A guide to solving condensation issues faced by the social housing sector
More than half a million social homes in England failed to meet basic health and safety standards, as reported by The Independent in the wake of the Grenfell Tower disaster(1).

Sleepless Nights for
Housing Providers

If you’re a social landlord, there’s no question that it is a major challenge to juggle maximising profits, protecting your investment, considering the welfare of your tenants and also cutting down on energy use.

June 2017 was undoubtedly a watershed for the quality of social housing. So, not only does the UK face its biggest housing shortfall on record, even more onus is also on housing providers to improve the quality of existing homes in the UK – 17% of which are social-rented according to the English Housing Survey2.

Interestingly, without energy efficiency, energy costs would now be three times higher than in 1970. And carbon emissions would have doubled. This is all according to Dr Nick Eyre of Oxford University who launched the new Centre for Research into Energy Demand Solutions, Eyre3.

As we endeavour to make our properties more energy efficient by keeping in the heat, we are losing fresh air and ventilation in our homes. If ventilation is of a poor standard anyway, adding condensation and moisture into the mix can lead to mould and damp problems which will affect the health of your tenants – and also the value of the property.

While this guide doesn’t promise to solve the plethora of issues facing social landlords, it does help to educate around the escalating issue of condensation in social housing, while providing solid and realistic guidance on improving ventilation, indoor air quality and energy efficiency.

Paul Harrington, Head of Residential Sales

Common Condensation Problems in the Home

Drying clothes
9 pints

Boiling a kettle and cooking
6 pints

Bath or show
2 pints

Washing machine
1 pint

Bottled gas or paraffin heater
3 pints

Total moisture produced in your home in one day
21 pints

What is Condensation Season and why does it occur?

Condensation season is what it says on the tin – a period of the year, in the colder autumn and winter months, when homes become affected by fogged glass and water droplets on cold wall surfaces.

Most people will have experienced condensation in the home from daily activities such as cooking, bathing, showering, and drying clothes. In fact, virtually all dwellings have some level of condensation. However, this is a major issue in social housing – the English Housing Survey4 states around 8% of houses had issues with condensation in 2016 (combined data for local authority and housing associations). This is predominantly due to tenants on low incomes not being able to afford to switch on their heating. It has been a growing issue for a number of years and one the ventilation industry has been working hard to eliminate.


The Science

Condensation is the change of water from its gaseous form (water vapor) into liquid water. It generally occurs in the atmosphere when warm air rises, cools and loses its capacity to hold water vapor. As a result, excess water vapor condenses to form cloud droplets. It is most common in winter as the external air temperature is low which causes external walls and windows to become cold. Household activities – as outlined in the diagram – create water-filled air and, when it comes into contact with these surfaces, it condenses. In poorly ventilated rooms, this causes a type of mould which can causes serious health issues as well as having damaging effects on the building.

A Common Misdiagnosis

It is vitally important that we highlight the difference between condensation and damp. It is worryingly common for unqualified surveyors to misdiagnose condensation as damp. This can result in unnecessary rising damp treatments which result in removing good plaster, disturbing the property’s interior and ultimately costing thousands of pounds.

The True Cost

If you fail to adhere to legal housing standards, it may result in the property no longer being able to let. Not only this, if your tenants are affected by mould and damp, they could claim against you. This could have consequences on income from rent and the value of property.

There are 3.9 million social homes in England and Wales5 and with people spending up to 90% of their lives indoors and 60% of that time at home6, it is no wonder the National Institute for Health and Care Excellence is placing more emphasis on guidance for indoor air quality. Health issues that can be caused by condensation include:

  • Exacerbation of asthma
  • Sinus problems
  • Skin rashes including eczema
  • Bronchitis

What type of ventilation system is currently being installed?

Positive Input Ventilation (PIV) has been the go-to method of ventilation for social housing providers for many years due its ability to provide fresh filtered air into homes. These systems help to prevent mould growth and condensation dampness as well as improving indoor air quality, and are particularly popular amongst social housing providers due to their low upfront cost and minimal energy usage.

