Time for action: Fixing London’s cold, damp and mouldy homes

The facts speak for themselves. London has a widescale problem with cold, damp and mouldy homes.

  • These are harming the physical and mental health of those who live in them.
  • It’s often the most vulnerable people who are affected.
  • A shocking 6% of London homes are blighted by significant condensation.
    • Only 1% of owner-occupied homes are affected.
    • Whereas 6 -8% of housing association, local authority or private rented homes are.
  • And it’s in the homes already at risk that fuel poverty, overcrowding and single-measure retrofits are compounding the problem.

Right now, we’re going to look and see exactly what’s needed to fix things.

Commenting on the London Assembly Environment Committee’s recent report, ‘Keeping Out the Chill: Fixing London's Cold, Damp and Mouldy Homes’, its Chair, Caroline Russell noted:

‘We’ve seen simple strategies which combine effective energy advice with the latest demand-controlled ventilation technology which could be rolled out relatively affordably.’

Let’s make sure they are rolled out.

Here’s a review of the report’s recommendations and the critical role it assigns to adequate ventilation in fixing London’s cold, damp and mouldy homes.


What are these simple strategies?

The strategies proposed for tackling this complex and deep-rooted problem are refreshingly simple.

In the broadest of brush strokes the report recommends:

1. Various initiatives to improve the ventilation of ‘at-risk’ homes.
2. The development of programmes offering energy-efficiency advice to the residents of these homes.



‘Ventilation is critical to prevent damp. Homes need to be better ventilated, especially those which are overcrowded.’

First, a little bit of myth-busting.

Both residents and housing providers need to be clear that ventilation does not let out all the heat.

The vast majority of a home’s heat is stored in solid objects, like its walls and furniture. When ventilation brings cold air into the room, these objects will warm it up.

This means that air heating and ventilation actually use only a sixth of the typical amount of energy to heat a home.

And now a factual observation.

Homes that are insulated, well-ventilated and efficient to heat will remain warm and dry.

Despite numerous efforts to increase retrofitting, many homes in London still fail to meet these conditions. And in many cases inappropriate retrofitting has made matters worse.

The single-minded focus on energy efficiency and heating methods has side-lined considerations of ventilation. The result is well insulated and air-tight buildings that keep warm air inside, but offer it nowhere to go. These conditions become a breeding ground for condensation and mould.

Symptomatic of our approach to ‘improving’ properties is the Decent Homes Standard’s requirements: these focus on adequate insulation and warmth, but remain curiously silent about matters of ventilation and mould prevention.

In practical terms, the report recommends that:

  • Future retrofit programmes must be multi-measure with sufficient focus on ventilation.
  • To meet the need for more multi-measure retrofits we must unlock funding for both social housing and private landlords.
  • New housing and retrofits, especially for social and affordable rent properties, should be designed with ventilation that can cope with any level of occupancy. Our range of MVHR units for new build and various dMEV with high pressure handling and ability to increase to rates above building regulations along with our intermittent ventilation units are ideal for retrofit developments.
  • Ventilation systems must be quiet (to avoid residents turning them off), use minimal power and be moisture-responsive. Our CV2 and CV3 units provide optimal ventilation and moisture control but are also designed with the occupant in mind, including features to minimise nuisance noise.

Energy advice

‘Good quality energy advice can help residents improve condensation and damp in their home.’

Given the impact the residents themselves can have on the success of any ventilation initiative, it is important that residents understand how important these measures are.  

In addition to this, energy efficiency advice can help alleviate the fuel poverty which the report identifies as contributing to damp. For instance, such advice can include information on checking for competitive energy tariffs and explaining eligibility for grants and benefits.

The report notes that many social housing providers do not currently offer any energy advice to their residents, many of whom are fuel poor.  

The report recommends that:

  • Social housing providers should review their energy advice strategies.
  • London should prioritise the training and deployment of energy advisors available to all ‘at risk’ residents, especially those in the private rented sector who at present lack any clear avenue for receiving energy advice.

Comfortable indoor ventilation

At Zehnder we have been offering cost-efficient and energy-efficient solutions to ventilation for many years.

We wholeheartedly echo the report’s recommendations.

And we offer our advice and expertise to those who want to help solve the problem of London’s cold, damp and mouldy homes.

View our comfortable indoor ventilation range, or call us for a chat about how we can help.

Any questions? Please send us a message.

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