinFresh Expert RA1-50-2
- VENTS: TwinFresh Expert specifications
- Rise: VENTS TwinFresh Expert RW1-85-2 V.2
- Zehnder America: ComfoAir 70
- Zehnder America: ComfoAir 70 technical specifications
- Zehnder America: all products (prices)
- Journal of Light Construction (2016): An effective retrofit ERV
- Merzkirch et al. (2016): Field tests of centralized and decentralized ventilation units in residential buildings
- Minnesota Department of Labor and Industry (December 2023): residential energy code handout (HRV and ERV listing)
- Green Building Advisor (2022): Lunos e2 HRV and Lunos eGO fans