March 15, 2013

The Lunos e² Primer

Modern Luxury Loft / Apartment by the seaThe Lunos e² decentralized high efficiency heat exchange whole house ventilation system is a breakthrough in building technology –  combining high performance with simplicity of installation and operation.

Rather than installing a central heat exchange unit, requiring extensive ducting  and construction intervention and coordination, one can now install Lunos e² units through exterior walls – without ducting.

See an introduction video here.

The basic operating principles are straightforward:

  1. The units operate continuously (but can be turned off with a switch)
  2. The units are installed in pairs, working in a counter-flow manner:  one supplies air while the other exhausts
  3. The flow directions and rates are synchronized for balanced ventilation, with 10-24 cfm flows reversing at approx. one minute intervals
  4. The system can simply provide airflow throughout the entire house/apartment
  5. The Lunos e² is part of a hybrid ventilation solution along with the Lunos eGO or separate intermittent bath exhaust on a timer or occupancy sensor

The units are small – practically the diameter of a compact disc.  The basic components of the units include:

  1. Exterior grill with insect screen
  2. Plastic insulation element
  3. Highly efficient ceramic heat buffer
  4. Ventilator engine in sound muffling plastic chassis.
  5. MERV 5 or pollen filter
  6. Airflow optimized interior shield

The functioning concept is a pulsing, directed and balanced airflow that provides thorough mixing and exchange of interior air.

  1. The 70 second cycles produce roughly a three foot pulse of fresh air to the space.  In less than 10 minutes from starting, the fresh air has completely circulated within the space.
  2. The pressure difference causes forced air direction from one side to the other.
  3. And back in the opposite direction.
  4. Providing intermediate mixing.

The farther you space the units apart, the better the mixing – although they can function properly as close as five feet from each other.

Important qualities of the Lunos e² units include:

  1. Quiet operation:  0.12 sones at the low (10 cfm) setting and 0.15 sones at the medium (15 cfm) setting. The units provide 42 decibel sound protection to outside.
  2. Dependable:  The units are designed to exceed 100,000 hours of operation.
  3. Affordable: Small homes and apartments can be ventilated more inexpensively than central systems of similar efficiency and quality.  This is true for new construction but particularly so in retrofit situations.
  4. Moisture Recovery:  The Lunos e² heat transfer core also absorbs and releases approximately 20-30% of the moisture in the air stream – helping to moderate humidity levels in winter (but not enough to call them ERVs).
  5. Frost Free Operation:  The Lunos e² requires no active frost protection. The units have been tested down to -32 °F and are successfully operating continuously through the winter in places like Norway, Estonia and Russia.
  6. Efficient:  Fans draw less than 1.4W each, with no stand-by/ghost power loads.  The heat recovery is impressive with efficiency curve solidly in the 84-92% range (see diagram). Rated efficiency is 90.6% for the standard (12″) e² units.
  7. Flexible:  The Lunos e² is suitable for a variety of applications
    • New construction of single and multi-family buildings.
    • All types of renovations. Standard size Lunos e² units require a minimum construction depth just under 12 inches. For thinner walls, either use standard Lunos e² fans with interior soffits (pictured at right), or Short (6.3″) Lunos e2 fans (84% efficiency).
    • Low energy and Passive House buildings. (See PHPP inputs for Lunos e2)
    • Can be installed anywhere you can fit them!
  8. Simple:
    • Low voltage (12V) DC power at fans.
    • No tools needed for maintenance.
    • No ductwork.

To find out more about the Lunos e² see the Related Blog Posts below, the product Spec Sheet here, the installation instructions here, and the product webpage here.

Related Blog Posts:


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12 Responses to The Lunos e² Primer

  1. Molly December 9, 2014 at 7:12 pm #

    So, if I’m reading this correctly, it’s possible that one can power the Lunos e2 directly from a DC solar system without running the power through an AC converter? That would be fantastic…

    • Ken December 10, 2014 at 5:14 am #

      Yes, that is correct. We like that capability too!

  2. Jenny Yasi March 3, 2015 at 5:25 am #

    This is our first winter with the Lunos E2s. I like them, but we just changed the filters (the red light came on) and I tried to reset according to the manual instructions, and I can’t get the red light to shut off. We’ve tried a couple of different ways in case we had the switches reversed, but no luck so far. They’re nice but little issues like that are worrisome.

    • John March 3, 2015 at 9:52 am #

      Jenny, glad to hear you like the e2 fans. As for the filter light: This light is simply a timed reminder to change, or clean, the filter. It is not connected to a sensor of any kind, and does not indicate there are any problems with your fans. The reminder light turns off simply by rocking the left switch back and forth. Give us a call if you have any problems (800-995-6329). We’re here to help.

      • Jenny Ruth Yasi March 31, 2015 at 10:59 am #

        FYI, we just turned the circuit breaker on and off to re-set the light. We’re really happy with the fans.

  3. John May 27, 2015 at 1:00 pm #

    I need to model Lunos e2 and eGo units in REM/rate software for a HERS Rating. Can you tell me what values should be used for the sensible recovery efficiency % and total recovery efficiency % inputs. Thanks.

  4. Floris July 6, 2015 at 12:03 pm #

    You can use the efficiency as determined by the German federal testing agency DiBT.
    This third party testing provides a tested result of 90.6% on average and at the high flow rate 85%.
    Efficiency of the system ranges from 1W in standy, 4W at 10CFM, 6W at 15CFM and 10W at 20CFM
    It can go up to 15W if running it on high (22CFM, german setting) and it is encounters external pressure.
    So if you like to be conservative use that number in REMrate

  5. Kristin March 16, 2017 at 9:06 pm #

    It seems like this is designed for regular houses/construction, not RVs or anything. But most homes are wired for AC, not DC. I assume one has to do some sort of conversion if we’re wiring for AC?

    • John March 17, 2017 at 1:01 pm #

      That’s right Kristin. Each Lunos order comes with a transformer that steps down the power to 12 volt DC. You’ll notice that if you put a Lunos e2 in the cart you automatically get 1 Transformer and 1 Controller along with the Lunos system of your choosing.

  6. Aaron April 9, 2018 at 11:09 pm #

    How does the controller work? It seems like it should be possible to tie the control of the units to a programmable thermostat that would run the units on a schedule, similar to how you can control the fan of a conventional forced air furnace. Can you confirm?


    • John April 12, 2018 at 10:04 am #

      Hello Aaron,

      We would not recommend experimenting with connecting the controller with other systems. Partially just because it’s not intended to operate that way. And partially because you don’t want the system to be changing automatically or shutting on and off. Most customers leave it on low 24 hours a day and 365 days a year, and are quite content with it. You only need the higher settings when you want extra ventilation in a space, maybe after cooking or during a party. Since those instances can’t be automated, it wouldn’t help to connect it to another system.


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