Originally developed in the 1970s, PIV systems work by supplying fresh air to a dwelling via a small fan. The fan takes in external air and then distributes this within a building in order to prevent and cure condensation dampness related problems in homes, of which it has been successful for decades. PIV units are also used to control other indoor air pollutants and have even proven to be an effective means for reducing Radon gas in some properties.

Although successful, ventilation in social housing and PIV technology has remained largely unchanged for years despite significant changes to the structure of the UK’s housing stock and its usage. With a big focus on energy efficiency, homes are becoming more air-tight with better insulation. While this helps to retain heat in a property, it can also lead to more moisture being harboured within a dwelling, making condensation more of an issue. What’s more, social housing providers need to focus on improving air quality as much as introducing energy efficiency measures, which is where more advanced ventilation technologies can play an integral role.

Traditional PIV Units - A Temperature Catch-22

Condensation Control Fans

Despite PIV being deemed an effective method of managing condensation, its benefits can be overshadowed by running costs associated with warming cold air entering the property.

In order to tackle the issue of cold air being delivered into homes during winter months, many PIV systems now feature an electric heater designed to increase the incoming air temperature to approximately 10°C. While this helps to maintain tenant comfort, the cost of using the heater can be a problem in itself.

PIV System

Some PIV heaters can consume as much as 500 watts which equates to £1 a day to run. In comparison to an average heating system, it is arguably far more cost effective to use a property’s boiler more during colder periods to improve comfort.

With both energy prices and the use of smart meters on the rise, an innovation that was originally intended to increase tenant acceptability could now be responsible for hindering it. What’s more, with fuel poverty a major concern across the UK, ensuring ventilation systems in social housing are energy efficient and cost effective is crucial. According to the National Infrastructure Commission’s ‘National Infrastructure Assessment’ (NIA report), upgrading the energy efficiency of social housing is a priority and will help the government meet its fuel poverty and carbon targets7.


Elta Fans’ SANO Intelligent PIV with Eco-LoFlo works by drawing in external air which is then passed through a filter before entering the home. If loft-mounted, the air increases in temperature before passing through the filter, utilising otherwise unused energy in the loft from solar gain or heat loss in the home. This increase is typically 3°C warmer than outside air during heating season, allowing significant energy gain and placing less strain on the unit’s motor. The tempered, filtered air is then supplied centrally to the home via the unit’s outlet duct and ceiling diffuser.

Modulating Technology

Featuring modulating technology, airflow can be automatically adjusted according to the temperature and moisture content of the incoming air. This ensures optimum air flow and provides the most efficient ventilation rates for the conditions, reducing running costs. Integral controls allow the unit to be set to suit the individual requirements of the home, and heat recovery can automatically be used when temperature allows.

An Intelligent Solution

Sano IPIV Loft
ECO-LoFlo Technology

Sano IPIV Loft

Intelligent Loft Mounted Positive Input Ventilation Unit

Sano IPIV Loft H
Integral Multicore Heater

Sano IPIV Loft H

Intelligent Loft Mounted Positive Input Ventilation Unit

Sano IPIV Wall
ECO-LoFlo Technology

Sano IPIV Wall

Intelligent Wall Mounted Positive Input Ventilation Unit

Sano IPIV Wall H
Integral Multicore Heater

Sano IPIV Wall H

Intelligent Wall Mounted Positive Input Ventilation Unit

More Condensation Solutions

With significant health and financial costs at play, now is the time to tackle condensation.

Conclusion: Upgrade Ventilation to Tackle Condensation Issues in Social Housing

There’s no denying that there has been significant strain placed on the social housing sector to improve the safety, efficiency and comfort of its properties across the UK. However, despite the larger challenges faced by the sector, solving condensation issues in these properties could be a simple and effective way of improving air quality and comfort for social tenants, while ultimately limiting damage to buildings themselves.

Get your copy of our guide to combatting condensation


  3. Energy in Buildings & Industry magazine Oct 2018 issue