Radon is a colorless and odorless gas that can enter your house through the basement or crawl space. It
Some Radon links:
Building Radon Out from the EPA:
Quite a bit of detail on types of systems and installation -- helpful for new or existing construction:
Many existing and new construction homes are being fitted with Radon mitigation systems that reduce the concentration of the Radon gas in the house. In some areas, Radon systems are required by building codes on new construction.
This is all to the good, but one negative aspect of many Radon mitigation systems is that the fan used to remove Radon gas is on 24/7, and can be a significant power use -- especially considering that it will operate for the entire life of the house.
For example, for a Radon fan that draws 80 watts:
Yearly Power use = (80 watts)(24 hours/day)(365 days/year)( 1KWH/1000 w-h) = 700 KWH per year
At fifteen cents per KWH, this is over $100 per year.
If your electricity is generated at a coal fired power plant (as much of US power is) this will result in 1400 lbs of CO2 emissions.
In addition, with some systems, the Radon system will draw some of its air from inside the house, and result in higher infiltration losses.
For a family that is careful about electricity use (as we all should be), this might be 10% of of the total electricity use!
For the millions of homes with Radon protection systems, this adds up significant CO2 emissions.
First, Radon exposure is not something to be casual about. Any steps you take reduce energy consumption of the Radon mitigation system must not compromise the systems ability to keep Radon levels low in the living space. A long term Radon test after making changes to your Radon system is a must!
Please read this...
Passive Radon systems --
This email pasted in below is what got me started on this, and describes another tactic that may be helpful in improving the effectiveness of passive Radon removal systems. It should be pointed out that the effectiveness of these wind powered vents in extracting more air for Radon systems has not (to my knowledge) been tested, but it seems sensible:
(Nice website- keep up the good work!)
Under the heading, “Wind Powered Radon-Mitigation”, a small epiphany:
I recently did an analysis of a neighbor’s active radon-mitigation system:
The fan runs 24hrs/365days drawing between 65-85W.
In this power market the residential delivered price is ~$.016/kWh
24h x 365d x (0.065 to 0.085 kW x $0.16/kWh= $91-119.year operating cost
The fan is rated at 250cubic feet per minute at zero back pressure, or 115cubic feet per minute at 1 water-column inch.
The fan exhausts through the roof via a 4” pvc stack. A $50-60 (delivered price) zero-maintenance 4” venturi-siphon wind operated vent is rated 65cfm @ 4mph (backpressure not specified), eg. Empire SV04A
The NOAA tabulated monthly average wind speed in our town (Worcester, MA) is 8.3mph on the slowest month, 11.7mph on the fastest
Venturis are fairly linear in performance, so it’s 8mph month average performance will be about 130cfm, and it’s 11mph month performance about 180cfm- the same rough order of magnitude as the fan (albeit somewhat smaller.)
The installation and subsequent radon testing have yet to be completed, but in a worst-case scenario (say, the radon levels are still too high in a long-term test), if the venturi is left on the stack with the fan running, it lowers the load on the fan, allowing it to operate at it’s lowest power level, and payback would still be less than 2 years.
Going with a higher-cfm rated “whirlybird” type attic turbine is less attractive since they have maintenance issues (it’s best to lubricate the bearings at least once/year), and have a minimum operational wind speed before they stall, becoming an impediment to the natural chimney-effect venting (or power venting). A venturi siphon still does some good at ANY non-zero wind speed.
Soil out-gassing of radon is a slow process so it’s the weekly or monthly average performance that matters, not the hourly or even daily draw. In places where passive radon mitigation is now code for new construction it would seem that passive systems should get the siphon-vent treatment either up-front as part of the system, or as an intermediate step before implementing a fan. Retrofit mitigation systems (like my neighbor’s) are also good candidates for keeping the load off-grid whenever/wherever possible, since the upfront costs are very low, and the benefit continues even if the system needs to be on-grid.
Of course, the system MUST be tested (preferably during the lowest wind-speed months)- it’s not a complete no brainer. But it is still worth the trouble, since payback is quick & guaranteed in higher-priced electricity markets, even when it’s not the total solution.
If the wind-powered venting system proves adequate, he will probably recycle the mitigation fan to drive a solar air heating panel (a much better use than as an impediment to air flow in the stack!)