The Issue
 

How do you bring fresh, breathable air inside your home, school or church without losing the dome’s energy efficiency?
Carbon dioxide gas (CO₂) has many sources. We produce CO₂ when we breathe and plants give off CO₂ when the sun is not shining. (They give off oxygen when the sun is shining.) Combustion also produces CO₂, as do coal-fired energy plants, cars, trucks, forest fires, etc.  High levels of CO₂ in a home may indicate poor overall air quality. For instance, one can assume that if CO₂ levels are high, so are other pollutant levels such as outgassing from carpets, furniture and pet dander.

Monitoring brings surprises

Since June of 2002, the Monolithic Dome Institute (MDI) has been monitoring CO₂ in many homes – both domes and conventional. 

They all have too much CO₂ most of the time. If windows are opened, CO₂ levels drop to 450 parts per million (ppm) – the same as outside. But modern houses are airtight, and Monolithic Domes are the tightest of them all. Consequently, CO₂ levels can rise drastically over short periods of time—generally from the breathing of the occupants. Obviously more people – more CO₂.

For commercial buildings, 1200 ppm is considered the trigger point upper limit for fresh air intake. So we are assuming that 1200 ppm is the maximum we should have in our houses. (Some say most we should allow is 1500 ppm.)
It was a surprise to us to discover (in both conventional and Monolithic Dome homes) how often we found CO₂ levels above 1200 ppm.  We were shocked to find that, at times, the CO₂ in some homes reached 4000 ppm. In fact, we found that most homes are always above the 1200 ppm number. (OSHA fines facilities with readings above 4000 ppm.) I have carried a portable monitor into many buildings and places.  It is amazing how few buildings with people inside stay below 1200 ppm. As I analyze this, I think it is because unless we measure we have to guess and most guesses are wrong.
 

The Answer
 

We believe we have found an answer to the CO₂ issue. It comes in the form of an ERV (Energy Recovery Ventilator or HRV Heat Recovery Ventilator). These machines bring outside “fresh” air into the home and exhaust an equal amount of the home’s stale air. And, as if by magic, ERVs also recapture most of the heat from the respective air streams. 

This is done in the box by an air-to-air heat exchanger. ERVs are an absolute must in our modern buildings. They are great additions to any building.  By recovering the heat, we spend less to heat or cool the exchanged air, thus saving huge amounts of energy while getting the fresh air we need.

In Canada, most new homes must install an ERV. Studies have led us to conclude that we should follow suit. After extensive 

research, MDI has found several ERV units that work well.