Fresh Air and the LUNOS e2 System

Marc Bilodeau/ Planning, Product Reviews, Smart Sensors, Tiny House

I first heard about the LUNOS e2 system from a tiny house builder on YouTube. Air exchangers allow fresh air to flow through a building. It’s simple and elegant. In my opinion, a must.

Today’s homes, big and small, are more air tight than ever. Air becomes stale and traps particles, mold, and other agents that can damage the home and possibly cause health issues.

A tiny house can easily pass fresh air throughout the house by opening the windows. It will quickly replace the inside air with the outside. However, this is not always possible depending on the weather and season.

There are many products and options available ranging both in size and price. That being said, the ideal system may vary depending on a number of factors.

Available Options

When researching the right system for the tiny house, I found there are three main types of fresh air exchange systems. Regardless of the system, they universally have benefits to people within the home.

They provide fresh air to the occupants since people deplete oxygen as they breathe. Without ventilation, people will feel the affects of lower oxygen levels in a reasonably airtight home. More quickly in a tiny house due to its tiny size.

Secondly, they remove contaminants. The human body emits toxins such as ammonia, benzene, carbon monoxide, and methane. Additionally, there are chemicals in building materials and furnishings that continue to off-gas for many years.

Additionally, some systems remove the excess humidity generated by normal human activity. This fights many types of molds and viruses, and helps with heating efficiency.

There are many other reasons why one should invest in a fresh air exchange system. However, the key takeaway is it helps maintain a healthier environment.

Fresh Air Exchanger

A fresh air exchanger is basically a fan that can pull air in or push air out of the building. The purpose is to quickly move air between the inside and outside. However, the disadvantage is there is no temperature or humidity control.

In many environments, this requires additional equipment to help control temperature and humidity during the year.

Heat Recovery Ventilation (HRV)

A Heat Recovery Ventilation (HRV) System uses the temperature from the stale indoor air to preheat or cool incoming air. This reduces the amount of energy needed to make the air ambient room temperature.

Outgoing and incoming air never mix in the heat recovery process. In a single unit system, the air passes through separate channels into the unit, allowing an exchange of heat through conduction. In some cases, there are multiple units that work together to exchange air. One pulls air in, while the other pushes air out.

HRVs are categorized by an efficiency rating. This measures how much energy will be saved using the system. Typically, efficiency ratings are between 55% – 75%. However, some units boast over a 90% efficiency rating. These units are more costly, but over time provide a return on investment.

Energy Recovery Ventilation (ERV)

An Energy Recovery Ventilation (ERV) System is similar to a HRV. The main difference is the unit keeps the humidity of the indoor air between the ideal range of 40% – 50%. The system precools and dehumidifies the air during the warmer seasons, while it humidifies and preheats the air in cooler seasons.

Many people use HRV and ERV interchangeably. All ERVs are HRVs since they both exchange air and bring air to ambient room temperature. However, all HRVs are not ERVs because HRVs do not control the humidity during the air exchange.

LUNOS e2 Short

After comparing various makes and models, I chose the LUNOS e2 short system due to its compact size, feedback from other tiny house dwellers, construction companies, and other online resources and feedback.

The LUNOS e2 is two separate fan units that work together. One fan draws the air in while the other pushes it out. The two units automatically switch direction every 50 seconds. The speed of the fans are controlled by two toggle switches.

Installing the LUNOS e2 Short

The documentation is very good and does a great job explaining the process. However, I love visuals and naturally YouTube helps with Do-It-Yourself gumption.

Since the LUNOS e2 works in pairs, each unit is in different parts of the tiny house. The first unit is in the great room above where the couch will be. 18 gauge solid (not stranded) thermostat wire runs between this unit and the relay controller.

Tiny House LUNOS e2 in the great room
Tiny House LUNOS e2 Short in the great room showing various stages of the installation.

The second unit is in the bathroom which is at the opposite end of the tiny house. Some people install their second unit in the loft. However, in the bathroom it helps vent moisture from the shower.

In terms of maintaining or replacing parts, the majority of the components such as the relay controller for the LUNOS e2 Short are behind the switches that control the speeds of the fans.

LUNOS e2 short unit in the tiny house bathroom
The LUNOS e2 Short unit in the bathroom during various stages of installation.

The outside of the units have a low profile look that sits mostly flush with the building. This will blend well when the siding is installed.

Tiny House LUNOS e2 short
The LUNOS e2 units from both sides of the Tiny House

Power Consumption

I’ve been tracking the total watt-hour usage of the tiny house. The goal is to have a solar system capable of supporting the tiny house while off-grid.

tiny house with Neurio and LUNOS e2 Short
Tiny House using the Neurio to measure the LUNOS e2 Short power usage

Using the Neurio, the amount of power the LUNOS e2 Short uses is very low. This was measured by turning off everything but the Neurio, Raspberry Pi, and LUNOS e2 Short. These numbers reflect the unit on it’s high setting. This data suggests the LUNOS e2 is an excellent option for off-grid solar, water, or wind electrical generation systems.


There are a plethora of choices when it comes to fresh air exchange systems. Before choosing a system, it’s important to look at the different types of systems and find the right one for your situation.

The LUNOS e2 Short fit my situation best. Prior to the installation, the air felt stale and had a heavy freshly cut wood odor. Now, the air is noticeably fresher when the tiny house sits sealed for a few days.

Overall, it was up and running within a few hours, and only some basic electrical skills were needed to finish the job.