1. Home
  2. Knowledge centre
  3. Radon and Retrofit (PART 2/2)

>PART 1: What is Radon and Why must we take it seriously in regard to retrofit in Ireland?

Managing the Radon risk, a proposal


We are about to embark on a national programme to Retrofit in Ireland a very large percentage of our homes. Research suggests that some of the retrofitting measures could have an impact on radon levels, for better or worse.


A Risk Pathway proposal


I would propose three risk pathways for buildings based on a simple assessment and test before work is agreed (this could be a short-term test, not less than 1 month). And that a full test is carried out at the end.

risk pathway aereco


Pathway A

  • Your house is in a low radon area
  • Test Confirms levels below 100 Bq/m3


  • Retest house after work is done.


Pathway B

  • Test confirms levels of between 100-200 Bq/m3 in any area.
  • Test confirms levels Below 100 Bq/m3 but house in high radon area


  • Confirm airtightness and ventilation performance as part of retrofit assessment.
  • Discuss with designer and contractor impacts of work on the performance of the dwelling and potential radon mitigation strategies as part of the plan.
  • Retest when work is complete


Pathway C

  • Test confirms levels over 200 Bq/m3


  • A mitigation plan and budget should form a central part of any works planned.
  • Confirm airtightness of house and ventilation performance as part of retrofit assessment.
  • Retest when work is complete to confirm a reduction in levels.


Note: Retrofit works can have a negative or positive impact on radon levels, depending on the initial building characteristics and the type of retrofit work carried out. It is therefore important to understand the building from the perspective of radon access pathways and how sealing the ground floor to improve airtightness and improving the ventilation can contribute to creating an overall radon-safe retrofit.

These measures can also contribute to energy savings, so with proper planning, both health and energy saving benefits can be delivered.


Short term vs Longer term tests


Short term tests were raised because the general feeling is that 3 months, plus organising and analysing time (closer to 4 months) was probably too long to get serious uptake of radon testing pre retrofit works.

Of course, where possible, long term tests should be encouraged.

A study by the EPA (A Comparison of One and Three Month Radon Measurements in Ireland, Rochford, Fenton et al) shows that a short-term tests can determine with a reasonable degree of certainty (95%) , that a result below 89 Bq/m3 would be below 200 Bq/m3 with a long-term test. And that a short-term test of above 235Bq/m3 would remain above 200Bq/m3 with a long-term test.


1-month passive test


3-month passive test (with 95% confidence)

<89 Bq/m3 


<200 Bq/m3

89-235 Bq/m3



>235 Bq/m3


>200 Bq/m3


So whether the thresholds of the short term tests are set at 89 or 100 or 200 or 235 Bq/m3 could be determined by others or at a later date with more data. But it further supports at least a safe high/low threshold (Pathway A and C) in my opinion and a requirement for a middle way (Pathway B).

The other thing to consider is that we are fast moving into a digital age. Alpha track detectors are not the only game in town. One could imagine, if the right safeguards where in place, that real time data loggers or even connected devices could be used in the shorter-term assessments and costs further reduced.


Remediation Costs


At present, there is no grant available to assist with the cost of radon remediation, with the exception of the Housing Aid for Older Persons.

Some radon reduction techniques are more expensive than others. Typically, the cost in Ireland to retrofit an active radon sump is about €925 (ranging from €400-€1500). Other options are available, for example, installing a fan to improve ventilation may form part of the retrofit works anyway. These options should be discussed with the designer and contractor for the retrofit.


In Summary

Starting with High Risk (Pathway C), I think it’s straight forward enough. Its high, it should be reduced, and the mitigation of radon should form a central part of the retrofit design. I can’t foresee an argument for engaging in works on a building with a known high radon level and not having a plan to mitigate it. It opens enormous liability otherwise in my opinion. At the other end of the scale I anticipated a number of scenarios where you could consider a building Low Risk (Pathway A). For example, very low radon, in a low radon area. I think that a reference to checking after works is completed is acceptable and perhaps could even be dropped with more evidence later.

Like a lot of risk assessments, it’s not the extremes that are hard to manage. How do we bring appropriate focus to the grey areas? The bit in the middle.

Are we comfortable for example, to see radon at 150 Bq/m3, in a high radon area in a leaky house and say its “safe” and not introduce radon mitigation into the conversation at the very least? Or better understand the starting state of the building as a prerequisite (how leaky is it, how effective is the ventilation)?

The main stay of the actions in Pathway B is that radon is introduced into the retrofit plan, this forces discussion with the stakeholders and an appropriate plan put in place. We know it’s already hard to get people to act on radon. But the liability is significantly reduced for those involved in retrofit (Designers, Contractors, Suppliers, and the state) if it has been discussed and documented.

This is not about saying a house is definitively safe or not at the start. Its more about saying:

  1. You have a low radon reading in a low radon area we suggest you just check again when work is done to be sure nothing changed.
  2. You have some radon, don’t panic, but you should find out a little more about your buildings performance before you start, and have a plan should the radon increase.
  3. You have high levels of radon, any design or planned works should incorporate mitigation.



To Finish

It is not unreasonable to suppose that without pre-retrofit tests for radon, we are already impacting homes with high levels and making it worse. The accusation could already be made that Retrofit here in Ireland is not being properly risk assessed and worst still, mis-sold. Multiply that to 500,000 retrofits over the next 10 years and that is a significant liability to all involved.

Not withstanding the human cost, none of us want the headline “retrofit causes lung cancer”. But that is where we could find ourselves if this is not managed better in my opinion. Just because radon is difficult to assess and the costs of mitigation are real, does not abdicate us from the responsibility of effectively managing the risk. It further highlights that we need a standard for the process of retrofit in Ireland (PAS2035) to manage exactly this kind of situation. And as far as PAS2035 in the UK is concerned I think it urgently needs to address this within its own framework.

At Aereco we will be advocating for this approach. We will be there as always to offer advice to our customers on the performance of their existing system and any changes needed.


Author: Simon Jones

A special thanks to James McGrath from NUIG, Eugene Monahan from All Clear Radon and Jeff Colley from Passive House Plus and many more who have been pestered by me one way or another over the last few months. Needless to say I’m not representing the views of others.


> Dowload this article as a PDF

Post a question

Your email address will not be published. Required fields are marked *