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Guidance for Landlords and Housing Providers
 

Why This Matters
 

Damp and mould are recognised health risks, particularly for vulnerable occupants. In recent years, a range of air treatment technologies have been promoted as solutions to mould problems. One such technology is Active Radiant Catalysis (ARC), developed by GreenTech Environmental.

This guidance explains what ARC technology may assist with, what it cannot do, and how it should (and should not) be used within housing stock.
 

What Is Active Radiant Catalysis (ARC)?
 

ARC is a form of air and surface treatment technology designed to operate continuously within occupied properties.

ARC systems use:

• Ultraviolet (UV) energy

• A multi-metal catalytic surface

• Moisture present in the air

This process produces very low levels of oxidising agents, sometimes referred to as Advanced Oxidation Products (AOPs), which disperse into the space and interact with airborne and surface contaminants.

ARC differs from conventional air filtration systems because it does not rely solely on air passing through a filter.
 

Where ARC May Offer Limited Support
 

1. Reducing Airborne Exposure to Mould Spores
 

Mould spreads via microscopic spores that can become airborne through normal daily activity.

ARC may:

• Reduce the viability of some airborne mould spores

• Lower inhalation exposure in occupied properties

This may be relevant where:

• Mould is present but remediation must be phased

• Immediate access to all affected areas is not possible

• Vulnerable occupants remain in situ
   

ARC does not remove mould from the property.
 

2. Supporting Occupants During Delayed Remediation
 

In housing stock where repairs cannot be completed immediately due to:

• Occupancy constraints

• Legal processes

• Resource limitations
   

ARC may be considered as a temporary risk-reduction measure while permanent solutions are progressed.
 

3. Odour and Indoor Air Quality Improvement
 

ARC may assist in reducing:

• Musty odours associated with damp

• Volatile Organic Compounds (VOCs) from furnishings or building materials
   

This may improve perceived air quality, but does not address the underlying cause of damp or mould.
 

What ARC Does Not Do!
 

ARC Does Not Resolve Damp or Condensation

ARC does not:

• Fix rising or penetrating damp

• Improve insulation

• Remove thermal bridging

• Correct ventilation deficiencies

• Reduce moisture within walls, floors, or ceilings
   

If moisture remains present, mould growth is likely to continue.
 

ARC Does Not Remove Existing Mould Growth
 

ARC cannot:

• Remove mould embedded in plaster, timber, or insulation

• Eliminate mould within building fabric

• Replace professional mould remediation where required
   

Any suggestion that ARC provides a permanent solution to mould is incorrect.
 

ARC Should Not Be Used as a Substitute for Repairs
 

For landlords and housing providers, it is important to understand that ARC:

• Does not discharge statutory repair obligations

• Does not replace maintenance or capital works

• Should not be relied upon to demonstrate compliance
   

Use of ARC without addressing the root cause of damp may expose landlords to:

• Ongoing complaints

• Regulatory scrutiny

• Legal challenge
   

Common Misunderstandings
 

Common Belief Clarification
 

“ARC fixes mould” - It may reduce airborne exposure only

“ARC solves condensation” - Moisture sources remain unchanged

“ARC replaces repairs” - Repairs remain essential

“ARC is a permanent solution” - It is temporary and supportive
 

When ARC Is Unlikely to Be Appropriate
 

ARC is unlikely to be effective where:

• Damp defects remain untreated

• Mould is extensive within building materials

• Ventilation is inadequate

• Units are undersized for the property

• Long-term resolution is required
   

In these cases, priority should be given to identifying and rectifying moisture sources.
 

A Proportionate Approach for Housing Providers
 

Where ARC is considered, it should form part of a broader management strategy, including:

• Proper damp and mould surveys

• Identification of moisture sources

• Planned remedial works

• Ventilation assessment

• Ongoing monitoring
   

ARC may be used only as an interim measure, not a solution.
 

Key Takeaway for Landlords and Housing Associations
 

Active Radiant Catalysis:
 

• ❌ Does not resolve damp or mould defects

• ❌ Does not remove mould from building materials

• ✅ May support short-term exposure reduction

• ✅ May assist in managing risk while repairs are planned
   

Sound building maintenance and moisture control remain essential.
 

Need Independent Advice?
Decisions around damp, mould, and occupant health should be evidence-led and property-specific.
 

An independent damp and mould survey can determine:
 

• Whether air treatment has any practical role

• What remedial works are required

• How risk can be managed proportionately and defensibly