Radon Mitigation

Cost of Ownership (Part 3)

Welcome to Part 3 in this series on radon mitigation – cost of ownership.  If you missed Part 1 or Part 2 you can click the link to catch up.

In part 3 of this series, we will look at the costs involved in installing either a sub-membrane or sub-slab depressurization system.

For this subject, we will focus on sub-slab depressurization only.  You can apply the same things to a sub-slab depressurization system.

There are several components to the cost of ownership for the homeowner that we will talk about.  Those items are picking a radon mitigation contractor, system optimization, costs, and maintenance.

Picking a radon contractor:

While the great state of Montana does not require radon mitigators to be certified you will be served better by working with a contractor that is certified for radon mitigation.

The DEQ Radon Control Program maintains a list of AARST Certified Radon Mitigators.

Two organizations certify contractors, the National Radon Proficiency Program (NRPP) and the National Radon Safety Board (NRSB).  Both organizations use the American Association of Radon Scientists and Technologists (AARST) standards as the bar for certification.

Why does this matter to you?  Any contractor that maintains this certification agrees to design their radon mitigation systems using the standards published by AARST.  AARST develops these standards following good building science and effective radon mitigation for new single-family dwelling construction, existing single-family dwellings, existing multi-family properties, and new multi-family & commercial construction.

They also maintain the standards for radon measurement tools, techniques, and quality control.  At Safe Home Environmental, we use AARST Certified Sun Radon 1028XP monitors and take advantage of the AARST quality control dashboard so that our monitors and quality control are always meeting the standards set forth by AARST.

When a contractor gets certified they agree to always use the AARST standards in their system design.  Here is the code of ethics for all AARST-certified contractors.  In a nutshell, we agree to design and install our radon mitigation systems in according to the standards set forth by AARST.

System Optimization:

When designing a radon mitigation system we need to effectively remove the radon gas while keeping the cost to operate the system as low as possible.

The best place to install radon mitigation systems is during the building of the home.  This will be the lowest cost for components and also allow the builder to optimize the system for the lowest cost of operation.  This is done by sealing all the places where radon gases could sneak into the home through cracks and holes.

During the construction process, it is typical for the builder to leave the concrete slab open for the plumbing to come through.  There are also cold joints between the slab and the foundation walls that are often left unsealed.

These spaces create opportunities for radon gases to enter the home.  These are also the places where an active (using a fan) radon depressurization system will pull the radon out of the exhaust along with some of the conditioned air from the home.  this means you are paying to heat or cool the air in your home and then the radon mitigation system is pulling that air out of the home causing your HVAC to replace that lost conditioned air.

During the building process, the contractor can seal the cold joints and plumbing access holes such that radon will not enter and conditioned air will not be pulled out of the home.

The contractor can also put soil gas matts and a soil gas vapor barrier to help ensure that all soil gases including radon are not entering the home by taking advantage of the stack effect to send them out through the installing gas matts and piping.

If the radon is still entering the home, a fan can easily be added to the piping in the attic space.  An electrical outlet is installed to ensure the fan can be powered properly.

For homes that are already existing, these same challenges exist.  The cracks, cold joints, and plumbing access in the basement slab need to be sealed.  If block wall construction was used, the tops of the block wall need to be sealed as well.  If it is not possible to route the exhaust piping within the home, it can be routed out the rim joist through the garage and into the attic or up the side of the home.

Larger homes that have foot walls may also require the use of multiple suction pits in the slab to reach the full extent of the home.  A contractor will use micromanometers to perform pressure field extension testing to ensure that all areas of the slab foundation are being reached by the suction pit.

With the same pressure field extension equipment the contractor can also determine the size of the fan needed to pull the radon and minimize how much air is also being lost out of the radon mitigation system.

Cost of Ownership:

I’m going to use a study published by Radon Home Measurement and Mitigation, Inc. out of Fort Collins, CO to demonstrate the cost of ownership and how this is impacted by the design of the radon mitigation system.

This study looks at many factors affecting the effectiveness of radon removal in conjunction with its corresponding costs.  All of this information is relevant but for our purposes, there is one graph that we will focus on on page 288.

Four systems are compared on their 40-year total costs to the customer.  The left four represent non-sealed systems, and the right-most data represents a high-energy efficient system hermetically sealed with a double membrane under the slab.

It is clear from the data that builders can reduce the cost of ownership the most effectively even when it may cost more to install the system.

This is the challenge for radon mitigators working with existing homes.  The more cracks, cold joints, plumbing openings, block walls, etc can be sealed the more the cost of ownership goes down.

Other factors along with sealing are fan and piping sizing which can only be done effectively with pressure field extension testing.

Cost of Ownership:

The challenge to mitigators for existing homes is to design a system that optimizes the cost of ownership by paying attention to system design.

Besides using pressure field extension testing to determine the optimal piping and fan size, dampers can also be used to balance multi-pit systems.

Dampers can also be used in crawlspaces to help lower the cost of ownership.  By dampening a system you can lower the power needed by the fan.

This is a damper that I placed in my system.  I used this damper to lower the power needed to operate the fan.  You can see from the two charts how the damper impacts the pressure in the piping.  As the damper is engaged across the piping space it helps to lower the pressure in the piping.  This in turn lowers the power needed to operate the fan.

I’ve lowered the power needed to operate the fan by 20%.  That not only saves me $$$, but it also increases the life of the fan as well as lowering the possibility of conditioned air the system could be pulling through it.

I’ve been monitoring my radon levels with the Luft monitor.  We’ll talk about monitoring and maintenance in our next and last post in this series.  Here are my latest readings from the Luft monitor showing my radon levels are held strong at under 1 pCi/L.

Now that we have reviewed the factors contributing to the cost of ownership, let’s take a look at what is important after the mitigation system is installed we have the radon levels down and the system is optimized for the lowest cost of ownership.

Committed to Your Safety and Peace of Mind – Jennifer Thorne Testing Services Manager  | IAC2 Certified for Mold & Radon | NRPP Certified: 113525-RMP, 113629-RMS | DEQ Meth Certified: MCP-0146-C